good afternoon class this is our first lecture of the semester in our uh human anatomy and physiology class um so this is unit one chapter one part a so this first chapter is is an introductory chapter uh and it's mostly definitions and um it's um like i said it's an introductory chapter why is why is it important to uh to understand anatomy and physiology well you know most people wonder why do i have a fever why am i so achy you know when we get the flu and uh you know it would be nice to come with an owner's manual but we don't uh have one for the uh for the uh human body so uh this is the closest we can we have so what is anatomy and physiologies uh anatomy is basically the study of the structure of body parts and how they relate to one another and physiology is the study of the function of those of the body parts so anatomy is the study of both the internal and external structures of the body and physiology is the study of how organisms perform their vital functions so let's say someone uh that studies physiology might consider how a muscle contracts or what forces a contracting muscle exerts on the skeleton let's start looking at subdivisions of anatomy so let's start with gross or microscopic anatomy which is the study of large visible structures so structures that are usually visible with the unaided eye and under this we have several approaches such as looking at the regional anatomy which looks at all structures in a particular area of the body for example the head neck or trunk region system anatomy looks at just one system such as the cardiovascular system or nervous system skeletal system and surface anatomy is the study of general form and superficial markings microscopic anatomy deals with structures that cannot be seen without magnification so for example with a light microscope you can see details basic details of cell structures whereas with an electron microscope you can see individual molecules that are only a few nanometers across using microscopy we can look at we can study cytology cytology is the analysis of the structure of individual cells and cells are the simplest units of life uh histology is the uh examination of tissues which are which are groups of specialized cells and cell products that work together to perform specific functions and you know tissues will combine to form organs examples of organs are the heart the kidney the liver or the brain also developmental anatomy is studies anatomical and physiological development through the lifetime of a human being embryology is the study of developments before birth so to study anatomy one must know anatomical terminology and be able to observe manipulate palpate and auscultate as we said earlier human physiology is the study of the functions of the human body these functions are complex and much more difficult to examine than most anatomical structures as a result there are even more specialties in physiology than in anatomy so there are subdivisions of physiology which could be based on organ systems for example renal physiology which is on uh you know talking about you know the kidney and and its workings neurophysiology is the nervous system and cardiovascular physiology and other physi organ systems also i can you know physiology can focus on the cellular and molecular levels of the body so cell physiology is the study of the functions of cells which is the cornerstone stone of human physiology cell physiology deals with events at the chemical and molecular levels both chemical processes within the cells and chemical interactions between cells just think of um well you know physicians uh normally will use a combination of anatomical uh physiological and such psychological information uh when they uh evaluate patients if you think back to your last trip to a doctor's office not only they examined your body they may have done you know look you know examined for any anatomical abnormalities but they also asked questions about your let's say observing your movements listening to body sounds taking your temperatures or even looking at chemical analysis of fluids such as blood or urine so anatomy and physiology are inseparable the link between structure and function is always present but not always understood for example the anatomy of the heart was clearly described in the 15th century but almost 200 years passed before the you know the pumping action of the heart was uh demonstrated an example of the complementarity of structure and function is seen in teeth uh so the sharp edges of incisors make them ideal for cutting like scissors whereas the flat surfaces of molars make them ideal for grinding it's kind of like a mortar and pestle one of the characteristics of living beings is this structural organization so the human body is very organized and if we look at its smallest component and how it's organized to form a whole organism so we start at the chemical level which is made up of atoms and molecules and organelles and cellular level is the single cell which we said is the uh the uh smallest uh unit of life uh the tissue level is groups of similar cells working together the organ level contains two or more types of tissues organ system level is when organs that work closely together and the organismal level is all the organ systems combined to make the whole organism an example of levels of structural organization is seen here in figure 1.2 so we start with the minute atoms that will combine together so atoms like the hydrogen atom oxygen carbon they form molecules and these molecules will form molecules such as co2 carbon dioxide and water which will some of these molecules will combine to form larger molecules called macromolecules we we will talk about those in a few classes and these macromolecules will form organelles so here we see a mitochondrion we're going to talk about this organelle in a few classes as well and its job is a powerhouse of the cell so organelles make up are the components of a cell so in this example we see the smooth muscle cell and similar cells will combine to form a tissue and here we see that uh so for example smooth muscle tissue is found within the walls of a blood vessel and so that's at the organ level so the blood vessel is an organ and um the blood vessel is a component of the organ system of the cardiovascular organ system and um and the cardiovascular system is part of the organism so the organism level so at the level of the organism we have different types of organ systems such as skeletal muscular nervous endocrine lymphatic respiratory digestive urinary reproductive system and shown here the cardiovascular system biologists have found that all living organisms share certain requirements that are necessary for life for example maintaining boundaries movement responsiveness digestion metabolism excretion reproduction and growth and we'll discuss each one of them one of the necessary life functions is the is being able to maintain boundaries uh in other words a separation between internal and external environments uh so we're going to when we look at the structure of cells we'll learn about the important role of the plasma membrane to be able to separate the cell and activis act as a selective selectively permeable membrane that will allow certain molecules to move in or out of the cell also the skin acts as a barrier that separates the organism from its environment another characteristic necessary for life is movement the ability to to so organisms are capable of producing movement which could be which involves a muscular system to allow for this movement uh so it could be movement of body parts via skeletal muscles so this is uh it's an external uh movement uh so moving through the environment as opposed to movement of substances via cardiac muscle so the movement of blood or the movement of food or other materials you know through smooth muscle and this type of movement is more is internal contractility refers to the movement at the cellular level responsiveness is the ability to sense and respond to stimuli organisms respond to changes in their immediate environment so like the withdrawal reflex will prevent injuries so you know you move your hand away from a hot stove uh also control of breathing rate which must change in response to different activities another characteristic of living organisms is digestion it's the ability to break down ingested foodstuffs followed by the absorption of simple molecules into blood organisms rely on complex chemical reactions to provide the energy for responsiveness growth reproduction and movement and metabolism is the uh refers to all the chemical operations underway in the body so it's the sum of all catabolic uh reactions which is the breakdown of molecules and anabolic reactions which is the synthesis of those uh molecules so many normal metabolic operations require the absorption of certain nutrients from the environment and these nutrients are for the uh maintenance uh of uh of the body and uh for as energy sources uh so metabolism often generates unneeded uh or potentially harmful waste products that have to be removed uh so for example urea is generated from the breakdown of proteins uh carbon dioxide is a byproduct of metabolism feces uh these is unabsorbed foods and these have to be removed from the body other characteristics uh necessary for life functions are reproduction and growth so uh for reproduction at the cellular level uh reproduction involves the division of cells so that the organism can grow or repair at the organism organismal level you know how organisms will reproduce creating subsequent generations of similar organisms growth is you know so over a lifetime organisms grow larger increase in size by increasing the size or number of their cells humans are multicellular that means they're made up of trillions of cells so to function these individual cells must be kept alive and the way uh that is achieved is through the uh um the uh coordinated um the coordination of the organ systems so there are 11 organ systems that work together to maintain life the digestive system um actually no let's look at this figure this is figure 1.3 this shows um examples of interrelationships among the body organ systems so for example the digestive system will take in nutrients such as carbohydrates protein like sugars and proteins and lipids such as fats and will the body will the elementary tract will break them down and anything that is not absorbed will be uh uh will be eliminated in the form of feces so those nutrients are are will will be absorbed and the cardiovascular system will distribute the nutrients to all the body cells uh and the respiratory system will take in the oxygen and will get rid of the carbon dioxide that is produced by the tissues uh and again the cardiovascular system is going to distribute the oxygen uh to all the body cells uh and will get rid of the uh waste and carbon dioxide to be disposed of within the urinary system which eliminates nitrogenous wastes and any excess ions so at the level of the interstitial uh or interstitial level nutrients and waste will pass between blood plasma and cells the integumentary system will protect the body as a whole from the external environment let's start looking at the body's organ systems the 11 organ systems let's start with the integumentary system so the major organs of the integumentary system are the skin hair nails we want maybe to include sweat glands as well so its major functions are things like making synthesizes vitamin d also protects against the environmental hazards also helps regulate body temperature and provides sensory information through the presence of cutaneous receptors like things like for pain pressure let's look at the skeletal system so major organs of the skeletal system are the bones uh associated cartilages sorry bones cartilages associated ligaments and bone marrow so some functions of the skeletal system are it provides support and protection for other tissues also stores calcium and other minerals and will form blood cells the muscular system is composed of the major organs are the skeletal muscles and associated tendons and some functions are it provides movement provides protection and support for other tissues generates heat that maintains body temperature the nervous system is made up of the brain the spinal cord peripheral nerves sense organs and some functions are it directs immediate responses to stimuli coordinates or moderates activities of other organ systems and provides and interprets sensory information about external conditions the endocrine system is made up of the pituitary gland pineal gland the thyroid gland the thymus the adrenal gland which is are found they're actually a paired paired gland found on top of the kidneys the pancreas ovary and females test this in in males some some functions are they will direct long-term changes in the activities of other organ systems will adjust metabolic activity and energy use by the body uh can will control many structural and functional changes uh during development the cardiovascular system major organs are the heart the blood vessels and blood functions are the distribution of blood cells water dissolved materials such as nutrients waste products oxygen and carbon dioxide another function is the distribution of heat and the control of body temperature the lymphatic system is made up of the spleen the thymus lymphatic vessels and lymph nodes and functions are it defends against infection and disease and also will return tissue fluids to the bloodstream major organs of the respiratory system are the nasal cavities the sinuses the larynx also known as the voice box the trachea the bronchi the lungs and within the lungs are those tiny little sacs called the alveoli their little air sacs functions are to deliver air to the alveoli that's where gas exchange occurs uh also provide oxygen to the bloodstream remove carbon dioxide from the bloodstream and production of sound for communication major organs of the digestive system are the teeth the tongue the pharynx which is a common passage for both food and air the esophagus that long tube the stomach the small intestine the large intestine the liver the gallbladder and the pancreas some functions are it processes and digests food absorbs and conserves water because of course we're terrestrial organisms so we need to conserve water or else we desiccate absorb nutrients such as ions water and also the breakdown products of dietary sugars proteins and fats and stores energy reserves the major organs of the urinary system are the kidneys the ureters the urinary bladder and the urethra so functions of the kidneys are the excretion of waste products from the blood also the kidneys will control water balance by regulating volume of urine produced the kidneys will also regulate blood ion concentration and ph whereas urinary bladder will store urine prior to voluntary elimination the major organs of the male reproductive system are the testes epididymis ductus deferens and the associated glands such as the prostate glanders also seminal vesicles which are not shown there also there's a penis and scrotum and the function of the male reproductive system is to well the testes will produce the male sex cells known as sperm and the hormone known as testosterone the major organs of the female reproductive system are the ovaries the uterine tubes the uterus the vagina and the mammary glands functions of the female reproductive system are the production of female sex cells known as ool sites and hormones such as progesterone and estrogen also it will support the developing embryo from conception to delivery and provides the mammary glands will provide milk to nourish a newborn infant humans will need nutrients oxygen water uh maintain a normal body temperature and a an appropriate atmospher atmospheric pressure uh these are several factors uh needed for survival they must be in the appropriate amount too much or too little can be harmful we obtain our nutrients through our diet which contains the chemical substances used for energy and cell building so nutrients are examples of nutrients are carbohydrates which are the major source of energy proteins are needed for cell building and cell chemistry uh the the role of fats is for long-term energy storage and uh also in nutrients are minerals and vitamins which are involved in chemical reactions as well as for structural purposes uh all the nutrients in the world are useless unless oxygen is also available uh so it's essential for release of energy from foods the body can survive only a few minutes without oxygen water accounts for 50 to 60 percent of our body weight as we age we have less water and it's the most abundant chemical in the body it provides the watery environment needed for all the biochemical reactions all of those metabolic reactions that occur in our body it's also uh also is fluid-based for secretions and excretions uh normal body temperature so you know for uh chemical reactions to continue you know there has to be this this normal body temperature and for humans it's 37 degrees celsius or 98.6 fahrenheit uh so metabolic reactions would be affected uh so in other words uh lower temperatures they would slow down at higher temperatures uh you know they they would also it would affect the enzymes i know we haven't talked about enzymes yet but it would be you know the enzymes are those molecules that are involved in the chemical reactions also the atmospheric pressure is the force that air exerts on the surface of the body uh and it's very important for adequate breathing and gas exchange in the lungs for example at high altitudes where atmospheric pressure is lower and the air is thin gas exchange may be inadequate homeostasis is the body's ability to maintain relatively stable internal conditions uh despite the continuous changes in the environment and it involves the contributions of all organ systems the body must constantly be monitored and regulated to maintain homeostasis uh its nervous system and endocrine system play the major role in maintaining the stable internal environment uh for example the nervous system will direct rapid short-term and very specific responses so for example let's say you accidentally put your hand on a hot stove the heat will produce a painful localized disturbance of homeostasis so your nervous system will respond by causing your contraction of these specific muscles that will pull your hand away from from the stove on the other hand the endocrine system will release the chemical messengers they're called through hormones uh and these responses may not be uh immediately apparent but when the effects appear they may persist for days or weeks there are variables these are factors that can change such as for example blood sugar levels body temperature blood volume and uh there are three components that control these variables the receptor the control center and the effector okay so let's look at these uh three components so the receptor is a sensor that is sensitive to a particular environmental change or stimulus the control center also knows known as the integration center will receive and processes the information supplied by the receptor and will determine an appropriate response and the third component is the effector which receives the output from the control center and provides the means to respond and the response can either reduce the stimulus as seen in a negative feedback mechanism or will enhance the stimulus as seen in a positive feedback mechanism most homeostatic regulatory mechanisms will involve negative feedback negative feedback thus tends to minimize change keeping variation in key systems within limits that are compatible with our long-term survival so examples of negative feedback are regulation of body temperature which is a nervous system mechanism and the regulation of blood glucose by insulin which is an endocrine system mechanism so an example of negative feedback showing how the three parts are involved so the receptors will sense and increase blood glucose blood glucose levels blood glucose is a blood sugar the pancreas is the control center which will secrete insulin which is which is a hormone into the blood and insulin will cause body cells which are the effectors to absorb more glucose which decreases blood glucose levels okay so uh in figure 1.5 uh we'll see an illustration of how this works uh so the uh let's say there's a an imbalance in the system uh the stimulus will produce a change in the variable the receptor will detect that change afferent uh pathways will bring the information to a control center the control center will send an output along an efferent pathway to the effector and the uh the response of the effector uh is to reduce the effect of the stimulus and return the variable to an homeostatic level uh so in figure 1.6 we can see in another example uh where in this case body temperature is regulated by a negative feedback mechanism so we said that the normal body temperature in humans is 37 37 degrees celsius that's when the body is in in balance in a in a balanced state so let's say we look at on the left the stimulus is heat so let's say the body temperature rises uh there are receptors why would the body temperature rise either through you know because of uh fever or maybe uh exercise or it's really warm outside so there are receptors these are temperature sensitive cells in the skin and the brain will send afferent pathways to the control center the thermoregulatory center in the brain which happens to be the hypothalamus we're going to learn about that in next semester and the response is sent through an efferent pathway to the effectors which are the sweat glands the sweat glands are activated and the response is the evaporation of sweat and the and then as a res uh as a result the body temperature will will decrease will fall and the stimulus ends now how about if the stimulus is cold in other words the body temperature will drop lower than 37 degrees uh this is sensed at the level of the receptors which are temperature sensitive cells in the skin and brain which will send uh uh impulses through an afferent pathway to the control center the thermoregulatory center in the brain which will respond through efferent pathways to the effectors which are the skeletal muscles which will start shivering and the body temperature will increase and the stimulus will end another example of a negative feedback mechanism is with the control of blood sugar so exercise if we start from the left uh exercise will cause uh a drop in blood sugar this is will stimulate the pancreatic alpha cells to release glucagon so they're specialized cells within the pancreas to release glucagon which is a hormone that will target the liver and the liver is going to break down glycogen which is a stored form of a sugar of a carbohydrate so it will break it down to glucose and glucose is going to be released into the blood uh and then and then it's going to restore blood sugar levels to a normal to a normal homeostatic level now how about if let's say we eat too much okay after eating a meal for example that will increase blood sugar levels and that will be the stimulus to cause the pancreatic beta cells these are specialized cells to release insulin insulin is a hormone that targets the fat cells also known as the adipose cells to take up glucose and and that will decrease blood sugar levels in a positive feedback mechanism an initial stimulus produces a response that exaggerates or enhances the change in the original conditions rather than opposing it usually in the body uh positive feedback loops are often incorporated into control mechanisms in which a potentially dangerous or stressful process must be completed quickly for example the immediate danger from a severe cut is the loss of blood which can lower blood pressure and reduce the efficiency of the heart so platelet plug formation and blood clotting is an example of where we see this positive feedback loop as well of enhancement of labor contractions by oxytocin figure 1-7 shows a positive feedback mechanism that regulates the formation of a platelet plug so let's say there's a break in the blood vessel wall which will cause bleeding so the positive feedback cycle is initiated uh so platelets which are one of the components of of blood there's the red blood cells the white blood cells and the third component these platelets will adhere to the site and release chemicals which will initiate uh clotting uh and additional chemicals will be released uh which will attract more platelets in a positive feedback loop and the feedback cycle will end once the plug is formed and um and then the bleeding will stop this is another example of a positive feedback loop so the first contractions of labor which acts as the stimulus push the baby toward the cervix which is the lowest part of the uterus the service contains uh stretch with sensitive nerve cells that monitor this degree of stretching that's these sensors these nerve cells uh send messages to the brain which in turn causes the pituitary gland at the base of the brain to release the hormone oxytocin into the bloodstream causes stronger contractions of the smooth muscles in uh the uterus which the uterus is the effectors pushing the baby further down the birth canal this causes even greater stretching of the cervix the cycle of stretching oxytocin release and increasing increasingly more forceful contractions stops only when the baby is born at this point the stretching of the cervix stops and this will end the release of oxytocin many diseases are a result of homeostatic imbalance or the body's inability to restore a functional stable internal environment um aging is a source of homeostatic imbalance as the control mechanisms of the feedback loops lose their efficiency diseases that result from a homeostatic imbalance include heart failure and diabetes but many more examples exist diabetes occurs when the control mechanism for insulin becomes imbalanced either because there's a deficiency of insulin or because cells have become resistant to insulin so we stop here for first class and we'll continue so more next time and that's it