A & P Week 3 Notes
A & P Week 3 Notes BIOL 2510 - 001
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This 4 page Class Notes was uploaded by Ashley Barranco on Thursday February 4, 2016. The Class Notes belongs to BIOL 2510 - 001 at Auburn University taught by Dr. Shobnom Ferdous in Spring 2016. Since its upload, it has received 48 views. For similar materials see Human Anatomy & Physiology II in Anatomy at Auburn University.
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Date Created: 02/04/16
Blood Vessels Blood vessels: form closed circulatory system begins/ends at the heart Types of vessels Arteries carry blood away from the heart Arterioles small arteries Veins carry blood to the heart Venules small veins Capillaries are in between arteries and veins Layers (tunics) of blood vessel walls Tunica intima: endothelium that lines the lumen of all the vessels innermost layer endothelium + basement membrane and loose CT Tunica media: smooth muscle cells and elastic fibers middle layer innervated by sympathetic NS sympathetic NS = vasoconstriction Tunica externa: collagen fibers outermost layer protects blood fibers and reinforce it anchor blood vessels to surrounding structures **If sympathetic vasoconstriction what causes vasodilation? inhibition of sympathetic not parasympathetic Atrial System Arteries 1) Elastic/conducting arteries (closed to heart) largest diameters thickest walls elastin allows for expansion and recoil allows blood to flow fairly constantly don’t typically vasoconstrict (still have smooth muscle but lots of elastic fibers) 2) Muscular/Distributing arteries branch form elastic arteries thickest tunica media vasoconstriction and vasodilation Arterioles branch from muscular arteries smallest of arterial system vasoconstriction for inactive tissue cells and vasodilation for active tissue cells (sends blood where it’s needed the most) Capillaries Smallest of all blood vessels Connect arterial system to venous system Only have tunica intima Allow for exchange of material (nutrients , gases, hormones) Capillaries make up capillary beds: interweaving networks of capillaries Venous System Venules capillaries converge to form venules smallest of venous system converge to form veins Veins thinner walls than arteries Large lumens Very thing Tmedia Blood reservoirs can hold up to 65% of total blood volume contain venous valves relatively low pressure in veins compared to arteries need help getting blood to heart prevent blood flowing backward: If not working varicose veins System Circulation : Heart elastic Arteriesmuscular Arteriescapillaries Venulesveinsheart Circulatory Terms Blood flow amount of blood flowing through vessel, organ, or circulatory system at a given time period (ml/min) Cardiac output volume blood pumped out by each ventricle in 1 min. (ml/min) Stroke volume volume of blood pumped out by each ventricle with each beat. (ml/beat) Total peripheral resistance total amount of friction blood encounters as it passes through peripheral (systemic) circulation ** CO basically measures of blood flow through whole circulation ** CO= HR x SV ** SV= EDVESV Blood pressure force per unit area exerted on artery wall by the contained blood measured as systolic pressure/diastolic pressure Systolic pressure arterial pressure during systole ventricular contraction Diastolic pressure arterial pressure during diastole (ventricular relaxation) During diastole pressure in aorta and arteries decrease and walls of aorta and arteries recoil 120/80 mmHg is the blood pressure of a healthy adult Pressure in aorta and arteries fluctuate up and down each heartbeat due to systolic and diastolic pressure MAP more accurate accounts for pulsatile pressures and takes into account that diastole longer than systole MAPnot exactly halfway point between systolic and diastolic pressures, though, because diastole is longer than systole Pressures decrease quite a bit by time gets to capillaries and no longer pulsatile Low pressure in venous system Pulse pressure= systolic P –diastolic P Mean arterial pressure (MAP) average arterial pressure during single cardiac cycle MAP= diastolic P + 1/3 (pulse P) ** What is the MAP of a person with a BP of 160/100? 120 mmHG Venous Adaptations Venous pressure low = need help getting blood to heart Skeletal muscle surround vein contract/relax= push blood Respiratory pump= pressure change in thoracic cavity during breathing moves blood to heart Smooth muscle in wall of veins under sympathetic control Total peripheral resistance Blood viscosity is relatively constant (except in cases of disorders) determined by hematocrit (percent of red blood cells in whole blood) 2 Main sources 1. Blood viscosity: Thin blood= low TPR, Thick blood = high TPR 2. Blood vessel diameter Regulation of BP extrinsic Neural short term baroreceptors cardiovascular center in medulla 1. cardioaccelertory center (affect heart rate and force) 2. vasomotor center 3. cardioinhibitory center (affect heart rate and force) Chemical –long term ADH, renin, angitension, and aldosterone Neural Control of Blood Pressure: Baroreceptor Baroreceptors stretch repceptors, detect changes BP Location: arch of aorta and carotid sinus Send signals to cardiovascular center of brain: medulla oblongata (vasomotor center, CAC, CIC) Carotid sinus at bifurcation of common carotids (split between internal and external) Neural Control of Blood Pressure: Baroreceptor reflex 1. Blood Pressure drop 2. Carorecptors sense drop in BP 3. Baroreceptors decrease afferent impulses to medulla ACTIVATE CAC AND VMC 4. Efferent signal via SNS release E/NE onto B1 receptors on the heart (increase HR, contractility, CO) Release of E/NE onto beta 1 receptor on blood vessels= vasoconstriction (increase TPR) 5. Increase BP back to normal Chemical Regulation of BP Antidiuretic hormone ( ADH or vasopressin) synthesized in the hypothalamus production/release triggered by decrease in BP Cause kidneys to reabsorb water, Increase Blood volume and BP Cause vasoconstriction in arterioles, increase TPR to increase BP Renin: hormone produced by kidneys release triggered by a decrease in BP triggers production of angiotension II Angiotensin II: cause vasoconstriction which increase TPR trigger release of ADH stimulate adrenal cortex to release aldosterone triggers thirst Direct renal mechanism increase blood volume, increase amount of blood filtered by kidney, increase urination Indirect renal mechanism reninanfiiotensin mechanism renin triggers production of angiotensin and ultimately angiotensin II Aldosterone: increase sodium reabsorption in kidney, water follows by osmosis and increases blood volume and BP