Module 9 Flashcards
Describe the path of blood from entering the heart to re-entering the heart
superior/inferior vena cava -> right atrium -> right AV valve -> right ventricle -> pulmonary semilunar valve -> pulmonary artery -> pulmonary capillaries (lungs) -> pulmonary vein -> left atrium -> left AV valve -> left ventricle -> aortic semilunar valve -> aorta -> arteries -> arterioles -> capillaries -> venules -> veins -> superior/inferior vena cava
Name the two distinct circulation loops
pulmonary circulation and systemic circulation
Name two smaller loops within systemic circulation
hepatic portal loop (digestive system) and hypothalamic-hypophyseal portal system (in brain)
List blood volume distribution throughout the circulatory system
70% veins; 10% arteries; 15% heart and lungs; 5% capillaries
Name the vessel type with the highest and lowest blood velocity
highest: arteries; lowest: capillaries
Name the vessel type with the highest and lowest blood pressure
highest: arteries; lowest: veins/venules
Name the vessel type with the highest and lowest cross-sectional area
highest: capillaries; lowest: arteries
Name the area with largest decrease in blood pressure and velocity and why
arteries to arterioles, because of large increase in cross sectional area
Explain the relationship between pressure, flow and resistance
flow is calculated by change in pressure divided by resistance (Flow = P1-P2/R); or simplified, Flow = P1-P2 x r^4
Explain laminar flow
streamlined flow has less resistance/turbulence, so larger or dilated vessels have less resistance than smaller or constricted vessels, where blood faces more resistance closer to vessel walls
Name three factors in resistance to blood flow
thickness/viscosity of blood; length of blood vessel; diameter or radius of blood vessel
Explain the equation for resistance and why it can be simplified
R=Ln/r^4, where L is length of blood vessel and n is viscosity, but since both remain constant over short periods of time, R=1/r^4
Name two ways to alter blood flow (remember equation)
change pressure gradient; change resistance (aka change radius of blood vessel)
Explain Korotkoff’s sounds and how they are used to take blood pressure
tapping sounds produced when flow becomes turbulent as it squeezes through blood vessels pinched off by pressure cuff as pressure releases; systolic pressure is when sounds start and diastolic pressure is when sounds end
Explain the structure of an artery
tunica externa (fibrous tissue), media (smooth muscle and elastic tissue), and interna (endothelial cells); lots of elastic tissue to withstand large pressure changes from the heart
Explain the structure of an arteriole
mostly smooth muscle to constrict and dilate as needed, and endothelial tissue
Explain the structure of a capillary
single layer of endothelial cells to allow diffusion; also has clefts and fenestrations, holes allowing movement of water
Explain the structure of a venule
no smooth muscle or elastic tissue, just fibrous tissue and endothelial layer
Explain the structure of a vein
tunica externa (fibrous tissue), media (smooth muscle and elastic tissue), and interna (endothelial cells); thinner than arteries, very little elastic tissue, more flexible
Name the four Starling Forces and which contribute to filtration and reabsorption
two hydrostatic pressures: capillary (Pc, filtration) and interstitial-fluid (Pif, reabsorption); two osmotic forces: due to plasma protein concentration (πp, reabsorption) and due to interstitial-fluid protein concentration (πif, filtration)
Explain the capillary hydrostatic pressure
Pc is pressure from fluid forcing outward on the walls of capillaries; contributes to filtration; is different at arterial and venous end of capillary
Explain the interstitial-fluid hydrostatic pressure
Pif is pressure from fluid pushing back on capillary; contributes to reabsorption (unless negative, then to filtration); generally zero unless otherwise specified; varies from organ to organ
Explain the osmotic force of plasma
πp draws fluid into capillary, contributing to reabsorption; since plasma has lots of proteins, force is generally high
Explain the osmotic force of proteins in the interstitial space
πif pulls fluid out of capillary, causing filtration; since interstitial fluid has little proteins, force is low
Describe the equation for net filtration pressure and overall net filtration
NFP = (Pc-Pif) - (πp-πif); calculated at arterial and venous end where Pc will differ, positive means filtration and negative means reabsorption; overall net filtration is adding them together
Describe how the lymphatic system works
small blind-ended capillaries absorb excess fluid; transport to larger collecting vessels that filter through lymph nodes then send fluid back to venous circulation
List factors contributing to edema
increase in Pc caused by increased blood pressure; decreased πp due to malnutrition; blockage or disruption of lymphatic system
Define autoregulation
the process by which individual capillary beds maintain relatively constant blood flow when moderate changes occur in blood pressure
Explain the myogenic theory
sudden increase in blood pressure to vital organ will cause vessels to dilate, so a reflex to contract smooth muscle in walls of arteriole supplying the organ will cause vasoconstriction to decrease blood pressure/flow and prevent damage to capillary network; opposite can happen
Explain the metabolic theory
changing metabolic activity will change blood flow to that organ; cardiovascular system will respond to increase in heat, CO2, lactic acid, and adenosine in muscles, causing vasodilation and increased blood flow to active tissue until metabolites are washed out
Explain humoral regulation
regulation of blood flow by chemical substances circulating in the blood other than local metabolites, like hormones; fall into two categories of vasodilators and vasoconstrictors
List agents responsible for vasoconstriction
epinephrine (weak effect on intestinal blood vessels); angiotensin ii (ang ii) (most powerful, associated with renal system); vasopressin (aka ADH) (also associated with renal system)
List agents responsible for vasodilation
epinephrine (in skeletal muscle and cardiac muscle); kinins (hormones formed in plasma and tissue); histamine (released from damaged cells); atrial natriuretic factor (ANF) (produced by atrial muscle cells)
Explain the equation for blood pressure, or mean arterial pressure
MAP = cardiac output (CO) x total peripheral resistance (TPR); increasing either will increase blood pressure; TPR is sum of all resistance in all blood vessels in the body
Briefly explain the baroreceptor reflex
negative feedback mechanism; special stretch receptors in walls of aortic arch and carotid sinuses detect increased blood pressure/stretching, send signals to cardioregulatory and vasomotor centers in medulla oblongata, send signals back through PSYN to decrease heart rate, send signals through SYN to dilate vessels and decrease blood pressure
