Lecture 18 Flashcards
What is the average resting CO in L/min?
5 L/min
What is the average exercising CO L/min?
25 L/min
What is the % change in CO flow to the heart from resting to exercising?
No change, it remains the same at ~4%
T or F? CO flow to the brain increases during exercise.
False, blood flow to the brain decreases, skeletal muscle increases.
T or F? Active tissue can require up to 20x increase in blood flow.
True
CO can increase to approximately ____ times normal during exercise.
6
CO alone cannot meet the demand of active tissues, what must happen to help increase blood flow to the tissues?
Changes in microcirculation, vasoconstriction.
Smooth muscle in small arteries and arterioles can be stimulated to contract or relax via ____ signals, _____ stimuli, ______, and changes in _____ environment
nervous signals, hormonal stimuli, stretch, chemical environment
T or F? Contraction of arteries and arterioles require an action potential to stimulate contraction.
False, no action potential needed
What 3 main categories regulates blood flow?
SNS
Local chemical factors
Long-term angiogenesis
T or F? The PNS innervates the majority of blood vessels.
False, PNS does not innervate the majority of blood vessels but does regulate dilation of some blood vessels in specific areas of the body, such as the genitals. SNS innervates blood vessels.
The SNS causes generalized vasoconstriction and venoconstriction due to stimulation of ________ receptors.
α1-adrenergic
The ____ and _____ circulations have poor SNS vasoconstrictor innervation so are spared the vasoconstrictor effect.
coronary ; cerebral
Local ____, and release of _____ _______, is the primary controller of coronary and cerebral blood flow.
metabolism;vasodilator substances
Stimulation of B2 receptors causes __________ in few vascular beds.
Vasodilation
What local chemical factors are released from metabolically active or hypoxic tissues that cause relaxation of smooth muscle and vasodilation of small arteries and arterioles?
Adenosine, CO2 , H+, K+, lactate.
Endothelial cells release _____ in response to sheer stress from blood flow, causing vasodilation.
nitric oxide
What produces nitric oxide (NO)?
Endothelial NOS (Nitric Oxide Synthase)
T or F? Local chemical factors such as autocrine/paracrine peptides endothelin, bradykinin, prostaglandins, and histamine causes arteriole dilation and capillary permeability.
False, all is true except endothelin. Endothelin causes vasoconstriction.
How is long term blood flow regulated to various tissues?
Angiogenesis
In response to chronic ischemia, tissues release angiogenic factors, (_______, etc) which stimulate angiogenesis.
VEGF
T or F? Angiogenesis can decrease the number of blood vessels than can occur.
True. Increase or decrease in number of blood vessels can occur.
What is the a abbreviation for oxygen consumption?
V(O2)
A-V(O2) difference is the abbreviation for what?
Arteriovenous oxygen difference.
What is A-V(O2) difference?
It is the difference in the Po2 between the arterial blood and the venous blood. (the Po2 of the blood entering a tissue -the Po2 of the blood leaving the tissue).
T or F? If the A-VO2 difference increases, it represents an increase in oxygen uptake by that tissue.
True
What factors contribute to the changes in HR, SV, CO, SBP, & DBP during exercise?
HR - Increase HR by SNS via B-1 SV - Increase contractility via B-1 CO - Increase HR /SV increases CO SBP - Increase CO increases SBP DBP - Decrease TPR decreases DBP
During exercise, how does more blood get to the muscles if SNS causes vasoconstriction?
Local factors such as adenosine, CO2, H+, K+, Lactate and NO2 causes vasodilation of small arteries and arterioles.
_______ _____ increases local factors to cause vasodilation in skeletal muscle and myocardium.
Metabolic rate
During exercise, SV increases at first, then levels off and stays constant?
HR increases, filling time is shorter. (Normally it’s contract, rest, rest; exercise it is contract, rest contract)
As Aseel plays racket ball, her SBP is expected to increase due to increase in CO. Why would her DBP remain the same or decreases?
The primary determinant of DBP is TPR since local factors override the SNS and vasodilate the arteries, the TPR is constant or may decrease.
What is rate-pressure product (pressure-rate product or double product)
It is an indirect index of myocardial O2 consumption, how hard the ventricle is working. (HRxSBP(or MAP))
