Exam Ch 15 Flashcards
Arteries
Carry blood away from the heart
Arterioles
Control blood flow, feed capillaries
Capillaries
provide site for nutrient and waste exchange
Venules
Collect blood from capillaries
Veins
Carry blood from venules back to heart
When is the highest pressure in artery
During systole
When is the pressure the lowest in artery
During diastole
Does diastolic pressure go up during dynamic exercise
during isometric exercise
No
Yes
Mean arterial pressure
average pressure over entire cardiac cycle
2/3 DBP+ 1/3 SBP
force that drives flow
Pressure
Where does pressure come from
provided by heart contraction
Force that opposes flow
Resistance
Where does resistance come from
provided by physical properties of vessels
Most important factor for resistance
Radius
Easiest way to change blood flow
change radius
Vasoconstriction
closing of blood vessels
Vasodilation
opening of blood vessels
Where is the most potent vasoconstriction and vasodilation
Arterioles
At rest what gets the most blood
Liver, kidneys receive 50% of Q
during heavy exercise what gets the most blood
Exercising muscles receive 80%
Flow to liver, kidneys 20%
Intrinsic control of blood flow
ability of local tissues to constrict or dilate arterioles that serve them
3 types of intrinsic control
Metabolic - buildup of local metabolic by-products
Endothelial - substances secreted by vascular endothelium
Myogenic - local pressure changes causing VC, VD
increase sympathetic activity
increase VC
decrease sympathetic activity
decrease VC (passive VD)
at rest how much volume of blood do veins contain
2/3
Venous resivoir can be liberated, sent back to heart and into arteries via
Sympathetic stimulation
Venoconstriction
What does an upright posture do to venous return
makes it more difficult
What 3 mechanisms assist in venous return
one way venous valves
Muscle pump
respiratory pump
Equation for whole blood
plasma + formed elements
Three exercise-related major functions of blood
Transportation
Temperature regulation
Acid-base balance
What percent of blood volume is plasma
55-60%
What percent of blood volume is formed elements
40-45%
total percent of volume composed of formed elements
hematocrit
how much O2 is in hemoglobin
4 O2 per hemoglobin
how many hemoglobin per red blood cells
250 million
how many mL of O2 per 100 mL of blood
20 mL
What increases as hematocrit increases
viscosity
what must increase as red blood cells increase
plasma volume
