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What are the four major structures that compose the conduction system of the heart?
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What is the pacemaker of the heart?
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A&P Midterm II
Ch. 19
| Question | Answer |
|---|---|
| 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
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