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Chapter 14: Cardiovascular Physiology (Pressure, Volume, Flow and…
Chapter 14: Cardiovascular Physiology
Overview of the Cardiovascular System
Cardiovascular System: circulatory system comprising a heart, blood vessels and blood
Capillaries: microscopic vessels where blood exchanges material with the interstitial fluid
Substances transported by the cardiovascular system can be divided into nutrients, water and gases that enter the body from the external environment; materials that move from cell to cell within the body; and wastes that the cells eliminate
Arteries: blood vessels that carry blood away from the heart
Veins: blood vessels that return blood to the heart
Heart is divided by central wall (septum) into right and left halves which each consist of an atrium and a ventricle
Atria receive blood returning to the heart from the blood vessels
Ventricles pump blood out into the blood vessels
Right half receives blood from the tissues and sends it to the lungs
Left half receives newly oxygenated blood from the lungs and pumps it to tissues throughout the body
Pathway of blood: right atrium, right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium, left ventricle, aorta, body & capillaries, vena cava
Pressure, Volume, Flow and Resistance
Pressure gradients: liquids and gases flow from regions of higher pressure to regions of lower pressure
Pressure: force exerted by the fluid on its container; measured as millimeters of mercury (mm Hg) in the circulatory system
Hydrostatic pressure: pressure exerted if fluid is not moving and force is exerted equally in all directions
Driving Pressure: pressure created in the ventricles which drives blood through the blood vessels
Resistance: tendency of the cardiovascular system to oppose blood flow
Poiseuille's law: shows the relationship between the radius of the tube, length of the tube and viscosity (thickness) of the fluid in terms of how they affect resistance
Vasoconstriction: decrease in blood vessel diameter
Vasodilation: increase in blood vessel diameter
Flow Rate (flow): volume of blood that passes a given point in the system per unit time
Velocity of Flow (velocity): distance a fixed volume of blood travels in a given period of time
Cardiac Muscles and the Heart
The apex is the bottom, the base is the top
Pericardium: tough membranous sac that encases the heart
Myocardium: cardiac muscle
Ventricles contract from the bottom up so the blood is squeezed out of the top
Atrioventricular valves: thin flaps of tissue joined at the base to a connective tissue ring; connect to the chordae tendineae and separate the atria and the ventricles
Papillary muscles: muscles where the chordae tendinae are tethered to which provide stability
Tricuspid valve: valve on the right side of the heart with three flaps
Bicuspid/mitral valve: valve on the left side of the heart with two flaps
Semilunar valves: valves between the ventricles and arteries
Aortic valve: between left ventricle and aorta
Pulmonary valve: between the right ventricle and pulmonary trunk
Autorhythmic/pacemaker cells set the rate of the heartbeat
Ca2+ induced Ca2+ realease (CICR): process of EC coupling in which the myocardial RyR channels open in response to Ca2+ binding