Human Circulatory System Flashcards
What is an artery?
blood vessels that carry blood away from the heart, thick walls, outer and inner layers made of connective tissue, middle layers made of muscle fibers and elastic connective tissue, pulse made by changes in diameter of arteries
What is the autonomic nervous system? Vasocontraction? Vasodilation?
controls motor nerves that regulate equilibrium
vasocontraction: nerve impulse causes smooth muscle in arterioles to contract, reducing diameter of blood vessel, decrease blood flow to tissue, rapid contraction and relaxing of skeletal muscles, heat produced by respiration
vasodilation: increases delivery of blood to tissues, more blood to skin capillaries, heat lost (sweating)
What are capillaries?
single layer thick, sites of fluid and gas exchange between blood and body cells, oxygenated blood diffuses from blood into surrounding tissues, connect arteries to veins
What are veins?
capillaries merge into larger vessels called venules which merge into veins, as blood passes through a greater number of narrower vessels, blood flow reduced, thin walls, large lumen, one-way valve to prevent backflow
What are the 3 circuits of blood flow?
pulmonary circuit (blood from heart to lungs to heart) systematic circuit (blood from heart to body to heart) coronary circuit (supply heart muscles with oxygen, aorta to coronary arteries to cardiac veins to heart)
What is the septum? Pericardium?
wall of muscle that separates the right and left sides of the heart, fluid filled membrane surrounding the heart, fluid prevents friction between the outer wall and membrane
What 4 chambers is the heart composed of?
two thin walled atria, two thick walled ventricles
atrium take blood from veins (lung/body), right atrium takes deoxygenated, left takes oxygenated
ventricles take blood from atria and deliver blood to arteries, right ventricle pumps to lungs, left ventricle pumps to body
What happens in the atria/atrium?
vena cava large vein, superior carry deox blood from heart and upper body to right atrium, inferior carry deox blood from all veins below diaphragm to same atrium
oxygenated blood flowing from lungs enter the left atrium by pulmonary veins (4 veins connected to left atrium, carry blood from lungs to left atrium, 2 from right to right lung, two from left to left lung)
blood from both pumped into ventricles
atrioventricular (AV) valves separate atria from ventricles (prevent backflow) (supported by bands of tissue called chordae tendineae)
semilunar valves are a secondary set of valves which separate the ventricles from the arteries
What are the main arteries?
aorta, largest artery, carries oxygenated blood away from heart
coronary arteries (branch of aorta), supply muscle cells of heart with oxygen and nutrients
pulmonary arteries connected to right ventricle, pump oxygenated blood to body
What does myogenic muscle mean?
heart (cardiac muscle) is myogenic, contracts without external nerve stimulation (heart will continue to beat after being taken out)
Describe the heart’s tempo
beat rate set by sinoatrial (SA node), bundle of specialized nerves and muscles in the upper right atrium, acts as a pacemaker, ~70 beats/min
contractions travel to second node, atrioventricular (AV node), conductor, pass nerve impulse using two large nerve fibers (Purkinje fibers) through septum to ventricles, carry impulse from AV node to bottom tip of heart, cause ventricles to pump
What is diastole? systole?
atria fills (diastole, atria and ventricles relax), blood flow from atria to ventricles, and filled ventricles contract, pressure forces AV valve shut and push blood through semilunar valves into arteries out of heart (systole)
What is blood pressure?
force of blood on walls of arteries, measured with sphygmomanometer
each time heart contracts, a low pitched sound is detected, gauge on sphyg measures pressure exerted by blood during ventricular contraction (systolic blood pressure)
cuff deflate, blood flows into artery during ventricular relaxation/filling (pressure called diastolic blood pressure)
What are the three main functions of the circulatory system?
transportation, defense, thermoregulation
