Anatomy Physiology II Exam 2 1 What is total peripheral resistance Peripheral resistance a measure of the amount of friction encountered as blood flows through blood vessels 2 What factors can impact the flow of blood through the system and how do they impact flow There are three important sources of resistance that can affect blood flow Blood viscosity viscosity is related to the thickness of blood or stickiness of blood the thicker the fluid the more internal resistance it has the greater the viscosity the less easily molecules pass one another therefore blood flow would be slower if red blood cell count is high polycythemia blood viscosity is higher and peripheral resistance increases blood flow decreases if red blood cell count is low anemia blood viscosity is less and peripheral resistance declines blood flow increases Blood vessel length Blood vessel diameter the longer the vessel length the greater the resistance ex body growth the smaller the diameter of the tube the greater the friction because relatively more fluid contacts the walls of the vessels blood flow decreases the larger the diameter of the tube the less friction because relatively less fulid contacts the walls of the vessels blood flow increases 3 Where in the capillary do filtration and absorption occur Exchange in capillaries hydrostatic pressure and oncotic pressure are what moves molecules into and out of the capillaries pre capillary sphincter band of smooth muscle that controls flow and connects arterioles to capillaries since capillaries can not alter flow themselves the only way to change flow is the dilation and constriction of the pre capillary sphincter Filtration moving substances out of capillaries in order to get them to the surrounding tissues since flow is greatest at the beginning of the capillary there is high hydrostatic pressure most filtration occurs here at beginning of capillary high hydrostatic pressure pushes molecules out of capillaries and to the tissues water comes out this is the most abundant substance being pushed out gases comes out O2 and N2 nutrients come out ions glucose etc Absorption reabsorbing water into capillaries from surroundings since filtration occurs at the beginning of the capillary by the end of the capillary a lot of water has been lost due to hydrostatic pressure which means the concentration of oncotic particles has increased high oncotic pressure attracts water back into the capillaries water that gets pulled back in contains gases CO2 ions waste 4 What is vasomotion Vasomotion contraction and relaxation of pre capillary sphincters resulting in changes in blood Vasoconstriction narrowing of blood vessels Vasodilation expanding of blood vessels 5 What is autoregulation flow brain 6 What are the local tissue dilators dilator What causes vasodilation Ability of the body to fix regulate a problem without a negative feedback loop involving the Possible because of local tissue factors and receptors that detect changes in their specific area Things that cause induce dilation without brain s help by stimulating the pre capillary sphincter 1 increases in CO2 levels in tissues OR decrease in O2 levels arterioles dilate to allow for more blood flow in order to deliver more O2 quickly and remove more CO2 quickly 2 production of lactic acid lactic acid is produced as a byproduct of anaerobic respiration if anaerobic respiration is occurring it is an indication that your body needs ATP fast and muscles are working very hard anaerobic respiration is faster than aerobic respiration more lactate when lactate enters blood hydrogen falls off production of lactic acid acidity in blood increases tissues need more blood flow because they are working hard and they need to get rid of more waste products faster 3 release of NO when one part of the body needs more O2 blood vessels in that area will release NO and vessels will dilate endothelial cells of arterioles release the chemical nitric oxide locally NO has become the most common chemical found in energy drinks and supplements because it increases blood flow and therefore O2 can get delivered more rapidly to muscle cells downfall to NO as performance enhancer when you consume NO directly it goes to the stomach then to heart and is circulated around entire body therefore blood vessels over entire body dilate now heart is working harder NOT GOOD for long term heart health ALSO not very efficient if you are doing a leg workout you really only need vasodilation in leg area not entire body 4 increase in H or K in blood or anywhere in body will increase vasodilation 5 inflammatory resonpse consequence of damage to the body vasodilation is first step of inflammatory response in order to get more blood flow and more WBC s etc 7 What are local tissue vasoconstrictors Aggregation of platelets caused by break in vessel bleeding which leads to clotting mechanism 1 platelets begin to clump together 2 convert inactive fibrinogen to fibrin lays down patch 3 vasoconstriction so that the platelet plug and fibrin patch can stop the blood flow so you don t bleed to death 8 What role do baroreceptors and chemoreceptors play in the regulation of blood vessel size and the flow of blood Neural Mechanisms If local vasodilation constriction don t work neural mechanisms for blood flow take over brain takes over 2 cardiovascular sensors in the brain located in the medulla 2 different brain centers one for vasoconstriction one for vasodilation medulla decides which to do nerve cells respond to the neurotransmitter norepinephrine released by medulla which signals smooth muscle stimulation on inside of tunica media of arteriole to either dilate or constrict based on the need for blood flow different than local vasodilator constrictors because these factors induce dilation and constriction based on the tissues needs around them where as this type of regulation goes to brain which releases neurotransmitter to induce changes in smooth muscles of arterioles baroreceptors pressure receptors located in the walls of the arteries highest concentration of baroreceptors in aortic arch and carotid arteries if pressure changes baroreceptors signal brain which release NOEI that can control smooth muscles in vessels when pressure increase dilation when pressure decreases constriction chemoreceptors regulate pH O2 levels CO2 levels detect levels in blood NOT what is in surrounding tissues local tissue factors control detection of levels in tissues 9 What is the role of