human anatomy and physiology part two this is a continuation of our lecture series on the cardiovascular system with a focus here in episode four on the circulatory system on this first slide we are looking at the various organ systems in the human body as you can imagine virtually every cell tissue and organ in the body is impacted and interacts with that circulatory system this includes the transport of materials capillary exchange the presence of white blood cells and antibodies hemostasis which plays a role when there is tissue damage and assist with coagul coagulation and as well the circulatory system plays a role in helping to maintain acidbase balance on this particular slide you can see the various organ systems and how the circulatory system interacts first if we look at the digestive system it plays a role in helping with nutrient and water absorption and it delivers nutrients to to the liver for processing as well and also plays a role uh in providing nutrients that are essential for the uh production of blood cells and uh the development of hemoglobin in the endocrine system the circulatory system plays a role by delivering hormones so hormones often travel through the bloodstream uh to Target various uh organs or systems in the body a few examples are listed on the screen here with the integumentary system the circulatory system plays a role in uh carrying clotting factors platelets and white blood cells for hemostasis as well as uh inimmune defense it also helps to regulate temperature by controlling blood flow uh to the surface uh such that heat can be dissipated an example of this would be during exercise now uh with the lymphatic system the circulatory system plays a role by transporting various white blood cells as well as antibodies to maintain Health the skeletal muscles is also implicated with the circulatory system in that it the circulatory system provides nutrients and oxygen for muscle contraction it helps to remove lactic acid and distributes Heat gener generated by muscle contraction as well as we've talked about in preceding lectures there is a skeletal muscle pump uh that exists um typically in the peripheries we think about skeletal muscles for example in our legs and how uh there are valves within the veins that help to return blood to the heart when it comes to the nervous system the circulatory system provides um cerebral spinal fluid it also contributes to the blood brain barrier and there are cardiac and vasomotor centers that help to regulate cardiac output and blood flow through vessels via the autonomic system so the autonomic nervous system you will recall uh is uh not under conscious control and rather it is automated in uh helping to facilitate changes in cardiac output and blood flow in response to physiological stress once again an example being exercise next uh with the reproductive system the cardiovascular system uh AIDS in uh the erection of the genitalia in both sexes during sexual arousal it also is able to transport gonadotropic hormones that help to regulate reproductive functions the respiratory system is critical uh and how it is uh implicated with the circulatory system the circulatory system is able to facilitate gas exchange uh and also dissipate carbon dioxide that builds up in tissues and can be carried through the bloodstream and uh out via the alvioli into the external environment the skeletal system uh is also implicated in the circulatory system in that calcium phosphate and other minerals that are critical for bone the bone matrix are provided by the circulatory system there are a number of hormones also available to the skeletal system owing to the circulatory system and how the hormones travel through the bloodstream lastly we'll look at the urinary system the circulatory system delivers about 20% of the resting circulation to the kidneys for filtering reabsorption of useful products and secretion of waste it also helps to regulate blood volume and blood pressure by regulating fluid loss in the form of urine and by reasing renin and renin is an mzy that is essential in the renin and tensin aldosterone mechanism we spoke about this with respect to the control of blood pressure this next diagram really just highlights the uh the pulmonary circuit you can see how blood uh enters into the right side of the heart from the vinaa so from the inferior and Superior V AA it enters into the right atrium it is then uh able to pass into the right ventricle as the pressure in the Atria exceeds the pressure in the ventricles and those valves uh those AB valves open once enough blood accumulates in the ventricles it can make its way into the pulmonary trunk and so those pulmonary semilunar valves will open once again uh due to a difference in pressure so high amount of volume of blood in the right ventricle creates pressure that pressure will exceed that of the pressure in the pulmonary trunk and those pulmonary semi lunar valves will open allowing blood to make its way to the lungs once that blood is oxygenated it comes back to the left side of the heart and that is owing to the left pulmonary veins and the right palm ponary veins these are a unique case of veins that are carrying oxygenated blood once again back to the left side of the heart as pressure builds up with the accumulation of blood in the left atrium the AV valves in this case it's on the left side of the heart so we know it to be our mitro valve will open and allow blood to enter the left ventricle the left ventricle really is the dominant pumping chamber for the heart and that is because because it is responsible for pumping blood to the systemic circulation when pressure builds up in the left side of the heart uh the blood will exit through the aorta and uh you will see the ascending aorta although not shown uh clearly here in terms of the the blood flow um that is where the systemic circulation will commence and that takes us now to the systemic circulation so there are a number of arteries uh in the human body uh this is more for your interest uh but you should be aware of a few things the arteries in our body are responsible for carrying blood away from the heart they operate under a very high pressure on the screen here the main picture that you're looking at is that of the aorta and you can see the aorta Arch off of the aorta you'll actually notice that uh there are several vessels the first vessels coming off of the aorta are in fact your coronary arteries these arteries are responsible for carrying blood to the heart muscle itself once again the heart itself is an organ it contains cardiac muscle that muscle requires oxygen and nutrients to be able to pump effectively so the coronary arteries are small branches off of the aorta and once again they are able to deliver oxygen to peruse the heart muscle you have ascending and descending portions of the aorta as it uh makes its way uh out of the heart blood is able to travel through the asending aorta the aortic ortic Arch and the descending aorta as the blood uh once again is is um leaving the heart and making its way to the body there are several branches off of the aorta uh the aortic Arch has a number of arteries that will carry blood to the upper her body and then as the aorta descends blood is being carried uh through the thorax and into the abdomen where uh there are multiple branches to the various organs you are not responsible for knowing uh the uh various uh arteries but rather this is more for your interest and having an understanding of just the complexity of the arteries in our body next um once again this is for your interest uh the common cored artery gives rise to external and internal cored arteries these uh give rise to many arteries in the head and once again supplying blood to the upper uh body and the head region this next slide I highlight simply because you can see how the arteries and the veins actually mirror each other typically arteries veins and nerves will travel in close proximity to each other and so while it is not um superimposed on each other what you can see is that the general structure is very similar in that uh you have uh arteries and veins which um will supply and then drain blood from a given region so for example you have a uh you have renal arteries that Supply blood to the kidney similarly you have renal veins which drain blood from the kidney and enter back into the inferior venne Cava and return to the heart once again you are not responsible for knowing each and every one of these rather the take-home point from this slide is really to understand how arteries and veins are enclose proximity to each other to ensure that a given organ or system is able to receive blood but also able to drain blood once the oxygen and nutrients uh have uh been able to um travel to the uh intense Ed organ or system on the next slide once again um this just highlights the complexity of the arterial tree and the lower body from the abdominal aorta um into the lower body there are number of arteries that Supply the pelvis and lower limbs similarly there are a number of arteries that Supply the thorax and Upper Limb as well this is more for your interest uh once again uh but you can see just uh the extent to which there is branching off of the aortic uh arch in this case um to the kateed arteries as well as to uh the subclavian uh vessels and the brachial calic trunk as well here uh is further complexity now we're looking at the lower limb and the major arteries that serve it most notably the external iliac artery will exit the body cavity and enter the femoral region of the lower leg as it passes through the body wall and into the lower extremity it then becomes known as the fural artery and that is the major vessel leading into the lower limb and it actually supplies the thigh and then continues to bifurcate or subdivide into various different arteries as you can see likewise I just wanted to highlight if we were to superimpose these two uh images you can see that um there are uh major systemic veins uh that essentially follow or trace the path of the arteries ensuring that once oxygen rich blood is delivered to the intended uh organs or organ systems that in fact uh there are veins which can drain uh those um drain blood as well and help to return it back to the heart uh the major vessels you should be aware of are in fact uh the uh inferior and Superior vinaa as they connect blood back to the right atrium once again beyond that uh this is more for your interest just to see the complexity and how the arteries and veins appear very similar um in the path they follow but also in the nomenclature or the naming of the vessels as well we see uh once again similar uh systems when we look at the veins of the head neck and Upper Limb obviously the circulation to the brain is critical and very complex there are many small uh vessels uh which make their their way uh to uh the head and this um next diagram really just uh reiterates uh the um importance of the superior vena and inferior vnea as they are able to receive blood from the various uh smaller veins in the body and ensure that it can be returned to the right atrium beyond that level of detail once again this is more just for your interest next I'm going to jump forward just two uh more clinically relevant uh cases and uh that is that includes I should say uh the hepatic portal system and and then we will move on to fetal shuns so with the hepatic portal system the liver receives blood from the systemic circul via the hepatic artery as does many different organs in the body in the case of the liver the it receives and processes blood from other organs and so these are delivered via the veins of the hepatic portal system all blood will exit the liver via the hepatic vein which delivers blood back to the inferior vnea so this is a unique system in that that blood is actually being received from other organs not just from the heart and that's what makes it a portal system usually blood goes from an artery to an organ or a tissue and then makes its way from a vein back to the heart in this case it actually is um re the liver is receiving blood from other organs and it is delivered via the veins of the hepatic portal system that's what makes this uh unique in particular blood will flow from the various abdominal organs and pass through the hepatic portal vein the liver sinusoids and into the hepatic vein before returning to the heart and that occurs via the inferior vena this is important because this system the hepatic cordal system essentially allows the liver to process and detoxify substances uh that are present within the gastrointestinal track and lastly that takes us to um the concept of fetal circulation it is important to note that that in fetal circulation blood vessels form from embryonic mesoderm and give rise to uh a vascular vasculature the placenta also develops and supplies oxygenated blood via the umbilical vein and removes deoxygenated blood via umbilical arteries there are three major fetal shunts to be aware of the foramin oval the ductus arteriosis and the ductus vosis there are some changes to be aware of after birth so firstly the umbilical cord is clamped ending any supply of blood from the mother notably prior to birth the mother's placenta will provide oxygen and nutrients to the fetus there thereby um blood bypasses the fetal lungs and digestive organs in addition after birth the lungs will expand with their first breaths and clear fluid from the Alvi there is an increase in blood pressure and a reduction in pulmonary pressures that lead to the closure of the ductus arteriosis in addition there is a closure of the Forin oval and the ductus arter iosis that completes the transition to the newborn circulation prior to birth these shunts allow for blood to flow from the right atrium to the left atrium in the case of the forment oval the ductus arteriosis connects the aorta to the pulmonary trunk and the ductus phosis links the umbilical vein to the inferior vnea through the liver so these shuns once again are important in the fetus but in normal anatomy and physiology they will close at Birth due to the factors that I have already mentioned