BIO 141 notes 10
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This 4 page Class Notes was uploaded by Camryn McCabe on Friday March 4, 2016. The Class Notes belongs to Biol 141 at a university taught by Janelle Malcos in Spring 2016. Since its upload, it has received 25 views.
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Date Created: 03/04/16
Lecture 10 notes Cardiovascular System Blood vessels network of transport throughout the body 0 Starting point the heart 0 Arteries take blood AWAY from the heart Oxygen rich except pulmonary trunk o Veins take blood towards the heart Oxygen poor except pulmonary veins Capillaries exchange locations 0 Neither arteries or veins Circulatory Routes 0 Normal ow of blood 0 Heart artery l arteriole l capillary Arteriole small artery Capillary bed bunch of capillaries Where exchange of materials occurs 0 Capillary l venule l vein l heart Venue small vein 0 Portal system exception to normal route 0 Has 2 capillary beds instead of one 2 places for exchange of materials 0 2 main systems 0 Pulmonary to lungs 0 Systemic to rest of body Structure of vessels Vessels have smooth muscle involuntary control 0 All vessels except capillaries have 3 layers of tissue 0 Tunica intima in intimate contact with blood lines interior portion the lumen open space inside of tube 0 Tunica media middle primarily made up of muscle and collagen allows for it to constrict and relax o Tunica externa helps anchor the vessel to surrounding Ussue Tunica layer 0 Variations between arteries and veins 0 Arteries have more tunica media more muscle and collagen because they are under higher pressure 0 Veins have valves Capillary beds 0 Only tunica intima is present Lecture 10 notes Promotes rapid diffusion of material into tissue or capillary Very narrow single le travel Tunica intima 1 cell thick 0 Flow of blood is controlled by sphincter muscle cells Sphincter circular muscle single muscle cell Respond to chemicals in tissue and chemicals from CNS Contraction of sphincters determines if capillary beds are open or closed Only about 14 of body s capillaries are quotopenquot at any given time Muscle cells are relaxed l blood ows into capillaries Muscle cells are contracted lgt lacking blood passes through without any exchange Veins Carry blood back to heart 0 Usually deoxygenated Thin walls less muscle and elastic Have valves that prevent back ow 0 Use skeletal muscle contraction as pump to move blood to heart 0 When valves are closed blood is forced back up to heart Blood pressure the force blood exerts against an arterial wall usually the brachial artery Systolic pressure pressure during ventricle contraction 0 1st number of BP 0 Peak pressure during contraction Diastolic pressure pressure during ventricle contraction o 2nCI number of BP 0 Lowest pressure because ventricles are relaxed and not pushing blood into arteries 0 Mean arterial pressure average pressure in vessels 0 Important when considering blood ow to prevent organ failure 0 Pulse pressure systolic diastolic Main variables of blood pressure 3 0 Cardiac output 0 Amount of blood the heart pumps per minute into arteries Lecture 10 notes Overall arterial volume is constant but amount of fkuid in arteries is altered 0 Higher output l more blood in arteries l higher pressure Sympathetic response 0 Lower output l less blood in arteries l lower pressure parasympathetic response Normal Cardiac output resting majority of blood in veins 0 High Cardiac output volume in veins lowers more in arteries Higher pressure in arteries 0 Resistance of blood ow in vessels 0 Combined effect of blood composition vessel diameter and vessel length 0 Vessel diameter can change vasomotion Vasoconstriction smaller vessels higher blood pressure Sympathetic action 0 Anything that raises pressure sympathetic Vasodilation relaxation larger vessels lower blood pressure Parasympathetic action 0 Response to lack of stimulation to contract 0 Blood volume total volume of blood in vessels 0 Mainly controlled by kidneys and hormones O Maintaining blood pressure at rest 0 When at rest goal is to maintain pressure using a visceral neural circuit 0 Things that can alter blood pressure at rest hydration state posture stress disease 0 Must gather sensory input 0 Input from baroreceptors pressure monitors about current pressure in major arteries 0 Proprioceptors in muscles also provide input BUT not important during rest Situation changes during exercise or ght or ight CNS must integrate sensory input 0 Occurs at cardiovascular control center CVCC in medulla Motor output negates any changes away from homeostasis 0 Negative feedback loops Lecture 10 notes Blood pressure neuronal circuit 0 Starts with sensory input to integrating center Baroreceptors and chemoreceptors provide sensory input to cardiovascular centers in the hindbrain o Baroreceptors neurons with mechanicalgated sodium channels in membranes of dendrites 0 Increase in pressure l artery stretches l channel opens l neurons depolarize 0 Rate of action potentials amount of stretch More stretch l more action potentials o Chemoreceptors important for monitoring pH that alters respiration Motor output from integrating center 0 Cells of parasympathetic release Ach Ach binds to SA node cells and cause them to depolarize slower 0 Cells of sympathetic release norepinephrine Norepinephrine causes SA node cells to depolarize faster Visceral motor responses either sympathetic or parasympathetic depending on sensory input 0 Sympathetic response Occurs when blood pressure is too low baroreceptors tell brain pressure is too low Visceral motor neurons cause 0 Increased heart rate 0 Activation of cardioacceleratory neurons Vasoconstriction o Constriction of blood vessels regulated by sympathetic release of norepinephrine or epinephrine from adrenal gland o Parasympathetic response Occurs when blood pressure is too high Visceral motor neurons cause Decreased heart rate 0 Activation of cardioinhibitory neurons Vasodilation o Dilation of blood vessels due to decrease in norepinephrine lack of secretion from adrenal gland 0 These response are for normal day activity not ght or ight
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