Lecture 1 - Introduction to Human Anatomy

追加: 2026-05-14

[00:00:02]hi everyone welcome to uh your first module here this week we're going to be looking at chapter one where i'm going to be introducing you to lots of the terminology that's going to follow you throughout both this semester and next semester we're going to start off looking at how the body overall is organized looking at the least complex structures all the way up to what sort of the building blocks that put us together as organisms then we're going to take a look at the 11 different organ systems specifically looking at their names the organs that make them up and then their general functions then we're going to take a look at quite a bit of terminology that's uh important that at this point that we really try to um you know create those glossaries create those flash cards and get this terminology mastered okay then we're going to move into looking at the body regions and the anatomical planes and then we're going to finish our time together looking at how our body works together to maintain balance and equilibrium and that is known as homeostasis so anatomy versus physiology well this is this course is titled human anatomy although we will take a look at some of the physiology of different organ systems but by definition anatomy is looking at the structures found within the human body uh and then how those structures are related to one another okay whereas with physiology physiology is looking at how those structures are functioning okay so when we get to our cardiovascular for example next year we're definitely going to be looking at both the structure of the cardiovascular system as well as how it functions okay in biology primarily next semester we'll take a look at some of the physiology of different organ systems so it'll be kind of split between the two courses but our main focus here is going to be looking at the structures and then building upon that to look at the functions now the human body is organized in such a way that if you picture it sort of as the smallest building blocks the atoms these are like the lego pieces and then if you take those lego pieces and you start to put them together you can build some larger structures those are the molecules you're looking from atoms to molecules you're going to spend a lot of your time in chemistry looking at this level this is the chemical level of organization all right now if you take certain molecules put them together you can form larger molecules known as macro molecules okay macro by definition is large okay so macromolecules larger molecules the four main organic macromolecules that make up the human body are carbohydrates lipids proteins and nucleic acids all right we're gonna learn a lot about those in weeks two and week three of biology now if you take those macromolecules and you put them together in a specific way we then have our cells okay this is the next level of complexity now most of you probably have at least seen that picture of the animal cell with the you know double layered membrane the nucleus the mitochondria all the organelles inside that's your basic animal cell and what we're going to learn in this course and see is that our cells are actually specialized within the body okay and those specialized cells then group together to form tissues and next week we're going to jump into looking at tissues here in anatomy and you're going to see that we have four main types of tissues we have epithelial tissue muscular tissue connective tissue and nervous tissue now if you take those four specialized tissue types put them together you create your organs that's something that's unique about all the organs in our body is that for the most part all organs are made up of those four different tissue types in different ways but still every organ contains those tissues all right so this here is just an example of our stomach so that would be an organ that we find in the digestive system all right so if you take a group of organs that have a similar function work together those organs are grouped into what's known as an organ system and then within an organism we have 11 different organ systems that are actively working to create the very complex you and me the organism so what you need to take away from this you need to be able to understand from the most basic level here at the atomic and molecular level okay this is all chemical all the way up to the highest most complex which is the organism all right and i have a pyramid on the next slide on slide seven that's going to further illustrate this for you okay and then you need to just be able to provide a specific example of each level so looking here that basic level of organization this is the least complex okay but also if you think about it you have the most the highest number of atoms and molecules compared to the only one organism that they all make up okay so that's what this pyramid is sort of showing you at the bottom of the pyramid to the top of the pyramid you're seeing complexity increase okay whereas the base of the pyramid here at the least complex is so wide because the the number of atoms and molecules that make you up are so large so the chemical level here we're looking at atoms that are formed into molecules and how those molecules are put together to make those four major organic macromolecules in the body then if you take those macromolecules put them together we have our cellular level of organization and then you take specialized cells put them together and that gives you our tissue level of organization the four specialized tissues muscular epithelial connective and nervous put those together and you create your organs and then those organs that have a specialized function are all grouped together into organ systems and those 11 organ systems work to help the organism to function all right so when we talk about organizational hierarchy in the human body this is what i'm talking about okay how the least complex structures act as the building blocks to build more complex structures that build more and more and more complex structures ultimately to build the most complex organism and everything that we've just talked about listed here in these next few slides one definition here that is very important is that you're going to hear this again from me in biology cells they are the basic structural and functional units of an organism okay so we're looking at the cellular level here we talk about cells those are the basic structural functional units of an organism all right so i created this chart and i i posted it as a worksheet if you go to the online learning modules for the resources under online new modules for this week you'll see that there this is just a really good way to organize the next 11 slides okay they're all full of information and what i want you to take away from that you can put all on this one chart all right i want you to be able to identify the names of the 11 organ systems that's first okay then i want you to be able to identify at least maybe two three major organs that you would find in each of those organ systems all right and then finally you need to understand the general functions of each of them okay now some of them have a list of five okay but there's going to be a couple functions that are going to be sort of those key main functions and that's essential for you to know at this point okay i should mention all of these organ systems we're gonna spend at least an entire week you know skeletal's coming up in week four and five we're going to spend two weeks just on that one organ system muscular two weeks nervous two weeks okay so you're going to know a lot more detail than what you're going to be able to come up with here from just this first lecture but this is just the starting point right this is just to get your feet wet and get you familiar with what we're going to be looking at from here until the end of the course so starting off here looking at the integumentary system the integumentary system contains one of our largest organs in the body and that is our skin all right and now think what is associated with the skin okay we'll take a look down uh just look at your arm okay arm hair you have your nails and then also sweat and oil glands okay just some other examples some of the functions of the integumentary system first off helping to regulate body temperature so let's think about this quickly when you get cold what does your body start to do you start to shiver the whole goal there is that the muscle contractions are going to start to create heat and that's going to help to bring up your temperature now what happens when you get hot we're building up heat in the body our body wants to maintain homeostasis and so you're going to start to sweat and that sweating takes place through the integumentary system and so the integumentary system is key at being able to help in the regulation of body temperature okay we're going to talk about this a lot throughout the rest of the course but we'll also feed back to this when we look at homeostasis at the end of the lecture another element here is protection so protection from the sun we have melanin within our skin and that melanin acts to protect us from uv rays there's also a physical barrier right the you know we don't just fall apart here the skin's actually holding us together so there's that element to it as well helping to make vitamin d this is also something we'll talk about more in week three but the uv rays when they interact with your skin uv rays from the sun when they're interacting with your skin they um there's a chemical reaction that goes on between them and the cholesterol in your skin and it forms an inactive or precursor to vitamin d which then eventually becomes metabolized as active vitamin d in your body and then last but not least the ability for detecting different sensations okay if somebody brushes up against you you can feel that you can feel a breeze or you can feel pressure sharpness stall you can feel vibration okay all those different sensations it's our integumentary system specifically our skin and the receptors in our skin that are detecting those the skeletal system we're going to spend some time on and i'm excited we'll get to use some 3d modeling tech to be able to visualize the the skeletal system in quite a bit more detail than just looking at static images um skeletal system is made up of all the bones that make up the skeleton all right and then anytime you have a bone articulating with another bone okay let's just say we're taking the radius here articulating with the humerus that forms a joint okay and at those joints you're going to have cartilage at the ends of both of those bones because bones when they're rubbing against each other they do not bone against bone essentially it just becomes very angry and it starts to grow gnarly outgrowths that's what happens in osteoarthritis for example so we have articular cartilage at the ends of these long bones to be able to reduce friction against those bones as those joints are moving okay so the skeletal system also besides just acting as basic structural support for a body also acts to protect if you look at the way our skeletal system set up we have bone that surrounds some key organs in our body first off we have our skull specifically the cranial part of the skull which houses our brain so we literally have a helmet that's surrounding this very pliable um organ made of nervous tissue and then further down then the brain descends into the spinal cord the spinal cord moves through and passes through all the bony vertebrae that make up our spine okay so there's another example of bony protection and then as well the rib cage rib cages surrounding our lungs as well as our heart and all those key key organs within our body so the skeletal system is acting not only as support but protection as well skeletal muscles need to attach from bone to bone all skeletal muscles are going to cause some sort of movement so the bones are acting as a result of the muscles uh contracting also this is something we're going to get into a lot more later but this is a term to remember hematocoesis see if i can do this here annotate okay hematopoiesis all right this is the process of blood cell production all right so within our bones we have red bone marrow at the ends of our long bones and the red bone marrow is key in producing blood not only red blood cells but all blood cells and then last but not least the ability to store minerals and lipids so lipids are fats in the shafts of all the long bones we have yellow bone marrow and that's where we store up that fat and then also our skeletal system stores up about 99 of all of the calcium in our body so it's a huge calcium reservoir all right now moving on to the muscular system uh muscular system will find three different types of muscle tissue that make up the muscles in our body so not only does the muscular system cover skeletal muscle tissue but also smooth and cardiac muscle tissue okay so now skeletal muscle tissue when you think about the muscular system that's probably what you're thinking of first and foremost it's all the skeletal muscle okay by definition skeletal muscle attaches from bone to bone okay now cardiac muscle you only find in the heart and then smooth muscle you'll find everywhere else in the body where something is moving or some sort of function is going on but there is no control on your part okay so both smooth and cardiac are involuntary whereas skeletal muscle is voluntary so the functions of the muscular system produce movement that's an obvious one maintain posture so even just when you're sitting there i don't know how you're actually listening to this lecture right now whether you're laying in bed or whatnot but maintaining posture being able to just sit in an upright position and hold your head up there's there's tonicity that is active within our skeletal muscular system without us even being aware of that to maintain posture and then lastly produce heat right we talked about regulating uh body temperature so when you get cold and it's gonna happen soon enough we're gonna end up going outside without those parkas on and you start shivering as a result of your body temperature dropping and so your body kicks in that automatic mechanism the contractions start happening shivering starts happening to produce the heat okay and the nervous system is where we're going to end this half of the course we're going to be taking a look at the brain the spinal cord and then all of the peripheral nerves that extend from both the brain and the spinal cord which are the peripheral nerves in the body uh in the nervous system think of this as like the plug that gets everything going right you have an extension cord you're gonna go from the outlet to whatever you need to to get electricity to to help it to work that's how your nervous system is working sending signals throughout the body receiving signals that are input and then sending out signals to make something happen um and the endocrine system this is going to be a new addition to our curriculum this year this will actually be the last uh topic that we talk about we're going to look at the specific glands in the body that form the endocrine system okay and so key term here endo refers to within okay so the endocrine system is made up of a series of glands that are scattered throughout the body that are responsible for producing hormones and where does it secrete those hormones within the body into our bloodstream okay so that's a key element there the endocrine system is responsible for hormone production and it secretes those hormones into our bloodstream okay so looking at it from a different perspective exocrine glands those are ones that are secreting to the external environment exo being outside of okay so your sweat glands would be an example of say an exocrine gland whereas your endocrine system is made up of endocrine glands that are also creating hormones into the blood and now the endocrine system and nervous system are kind of similar in that they're trying to communicate a message that's the whole point of a hormone the hormone's supposed to go somewhere to tell the body to do something all right whereas the nervous system is really going to be instantaneous right it's getting that electrical signal there because you need to do that you have a spider on your leg and you need to swat it off that one almost knocked that over that's going to happen really instantaneously okay whereas with the endocrine system usually hormonal regulation of any kind of response is something that's supposed to be more sustained or longer term not needing as much of an immediate response we'll move into the cardiovascular system we're going to look at the heart all of the blood vessels associated and attached to the heart and we'll be taking a look at uh blood as well now a lot of functions here the cardiovascular system number one the heart acts as the main pump okay so the heart is driving and propelling all the blood uh away from the heart and then once it drains back through the veins which are colored here in blue it then is responsible for pumping that blood out to the lungs to get oxygen sends it back to the heart and then sends that oxygenated blood out to the rest of the body okay so because our body needs oxygen and it needs to get rid of carbon dioxide so the cardiovascular system is working to be able to transport that oxygen to our tissues to all the cells in the body and then to take the co2 the carbon dioxide and get that back to the lungs so we can breathe it out now there's we're also going to take a look at once we get into looking at the urinary system and how we're able to regulate the acidity of our blood through secretion of protons and we'll get to that more later on next semester and then also our white blood cells which are our immune cells they circulate throughout our blood as well to be able to get to specific sites of infection and be able to help to ward off or fight any kind of infectious diseases so the respiratory system respiratory system is made up of the lungs as the primary organ and then all of the passageways so here it's we've just shown you pharynx and larynx once you get to the respiratory system we're going to talk about the entire passages you breathe air in either through your nose or or through your oral cavity passes through that pharynx into the larynx trachea bronchi bronchioles okay you don't need to know all of those structures at this point just understand that there's the lungs and then there's all of the tubular system that connects the external environment into your lungs all right and the whole purpose here we need to get oxygen from outside in and then we need to get carbon dioxide that we've produced from cellular respiration we need to get that out of our bodies all right so the respiratory system is is working dual fold there the digestive system composed of the organs of the gi tract so gi stands for gastrointestinal starting up here you ingest food through the oral cavity through your mouth and as you swallow it moves into the pharynx which that's an anatomical term for your throat and then from the pharynx directly into the esophagus the esophagus is that tube that's connecting the pharynx your throat down to your stomach so the food moves into the stomach and from there it goes through the small intestines you can see those visualized here centrally and then from the small intestine into the large intestine which then wraps itself around here and you can trace this on yourself from the lower right quadrant here of your abdominal region it comes upwards towards your ribs and then goes across transversely comes back down the left-hand side and then passes out through the rectum and then the anus and now relatively obvious but the whole purpose of the digestive system is to physically and chemically break down food so there's a difference here with physical breakdown of food we're looking at okay our teeth are going to be mashing it up um our muscles in the stomach are going to be churning and that's going to cause food to to break down mechanically so think about with mechanical or physical breakdown of food you're literally smashing it up into smaller pieces with chemical breakdown of food we have specific enzymes that are going to break the bonds of those food particles down into smaller macromolecules so that we can then absorb those as nutrients into the body all right and then anything that's left over is passed out through secretionis or excretion sorry as solid waste the urinary system composed of the kidneys the kidneys are where the urine is produced they connect to the ureters which are the tubes that run from the kidney to the urinary bladder and then the urine is stored in the urinary bladder and then it passes out to the external environment through the urethra okay so there's a difference here ureter and urethra all right so ureters connect kidney to the bladder and then urethra connects the bladder to the external environment and second to last i believe yeah lymphatics last uh is the reproductive system when we get there we're going to be taking a look at the essential reproductive organs which are the gonads and the reason that they're listed as essential is because they are responsible for producing um the gametes which are the sex cells so in a male the testes are the gonads and they are responsible for producing the spermatozoa sperm and in females the ovaries are the gonads and they are responsible for producing the oocyte which is the egg cell right now for those um both of those sex cells to be able to go from the gonads where they're produced um they need to pass through a series of associated structures mainly tubular structures tubular passageways um through the body so the female those tubular structures are the fallopian tube which connects the ovary directly to the uterus and in the males the sperm are then stored from the teste in the epididymis and then they pass through the ductus or vas deferens and then pass out through the penis and then finally with the lymphatic system you see here in brackets immune okay well this is because there's a huge connection between the lymphatic system and our immune cells okay the lymphatic system essentially gives a passageway throughout the body you can see here all of the the network like connections here of the lymphatic vessels each lymphatic vessel has lymph floating through it it's circulating through it and that lymph is the fluid-like substance that contains all of our immune cells and so as that lymph is then drained from the periphery back towards and ultimately into the cardiovascular system in the heart those lymphatic vessels pass through lymph nodes where the flow is slowed down so that the immune cells have a chance to fight any kinds of invaders that are there that shouldn't be there any pathogens but ultimately the lymphatic system is this this network throughout the body whereby if any kind of infection bacterial gets into the body then our immune cells have a way of being able to circulate through and be able to attack these foreign pathogens and protect us some other structures that are part of lymphatic system lymphatic vessels we just mentioned the spleen thymus as well as lymph nodes we've talked about and then tonsils so the tonsils are acting as immune support here protecting you from the external environment so really anywhere that you have exposure to the external environment you're going to have some sort of lymphatic tissue that's going to provide you with that immune support um specifically in the gi tract we have what are known as pyres patches and they're lymphatic nodules that exist within our small intestine to be able to protect us from foreign pathogens as well all right so from all of those slides and all of that information what i want you to be able to do is to go back to that initial chart okay first off write down the names of the organ systems okay that's the easy part that's the fun part okay and then from there come back and go through each slide and then come up with the main sort of like you know three this one has a number of them but i would say for example here with the lymphatic system you've got your lymphatic vessels your lymph nodes and your lymph those are sort of the main key players here also with the spleen i would add those four probably lymph lymphatic vessels spleen and lymph nodes okay and then go through the rest of them and you can do the same thing as you pass through the rest of the systems okay so during our tutorial time together and even in the weeks that follow if you have any questions about you know is this enough detail too much detail whatever bring all your questions with you and we'll have plenty of time to be able to uh to address all of those questions as they come up so moving forward we're going to be taking a look now at a series of anatomical terms and i have included i'm going to flip forward here i've included these two diagrams and what i want you to do is to print off as many i say at least two copies but i would just say print off a number of them that way that you can practice okay you can use these as just sort of start from blank and the first thing you're going to do fill it out using your notes all right and then study that and then come back to your next copy and then start to practice start to just fill it out from memory and each time you do that you're going to just be reinforcing all of these terms and it's one it's a really good way repetition i can't enforce this enough repetition is the key to success in anatomy so let's work through these anatomical terms here together okay so first off you take a look at this individual here okay she is in anatomical position that means she is looking at you okay so you're looking at the anterior surface which is the front of her body her palms are facing you that's important and her toes are facing you as well okay so three key elements there now if something somebody is in anatomical position they are looking at you you can see their eyes their palms are facing you and their toes are facing you now other terminology and this matters in terms of orienting yourself to an individual and knowing you know side of the body and and whatnot where you would expect to find specific organs and all of that are these two terms here prone versus supine now these are terms used to describe an individual in a horizontal position so for example say you are a nurse and you're going into a room to visit your patient they are going to be in that bed in a supine position okay so supine meaning that they are laying on their back and they are uh looking up right so one way i usually say to to remember this is supine starts with s u so think sunny side up now prone prone's the opposite so think that uh picture now you're a nurse uh in an operating room and uh the individual is having surgery on their their back okay so here in this case they're gonna be laying in the prone position okay so their face is going to be down for those of us who are stomach sleepers we sleep in the prone position for those of us who are back sleepers we sleep in the supine position and for those of us who are side sleepers we sleep in the lateral recumbent but that doesn't matter right now okay so prone face down supine face up an anatomical position is really important because you need to unless i am telling you otherwise in any questions on an exam have you always assume anatomical position i'm going to show you why this matters so take for example looking at the five digits of the hand so the thumb is number one give yourself a thumbs up okay so thumb is number one and then you count towards the fifth digit which is the pinky okay so thumb is number one then you've got two three four five so we can all agree in anatomical position the fifth digit is closer to the body than the first digit yes now say she was to all of a sudden turn her hands so that they were facing so uh posteriorly so towards the back of her body so you can all do this stand in anatomical position and now rotate your hands so they're facing backwards so the palms are facing backwards well now your thumbs are going to be closer to the midline well that that's a big deal in anatomy okay because you need to be able to uh you might need to tell me in anatomical position or from a posterior perspective which is more medial or which is more lateral which is closer to the midline which is further if i ask you which of these digits is closest to the midline in anatomical position you know right away number five okay which is most lateral or furthest away from the midline number one all right so that's where anatomical position comes into play so we're going to take a look at the basic major regions of the body we have the cephalic region which encompasses the head the cervical region is the neck the trunk which spans from the thoracic through the abdominal pelvic region and then we have the extremities so we have the upper extremities or the upper limb and then we have the lower extremity or the lower limb so within the cephalic region we can further subdivide that so the cranial region is um this portion here that surrounds the brain essentially so the cranium is that main part of your skull that you find the brain housed in now the anterior portion is the facial region okay and then here above the eyebrows on the forehead that's the frontal region and once you get to skeletal terminology when we're learning the names of the different bones there's cranial bones that make up the cranium and then there's facial bones that make up the face all right and one of those cranial bones is the frontal bone because it's located right here on the forehead now moving down into the face we have the nasal region which is uh the nose and the oral for the mouth and then as i mentioned before moving through the cervical region we're going to look at specific numbers of vertebrae once we get to there in the skeletal system but for now cervical refers to the neck so now with the regions of the trunk and we further subdivided as i mentioned in the thoracic region and the thoracic region is bound by the twelve thoracic vertebrae and each of them have the ribs attached so if you're trying to think well where's the thoracic region it's essentially wherever you have your ribs that's your thoracic region and then one key landmark here within the thoracic region is the sternal region okay which is named after the sternum which is your breast bone mammary refers to the breast and then moving down into the abdominal region because your abdomen is known as the abdominal region you have the umbilical region named for the umbilicus which is the belly button and moving inferior to the abdominal region we have the pelvic region now abdominal pelvic refers to this whole region together okay so sometimes it's referred to just the abdominal region sometimes just the pelvic and then other times we can refer to this whole region as the abdominal pelvic region and then lastly the inguinal region is between the thigh and the pelvic region here okay forming the groin all right so now let's move into the upper limb a number of structures here when you know these names of these different regions especially up here in the auxiliary and brachial this is going to be used when we get to cardiovascular to name different arteries because they're named based on the region that they're in okay so first off here the armpit known as the axilla this is the axillary region moving down the brachial region or the brachium that's the arm and then past the elbow and then have the forearm which is the antibrachial region and a way to remember this is anti-anterior in front of okay so anti-brachial refers to the region that's in front of the arm in front of the brachial region and then coming down here to the wrist the carpal region and the hand is the manual region and the thumb be the pollux now anteriorly looking at the lower limb the gluteal region we're going to take a look at on the next slide in the posterior from the posterior perspective but here in anatomical position you have the femoral region which is the thigh and then right here at the knee joint you have your patella that sits over top your kneecap so that's the patellar region and then moving down we have the foot which is the pedal region and then that's broken down into the ankle which is the tarsals and then the toes phalangeal okay now the phalanges are the bones that make up the toes and phalanges are also the bones that make up the fingers so the reason we just included it here was so there was no confusion at this point okay so phalangeal region just think of toes at this point all right and then from a posterior perspective in the cephalic region so i would make this connection in the cephalic region at the base of the skull we have the occipital bone and so that's why this is known as the occipital region moving down into the thoracic region we have the shoulder blade and that's the scapular region all the way down through the cervical and thoracic down into even the abdominal because the lumbar vertebrae exists there um this would be the spinal column so that's the vertebral region and then as i mentioned the gluteal region the buttocks and then down the posterior aspect of the thigh remember that's the femoral region we have this portion of the posterior part of the knee okay so remember the anterior part was the patellar region and the posterior part of the knee is the popliteal region okay so a number of terms i think you're probably already noticing okay it's this lecture is heavy this chapter is heavy on terminology so one of my best pieces of advice start to create a glossary any term that is not naturally intuitive to you something that you don't hear and think okay i know that put that in this glossary and start now and start creating a glossary list of terms and add to it lecture after lecture and as you go through you start to review each lecture as they go by and you're going to start to just become more familiar the more times that you can see it you can read it you can write it the easier that this is just going to be put to memory okay i know it seems like a lot at the beginning but as you work through this material it'll really just start to become part of your own language all right so as i mentioned before print a number of copies of these so that you can practice with them practice labeling because that's going to be a key component of your evaluations all right so i've kind of used some of these directional terms already so we've and some of them are more intuitive than others so um we're just going to work through these now and then during the tutorial we can we can slow it down and i can answer any of your questions about them okay so first directional term superior versus inferior so superior something is above versus inferior something is below okay so for example here let's take a look the lungs are superior to the stomach okay the intestines are inferior to the stomach all right so superior up towards inferior below anterior versus posterior so anterior you're looking at front of okay whereas posterior behind um superficial being further towards the outside of the body and then deep being deeper within okay so that's one example there those ones are are quite a bit more intuitive than some of the others medial versus lateral medial being closer to the midline versus lateral being further away from the midline so if you look here um let's see what's an example here the stomach would be medial to the elbow it's not a great example uh we could even talk about here let's go to let's just go to the skeletal system uh your sternum is medial to the humerus right so the humerus being the bone here that makes up the arm the sternum would be medial so closer to the midline compared to the humerus and then we can flip that around the humerus is lateral to the sternum you see how that works so when you're referring so the sternum is closer to the midlines look medial to the humerus or the humerus is lateral further away from the midline compared to the sternum all right uh ipsilateral versus contralateral ipsa refers to same side so ipsilateral you could be talking about the second second and third digits on the ipsilateral arm or you could be talking about the first digits on the contralateral side which means opposite side of okay so ipsilateral referring to same side so you could let's use another example here the elbow and the wrist the ipsilateral side versus the contralateral wrist compared to the right elbow okay so ipsilateral referring to same side contra referring to uh opposite side and then the last terms here proximal versus distal so proximal refers to closest to the trunk whereas distal means further away from the trunk so these terms are used and write this down okay proximal and distal are used specifically when talking about relations um of structures in the upper extremity and the lower extremity okay so here's an example the wrist is distal to the shoulder okay so the wrist is distal meaning wrist is further away from the shoulder the shoulder is proximal to the elbow it's proximal to the wrist it's proximal it's proximal everything else past it okay because it's closer to the trunk of the body all right you can apply the same terminology then to the lower extremity but remember that proximal versus distal those all apply to the extremities okay upper and lower all right and so all of those definitions there are listed for you ones that i included were ipsilateral contralateral okay so just make sure you have those definitions down and we're going to move on now to looking at body planes specifically here you can see the planes that are dividing the anatomy there are three main planes on different axes okay and they divide the body into different sections now one place that we see this applied is in medical radiation technology right if you're looking at mri slices or if you're looking at ct slices they're all taken at a specific orientation okay so this terminology the different planes that we're looking at they help us to know how the body's been divided and therefore what kind of a section we're looking at when looking at anatomy okay and so here's all the definitions of all of the different body planes um so we're going to just take a look here at the images as i talk through those okay so the first two here looking at the sagittal plane so first off we have the mid-sagittal okay the mid sagittal plane runs right through the center of the body running from an anterior to posterior perspective okay and it's cutting the body into equal left and right portions okay so you see here the mid-sagittal plane runs right through and is cutting the body into equal left and right portions now anywhere out from that mid-sagittal plane any other slice that you were to take from that midpoint would be known as a parasagital slice okay so those this is an example of the parasagital plane okay so it's taken off center it's a way to think of it all right but still dividing the body into left and right portions but they're not equal and they're not mirror images of each other right okay so here you have the mid-sagittal plane is going to be dividing the body into equal left and right portions whereas the parasagital plane divides the body into left and right portions but the key here is they're not equal in parasagittal okay mid-sagittal straight down the middle equal left and right portions now taking a look at the next plane here this is the frontal plane and the frontal plane here you can see is cutting essentially think of the frontal plane is cutting the face off okay so it's running down through the body and it's dividing the body into anterior which you can see here and posterior portions behind the plane okay and that's located here in the definition so the frontal plane also known as the coronal plane divides the body into anterior and posterior portions the transverse plane also known as cross section and you've probably heard that term many times before the transverse plane um runs perpendicular to the long axis of the body okay and this is key if you were to raise your arm right now and i'm going to do this with you in tutorial so you can get a good visual of this if you raise the arm that's out of anatomical position if you're still cutting straight through the arm in this fashion that's part of the transverse plane okay so it's important that you're always going back to anatomical position when you're thinking how was this cut made okay because these cuts are always going to be made in anatomical position so the transverse plane also known as a cross section cuts essentially cross-sections through the longitudinal axis of the body and then lastly the oblique plane this is a plane that divides the body or any organ at an angle now oblique planes are important in radiology for example because to visualize specific structures within the vertebral column of the neck you need to turn the patient 45 degree on a 45 degree angle so that those x-rays can penetrate the tissue at that angle to visualize those structures so an oblique plane would be one that's just running at an angle to the organism in whichever direction this would be okay you can see an example of it down there there's the leak okay so now now we've taken this individual okay so we're going to look at the brain now so the brain here we're looking from a lateral perspective which means the person is turned to their side so this is not an anatomical position what's one way you can figure that out well the anterior is the front posterior is the back so anterior to the left posterior to the right you know you're looking at this from the side from a lateral position okay so here the planes have just been sort of turned at that 90 degree angle so now we're seeing the frontal plane from the side and we're seeing the midsagittal face on all right so some practice here that we can run through here again we're looking at the brain pretty much in a lateral position this would be the anterior surface of the brain and this would be the posterior surface of the brain okay superior inferior so if we have a plane that's running directly at a 90 degree angle to the longitudinal axis of the body that's going to be your pause for dramatic effect your cross section okay that's your transverse plane and then coming down here this one cutting the face off right dividing the brain into anterior versus posterior portion so that would be your frontal plane and then lastly here dividing the brain in half that is the mid sagittal plane you know it's mid-sagittal because you can see it's going right down the middle of the brain there through the longitudinal axis any other deviation from that left or right that's going to be parasol all right and again frontal mid sagittal plane transverse plane all right so through what plane was this cut made so are you able to visualize any structures it's difficult at this point in the curriculum because we haven't looked at too much but here's something that you can see you see the ears right okay so if you're seeing both ears you know that maybe you're looking at this person from this looks like an interior perspective okay and this is an example here of a frontal plane slice that's been taken okay so what i mentioned before cuts the face off so this was a frontal slice that was taken at some point through it looks like just in front of the ears so you can visualize here you can see the cranium deep to the skin you can see the brain you can see also in here you've got the tongue part of the mouth as well as part of the nasal cavity there okay so lots of structures that you can kind of figure out as you go but there that's an example of a frontal plane slice okay so moving on to the body cavities so we've just taken a look at how we can divide the body using different planes and being able to orient ourselves and now we're going to take a look at the cavities that store all of the major organs in the body okay so first off you can see here all of them are labeled but they're all color coded too and that helps us out a little bit we have two main divisions of body cavities we have the dorsal cavities and the ventral cavities okay so the dorsal cavities those are the cranial and vertebral okay it's not as obvious with cranial because the cranium is sort of just sitting on top encompassing the entire skull there but once you get into the vertebral you can see yes the vertebral cavity then runs dorsally and because they're interconnected refer to them both as dorsal cavities all right so the cranium our cranial cavity houses the brain and the vertebral cavity houses the spinal cord so then moving to the ventral cavities okay ventral referring to um front of okay ventral is especially in a human we'll get to that in a second um you can see here the thoracic cavity and then below the thoracic the abdominal pelvic cavity now something i hadn't mentioned before but we refer to the front as anterior and the back as posterior when you think of the term dorsal what do you think of where have you heard that term before probably dorsal fin right and where's the dorsal fin on a fish on a dolphin it's on its back right now because they swim uh with their body at in a horizontal position the dorsum is the top of their body and then the ventral surface is opposite that bottom of their body but because we are bipedal which means we walk on two feet and we stand upright anterior and posterior are the same as dorsal are back and ventral okay so those terms can be used interchangeably so you can use anterior or ventral and you can use dorsal or posterior so the thoracic cavity and the abdominal pelvic cavity those are both ventral cavities okay they sit in the front of the body whereas the cranial and vertebral cavities are dorsal cavities and they sit in the posterior part of the body now within each of these cavities there are what are known as serous membranes and these are very thin slippery double layered membranes that cover the organs and they line the outside of the cavity so looking at these cavities here um there are no organs in here picture the the pinkish sort of color that you're seeing here as like a lining okay so you have a double layered lining and there's an outer layer that's actually contacting the rib cage and then an inner lining that's going to be contacting the organs inside of that okay same thing here in the abdominal pelvic cavity so all of this area that's shaded or like a teal color there's going to be a layer that's contacting the outside part of the cavity so lining the cavity and then the inner inner layer is going to be contacting all the organs on the inside okay so that's a key component here serous membranes are double layered membranes i want you to picture them like the bags at the grocery store when you're trying to frustrated trying to get those produce bags separated from one another and you know if it's the middle of winter you're going over trying to get some spray from the produce area or something just to get your hands wet to hopefully increase some friction and get those big layers separated right these serous membranes are like that they're very thin they're double layered okay and so what they need is serous fluid to help lubricate them so that as any of these organs are moving these two layers of the membrane aren't you know rubbing against each other in a way that's uh increasing friction now as i mentioned before there's an outer layer that lines the actual wall of the cavity okay and that layer is known as the parietal layer so the parietal layer is the one that's lining the outside of the cavity and then the visceral layer visceral refers to organ this is the inner layer that's then attaching or adhering to all of the organs within the cavity and then between those two layers you have the serous fluid and that fluid is there to lubricate so this is how i want you to picture it right here you see how there's two layers there's an outer this purple line here so the outer line would be your parietal layer and then your inner portion here would be your visceral layer okay and then the purple region between them that is full of serous fluid okay to help to lubricate and reduce friction between those two layers within our thoracic cavity we can further subdivide the thoracic cavity into three main regions the center one being the mediastinum and then the outer two cavities being the pleural cavities and the pleural cavities are named as such because they house the lungs so we have pleural membranes those are the serous membranes that are surrounding the lungs within the pleural cavity and then we have as well the pericardium which is surrounding the the heart within the mediastinum all right so if we go through the four main cavities we talked about these cranial and vertebral those are both dorsal cavities and then the thoracic and the abdominal pelvic those are both ventral okay so within the thoracic cavity we have the chest cavity and we have different serous membranes that go by different names that are then lining each of those cavities so the pleural cavity this is one of the pleural cavities and this is the other pleural cavity okay they are lined by a specific serous membrane known as the pleura and the pleura surrounds the lung within the pericardial cavity we have the double layered member serous membrane it's known as the pericardium and that surrounds the heart and then they all exist the pericardium as well as all the other organs exist within the mediastinum which is that central portion to the thoracic cavity okay and it's really the major major organs that are in there are the trachea which feeds from the pharynx down into the lungs and then the major blood vessels like the aorta the superior and inferior vena cava and as well the esophagus actually runs through the mediastinum as it passes from the pharynx down into the abdominal cavity where it feeds into the stomach and then last but not least the abdominal pelvic cavity specifically the abdominal portion so let's go back to show you that remember how i mentioned the abdominal pelvic is both of them combined okay so here we're looking at the abdominal cavity alone the abdominal cavity is lined by another serous membrane that's called the peritoneum okay so i would probably add some of these labels here okay so you know that your pleural your pleura is found here lining the pleural cavities you have your pericardium you can't see it here because we don't have the heart visualized but the pericardium is the serous membrane that surrounds the heart and then the peritoneum is this teal colored serous membrane that lines the abdominal cavity now in the abdominal pelvic region we can divide that into well you can divide it into regions as well we don't go over the regions we go over the quadrant divisions and the way that you divide into quadrants is you take a line right around the level of the umbilicus and you're going to draw a horizontal line across okay and then through the mid-sagittal plane that's going to divide from the left and the right sides okay so from the left quadrants and the white quadrants via the mid sagittal plane and then this transverse plane that you're taking right through the umbilicus that's going to divide the upper from the lower quadrants so all together you end up with four quadrants so trace this with me okay so find your right lower so right here you should be sort of down near where your appendix would be okay that's the right lower quadrant and then come up you're now in the right upper quadrant okay remember you're going to be below the ribs but still on the abdomen and then move across the midline you're over the left upper quadrant and then come down past the umbilicus you're in the left lower quadrant okay so those are the four quadrants and we can abbreviate those um so know that as well r uq right upper quadrant l u q left upper quadrant and so on okay so make sure you've got those understand when you see it abbreviated what it's referring to all right so these structures we can go through these i'll actually do this right now with you and we'll review that as well if we have time in the tutorial okay first off the appendix as i mentioned okay that's going to be your right lower quadrant the appendix comes right off of the large intestine there okay so rlq your gallbladder is going to be in your right upper quadrant okay the gallbladder you can see here is that greenish sort of structure it sits right under the liver okay so your gallbladder is right upper quadrant your liver right here is your right upper quadrant it actually spans both because it has a right and a left lobe but for your purposes here and now think of it as the right upper quadrant okay the spleen and the stomach you're looking at your left upper quadrants for both of those and the urinary bladder this one's a bit of a tricky one because the urinary bladder is going to be sort of more midline so it's going to span both right and left lower abdominal pelvic quadrants okay so urinary bladder right and left lower quadrants okay and that brings us to our final topic for this chapter and that is homeostasis and the feedback mechanisms that help to maintain homeostasis so homeostasis is the ability for our bodies to be able to maintain equilibrium that's a really sort of simple way of thinking about it okay our bodies are always wanting to do this it's always trying to if you're working out and you're starting to to you know your body temperature's starting to increase your pseudorifferous sweat glands are going to be triggered and your body's going to start sweating and that's going to start to help to bring down your body temperature so that's one example of a feedback mechanism to help maintain homeostasis if your blood sugar goes up right we don't want it to stay up there and so our pancreas is going to be releasing insulin which is going to help the cells to take in that glucose and help to reduce our blood glucose okay so these are all examples of different feedback mechanisms it just so happens the ones i've just mentioned are negative feedback mechanisms okay so we're always wanting to come back to some sort of level of equilibrium so here's the key in the definition okay feedback systems we have negative feedback and positive feedbacks the ones that i just talked about are more negative where we're trying to take a stimulus and bring it back to a baseline okay whereas positive feedback mechanisms we're wanting to continue to amplify a response until some sort of end goal has been met and we'll talk about the specific examples of where we see positive feedback in the body feedback in the body is regulated by the nervous system as i mentioned that is a more rapid type of feedback okay but also hormonal regulation which is much slower but can be sustained over longer periods of time so we have both the nervous system and the endocrine system are working to help to regulate homeostasis within the body and through these feedback mechanisms and there's three basic components okay so we have some sort of receptor then we have the control center where the message is sent to and in all pretty much all examples we're going to talk about today the control center think about it just for now as the brain all right the brain is that control center and then the last component here is the outflow of the decision what has to happen to bring back homeostasis so that's known as the effector it's going to be having the effect okay so the receptor is receiving some sort of signal the control center the brain is going to tell it what to do and the effector is then going to be what is going to give the response okay so i have an example here we're just looking at a simple thermostat our brain works in the same way with our body temperature okay so the receptor is the receptor in this case is the thermometer and so we've had say the room temperature starting to go up so what's going to happen this has happened all summer right the air conditioner is going to be kicked in by the thermostat and turned on to help bring down the room temperature all right so in that case the thermostat's acting as the control center just like our brain does the receptor was the thermometer just like our thermoreceptors in our skin are and then the effector in this case was an air conditioner but we don't have that as a mechanism to help to temperature drop we start sweating to help our temperature to drop okay and the same sort of cycle continues right if if our body temperature is dropping uh if we're looking at uh just say like this example of the thermostat again if the temperature of the room is dropping well we've got our furnace that's going to kick in it's going to start to heat up but instead for us our thermoreceptors are going to detect that our body temperature is dropping it's going to tell our brain hey body's getting cold need to do something about that and then the brain is going to tell all of our skeletal muscles to start to contract and that's what shivering is and that helps to bring back up our body temperature to normal and the cycle's completed okay so the idea here of feedback is that there's the three basic components your receptors your control centers and your effectors that are all working together to help to maintain that equilibrium and balance all right so with negative feedback mechanisms you're always trying to counteract the original stimulus this is the the key element here okay and a negative feedback loop the response is going to counteract the original stimulus so your body temperature goes up the response is going to try to bring your body temperature back down okay now with a positive feedback loop the response is going to stimulate or increase the original stimulus all right so some examples of positive feedback mechanisms there's three and i want you to write them down we'll talk about them throughout the rest of the course one is labor and delivery okay so as a a mother is getting ready to give birth oxytocin's release that starts uterine contractions and then as the the um the head of the fetus starts to descend further stretching occurs and that stretching sends signals back to the brain which causes more oxytocin to be released and it's just this cycle that keeps continuing i always say positive feedback mechanism is like a runaway train okay until you know the final event of whatever was trying was supposed to happen happens the stimulus continues to be reinforced until you know you get to that point the other positive feedback mechanisms the two others i want you to think about for now lactation is another one uh as well as the blood clotting mechanism okay so we can talk more about those if you have questions specifically in our tutorial sessions together but for now take away negative feedback mechanisms are the most common in the body and this is where you're trying to see that some sort of response is working in the opposite direction of the stimulus whereas positive feedback trying to reinforce runaway train scenario okay and so that brings us to the end of uh this lecture so i'm sure you have lots of questions you can always reach me via email but weekly we are going to be meeting in our tutorial sessions and i look forward to being able to to work with you uh in a group setting but also willing to to work with you one-on-one should the need arise okay so just never be be afraid to reach out and let me know that you need help i'm more than willing to to help and get back to you as soon as i can okay until we see you take care