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ANT 3120: Chapter 21
Physiology
47
Anatomy
Undergraduate 1
03/07/2013

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Term
contributors to venous return to the heart
Definition
1) skeletal muscle contractions (major)
2) respiratory pump (minor)
3) hydrostatic pressure (minor)
Term
function of respiratory pump
Definition
expands thoracic cavity during inhalation which increases venous return by lowering pericardial cavity pressure
Term
hydrostatic pressure [description]
Definition
1) very low pressure gradient in venous system
2) valves in place to prevent back flow of blood below heart
Term
vascular hemodynamics
Definition
study of blood flow
Term
laminar flow
Definition
smooth blood flow occurring in parallel, concentric layers
Term
turbulent flow
Definition
rough, chaotic blood flow
Term
resistance of laminar flow
Definition
little resistance to blood flow
Term
resistance of turbulent flow
Definition
increases resistance of blood flow
Term
where does turbulent flow occur?
Definition
occurs at the areas of blood vessel branching
Term
turbulent flow contributes to
Definition
atherosclerosis by causing inflammation of blood vessels
Term
what contributes to turbulent blood flow?
Definition
atherosclerosis and thrombi
Term
Poiseuille's Law
Definition
describes the flow of blood in a vessel
Term
greatest effect on resistance to blood flow
Definition
radius
Term
arterial radius is affected by
Definition
1) sympathetic tone
2) local factors
Term
vasoconstriction
Definition
decreases blood vessel radius
Term
vasodilation
Definition
increases blood vessel radius
Term
viscosity
Definition
measure of the thickness of a fluid
Term
what happens if viscosity is increased?
Definition
increase in resistance
Term
how is viscosity increased?
Definition
increasing substances in blood
Term
factors that increase viscosity
Definition
1) increase in hematocrit
2) dehydration
3) high cholesterol and/or triglyceride levels
4) stasis
Term
control of blood flow is done by
Definition
controlling smooth muscle tone by
1) vasomotor centers
2) local factors
Term
local factors that cause smooth muscle relaxation (vasodilation)
Definition
1) arginine
2) histamine
3) decrease in pH
4) increase in CO2
5) decrease in O2
Term
local factors that cause smooth muscle contraction (vasoconstriction)
Definition
1) thromboxanes
2) ADH/vasopressin
3) increase in pH
4) decrease in CO2
5) increase in O2
Term
output of vasomotor centers in brainstem via
Definition
sympathetics
Term
stimulation of vasomotor centers
Definition
causes smooth muscle contraction (vasoconstriction)
Term
inhibition of vasomotor centers
Definition
causes smooth muscle relaxation (vasodilation)
Term
blood pressure is measured in
Definition
millimeters of mercury
Term
blood pressure
Definition
measure of the force that blood exerts against blood vessel walls
Term
mean arterial pressure (MAP)
Definition
average blood pressure in the arterial circulation
Term
what type of average is MAP
Definition
weighted average because heart spends 1/3 in systole and 2/3 in diastole
Term
factors that affect TPR
Definition
1) arterial radius
2) viscosity
3) friction
Term
TPR
Definition
opposing force to blood flow
Term
hypotension
Definition
abnormally low blood pressure when the blood pressure gradient for flow is diminished
Term
critical closing pressure
Definition
pressure below which a blood vessel collapses
Term
circulatory shock
Definition
severe decreases in blood pressure which leads to inadequate blood flow
Term
types of circulatory shock
Definition
1) hypovolemic shock
2) vasodilatory shock
3) cardiogenic shock
Term
hypovolemic shock
Definition
loss of blood volume decreases blood pressure
Term
vasodilatory shock
Definition
vasodilation decreases blood pressure
Term
cardiogenic shock
Definition
inadequate cardiac output decreases blood pressure
Term
reasons for circulatory shock
Definition
1) hemorrhagic shock
2) anaphylactic shock
3) septic shock
4) emotional shock
5) neurogenic shock
Term
hemorrhagic shock (hypovolumic)
Definition
bleeding that causes loss of blood volume
Term
anaphylactic shock (vasodilatory)
Definition
severe allergic response that causes the massive release of inflammatory chemicals (causes severe vasodilation)
Term
septic shock (hypovolumic, vasodilatory, and cardiogenic)
Definition
systemic blood infection that releases toxins in the blood
Term
symptoms of septic shock
Definition
1) bleeding caused by damaged capillary beds
2) vasodilation
3) decreases heart rate and contractility
Term
emotional shock (vasodilatory and cardiogenic)
Definition
sudden emotional trauma
Term
symptoms of emotional shock
Definition
1) causes strong parasympathetic stimulation which decreases heart rate
2) causes strong sympathetic inhibition which causes vasodilation and decreases heart rate and contractility
Term
neurogenic shock (vasodilatory and cardiogenic)
Definition
causes strong inhibition of sympathetics which causes vasodilation and decreases heart rate and contractility
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