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chapter 19
blood vessels
41
Physiology
Undergraduate 2
04/23/2015

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Term
How is blood carried?(generally)
Definition
Blood is a carried in a closed system of vessels that begins and ends at the heart.
Term
What are the three major type of vessels? and how does each one carry blood?
Definition
Veins, Arteries and capillaries. Veins are carried toward the heart, arteries carry blood away from heart and capillaries contact tissue cells and serve cellular needs
Term
Tell me about the structure and functions of elastic conducting arteries?
Definition
thick walled arteries near the heart , the aorta and its major branches. it contains elastin in all three tunics. it withstands and fluctuates large blood pressure. allows blood to flow smoothly throughout the body
Term
tell me about the functions of muscular arteries and arterioles.
Definition
muscular arteries are distal to elastic arteries. have thick tunica media with more smooth muscle and less elastic tissue. active in vaso constriction . arterioles are the smallest arteries, leads to capillary beds . control flow into capillary beds via vasodilation and constriction.
Term
what are capillaries?
Definition
capillaries are the smallest blood vessels. the walls consist of a thin tunica interna, one cell thick. allows only a single rbc to flow at a time
Term
when you exercise? does the blood vessels vasodilate or vasoconstrict?
Definition
vasodilate
Term
what is a precapillary spinchter?
Definition
cuff of smooth muscle that surrounds each true capillary. regulates blood flow into the capillary
Term
how is blood flow regulated in the precapillary beds?
Definition
blood flow is regulated by vasomotor nerves and local chemical conditions, so it can either bypass or flood the capillary bed
Term
how is the venous system aka venules formed? what are postcapillary venules and large venules
Definition
when capillary beds unite, they allow wbc to pass from bloodsteam to tissues. post capillary venules are the smallest venules composed of endothelium, large venules have one or two layers of smooth muscle (tunica media)
Term
how are veins formed and what are they composed of?
Definition
when venules converge and composed of three tunics, thin tunica interna and thick tunica externa consisting of collagen and elastic networks
Term
which has lower pressure, veins or arteries?
Definition
veins
Term
to return blood back to the heart, veins have special adaptations, explain them
Definition
large diameter lumens which offer little resistance to flow and valves which prevent backflow of blood
Term
what is vascular anastomoses?
Definition
merging blood vessels, more common in veins then arteries. aetrial anastomoses provide alternate pathways (collaterel channels)for blood to reach a given body region . if one branch is blocked , the collateral channel can supply the region with adequate blood
Term
Actual volume of blood flowing through a vessel, an organ, or the entire circulation in a given period is measured in? constant or not constant at rest, varies or doesnt varie
Definition
ml per min, constant, varies widely through individual organs, according to immediate needs
Term
most of the arteries carry oxygenated blood except? all veins carry deoxygenated blood except
Definition
polmonary arteries, polmonary veins
Term
what is blood pressure
Definition
force per unit area exerted on the wall of a blood vessel its contained blood. expressed in millimeters of mercury (mm hg). The differences in BP within the vascular system provide the driving force that keeps blood moving from higher to lower pressure areas
Term
what is resistance?
Definition
the opposition to flow, measure of friction blood encounters as it passes through vessels. the three important sources of resistance are blood viscocity, blood diameter, and blood vessel length
Term
explain blood viscocity, vessel legnth
Definition
blood viscoity - thickness of blood. blood vessel length, the longer the vessel, the greater the resistance encountered
Term
small
Definition
Term
small diameter arterioles are the major determination of?
Definition
periphal resistance
Term
fatty plaque acids from artherscrelosis cause
Definition
turbulent , dramatically increase resistance due to turbulence
Term
If blood pressure(AP) increases, blood flow _______. and if blood pressure(ap) decreases, blood flow declines
Definition
speeds up, declines
Term
if (R) resistance increases, blood flow ______
Definition
decreases
Term
blood flow is directly __________ to the difference in blood pressure between two points in a circulation
Definition
proportional
Term
blood flow is inversely _______ to resistance
Definition
proportional
Term
what is systemic blood pressure?
Definition
the pumping action of the heart genereates blood flow through the vessels along a pressure gradient, always moving from a higher to lower pressure areas. pressure results when flow is opposed by resistance
Term
systemic pressure is highest in
Definition
aorta and declines throughout the length of the pathway. is 0 hg in the right atrium
Term
arterial blood pressure reflects two factors
Definition
their elasticity, the amount of blood forced into them at any given time
Term
what is systolic pressure, diastolic pressure, pulse pressure, mean arterial pressure,
Definition
systolic pressure pressure exerted on arterial walls during a ventricular cycle , pulse pressure - the difference between systolic and diastolic pressure , mean arterial pressure(map)- pressure that propels the blood to the tissues. MAP = pressure
Term
how much is the capillary blood pressure? and why is it desirable at this blood pressure?
Definition
20 to 40 mm hG, because high blood pressure would rupture thin walled capillaries, low bp is sufficient to force filtrate out into interstitial space and distribute nutrients gases and hormones between blood and tissues.
Term
is venous blood pressure steady or unstable?
Definition
steady and changes little during the cardiac cycle. the pressure gradient in the venous system is only about 20 mm Hg.
Term
venous bp alone is too low to promote adequate blood return and is aided by
Definition
the respiratory pump - pressure changes created during breathing suck blood toward the heart by squeezing local veins.
muscular pump - contraction of skeletal muscles milk blood toward the heart
Term
valves prevent _______ during venous return
Definition
backflow
Term
what are the main factors influencing blood pressure?
Definition
cardiac output, periphal resistance, blood volume
Term
blood pressure -
Definition
CO x PR
Term
blood pressure varies directly with CO, PR, and BLOOD VOLUME
Definition
true or false
Term
neural controls of periphal resistance alter? maintain mAP by altering ?
Definition
blood distribution to respond to specific demands. blood vessel diameter
Term
neural controls operate via reflex arcs involving?
Definition
baroreceptors, vasomotor centers of the medulla and vascular smooth muscle.
Term
symphatetic activity causes blood pressure?
Definition
vasoconstriction and rise in blood pressure if increased and blood pressure to decline is basal levels if decreased
Term
vasomotor activity is modified by
Definition
baroreceptors (pressure-sensitive), chemoreceptors(o2, Co2, and h plus senssitive), higher brain centers, bloodborne chemicals and hormones
Term
increased blood pressure stimulates the cardioinhibitory center to
Definition
increase vessel diameter, decreased heart rate , cardiac output , periphal resistance and
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