welcome back to anatomy and physiology one laboratory I'm Kevin toke off and in this video we're gonna go over some of the major concepts from exercise 2 which has to deal with organ systems but also feedback loops homeostasis and divisions of the body as in cavities and membranes so on and so forth let's first talk about an overview of some of the myth of the organ systems of the body and some of these we'll be covering in A&P one and the rest we'll cover in the second semester of the course and I'm just going to go over some of the very basic information that you would need to know first let's talk about the integumentary system which consists mainly of the skin but also the hair on your body and then nails on your fingers and toes the integumentary system really is just a big protective barrier for the body it prevents deeper tissues underneath the skin for example from getting injured it also prevents dehydration now one of the other important things that the skin does is its instrumental in the formation of vitamin D which is necessary for life and health alright moving on to the nervous system we'll also cover this in this course the nervous system is all about detection of stimuli both external and internal and in terms of detection we're talking about so sensory so detecting some things hot perceiving a color with your vision but also control of movements so when you move your arms to write on a test that's initiated by the nervous system and we can consider the brain the spinal cord and every neuron in your body and also all the sensory organs all right also covered in this course is going to be the muscular system and this I think pretty much speaks for itself it's the muscles and the muscles move the body they are the direct movers of the body the muscles are actually gonna pull on bones which we'll look at next to produce movement another thing that you should be aware of is the muscles also generate heat they have a very high metabolic rate and so heat is produced by muscles now if you get a question on a quiz or exam that says which system generates movement you go with the muscles okay it is true muscles pull on bones and it is true that the nervous system initiates movements but the direct generators of the movement are the muscles okay also we'll cover in this class the skeletal system which is really just bones okay and the bones provide support and they protect internal body parts for example the ribcage protects the heart and the lungs the skull obviously protects the brain okay and like I said because muscles pull on bones the bones serve as points of attachment for muscles okay and the skeletal system also produces many blood cells all right now the rest of these are covered in the second semester of this course here's the circulatory system this is mainly involved in transporting nutrients of all kinds and wastes for that matter throughout the body so for example the heart beats which pumps blood and that moves through all these blood vessels to give say oxygen and glucose to your cells in the periphery okay so this is all about nutrient transport alright endocrine system endocrine system is a system of the body that consists of organs all over the place and tissues and they produce hormone and these hormones can act in different ways in control different aspects of the body one hormone that you've probably heard of his insulin so the pancreas releases insulin and that causes cells to uptake glucose from the blood right so the endocrine system makes all sorts of different kinds of hormones which you'll cover in A&P too right the lymphatic system often a neglected system it's probably one of the most boring systems if we're being honest but the lymphatic system is all about fluid collection and fluid return so in your blood vessels obviously there's blood and lymphatic vessels run with all the blood vessels they were kind of run next to them and the lymphatic vessels pick up any excess fluid that that would drain out of the blood vessels it picks it up and returns it back to the circulation okay also the lymphatic system can defend the body against infection all right here we have the respiratory system and you might guess it involves the lungs and all the Airways up here that lead up to the mouth all right so the respiratory system is mainly involved in when you inhale you intake oxygen which will then redistribute so your tissues but also the respiratory system when you exhale it gets rid of wastes such as carbon dioxide so the respiratory system both helps you receive nutrients from the air as an oxygen but also get rid of waste like carbon dioxide okay the digestive system you have all these organs in here we have the esophagus the stomach the liver all the intestines in here the digestive system is obviously involved in breaking nutrients down that we eat so that they can be absorbed into the bloodstream and utilized by all the tissues of the body so we break things down and we absorb them right and also in terms of the rectum and the end of the colon the digestive system helps eliminate waste as fecal matter right now the urinary system this first of all helps maintain the blood volume that's part of it and the composition of the blood but whenever there's excess wastes in your blood the urinary system filters it out and you basically urinate the waste away so the urinary system is the main system involved in regulating waste from your internal environment such as the blood all right and then I don't think we need to go much into the reproductive system but in terms of specifics the male reproductive system is going to produce hormones and sperm cells for their half of the reproduction and female reproductive system is going to produce eggs and hormones such as estrogen and so on and so forth for their half of reproduction all right and also hormones produced from these areas can also trigger secondary sex characteristics again just kind of know a basic amount of each of these organ systems okay all right now let's talk about homeostasis and feedback loops so the body needs to maintain any physiological variable within a healthy range of normal values and here you have a graph kind of illustrating this any physiological variables such as blood pressure or blood glucose anything has to be maintained within a pretty narrow range of values so down here at this dotted line on the bottom that's maybe the lower limit here is the upper limit for a healthy range and as long as you're in this range in blue you're healthy let's say this is blood pressure we know that throughout the day blood pressure goes up and down for example you have to slam on your brakes to avoid a crazy driver your blood pressure probably goes up then if you sit down for a little bit you know and you're relaxing if you don't have an exam or whatever your blood pressure probably goes down and it cycles up and up and down and down and so on and so forth and only when you generally get into these higher areas or in some cases very low areas do you have the possibility of disease and so in order to maintain homeostasis you have to have what are called negative feedback systems or negative feedback loops so over here is kind of a general diagram of a feedback loop and this one is really more or less a negative feedback loop so let's talk about it so homeostasis is when we're balanced all right so what happens if we tip this seesaw out of balance so in other words we produce an imbalance well something like a receptor is going to detect that change it's going to detect that deviation from homeostasis or that imbalance and then the information is going to be sent to a control center and many times the control center is the brain but it doesn't have to be in the case of blood glucose levels the control center is actually the pancreas and then that control center is going to send information to some effector some output information that says here's what we need to do to fix the problem and then the effector actually does fix the problem by doing some action and then the amounts will be corrected back to homeostasis okay so again to reiterate this so if we get out of homeostasis whatever the variable is that changes it's detected the information is sent to a control center and the control center sends information out to some effector which is just a term for something that is able to respond to the change and change the imbalance back to a balanced or homeostasis now the most common type of feed Loup that we have like this is that of negative feedback so here's a key concept negative feedback is a feedback loop in which the original stimulus is reversed to return the body to homo Youth homeostasis so if our imbalance initially right here was high blood glucose the end result of negative feedback would be lowered blood glucose so if we're on this graph right here and our blood glucose starts to rise a lot like up to right here are my Mouse's the negative feedback would cause it to come back down okay likewise if our blood glucose starts falling because we are fasting then glucagon another hormone would be released and we'd bring it back up and that bringing back up is another type of negative feedback so the original stimulus or the original imbalance is reversed with negative feedback so if you start with a variable whatever that physiological variable is is too high negative feedback will bring it down if that physiological variable is too low negative feedback will bring it back up so I've got this thing right here so the example acutely elevated blood glucose is decreased back to normal levels by the action of insulin so the key with negative feedback is you'll may start with an increase but then the negative feedback will decrease it back to normal or if you start with a decreased level of something negative feedback will increase it back to normal the response for negative feedback is always opposite because only by doing the opposite can you bring it back to a healthy level to homeostasis okay now another type of feedback loop is positive feedback and this is where the original stimulus is amplified rather than reversed okay so it's sort of like if you start with two of something you'll then go to four and then eight and then 60 and you keep getting more and more and more of something a great classic example of positive feedback is during childbirth whenever a baby is being birthed the oxytocin levels by the mother increase more and more and more and more so you start with a little oxytocin and it just keeps increasing until you have a ton of oxytocin okay and it keeps going and going and no going up and up and up now there is a way to shut it off but we're not going to talk about that the key with positive feedback is the original stimulus is amplified whereas with negative feedback the original stimulus is reversed so a negative feedback if it goes up then it goes back down or if it starts going down it goes back up so hopefully that makes a little bit of sense now let's move on to body cavities so a body cavity is just a space and they're not necessarily empty they have things in them for example I think we know the cranial cavity probably has the brain in it but these cavities are just spaces where things might be stored here's a lateral view of a person let's look at some of the cavities you can see from this view obviously in the skull we have the cranial cavity okay and notice we also have a vertebral cavity which is basically a cavity that runs ultimately through the spine okay down here we have a green the pelvic cavity and in pink right here the abdominal cavity and sometimes you'll see the abdominal cavity and pelvic cavity combined into one term called abdominal pelvic cavity but understand this is a conglomerate of these two individual ones abdominal and pelvic alright now if we look in the upper chest area if we look in the anterior view we can see some more things so for example in purple here that's approximately what each lung is right so each of these is actually what we call a pleural cavity so pleural is the word that generally means lung so you can see pleura pleural you're talking about the lungs here we have in greens or this bluish green this is the pericardial cavity okay so pericardial means heart in fact really the cardia is what means heart but we call this the pericardial cavity right here in blueish green and up here at the top in orange this is what's called the superior mediastinal okay now you'll be asked about the different cavities which one each is make sure you default to your lab manual to know which one of these which ones of these cavities are ones that are important for you to know now what's also important about body cavities is that they tend to be lined by membranes called serous membranes now let's talk about what a membrane actually is okay when you usually think of membrane you think of the cell membrane well a membrane is not just that a membrane is anything that covers something else technically your skin is a membrane it covers your whole body if you want to think of the bottle cap of a water bottle that could be a membrane so to speak and cover something okay so membranes just cover something in serous membranes lie in these cavities now you're gonna come across two terms in A&P only one of which we're covering here and that serous membranes serous membranes are a type of membranes that do not open to the outside meaning there's no possible opening for the external environment to be connected to these membranes okay in contrast to mucous membranes which do open to the outside we won't talk about those yet serous membranes do not open to the outside and they line all of these cavities let's talk about this the serous membranes that are important for us so we have over here the pericardial area these are the pericardial membranes here are pleural membranes cuz use of the lungs and in terms of the abdominal pelvic cavity these membranes are called peritoneum okay now there's parietal and visceral of each parietal visceral we have parietal and visceral how do you tell the difference in which one is which alright the parietal always lines the wall of the cavity if we go back over here and look at the pleural area the membrane the serous membrane that lines the cavity where we could say that is the most superficial membrane is always the parietal okay the parietal is always the most superficial the visceral membrane in each case lines the surface of the organ I think you can see it best with this heart so let's look at this notice the parietal membrane which in this case because their pericardium you call it parietal pericardium notice it lines the outermost superficial part of the heart whereas the visceral pericardium this Earl is lining the actual organ itself and that's a key thing to remember visceral always lines the organ parietal always is superficial that normally on the wall of the cavity okay if we look at the lungs down here now we change it to pleura because the these are pleural membranes so you kind of have to blow it up but look in blue right here blue this lines the lung directly so it's the visceral pleura whereas the red one which is superficial lines the pleural cavity and so it's the parietal pleura so we have parietal and visceral and this one's a lot harder to see but again if you look here where my mouse is that's the actual wall of the cavity and you see it's lined by the parietal peritoneum but then down here if you look at this darker green one right here that lines the outer surface of these organs whatever they happen to be these probably are the intestines down here it's lining organs so those are the visceral peritoneum okay so remember you just need to keep in mind that peritoneum is for the abdominal pelvic cavity pleura are for lungs and pericardium are for the heart and then just remember that parietal always lines the wall of the cavity and is most superficial visceral lines the organ itself and is the deepest I guess we could say all right those are our serous membranes all right now I'm not gonna go in a whole lot of detail here because I think these pictures serve a thousand words and you'll be asked to do this in lab but we have two kinds of divisions of the abdominal pelvic areas that you need to know for the quizzes and exams over here on the Left we have what are called abdominal pelvic regions and notice there's nine of them over here on the right we have abdominal pelvic quadrants quad means four these are they really the easiest to remember because there's a right and a left and an upper and a lower and you just combine them to make the combinations for example this one right here are my Mouse's that's the left upper quadrant now remember right and left when we're still getting used to this but left has to do with the patient's perspective so you're looking on their anterior but from their perspective this is their left side where my mouse is and so if the upper one so it's the left upper quadrant likewise down here across the X so to speak down here is their right side and it's the lower one so this is the right lower quadrant and you should probably be aware of some of the organs that are in each quadrant for example left upper quadrant here's the stomach right here we have the upper aspect of the colon right here in some of the small intestines I guess in the right upper quadrant we have a gallbladder which is in green we've got the liver we've got some of the stomach but mainly in the lower quadrants we have the intestines both large and small ok so just be aware of generally what's in each one of those again these are more difficult over here for the abdominal pelvic regions because there's nine of them alright now again you have right over here and you have left over here but they kind of have weird names all right so on the left side we have at the top left hypochondriac region and going down left lumbar region and at the bottom left iliac region okay so going down hypochondriac lumbar and iliac we have the same thing on the right side up here is the right hypochondriac this is the right lumbar and the right iliac and on the right side we have right hypochondriac right lumbar and right iliac region and then in the middle going down these aren't named in any of the same ways really we have epigastric right here this is the umbilical region you can imagine the belly buttons probably in this area somewhere and then hypogastric region alright and to some extent you should be aware of some of the organs that might be in each of these mainly understand that the liver is going to be in the epigastric and right hypochondriac the stomach is shared by the left type of Kandra ACK and the epigastric and in general these other regions really have mostly the intestines both large and small okay but just make sure most importantly that you can identify each of these nine over here and each of these four over here because some typical quiz and exam questions could be something like you have an arrow pointed to one of these and you have to say which one it is this is umbilical region over here or this one right here is right upper quadrant all right and you'll have activities where you cover some of these in class today all right so this has been an overview of the major concepts from exercise 2 in the anatomy physiology lab manual we're going to be covering all of this today in class so again you can use this study for the quizzes and the exams I'll see you in class today and then also tomorrow we will cover exercise 3 thank you