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A&P Midterm II

Ch. 19

What are the four major structures that compose the conduction system of the heart? SInoatrial node (SA node), Atrioventricular node (AV node), AV bundle (Bundle of His), Purkinje system
What is the pacemaker of the heart? SA node- initiates each heartbeat and sets its pace
What generates contraction in the atria? SA node and AV node
What generates contraction in ventricles? Right and left branches of bundle fibers and Purkinje fibers
What is a graphic record of the hearts electrical activity (its conduction of impulses)? Electrocardiogram (ECG, EKG)
What is a normal EKG comprised of? P wave (depolarization of the atria), QRS wave (depolarization of ventricles), T wave (re-polarization of the ventricles)
What is another word for contraction? systole
What is another word for relaxation? diastole
What is a complete heartbeat consisting of systole and diastole of both atria and both ventricles? cardiac cycle
What consists of a later, longer period of slow ventricular filling at the end of ventricular diastole lasting approximately 0.2 second; characterized by a gradual increase in ventricular pressure and volume? Diastasis
What is the first sound, believed to be caused primarily by the contraction of the ventricles and by vibrations of the closing AV valves? Systolic sounds
What consists of short, sharp sound; thought to be caused by vibrations of the closing of SL valves? Diastolic sounds
P1-P2 is the symbol used to stand for what? Pressure gradient
What represents the higher pressure? P1 (P2 represents the lower pressure)
What is the pressure gradient needed to maintain blood flow through a local tissue? Perfusion pressure
Volume of blood pumped out of the heart per unit of time is called what? cardiac output
What is cardiac output determined by? stroke volume and heart rate
What is stroke volume? volume pumped per heartbeat
What does Starling's Law of the heart state? Within limits, the longer, or more stretched, the heart fibers at the beginning of contraction, the stronger the contraction
What is the main factor that affects hearts rate? cardiac pressoreflexes
What are the two types cardiac pressoreflexes? Carotid sinus reflex (baroreceptors, parasympathetic), Aortic reflex (sympathetic)
What is resistance to blood flow imposed by the force of friction between blood and the walls of its vessels? Peripheral resistance
What are two factors that influence peripheral resistance? Diameter of arterioles and blood viscosity
What are muscles in the walls of arteriole that may constrict or dilate, thus changing diameter or arteriole? Vasomotor mechanism
Small changes in blood vessel diameter cause large changes in resistance, making the vasomotor mechanism ideal for regulating blood flow and what?? Regulating blood pressure
What is the the thickness of blood as a fluid called? blood viscosity
What, in high concentration, can slightly increase blood viscosity? High plasma protein
What can increase blood viscosity? High hematocrit (% RBCs)
What are chemoreceptors located in aortic and carotid bodies are sensitive to hypercapnia, hypoxia, and decreased arterial blood pH? Vasomotor chemoreflexes
What is the amount of blood returned to the heart by the veins? venous return
What structure in veins prevents backflow of blood? semilunar valves
What are changes in blood volume? mechanisms that change total blood volume most quickly are those that cause water to quickly move into or out of the plasma
What decreases the amount of water lost by the body by increasing the amount of water that kidneys reabsorb from urine before the urine is excreted from the body; triggered by input from baroreceptors and osmoreceptors? ADH
What is released when blood pressure in kidney is low; leads to increased secretion of aldosterone, which stimulates retention of sodium, causing increased retention of water and an increase in blood volume? Renin
What is an intermediate compound that causes vasoconstriction, which complements the volume-increasing effects of renin and promotes an increase in overall blood flow? Angiotensin II
What is the combination of Renin and Angiotensin II called when it changes total blood volume? Renin-angiotensin mechanism
What adjusts venous return from an abnormally high level by promoting the loss of water from plasma, causing a decrease in blood volume; increases urine sodium loss, which causes water to follow osmotically? ANH mechanism (Atrial Natriuretic Hormone)
What is systolic blood pressure? Highest pressure (force) of the blood pushing against the Aorta (while ventricles are contracting)
What is diastolic blood pressure? Lowest pressure (force) of the blood pushing against the Aorta (when ventricles are relaxed)
What is pulse pressure? difference between systolic and diastolic blood pressure
What is pulse? alternate expansion and recoil of an artery
Created by: courtney.marie23