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Introduction to Human Body
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0:01
Hi Everyone. Welcome to anatomy and physiology. In this first chapter, An Introduction to the Human Body, we are going to look at and examine some anatomical terms, anatomical structures, we are going to examine some prefixes, and we are also going to examine the structural organization of the human body. So we're going to talk a little bit about the eleven organ systems that you will be studying throughout the anatomy and physiology courses of Anatomy 1 and
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Anatomy 2. So let's take a look and see what Anatomy means. Anatomy is the study of the structure of body parts and the relationships to one another. That's going to be different from physiology, which we'll get to in a second, which is the study of the function of those body parts. So when we look at the form or structure, we can divide anatomy into what we call gross or microscopic anatomy. Gross anatomy is the study of structures large enough to be seen with
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the naked eye. Microscopic, which can be further subdivided into cytology and histology, is a study of structures that are too small to be seen with the naked eye. And when you get into lab you will study histology in more detail. So here is an example of gross anatomy where we could look at large structures such as the brain. We could also examine the heart the stomach as other examples. Microscopic we can't see with the naked eye so we generally use a microscope and
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in lab you'll be using a compound microscope to study certain histological structures like different forms of epithelial tissue or connective tissue. In this example, we're looking at a neuron and you can see the neuron cells and we can even see the little dark spot in the center of the cell which is the nucleus. You'll be examining various organelles of the cell later on. So gross anatomy we can even further subdivide into regional, surface, or systemic anatomy. Surface anatomy is the study
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of internal structures as they relate to the overlying skin surface. Regional anatomy considers the regions of the body like the head and the extremities and all the systems in a particular region. We will be studying different regions of the body like the abdominal pelvic region which looks at the abdominal organs and the pelvic organs or the thoracic region which encompasses the lungs. Systemic anatomy gives attention to all the structures of a particular system in the body regardless
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of location. Microscopic anatomy, again micro means small, so we're concerned here with structures that are too small to be seen with the naked eye. Now there's different types of microscopes that we can use to study these structures again in our lab, we will be using the compound light microscope but there are also dissecting microscopes that you may use in other courses. The electron microscope, which allows us to see even further detail. Now within microscopic anatomy, cytology
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is the study of individual cells (cyto = cells) and histology (histo means tissues) so we're looking at the study of tissues and their functions. Physiology is the study of function and physiology has various there's several topics most of which consider the function of specific organ systems. Physiology often focuses on events that are going on either within the cell or even at a molecular level. So there is cell physiology, for example immunology, renal physiology, and cardio
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vascular physiology. And those are just a few examples of the subdivisions of different organ systems. So renal, we would look at the kidneys for example. Cardiovascular, we would study the operation of the heart and blood vessels.
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Now the basic principles of cell theory are that 1) cells are the building blocks and that includes all plants and animals; 2) cells are produced by the division of pre-existing cells through mitotic division for example and 3) cells are the smallest structural units that perform all vital functions. We will examine the cell in more detail. The cellular level is the smallest unit of life and it varies widely in size and shape according to the cells function. Now if
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we look at the different levels of organization we can see that we have the molecular level and for example, hydrogen and oxygen atoms. So atoms they are the building blocks of matter. Now they can combine to form molecules. Molecules combine in specific ways to form organelles which are the basic unit of living cells. So at the cellular level, we can examine for example interactions between molecules and compounds that form the organelles of cells. Cells again
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they are the structural building block of all plants and animals. And then we have the tissue level. Tissues are groups of similar cells. A tissue level is a group of cells that have a common function. So these are cells that work together to perform one or more specific functions. Examples would be muscle tissue, nerve tissue, connective tissue, or even epithelial tissue. Next, we have the organ level. So organs contain two or more types of tissues. The organ level is
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made up of discrete structures that are composed of at least two groups of
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specific function in the body. Then we have the organ system. These are organs that work closely together. The organ system level is a group of organs that work closely together to accomplish a specific purpose. The types of tissues that comprise organs and organ systems perform vital functions of the body. Then finally we have all organ systems, the highest level This is the total of all structures working together to promote homeostasis in the body. And we will be examining
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different organ systems. So here's some examples of organ systems that we will study throughout your course in anatomy one and in anatomy two: 1) the lymphatic system. The lymphatic system is composed of lymph nodes, spleen, thymus gland, bone marrow, and tonsils. It also houses the immune system cells of the body, provides protection against infection and disease, transports tissue fluid called lymph, and absorbs fats. 2) The respiratory system is also shown
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here and it's composed of the lungs, trachea, larynx, and nasal passages. This is where we have the exchange of respiratory gases like oxygen and carbon dioxide between the air and circulating blood. 3) The muscular system is composed of muscles attached to the skeleton which provide locomotion, support, and body heat production. 4) The nervous system is composed of the brain, spinal cord, and peripheral nerves. The nervous system is one of our two communication systems
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of the body with the endocrine system being the other. The nervous system directs immediate responses to stimuli usually by coordinating the activities of other organ systems. 5) The integumentary system is composed of the skin, hair, and nails. It provides external support and protection of the body and also is involved in temperature regulation. 6) The skeletal system is composed of bones and it provides internal support and a flexible framework for body movement. In
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addition, it forms blood cells and stores minerals. 7) The endocrine system is composed of hormone secreting glands like your thyroid gland, pituitary gland, adrenal gland, pancreas, pineal and others. The endocrine system functions to secrete hormones that direct long-term changes in the activities of other organ systems. 8) The cardiovascular system is composed of the blood, heart, and blood vessels. It provides internal transport of nutrients and oxygen to body cells while also
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removing wastes and carbon dioxide being transported away from body cells. 9) The digestive system is composed of the salivary glands, esophagus, stomach, small intestine, large intestine, liver, and gallbladder. The digestive system is involved in taking in nutrients, breaking them down, and allowing for the absorption of food in order for the cells of the body to acquire nutrients, minerals, vitamins, and water while also eliminating waste products in the form
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of fecal material. 10) The urinary system is composed of the kidneys, ureters, urinary bladder, and urethra. The urinary system filters the blood to remove nitrogenous waste products, eliminate excess water, salts, and waste products, while also controlling pH and electrolyte balance of the body. 11) The reproductive system we have both the male and female. Female reproductive system which is composed of ovaries, the uterus, vagina, and mammary glands in the female
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and in the male you have the testes, scrotum, prostate gland, seminal vesicles, and penis. The reproductive system is involved in the production of sperm and egg as well as the secretion of sex hormones and copulation. So these are the organ systems of the body and you need to be sure that you can identify the major organs of each of the 11 organ systems and also be sure you can identify the major functions of each of the 11 organ systems that we just went over.
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remember the cells of the body depend on the organ systems to meet their survival needs and the organ systems of the body work cooperatively to perform necessary life functions and there is a couple of tables listed here which gives you some information and characteristics of living organisms so a living organism is able to respond it means it has the ability to sense and detect both internal and external stimuli and to generate a response appropriate to that
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stimulus that's required in order for an organism to adapt be able to change their behavior modify provide capabilities or structure because we're constantly in a changing environment and so we have to be able to adapt for example to different changes in temperature may be different changes in oxygen level if we travel to higher altitudes so those are a couple of examples growth and development we have to be able to increase in cell size in size and cell number so we have
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patterns for growth and development reproduction we have to be able to reproduce in order to produce the next generation we have to be able to move about so we have to distribute materials throughout large organisms be able to change our position or orientation even a plant has to do that maybe to get more sunlight or the roots to grow in order to have access to water animals we have to be able to move around respiration we have to be able to take in oxygen distribute it to our cells and get rid
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of the metabolic waste product from breathing which is carbon dioxide
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now the other requirement or characteristic of living organisms circulation is the movement of fluid so we transport fluids within the organism and within the human body that involves the cardiovascular system which is our heart as the pump and we have a network of blood vessels digestion the breakdown of ingested foodstuffs in very simple molecules that can be easily used for chemical reactions in the body and be absorbed across cell boundaries excretion we have to be able to remove
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chemical waste products that are a natural part of the multitude of metabolic processes that occur within the human body so here's an example marathon they demonstrate two characteristics of living or humans or organisms they can respond and move there is anatomical structures and physiological processes in place that allow runners to coordinate actions of muscle groups and also sweat in response to rising internal body temperature which allows the body to cool metabolism so metabolic
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processes are constantly occurring in the body and there is a series of reactions anabolic reactions those are reactions that build things and catabolic reactions which break materials down and release energy metabolism includes both anabolic and catabolic reactions catabolic reactions again they release energy so when we take in food for example we break that food down into smaller and smaller components so that the body can absorb those nutrients we release energy in the
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process if we want to build things within the body like hormones that's an anabolic process and that requires energy input now the requirements for human life are we need oxygen nutrients a narrow range of temperatures and atmospheric pressure oxygen oxygen is only a small percentage of atmospheric air about 20% but that oxygen is a key component of the chemical reactions within our bodies that help keep us alive and this includes reactions that you will study later on that produce ATP
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nutrients substances in our food in our beverages that are essential to human survival the three basic classes of nutrients are water the energy building are yielding nutrients carbohydrates and lipids and body building nutrients proteins and the micronutrients vitamins and minerals we also need a narrow range of temperature so the body can respond to short-term changes in body temperature for example as you just saw sweating went to hot or shivering when it's too cold when body temperatures
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rise well above or drop well below those normal levels certain proteins or enzymes that may facilitate chemical reactions might lose their normal structure and their ability to function and the chemical reactions of metabolism cannot proceed we also need a stable atmospheric pressure atmospheric pressure is the pressure that's exerted by the mixture of gases which are primarily nitrogen and oxygen in the Earth's atmosphere although you may not perceive it readily atmospheric pressure
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is constantly pressing down on your body this pressure keeps gases within your body dissolved in your blood plasma your ability to breathe take in oxygen and release carbon dioxide also depends on a precise atmospheric pressure and you will study this in further detail in anp2 when you discuss the respiratory system so some examples of these requirements for human life are shown here harsh conditions like at a high altitude found on Mount Everest climbers to accommodate extremes in temperature
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low oxygen levels low barometric pressure so the body has to adapt or they must have resources in place in order to survive in those conditions extreme temperatures humans can adapt to some degree to repeated exposure to high temperatures but the temperature again cannot get too high or it can damage certain proteins or enzymes within the body and all of this is important to homeostasis homeostasis is the ability of the body to maintain a relatively constant internal environment regardless of
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environmental changes it involves continuous monitoring and regulation of many factors or variables which include for example both volume of fluid composition of chemicals in our in our fluid and we have systems in place that measure and monitor homeostasis so we have to maintain homeostasis this steady-state environment a balance or equilibrium where our internal conditions remain relatively constant despite changes in external conditions this is vital to an organisms survival
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failure to maintain homeostasis results in illness disease and can even result in death homeostatic control is not precise it maintains a normal range rather than an absolute value or setpoint and an example of this can be seen within our blood pH our blood pH ranges between seven point three five and seven point four five now the setpoint is seven point four but it can vary little bit on either side of that now homeostatic regulation involves feedback mechanisms that consist of two three
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components a receptor a control center and an effector now let's look at example of this so the receptor is also known as the sensor it detects changes in either the internal or external environment or stimulus the control center receives and processes that information supplied by the receptor and sends out a command and that command goes to the effector which responds to the commands by opposing the stimulus this is an example of a negative feedback loop which provides stability
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and is the main way the body maintains homeostasis so an example of that is provided here body temperature it exceeds 37 degrees Celsius your nerve cells in your skin in your brain sense this that information is sent to your temperature regulatory Center in your brain which sends out signals to your sweat glands throughout the body to perspire which cools the body as the sweat evaporates now homeostasis is not precise there is some oscillation around the setpoint and that is pretty much a
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characteristic of homeostatic control mechanisms now another type of feedback mechanism that you should be familiar with is positive feedback negative feedback as you saw goes in the opposite direction of the change positive feedback mechanisms enhance or exaggerate the original stimulus so it causes sometimes a cascade or amplification effect and it accelerates a process generally to completion so it intensifies or enhances the original stimuli an example is shown
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here with childbirth labor contractions so the brain stimulates the pituitary gland to secrete oxytocin a hormone oxytocin goes via the blood stream to the uterus it stimulates uterine contractions and pushes the baby towards a cervix as this process continues the head of the baby pushes against the cervix and then the nerve impulses from the cervix is transmitted to the brain so once the baby is born the stimulus is removed and the process is shut off positive feedback mechanisms typically
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activate events that are again self-perpetuating most positive feedback mechanisms are not related to the maintenance of homeostasis in the body blood clotting is another example and homeostatic mechanisms are generally maintained through negative feedback now anatomical terms there is some anatomical terms that you must be familiar with and there is a series of tables that are presented here which will demonstrate various anatomical terminology so we have to know these anatomical terms roots
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prefixes suffixes you're even going to have to learn regional terms that indicate location in the body directional terms that are used for points of reference and so on so Anatomy uses a special language it does have an origin in Latin and Greek which is named after the discovery and knowing these terms will help you throughout your study in this course so word roots prefixes and suffixes are listed here for you make sure you know all of these roots prefixes and suffixes
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so for example cardio means heart endo within chemo blood this will help you later on Myo muscle and then you've got different regions of the human body now one thing to note in this picture is the anatomical position is being demonstrated so to further increase precision anatomist standardized the way in which they view the body so just like a map is normally orientated with north at the top the standard body map or anatomical position is that of the body standing upright with the feet at
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shoulder width and parallel toes facing forward the upper limbs are held out to each side and the palms of the hands face forward a body that is lying down is described as either prone or supine prone describes a face down orientation supine describes a face up orientation so there's various regions of the human body and they are used to indicate locations on or in the body like the abdominal region anterior torso below the diaphragm the brachial is the arm axillary is the armpit buccal is
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cheek coxal hip so you have to know all of these regional terms that indicate locations on or in the body you also have to be familiar with directional terms and sectional terms that describe specific points of reference on the body so anterior or ventral is toward or at the front of the body posterior area or dorsal is toward or at the back of the body superior or cranial is above toward the head end or upper part of the structure or body inferior or caudal is
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below away from the head end or toward the lower part of the structure or body medial toward or at the longitudinal axis of the body towards the midline lateral away from the longitudinal axis away from the body
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proximal closer to the origin of the body part or the point of attachment of a limb to the body trunk distal farther from the origin of a body part or the point of attachment and then we have superficial or external toward or at the body surface and deep or internal away from the body surface more internal we also have various sectional planes a sagittal plane is a vertical plane that divides the body into right and left parts now we can have a midsagittal plane which divides the body exactly in
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the midline parasagittal are all other sagittal planes that are offset from the midline frontal or coronal any plane dividing the body into an anterior and posterior portion and a transverse or horizontal is a plane dividing the body into superior and inferior portions not shown here is an oblique which is a cut that's made diagonally between a horizontal and a vertical plane in addition you have to learn body cavities body cavities protect internal organs from shock or impact and allow them to
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change shape so you have the dorsal body cavity which is composed of two smaller cavities the cranial cavity and the vertebral cavity the cranial cavity contains the brain the vertebral cavity contains the spinal cord the ventral body cavity also known as the coelom houses internal organs of the body and those are collectively generally referred to as the viscera or guts you have the thoracic cavity which contains the pleural cavity the right and left contains the lungs and the mediastinum
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is the space between the pleural cavities containing the thymus lymph vessels esophagus trachea and nerves now you see they have the abdominal cavity and the pelvic cavity this is sometimes also referred to as the abdominal pelvic cavity the abdominal cavity contains digestive organs the pelvic cavity contains the bladder reproductive organs and rectum the
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dorsal and ventral body cavities are shown here again the ventral body cavity however includes membranes ventral body cavities are lined with serous membranes all serous membranes are double layered the outer layer is the parietal layer which is the layer that's more towards the body wall while the inner layer is called the visceral more towards the organs and between the parietal and visceral layers is a watery lubricating fluid called serous fluid and you'll be
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studying serous membranes throughout the course so here's some tables again they give you the regions of the human body some of the areas you have to know and in the abdominal pelvic region we can also divide this into quadrants and regions so the abdominal pelvic quadrants you have the right upper quadrant which contains the liver the left upper quadrant contains the stomach and spleen the left lower quadrant contains the descending colon and the right lower quadrant contains the cecum
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and ascending colon and so that would be this blue line here which is dividing it into four quadrants the red lines are dividing the abdominal pelvic into regions you should know the quadrants and regions and the organs contained within the umbilical region is the centermost region deep to and surrounding the navel the epigastric is superior to the umbilical region the hypogastric is located inferior to the umbilical region the right and left hypochondriac flanks the
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epigastric region laterally the right and left lumbar lies lateral to the umbilical region and the right and left iliac or in Guino is lateral to the hypogastric region and you've got some pictures here that show those different regions that I just went through so there's your different abdominal pelvic regions here is the serous membranes that I refer to so again visceral more toward the organ parietal lining the body wall the example shown here is the heart where you've got the
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parietal pericardium which lines the perio cardial cavity and you can see the visceral pericardium so serous membranes again they usually are their double layered and between the visceral and the parietal is that lubricating fluid called serous fluid now there's many different ways that we can take images of the human body without actually having to go through an invasive procedure so different types of medical imaging that can be used or x-ray machines CT machines MRI machines
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pet machines or ultra sonography and you're going to see some examples of those next so an x-ray is a high-energy electromagnetic radiation which allows us to see internal structures of the body like our bones so if you've ever broken a bone or has suspected breaking a bone you may have had an x-ray taken other types of medical imaging or shown here so a CT scan in this top portion here shows different areas of the head and these are transverse sections an MRI machine
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uses a magnetic fields PET scans are another way to create images and they can show active blood flow or the activity of an organ that they're examining ultrasound technology is quite often used to monitor pregnancies because it's the least invasive imaging technique and there is no electromagnetic radiation therefore it's not harmful to the developing fetus this concludes chapter one an introduction to anatomy and physiology
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