NPB Study Guide Midterm 2

Capillaries7 exchange vessels thin epithelial walls

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Unformatted text preview: low A. Atrioventricular valves (AV) - prevents blood from entering atria when ventricles contract Right hand side → tricuspid valve Left hand side → bicuspid valve (mitral valve) B. Semilunar valves (SV) - exists between ventricles and arteries - prevent backwards flow 3. Arteriolar Vasoconstriction → arteriole diameter becomes smaller 4. Vasodilation → resistance drops - release of metabolytes - decrease sympathetic nervous system signaling The Cardiovascular System 2 1. Blood is the Last Component A. Blood serves as the medium that carries molecules throughout the body - liquidy connective tissue B. Components - cells and formed elements (like platelets) - plasma (the watery part) - proteins;7 synthesized by the liver or immune system 2. Exchange of Molecules Across Capillaries A. As the blood enters the capillaries it slows down - the significance is that this gives us time to exchange molecules B. Molecules move via diffusion - from high concentration to low concentration;7 diffusing down the concentration gradient → passive transport because it doesn’t require ATP 3. Cardiac Output A. Cardiac output (CO) is the volume of blood that is pumped per unit of time - determined by heart rate and stroke volume\ B. CO is a function of;7 - heart rate (beats/min);7 average = 70 bpm - stroke volume (volume of blood/beat);7 average - 70 ml/min - put the two together CO = HR x SV ~at rest, CO + 5 liters/min ~with exercise, CO can increase to as much as 25 liters/min 4. Changes in Heart Rate and Stroke Volume Will Alter Cardiac Output A. Heart Rate - controlled by the autonomic nervous system - sympathetic nervous system speeds up the heart and increase CO - parasympathetic NS decreases CO and slows heart B. Via the autonomic nervous system - increased SNS: large stroke volume - decreased SNS: small stroke volume C. Via changes in venous return - how much blood comes back to the heart from the veins → decrease leads to drop in stroke volume 5. So How Does This All Work? A. Remember that the CV system transports molecules throughout the body, and it carries those molecules in a liquid medium called blood. B. We can get blood to move from one point to another if there is a pressure difference - think of turning on a faucet;7 water pressure drives the water out 6. We “Need” High Blood Pressure to Drive Blood Flow Through Our Blood Vessels A. The blood pressure at the large arteries must be high in order to drive blood flow - Mean Arterial Pressure (MAP) B. Elevated MAP is bad because it makes the heart work harder, not smarter...
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