Transcript for:
Introduction to Human Anatomy

i want to welcome you to this particular class my name is dr vedau labu and i have a series of lectures on human anatomy in this particular lecture i want to just give you an introduction to what human anatomy is i prefer giving this lecture in two parts the first part i want to talk about the definitions and scope of human anatomy which you are going to do in this particular session and in the second part which is still part of introductory series i prefer handling definition of some terminologies which you use in human anatomy so in this first part of the introduction as i've told you we will focus on definitions and scope of human anatomy we are going to look at the various divisions of human anatomy and what each of those divisions entail so the intended learning outcomes are the following perhaps it will be important that we define what is human anatomy what is physiology and what is pathology in as much as we are not going to talk about physiology and pathology in this particular lecture but it is important that we define all those and we see how they are related to an atom after those definitions we are going to look at the three divisions of human anatomy that means that anatomy has three divisions and for each of the divisions we are going to state the scope in this lecture also i'm going to take you through an overview of the body regions and perhaps the subpart of each region also we are going to see how the body is organized in a particular hierarchy from simple to complex structures lastly we're also going to look at the different organ systems in the body and state the key functions in each of the systems so let's revert to our first agenda which is to define anatomy physiology and pathology we'll start by defining anatomy anatomy is basically a branch of science that deals with the study of the structure of the body it could be the whole body or could be just some part of the body the point i want you to take at this juncture is that when you talk about anatomy we are talking about the study of this structure the water underlying the structure and so when you talk about human anatomy it means we are not just studying the structure of anything but the structure of the human body when we are focusing on to the human body then that's why we're calling it human anatomy this is particularly important for any student training in any field that is concerned with healthcare now closely related to anatomy is physiology what is physiology physiology is the branch of science that is concerned with studying functional processes that take place within a living organism remember not only focus on the structure but physiology now focuses on the functional processes in particular physiology looks at the physical chemical and biological processes that take place within a living organism and also look at how these processes are controlled within this living organism the process must be controlled you understand they must be regulated so that we don't have extremes of function the process must function within a particular limits that are allowed so we see how that is regulated physiology looks at that particular concept then the third thing we agreed that we are going to define is pathology literally speaking the term pathology refers to the study of suffering you know logos means study and pathos mean suffering that's too literal in a better way pathology is the study of disordered body function study of alterations within the body maybe a more comprehensive thing would be to say that pathology focuses on the structural remember anatomy and functional remember physiology but now changes there are alterations it focuses on structural and functional alterations which take place either at the level of the cell the tissues or organs and how these ones are related to development of disease because these changes are the ones which then explain the disease processes so pathology focuses on study of disease processes in simple terms having defined those three we can now look at our second major objective which is to talk about the three divisions of anatomy while we're here we're also going to look at the scope of each division so there are three divisions of anatomy the first one is gross anatomy the second one is microscopic anatomy and the third one is developmental anatomy there could be other terminologies which are used to refer to the other two for example microscopic anatomy is commonly called histology and a developmental anatomy is commonly called embryology let's focus on these three divisions of anatomy one by one and try to understand what each of them entail i'll start with gross anatomy so having agreed on what anatomy is we know is the study of structure what exactly is gross anatomy gross anatomy study the structure or any of its parts as visualized with your naked eye and i'm using the term neck and eye in quotes to refer to the fact that we are not magnifying beyond normal human vision if you have spectacles for example the way i do we are not really my spectacles are not really magnifying beyond what normal human visual can appreciate so even if i'm using spectacles to study the parts of the body that is still grosser naturally and as i said i could be studying the whole person as an individual but i could also be studying different organs within this individual for example i take the heart and just look at the surface of the heart either inside or outside maybe it's the lamb or the brain as long as i'm appreciating the structure using my naked eye we consider that gross anatomy in terms of implementation there are two main approaches that are used in the study of gross anatomy this is what we call the topographic approach a topographic approach to the study of gross anatomy or genera to the study of anatomy is where we are studying the body structure according to the different regions of the body and in a short trial i'll be taking you through so what are these different body regions at this point in time i want you to understand that topographic approach is where we are studying the body according to its regions maybe is the head neck thorax abdomen whatever it is leg foot we are focusing on a particular region and so we call that topographic anatomy then we have the systemic approach systemic approach is where we are studying anatomy of the body according to the different organ systems which the body has and again in a short trial as we agreed in our objectives we are going to see what are these organ systems in the body so if you do that then we are saying that that is systemic anatomy let me say at this point that topographic anatomy is a bit very detailed so to speak compared to systemic anatomy it's easy to teach anatomy from a systemic approach and you finish very quickly topographic approach on the other hand requires a lot of skills a lot of patience a lot of details and so depending on whatever unit you're doing whatever course you're doing there could be different curriculum for different people depending on the depth of anatomy that you are training requires you some syllabuses will go with systemic approach and some courses will go with topographic approach for example if you are training doctors who are going to be surgeons then you will expect them to be having a topographic approach as a key element in the training because they need to know what is next to what when they're cutting now for the sake of just having a clue of almost everything i prefer to do what i call a hybrid approach a hybrid approach is where you incorporate both topographic as well as systemic approach this hybrid approach may not be used all the time it could just be used in some situations where appropriate for example if you are teaching on musculoskeletal system for example that's a systemic approach then you feel like perhaps i need to tell this particular group of students more about the anatomy of the leg just an overview you see when you talk of an atom in the leg that's a topographic approach now in hybrid approach you then bring in topographic aspects of anatomy in as much as your primary template is systemic approach so for example you teach through a systemic approach and you done with a particular system let's say you're done with respiratory system or that time that you're studying the respiratory system then that could be the best time to then give the student an overview of the anatomy of the thorax so just say a hybrid approach is where you bring in topographical aspects but primarily you've been using a systemic approach again that will depend on what cause you are doing as a student maybe there are some aspects of topographic anatomy that is required of you in some parts okay now having explained to you what is topographic anatomy and what is systemic anatomy and agree that topographic anatomy focuses on the study of the body according to the different regions perhaps then it is important that we understand at this point what are these body regions they are different parts of the body i prefer grouping the different body regions under four large categories the first one being the head and neck region so i believe anybody who is in this class is aware of what is head and what is neck basically that is the head and this is the neck so when you talk of head and neck region we are talking about the head as well as the neck there that's what you call neck that's what you call head i prefer considering that a big body region the head and neck region then we have what we call the trunk or the torso it also is t-o-r-s-o the trunk is this region from where i'm pointing right now up to there so the whole of this is the trunk within the trunk we have the thorax which is this one from there to somewhere there we have the abdomen which is this one here we have the pelvis which is where the different reproductive organs are found most of them and we have the back and i believe all of you know where the back is so those are the sub regions within the trunk the third big body region is what we call the upper limb this is the upper limb from there all the way to somewhere there so please note don't call this whole thing the hand we call it the upper limb and the upper limb also has about four or five subparts there's some parts of the upper limb that are attached and there's some parts of the upper limb which are free the attached part of upper limb are these ones so this region of the upper limb this region of the upper limb that's attached to the anterior the the front part of the chest is what we call the pectoral region then this region of the upper limb that also extends slightly to the back there that's what we call the shoulder region so the pectoral region on the shoulder region are basically the attached parts of the upper limb then we have the free part of the upper limb i believe you are aware there is a joint there which we call the shoulder joint and a joint here which he called the elbow joint so this segment from the shoulder joint to the elbow joint that one is what we call the arm the arm is also called the brachium i also believe that you are aware that the joint is for the wrist this segment between the elbow joint and the wrist joint this one is what we call the forearm you can call it antebrachium then lastly from the wrist down this is what we call the hand so now today you know what the hand is don't call the hole of this the hand only this is called the hand this is the forearm that's the arm again don't call this one the upper arm it is the arm if you want to talk about upper arm and lower arm then it's about dividing the arm into upper and lower region but the whole segment is called the arm maybe i mentioned something about the hand if you look at your hand it has two surfaces this surface here which is that one on that surface is what we call the palm of the hand and then this is called the dust some of the hand right those are the parts of the upper limb the last big body region is the lower limb just like the upper limb the lower limb also has some sub parts or the segments let's start with this one here which you call the glute region it may go with many other names depending on the society you come from but in this scientific class let's just call it the glitch region of the buttocks so that is a segment then we know that we have a hip joint there and down here we have a knee joint this segment between the hip and the knee is what we call the thigh i believe that on everyone knows then you know that we have a joint here called the ankle joint so this segment between the knee and the ankle joint that's what we call the leg again i want you to understand that the whole of this is not called the leg only this segment between the knee and the ankle is called the leg the hole of that is the lower limb lastly the part below the ankle joint is called the foot and just like we did for the hand the foot also has two surfaces the surface of the foot that faces the ground is called the sole of the foot so that the soul of the food you can call it planter aspect of the food and then this is the dose some of the food just like dosa move the hand so don't confuse the thumb dorsum is used for both foot and hand fine but when you look at the front side of the hand we call that the palm and the one for the food is the planter so we talk of palm of the hands and plant out the food and not the other way around great so i've taken you through the major regions so once again if you're studying anatomy from a topographic approach then you study anatomy according to the regions that have just given you although sometimes you can still go into finer details for example the hand still has some specific structures like there's a calm there's index finger there is a ring finger there is a middle finger you can still opt to study even those individual details that is still topographic anatomy region by region now i want us to talk about the hierarchical organization of the body perhaps i need to mention that the human body and indeed living organisms are organized in particular hierarchy this hierarchy sees to it that the body is built up from simple structures to most come to more complex structures and from your chemistry you must have remember that there are some tiny things that constitute some structures of matter perhaps it will be good to start at the level of the atom although i know you are aware again that the atom is still made up of some simpler things like you know protons electrons and neutrons but let's not go there atoms make up matter and in our definition from high school an atom is the smallest unit of an element that participates in chemical reactions let me give you two three seconds to think about some examples of atoms okay if you do remember your periodic table that shouldn't be a big deal when atoms combine they form molecules again in your definition of molecules from high school you may have said that molecules are the smallest unit of an element or compound that exists on its own examples of molecules will be you know co2 that is a carbon dioxide molecule o2 that is the oxygen molecule h2o that's a water molecule and such examples some molecule will be a combination of different atoms it's a group of atoms that can exist on its own when molecules combine remember our objective here is to build the body and think about your body in this case so with that in mind then we are going to do this after molecules combine with the purpose of building up the whole body they form what we call macro molecules the term macro here just means big so macromolecules are large molecules that build up the body which are these large molecules that build up the body i'll give you four of them the body is buildup of proteins carbohydrates lipids and and nucleic acids so proteins carbohydrates lipids and nucleic acids are examples of macromolecules that build up the body when you talk of nucleic acids we are referring to the dna and the rna what happens when these macromolecules combine when these macromolecules combine they constitute the organelles what are examples of organelles i'm giving you another five seconds to just trouble your mind around that examples of organelles all right so i believe you have in mind mitochondria i wonder why almost every student who must think through that like almost be the first example that comes in your mind but fair enough mitochondria ribosomes golgi operators endoplasmic reticulum peroxisomes you know them those are organelles when organelles combine they now form the cell and perhaps from high school you define the cell as the smallest unit of life maybe let's say that we don't have a very nice definition of what the cell is and that definition of the smallest unit of life is perhaps the best we can take although there are also some challenges with regard to that definition you know by saying that the cell is the smallest unit of life in simple terms we are saying that in this hierarchy that we're describing what we call life begins at the level of the cell onwards if that holds water then it makes us question some things if you say that life begins at this level onwards does it mean then that the mitochondria that we just mentioned are dead you know that's a bit hard to decipher again if we say that life begins at the level of the cell so these things about viruses you know they're tiny they're nucleic acids are they alive or they're dead well those are debates for you so that concept of the cell is the smallest unit of life is a theory it's one of the cell theories multiple cells would combine we have many cells in the body many many cells in the body but these cells can combine similar cells combined to form tissues similar cells combine to form tissues let me put it this way we have billions and billions of cells in the body if you are to classify the cells in the body according to their types perhaps you'll get over 100 different types of cells in the body you know red blood cells white blood cells nerve cell and even those white blood cells there are different types of white blood cells you know neutrophils mast cells so that's what i'm saying we have different types of cells in the body according to varieties there are over 100 different types of cells in the body but when these cells combine to form tissues we have still a good number of tissues maybe over 20 different types of tissues in the body and you can give examples of tissues in the body again let me give you some five seconds mind break to just think through examples of tissues in the body so perhaps you have in mind epithelial tissues bone tissue cartilage tissue adipose tissue and they like when tissues combine they form organs and think through different organs in the body in this image we can see stomach now think through the organs in the body stomach is an organ kidney lung heart liver uterus all those are organs when organs combine they form organ systems and i'll be giving a chance to just think through different organ systems in the body when organ systems combine them they form the organism and so you and i are examples of this organism but we are made up of different organ systems each organ system is made up of different organs an organ is made up of multiple tissues a tissue is made up of many cells a cell has several organelles an organelle is made up of macromolecules each macromolecular several molecules within it and each molecule has atoms we've seen that the body is organized in a particular hierarchy from simple to a complex structure having said so i want us to now talk about the different organ systems which are in the body in an attempt to explain to you what we do when we study gross anatomy from a systemic approach so this is your question perhaps take a minute okay maybe a few seconds to just list the major organ systems in the body and if you're able to state one key function or the key functions of each organ system in the body that would be good so let me give you a minute to just struggle through that you foreign okay i believe one minute is over now i'm hoping you've listed as many as possible i'm hoping your list has at least 10 organ systems i want to take you through an overview of the key organ systems of the body let's start with the one you're seeing in front of you now this is what we call the skeletal system so what are they what do you know about the skeletal system the skeletal system is basically the system made up of different bones and uh we know that skeletal system is important for movement that's what you call locomotion it also protects you like it protects internal organs for example your rib cage protects the heart and the lungs your skull protects the brain your vertebral column protects the spinal cord it also provides structural support you'd imagine that if we didn't have bones maybe we'll just be a heap of meat so because we have bones therefore things can attach into these bones and offer structural support and bonuses are very good reserve for the mineral culture over 90 percent of calcium in the body is stored within bone tissue closely related to the skeletal system is another system that is very easy for you to forget and i want to be surprised if it didn't appear on your list and that's the articular system the articular system in particular refers to this system made up of joints so basically joints fall under the articular system and the primary role for joints is to allow movements you know you move along joints around joints different bones move around joints so we've named two systems so far closely related to the skeletal and articular systems is the muscular system the muscular system is closely related to the skeletal and the articular system when you talk of muscular system we are referring to this system which is largely made up of the skeletal muscles and perhaps their modes of attachment we know that muscles are important in movement so when they contract they move bones and their bones move around joints apart from that muscles help us to generate thought first if you want to push something you want to pull something you want to lift something you want to jump use your muscles to generate the force where you're going to use to perform these activities and think through water pains when it's cold your skeletal musculature usually contract in the act of shivering to generate heat for the body so we can say that muscular system is important in thermoregulation now we mentioned three major systems the skeletal system the articular system and the muscular system these three systems are commonly referred to as the locomotor super system so that when you talk of the locomotive super system we are referring to those three systems combined skeletal the muscular and the articular system and another common term that perhaps you'll be hearing more often is the musculoskeletal system based on the fact that we are thinking through the skeletal and the muscular parts but remember that also where the articular one also hides in as much as not being pronounced so much in the term musculoskeletal system when you talk of musculoskeletal system we are still referring to the local motor super system right let's talk about the thought system and the system you're seeing is the nervous system i know in your learning you'll come across central nervous system and peripheral nervous system but for now let's just call the whole system the nervous system whether central or peripheral nervous systems basically coordinate and integrate body functions and in so doing they regulate body functions to maintain homeostasis homeostasis those the maintenance of some activities in the body within some narrow physiological limits for example you want to maintain the body temperature within a particular range you want to maintain the concentration of blood glucose within a particular range so the nervous system helps to maintain those physiological ranges in the body closely related to the nervous system is the endocrine system the endocrine system is this system concerned with some glands or cells which secrete chemical messengers that are called hormones so in terms of function the endocrine system and the nervous system will still perform the role of coordination and integration of functions and also in terms of maintaining some homeostasis the endocrine system and the nervous system are commonly called the integration systems for that purpose the integration systems some people may just want to use the term neural endocrine system so that when you talk of neuroendocrine system we are referring to the nervous system as well as the endocrine system in your list we've now mentioned five if you're counting well the sixth system i want to talk about is the cardiovascular system and when we talk of cardiovascular system we are referring to this system that is made up of the hearts and blood vessels so the heart and blood vessels fall under the cardiovascular system we know that the role of the cardiovascular system is just to pump blood to the rest of the body at least the heart does that and the blood vessels transport the blood well the heart also produces some chemical messengers in terms of hormones so we can say that still has some endocrine functions closely related to the cardiovascular system is actually the blood that flows within the heart and the blood vessels i prefer calling this the hematologic system the hematologic system is important for transportation and delivery of substances in the body it's also important for immunity it contains cells that help us to help to fight infections it also helped to maintain homeostasis of some physiological parameters let's say body temperature for example or even the level of acidity and alkalinity in the body sometimes you hear the term circulatory system being used and that term circulatory system may be used to refer to the hematologic system sometimes it may be used to refer to the cardiovascular system sometimes it may be used to refer to all of them as one big umbrella and so when you hear that term circulatory system it will be important that you actually understand what the person talking to you is actually referring to because all of them are actually right the term circulation system can be used to refer to both of them or just the hematologic system some people use it still for the cardiovascular system anyway closely related to those two systems is the lymphatic system when you talk of lymphatic system we are referring to this system that contain lymphoid organs basically so this system is primarily responsible for defending our body against infections but it's also important in terms of being site for formation of blood tissue and in the intestines the lymphatic system is important in terms of absorption of fats fat from the intestine does not go into the bloodstream direct but it enters into the lymphatic system then the lymphatic system will eventually transport it into the bloodstream at the appropriate site i've lost count on the number of systems we're talking about but most likely we're at around the eighth system if i'm not wrong so the ninth one would then be this one i think when you look at this one you already know this is the digestive system and nobody here needs to be reminded the functions of the digestive system so basically for the sake of completion we can still just talk about it that yes the digestive system supplies a body with water nutrients there are some organs within the digestive system that also produce hormones like the pancreas produces hormones so there are endocrine functions as well also there are some organs which excrete some wastes like the liver so there's some excretory functions as well and again you know the liver also helped to detoxify some things in the body so the detoxification is still a function of the digestive system again this other system already know it i think this is should be number 10 now this is the respiratory system primarily the respiratory system is important for gas exchange that we take in oxygen and we take out carbon dioxide so that's the primary role of the respiratory system but that's not the only function of the respiratory system as you hear me talk you know i'm using my respiratory system to talk to you the act of production of sound is what you call phonation as a function of the respiratory system the sense of smell is actually located along the path of the respiratory system you know your nose is part of your respiratory system and the nose is the one that houses the receptor for smell so we can cell function it's also a function of the respiratory system the respiratory system also helps to balance the acidity and alkalinity of the body perhaps we don't know this yet but there are three major things that help in acid-base balance we have we have the lungs and we have the kidneys also the respiratory system may have some endocrine functions and may be too much to say at this particular point in terms of the endocrine functions of the respiratory system but as you go along in your anatomy and maybe physiology you'll come across so what's the endocrine function of the lungs i believe we've mentioned 10 of them now so this should be the 11th system urinary system the one made up of the kidneys urethrals urinary blood and urethra basically the urinary system is largely for excretion of waste substances but apart from that it also has some endocrine functions it is important in regulating those molarity we call that osmoregulation basically controlling the amount of electrolytes or minerals as well as water and that's what we call osmoregulation controlling the levels of electrolytes or let me call it minerals like sodium potassium magnesium as well as the amount of water in the body so so that in a particular osmotic pressure we call this osmo regulation in so doing the kidneys are also able to regulate your blood pressure and as i mentioned earlier the kidney is also important in controlling the amount of hydrogen ions in the circulation or by carbonate ions in the circulation that's acid based balance the 11 system let's call them the reproductive systems or the genital systems maybe the term reproductive is much better the reproductive systems remember that too you can talk of the male reproductive system and you can also talk about the female reproductive system but let's look at them as one and just list the key functions of the reproductive systems so production of the gamete cells is one of the key functions of the reproductive system you know the sperm and the oocytes we call that gametogenesis production gametes apart from just producing the gametes the reproductive systems also help in transporting these gametes the fallopian tube transports the gametes the vast difference transport the sperms the genital system is also important in production of sex hormones estrogen progesterone testosterone dihydrotest these are sex hormones which are produced by the reproductive the organs of the reproductive system in particular the governance which are referring to the testes in males and ovarian female importantly and this could just be narrowed down to the uterus that the uterus the site of prenatal development the baby develops in the in the uterus for some nine months before birth so the site of prenatal development you may have considered those to be two systems or just one big system either way we know that's there the last system i want to talk about is the integument system the integument system is basically the system referring to skin and its appendages the skin is important for protection apart from protection the skin is also important in thermoregulation it help to protect against infections it has excretory functions like through sweat and it also has sensory functions we have different receptors which are on the skin great so i've taken you through the different organ systems in the body we've mentioned about 13 or 14 different systems in the body and so that was just helping in us trying to rubber stamp the concept of systemic anatomy as an approach to the study of gross anatomy and so that summarizes the concept of gross anatomy we've seen that we can have two approaches the topographic approach where we study our contour regions and systemic approach where we start according to the different systems now i want us to then look at the second division of anatomy which is microscopic anatomy the second and the third division are going to be pretty short don't worry so microscopic anatomy is the study of those minute things that your eyes can't see those tiny things that your eyes cannot appreciate if you're using just naked eye or spectacles you can't see but there's still parts of the body we can only study them using a microscope and that's why we call it microscopic anatomy because we're studying many things which we cannot see the naked eye so we have to use a microscope you know that we can either have a light microscope or an electron microscope you should be aware about uh those two types of microscopes microscopic anatomy generally can be divided into two there's what we call cytology and this is what we call histology cytology is the study of cells and when we study cells we go into greater details of the cell biology the best microscope that helps us to study cells is actually the electron microscope you can feel certain cells using light microscopy but the best one that help to study cells appropriately is the electron microscope then histology is the study of tissues the best microscope that helps to study tissues is the light microscopy and as much as again you can still use electron microscopy to study tissues now microscopic anatomy is commonly referred to as histology largely because the aspects of cytology usually aren't that much but the aspects of histology is quite voluminous and forms a big part of any stud of any curriculum that emphasizes on some good detail of anatomy it's for that reason therefore that we sometimes interchange the term microscopic anatomy with histology and so sometimes when you hear maybe your teacher talking about histology as the unit just understand that yeah the term histology can be interchangeable with microscopic anatomy even if within that histology you're still going to study cytology so what's the scope of cytology in human anatomy cytology focuses on some four key areas now in physiology there'll be even more and much much more that physiology will focus on but in human anatomy just some four key areas of the cell the first one is cell structure in cytology a human anatomy we look at cell structure and we focus on the overall structure of the cell how does it look like under microscope and what are the different organelles within the cell how do they look like and because we don't just want to study the structure only we need to know the role of these organelles so in as much as we're still talking about anatomy we're interested in knowing the functions of each of these organelles so that usually falls under that lecture called cell structure and i believe you usually you have a lecture on the cell structure then another one is cell adaptations this is the background of this is this that we know that a cell a human cell will have three major components a cell membrane a cytoplasm and a nucleus those are the three basic components of a cell however we know that different cells perform different functions there's one cell that will be largely for contraction the muscle cell this is another cell that is largely involved in releasing some [Music] hormones it's an endocrine cell there is another cell that is likely focused in absorption of nutrients from your intestines maybe another one for transmission of signals in the brain so in as much as we know that each cell will have three major components the cell membrane the cytoplasm and the nucleus not all cells will be the same they will have some structural endowment for them to perform the different functions that they do for form i would not expect a cell that transports substances in my intestines to be similar to a cell that transmits signals in my brain and as much as all of them will have a cell membrane a cytoplasm and a nucleus so with that background in this chapter on cell adaptations we try to look at the structural adaptations that different cells have to enable them perform those different functions then the third one we talk about the cellular genetics the genetics of the cell and anatomy is not the best unit to talk about genetics to be honest because there's a lot about genetics that anatomy doesn't go into perhaps the only reason why anatomy talks about genetics is so that it can bring you to the level of understanding that there could be some things called mutations and there could be some things called chromosomes because now in this unit of anatomy there'll be some abnormalities of chromosomes that we see that give us some structural abnormalities and we want to talk about them so much perhaps that's why we bring cellular genetics and anatomic otherwise anatomy is not the best place to study cell genetics don't study cell genetics in anatomy then you think that you know so much about genetics lastly we study the cell cycle and cell division cell cycle is basically the events and stages that the cell undergoes from the time a cell is formed until that cell divides into two daughter cells so that's what we call cell cycle the phases and stages and events that a cell undergoes from the time a cell is formed up to the time that the cell divides into two data cells and cell division is when a cell divides into two daughter cells basically so we look at that as well we look at the phases of the cell cycle we look at the process of mitosis we look at the process of meiosis you are most likely familiar already with mitosis analysis and perhaps not so familiar with cell cycle if you are being introduced to human anatomy for the first time fair enough so this is the scope of cytology how about the scope of histology we generally divide histology into two we have what you call basic histology and systemic histology when you talk of basic histology we focus on the histological organization of the four basic tissues now i need to highlight this i told you that we have over 100 different cell types in the body if you have to just list them but these cell types when they combine the form tissues and i told you we have over 20 different types of tissues in the body however if you group these tissues even though there are over 20 different types of tissues this over 20 different types of tissues can be grouped into four major categories and those four major categories are the ones we are calling the four basic tissues the four basic tissues are these ones we have epithelial tissues have connective tissues we have propulsion tissues and we have never stitches these are the four basic tissues so you most likely have a lecture on epithelial tissues a separate collection connective tissues maybe multiple of them separate electron propulsion tissue and nervous stitch again maybe multiple of them for that one when you look at the organization of the four basic tissues we call that basic histology then there's what we call systemic histology systemic histology is when you look at the microscopic organization of the various organs in the body but not randomly you look at them according to their organ systems for example you can say today we are going to look at the microscopic organization of the organs of the digestive system so look at microscopic organization or microscopic structure of the esophagus stomach liver rectum pancreas so that becomes what you call systemic histology you are looking at the histological organization of each organ system in the body of different organs according to their organ systems depending on the mode that your cause requires in terms of delivering anatomy that may have different facets it may be incorporated as part of your systemic uh gross anatomy then highlighted within or could be just a separate lecture on its own for each system it depends on the level of detail that's required of your course right the third division of anatomy that i want to finish with is developmental anatomy when you talk of developmental anatomy what are we referring to developmental anatomy is the study of prenatal developmental processes we are studying the things which happen before birth so in terms of delivery we usually start from the times from the time that the gametes are formed the time that the sperm is formed the time that the oocyte is formed remember the male gamete is called the sperm the female gamete is called the oocyte of the ovum so from the time the gametes are formed the term we used earlier for that is gametogenesis we start from gametogenesis and when do we stop when that baby is born assuming that the whole thing is a success when we do this we don't just look at the normal process we also focus on the abnormal developmental processes so developmental anatomy does not just look at the normal it also highlights the abnormal processes those abnormal processes that may have happened during embryonic period and therefore may have implications on the child or on the pregnancy so you focus on them and so this is the division of anatomy that will help us to understand the basis of congenital malformations congenital malformations are birth defects this is a division of an atom that help us to understand bad defect for example if a child is born and they don't have a brain how do we explain that if a child is born and they don't have one of the limbs how do we explain that so this is the division of anatomy that help us to understand the basis of those birth defects assume my baby has been born and you look and you wonder are they male or are they female you can't tell or this baby has been born and they only have one eye in their forehead instead of two that we expect how do we explain this this is a division of anatomy that tries to explain the basis of malformations in terms of delivery we talk about some events that take place before conception and remember this would be the gametogenesis gametogenesis the process of development of the garments so when you form the sperm you call it spermatogenesis and when you form the oocyte we call it ogenesis gametogenesis takes place within the gonads the male gonna discard this the testes and the female government is called the ovary so spermatogenesis takes place in the test is genesis takes place in the ovary when that has happened the next step that we talk about is fertilization this is the process of fusion of the sperm and the oocyte the fusion takes place within the fallopian tube so in this division of anatomy we look at gametogenesis we also look at the process of fertilization once fertilization has happened then we know that the woman has conceived or at least conception has taken place you know these days the conception doesn't have to happen within the woman as intervention can still happen in a test tube as part of interventions and you'll be taught more about that depending on the cause you're doing but assuming a natural process fertilization takes place within the fallopian tube once conception has taken place we are now ready for development after conception i prefer dividing the period into three for the sake of understanding some key events that take place the first period is what i call the pre-embryonic period or the early developmental period you can call it early developmental period of the pre-embryonic period and this in particular refers to the first two weeks after conception the first two weeks after conception this is what you are calling the pre-embryonic period during these first two weeks some key things happen one of them is basically that the concept as whatever has been formed will move from the site of fertilization to the site of implantation implantation is the attachment apart from that during this period we also have implantation itself and when the concept has implants usually inside the uterus when it implants on the wall of the uterus then we say now pregnancy has been established so the woman is now pregnant before that implantation we can talk of pregnancy in particular implantation largely takes place during the second week after fertilization the period from the third to the eighth week after fertilization is known as the embryonic period of development the embryonic period of development is an important period of development because this is the period when the body organs actually form so we call it the period of organogenesis the period when body organs of the baby form the period of organogenesis it becomes the most sensitive period in embryology because this is the time the different organs and organ systems are established almost all of them it is therefore the most sensitive period print development and i'm saying that to mean that if there's some um maybe not so good chemicals that interfere with the development of this period then there are higher chances of the baby developing some congenital malformations so this is the period that most that the concept has is most at risk of development of congenital malformations after the eighth week from the time of conception we talk of the fetal period of development so the fetal period of development is a period from the ninth week until when the baby is born there's a fitter period of development the phytoplankton is largely a period of maturation of body organs the body organs mature but it is also like the period of ossification ossification is basically formation of bones the bones don't particularly form during this period but they form largely in this period most of them now in terms of bank in terms of bank this embryonic period of development has a lot because it's the one that explains to us more about the development of each organ system in the body so over 90 percent of books of developmental anatomy are dedicated largely on the embryonic period of development according to the different organ systems and so embryology can also be taught to you in a different way depending on the course you're doing we may divide the embryology into two so we may have developmental anatomy into two that we have what we call the basic and there's what we call the systemic or the general and the systemic in general embryology that's when you'll be taught more about gametogenesis and fertilization you'll be taught about what happens in the first two weeks of development you may be taught about the things that happen the third and the fourth week of development in general and you can be given an overview of what happens in the fetal period of development but now in the systemic embryology it focuses largely on the embryonic period of development for each and every system in the body largely talking about how do the body organs form according to the organ systems it forms a bulk of developmental anatomy it is for that reason therefore that developmental anatomy is also termed embryology and i hope you notice that even me i use the term embryology even before telling you why i use the timing build because largely subconscious so developmental anatomy is commonly referred to as embryology for that reason and so you can use the term interchangeably again you can call it embryology or developmental anatomy the common term is actually embryology but i just wanted to use a more scientific correct term before i can explain to you why it can also be called embryology subsequently you can just call it embryology maybe i say something again about this dating thing the debts i've given you here if you were keen you noted that i was talking about after conception so we call that the embryonic dating the embryonic dating is based on the number of days or period after conception so that perhaps conception is considered day one but that's not the kind of dating that you'll be hearing often in clinical practice or in basically in the market place you will not be hearing that much the one that will be hearing more are the best on the menstrual period of a woman now let me clarify this that uh in the menstrual cycle of a woman most women their menstrual days last menstrual cycle last each cycle lasts 28 days most women in such a case such a woman most likely ovulates around the 14th day of the menstrual cycle so if your cycle length is 28 days then you most likely as a woman of the elect on your 14th day and remember these days are not necessarily calendar days they are physiological days we consider day one of the men's cycle as the first day that the woman or a woman sees the menstrual flow so if the day that she sees the menstrual flow is considered the first day 14 days later that's around the time that we expect her to village if she her cycle length is 28 days around the time of ovulation is the time around which conception will also take place that means what that there is a period of two weeks between the day that the woman starts to see her menstrual flow and the day that she actually conceives there's a period of about two weeks difference but we don't use the conception days for practical purposes you know it'd be very difficult for one to tell you i conceived on this day and especially if she has sex almost every day it's not possible unless there's some particular intentions about it which may not be practical all the time so for practical purposes in as much as in developmental anatomy we use the embryonic dating and we'll be clarifying that one days after conception for practical purposes in the marketplace you'll be using what we call uh the gestational deaths gestational deaths are basically based on the days based on the menstrual flow of a woman and so they should have a difference of two weeks so when i say this woman is five weeks pregnant according to the gestational deaths in actual sense that embryo is three weeks old according to the embryonic dating i want you to be able to understand that because it may give you a lot of confusion when you interpret some things in the clinical practice and some things in embryology textbooks having said so you'll hear of the pregnancy a full-time pregnancy reaching 40 weeks so those 40 weeks are based on the gestational dating where the first day is the day that the woman saw the last normal menstrual flow the first day of the last normal menstrual flow if you count from there then give it 40 weeks but if you have to count the embryonic age then we'll go with 38 weeks right i think i have over emphasized on that one and so maybe just to juggle your mind a bit in terms of what you've done in this lecture we have defined what is human anatomy i believe you can do it i believe you can also name the main regions and sub-regions in the body i believe you can name now cartino 14 organ systems and state at least one key role for each i believe you can also describe the levels of organization of the human body from simple you can start from atom up to complex the organism you're able to name the four key basic tissues and you can outline for us the prenatal developmental periods as i've done to you and so that will be the end for that lecture thank you very much that was the end of the first part of the introductory lecture which was focusing on definitions and scope of human anatomy so you can watch out for the second part of the lecture that will focus on anatomical terms and the aim of this is basically to help us familiarize with the anatomical language thank you very much we'll stop there