Lesson 4: Cell Types and Modifications (Part 1 of 2)

本站添加: 2026-05-22

[00:00:02]good day everyone and welcome to another lecture video on the cell types and modifications so this is your um first colloquium lecture video after your first monthly exam and this is your fourth lesson and the final lesson for the coverage of your first quarterly achievement test so let's get started so for the objectives of our lesson we will will first need to describe the structure and function of the different cell types of the body and then give examples of cell modifications found in plants and animals so for this lecture we will only be covering the first objective to describe the structure and function of the different cell types of the body so first things first what kind of cells do you have in your body I will give give you the time to think can you remember the names of the cells that are found in your body perhaps you can recall your cheek cells which you have seen already under the microscope in your space lab activity last time or you can remember your blood cells or even your bone cells some of you would say brain cells or even sperm cells egg cells all of the these are actually cells that are found in your body so let's now try to describe the structure and function of these different cell types in our body and we begin it first with the stem cells stem cells are unspecialized cells this means they are very basic in terms of their Form and Function at the same time they can actually or they have the capability to differentiate into specialized cells that means they are totipotent so this basically means that this cell has the capability of becoming any type of cell for example a stem cell can become a future blood cell or it can be a future brain cell or it can be a future sperm cell or any other cell in the body but if you are fated to become a different cell you can no longer go back okay so for example if you're fated to be a brain cell you'll never become a blood cell or you'll never become a kidney cell or any cell apart from being a brain cell right so just remember when you are toti poent you are capable of becoming anything if you're already specialized you cannot return to your toti poent state and you cannot transform into other types of cells okay now stem cells aside from the fact that they are unspecialized they can divide and replicate many many times to replenish and even repair the damaged tissues of the body as you can see on the diagram on the right a stem cell is fated to become anything that it can be it can be an immune cell or a cell that is like a white blood cell it can be it can become the sex cells or muscle cells or even fat cells bone cells blood cells and nervous cells or even epithelial cells but when they become specialized they can no longer return to their original state okay so basically for human beings we came from stem cells and the very first stem cell in our history as an individual person will be the zygote as you recall the zygote is the union between your egg cell and the sperm cell when they met they become fertilized and they became you and just imagine that very single cell is toti poent it is a stem cell in itself which is capable of becoming the future parts of your body so for every cell that you have from head down to your foot all of these cells came from a very single cell at the time when you were inside the womb of your mother that cell is the zygote and the zygote again is a type of a stem cell okay and aside from stem cells we also have blood cells and you are familiar with this already hopefully blood cells have different types they can be the red and white blood cells and even the platelets so we begin first with the red blood cells as you can see in the illustration or the 3D model on the right red blood cells have their own color because of the pigment called hemoglobin and hemoglobin is a type of protein that has iron in it and that iron easily attracts oxygen okay and when blood is oxygenated the reaction between the iron and the oxygen will cause the reddish coloration okay so the red color of the blood is due to the hemoglobin that interacts with oxygen okay at the same time okay our red blood cells is capable of carrying that oxygen okay from the lungs to the rest of the body through our blood vessels we need to know that oxygen is needed by the body okay so that we can process energy remember remember the role of the mitochondria okay the mitochondria aside from it being the PowerHouse of the cell it is capable to transform energy coming from food molecules and that process will involve many oxygen okay so that oxygen should come from the red blood cells that circulate around the body so basically the red blood cells function for just transporting that oxygen we need inside the bloodstream okay at the same time what shape does the red blood cell have okay what how can you describe the shape of the red blood cells so in this case as you can see okay they look like donuts some of you would would say that they look like plates or like Wheels um but but um the way we describe it in our terms as biologist is that they are by concave okay so they look like donuts with spaces inside them and the reason why they are shaped like that is because of what so I hope you can try to think of an answer okay when I asked this question in the previous colloquium they answered that this is for the red blood cells to get into the blood vessels easily smoothly no and smoothly so in this in that case that shape will allow the smooth entry of the blood cells into the bloodstream at the same time because they are shaped like donuts they have spaces inside them okay that part can actually be concentrated with oxygen that can be carried through out the bloodstream okay so the reason why the red blood cells have that kind of biconcave shape is due to two reasons one is for the smooth flow of the blood cells throughout the bloodstream and second for it to carry enough oxygen inside its B concave structure okay aside from the red blood cells we also have the white blood cells and if you will recall cell at work which is an anime series about blood cells I hope you'll watch it I I recommend that um anime and um as you will see from that um anime series white blood cells there are actually the soldiers of the body and it's because they are the cells of our immune system which destroy the pathogens and provides us our immunity and let's recall what are pathogens again okay pathogens are the harmful creatures that enter our body which could be in the form of bacteria viruses or even parasites like worms that can enter into our bloodstream so basically these white blood cells can actually engulf these foreign particles that would prevent us from getting disease later on okay so why blood cells are typically larger than red blood cells and um they come in various shapes various sizes and various functions to kill the pathogens around them okay and finally we have the platelets and in the anime cells at work they're actually the kids who are carrying these cloth-like structures to heal the wounds and that's the function of the platelet okay these are small structures in our bloodstream that help to clot the blood and prevent excessive blood loss due to damag blood cells or blood vessels rather okay so when you have a damage on your blood vessels your platelets will work okay such that they will carry this cloth of fibrin which will later on become the wound and eventually that will wound would be healed later on and again the role of those wounds is to prevent blood from going out of your body okay so let's recall again our blood cells we have your red blood cells that function for transport your white blood cells that act for defense and your platelets which function for preventing excessive blood loss okay and the formation of your wounds I hope that is clear with all of you okay and how do these blood cells form okay if you'll go back if you have watched cells at work there is this one episode that would show you how the cells were born and even trained okay before they enter the bloodstream and they actually take place in your red bone marrow okay your red bone marrow is located inside the bones of the body and in these bones okay your blood cells are manufactured so they typically come from stem cells that are located in the bone marrow okay so typically in the long bones of children and adults you will see that it's the red bone marrow that forms all of these blood cells sometimes it could come from the bones of um in the bones of the adult it would come from the skull and the rest of the flat bones okay okay so take note it's not the heart that makes the blood okay it's the heart that pumps the blood okay that's the role of the heart it's just a muscle that will pump the blood all throughout the body but the blood is formed inside the bones okay and then we have fat cells which are also known as adipocytes okay these are the major components of your adipose tissues or basically your fat tissues and they contain stored fat molecules that are later used for energy okay but aside from that fat cells have a lot of interesting functions okay it's not just for the storage of fat but they also have endocrine roles to make hormones that influence the following activities inside the body one is sex hormone metabolism fat cells can also make hormones that can also influence blood pressure regulation it can also induce insulin sensitivity okay to sugar or blood sugar levels inside our body it can also be used for storage and use of fats and finally fat cells can also induce hormones for blood clotting and signaling or communication between the cells and then we have the epithelial cells epithelial cells are all the cells that line up the outer surfaces of the organs and lining of blood vessels and Cavities you've seen them already under the microscope let's recall your cheek cells which you have obtained inside your mouth they basically line up okay the covering of our mouth so in that case what you're observing under the microscope back then were actually epithelial cells of the cheek okay again the role of the epithelial cells are to cover okay or to line or to to make up this lining of our organs um inside the body okay and then we have endothelial cells and these are a type of epithelial cells that line up the circulatory and lymphatic systems so they basically line up the blood vessels okay and the lymph nodes or the lymph vessels inside the body again when we talk about the lining okay all you need to remember is that it's the epithelial cells that would line up or cover these organs okay recall your cheek cells they are flat structures and they basic they're basically flat because they just need to line up anything okay and now we have nerve cells or also known as neurons and these cells make up the basic unit of the nervous system so what makes up the nervous system let's recall that will be your brain your spinal cord and all the nerves inside your body okay the nerve cells contain two main parts the first is a cell body okay which contains the nucleus of the neuron and the nerve processes or the finger-like projections that conduct or transmit signals okay from the cell body or to the cell body so let's see what are these structures inside the nerve cells and now how does these signals transfer from one place to another so let's recall the finger-like projections as you can see in the nerve cells so here we have a central cell body okay which again contains the nucleus of the neuron including the other organel that are found in the cell and the finger like projections or the root likee projections that come out from the cell body would be the dendrites okay these structures that emerge from the cell body are called your dendrites and the dendrites are the ones that receive signals from other nerve cells okay now as the signals are received by the dendrites the signals are transferred to the cell body and eventually the signal will be transferred to the axon okay and the axon is found as the tail of the nerve cell and the axon will send the signals to the next neuron or to the next nerve cell so how do we transfer the messages or the signals we have the dendrites as the receiving part the central body or the cell body and then we have the axon which will send the signal away from the cell so after sending it away from the neuron it will send the signal to the dendr of the next cell and then that dendroid will transfer the signal then to the cell body and then transferred to the axon and then it will be transferred again to another denite of another neuron okay so I hope that way of messaging is clear for the nerve cells and then we have the sex cells which are also known as gametes so for every biological sex there is a different form of gametes so for biological males they have the sperm cell and for biological females they have the egg cells so sperm cells are relatively smaller than your egg cells at the same time they have this tail which we call a flagello which allows the sperm to move towards the egg however the egg on the other hand is larger than the sperm cell and at the same time it is imole that means it can cannot move on its own so it just Waits there persist persistently for a sperm cell to arrive okay and when they unite okay the zygote will form so sex cells from each sex need to meet so that they can form a new organism of the same species so that Union is a process which we call fertilization which results to a zygote and as we recall from the earlier slides the zygote is the first stem cell of human beings from the zygote all of the cells of the body will arise okay and at the same time sex cells undergo meiosis rather than mitosis I hope you can still recall the lessons you've learned from your Junior High School on cell division so when we say meiosis it's the division of cells resulting to new cells that have half the number of chromosomes as their parent cells for humans we have 46 cells inside our cells of our body but when we need to form sperm cells or egg cells they need to have 23 chromosomes okay and why because you need 46 chromosomes in the new organism later on so if you need to develop a new human being it needs to have 46 chromosomes so 23 should come from the sperm and then 23 should come from the Exel so you get half of the chromosomes from either your mother and your father okay so again meosis is the type of cell division that allows the reduction of chromosomes into half but if it's mitosis okay the resulting cells will have the same number of chromosomes as their parent okay so I hope that's clear but don't worry we will discuss more meiosis and mitosis in our future lectures in the upcoming second quarter okay and then we have the cancer cells which are cells that result from mutations that are often influenced by the several factors mentioned we have chemical exposure such as to carcinogen so when a substance is considered carcinogenic it has the capability to induce cancer okay an example of carcinogenic substances would include the black spots you see on barbecue when you grill them so these black spots when you consume a lot of amounts of it that is going to be a risk for cancer another cause of cancer are radiation and ultraviolet light so when you're exposed to UV rays especially if they come from the Sun okay and you exposed for a long period of time they tend to cause D damage in your DNA that would eventually trigger the formation of cancer cells okay aside from radiation and chemical exposure sometimes cancer cells arrive randomly okay they tend to to form randomly because of random replication errors in the DNA so there were cases that when DNA was duplicated in in the cell there were chances that some nucleotides were mismatched and in that case those M mismatches can cause cancer later on and then we have viral infection sometimes it's the viruses that cause the DNA damage triggering the formation of cancer cells okay and another interesting property or characteristic of cancer cells is that they tend to multiply very rapidly this is because they lose their sensitivity to anti-growth signals that is the regulation process of the cell itself okay that regulation process is anchored on the DNA of the cell and when that regulation has been destroyed because of mutations okay what happens okay the DNA won't make its instruction for the formation of its regulatory proteins that means there will be no police officers inside that cell that would monitor the quality of the DNA so even if the DNA replication went wrong nothing would stop it thus it will keep on dividing and dividing even if it has the wrong quality of DNA okay so this causes the cells to lose already the capability or the ability to undergo cell death or apoptosis so apoptosis is the programmed cell death okay which allows the cell to die because it has the wrong DNA but since the the cell itself doesn't know how to control itself anymore okay nothing would stop it thus it will keep on multiplying so when you have cancer you have actually a different organism that lives inside you because it has already a different DNA in its own okay its DNA is manipulated very different already from the DNA you have and sometimes cancer is rarely or can rarely be stopped okay that's why until now we're try we're we're still trying to figure out what's the best cure for cancer okay so I hope you will realize something about this about this part but um don't worry we will be discussing more about cancer on the lessons on mitosis iosis and how the cell divides okay so that will be taken in the second grading period so for any questions please reach me out through my email Andre ja. dyc.edu pH okay so you may also reach out to your l so that they can send me the questions through the L group chat okay and now here's our question cancer cells can produce tumors that event lead to cancer this is one of the top causes of deaths in the Philippines and around the planet now the question is take note when you have cancer it's actually a burden inside your body it's something that is not you but it lives inside you right so we have to get rid of them what does that tell about cancers of society how can we get rid of them I hope you can ponder something about this of course I know it's not related to biology but I hope you can still relate to it no when it comes to how we view the world around us and our society okay and this is where I end my lecture video on the different cell types we can see in our body see you in our next video you