Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

40 Cards in this Set

  • Front
  • Back
What are the 2 main determinants of how blood flow is regulated by the tissues?
Supply and demand.
If demand is increased, supply will increase until no longer needed, and vice versa.
What regulates supply of bloodflow to tissues?
What 3 tissue types have very high bloodflow per mass?
What 3 tissues have intermediary bloodflow per mass?
What 3 tissues have relatively low bloodflow per mass?
Inactive muscle
How does an increased metabolic rate affect blood flow?
It causes BF to increase, but not to the same extent that you would expect; rather 1/2
Why doesn't bloodflow increase as much as you would expect during increased metabolism?
Because hemoglobin has other mechanisms for increasing O2 delivery without the global bloodflow needing to increase that much.
What are the 2 main tissue changes that will cause bloodflow to increase?
1. Metabolic rate
2. Blood O2 saturation (Po2)
What structures are responsible for local changes in vascular flow to tissues?
-Metaarteriole smooth muscle
-Precapillary sphincters
What is it called when metabolism regulates bloodflow?
Metabolic Autoregulation
What are the 2 theories of Metabolic Autoregulation?
1. Vasodilator substances
2. Oxygen deficit
What substances are capable of vasodilating blood vessels? (6)
-H+ and Lactic acid
-Histamine and K+
What are the steps in Metabolic Autoregulation Vasodilator Substance Theory?
1. Increase metabolic rate
2. Release vasodilators
3. Decrease Arteriole Resistance and precap sphincters
4. Increase blood flow
What type of feedback is metabolic autoregulation?
Negative - either of the theories.
What are the steps in Metabolic Autoregulation Vasodilator Oxygen deficit Theory?
1. Increase metabolic rate
2. Dcrease Tissue O2 conc.
3. Decrease Arteriole resistance
4. Increase blood flow
2 Special examples of metabolic control of local blood flow:
1. Functional hyperemia
2. Reactive hyperemia
What type of autoregulation is seen in Functional Hyperemia?
Vasodilator substance release
What is Functional Hyperemia?
Active hyperemia - exercise induced - increase in BF due to build up of metabolites (vasodilator substances).
What is Reactive Hyperemia? What type of autoregulation?
The excess of tissue bloodflow following occlusion or decreased O2 concentration.
How does the responsive flow increase differ between Functional Hyperemia and Reactive hyperemia?
Reactive shows an OVERSHOOT in response proportional to the length of time of occlusion.
Why is the ability for muscle to change its resistance a good thing?
Because it allows bloodflow to remain constant over a wide range of arterial pressure.
What if the arteriole resistance could not change?
BF would just increase directly ppl to Pressure increase and skyrocket.
What is the change in muscle resistance called?
Myogenic autoregulation
What happens to myogenic autoregulation in the longterm?
It keeps bloodflow constant over an even WIDER range of BPs by muscular remodeling.
What type of feedback is myogenic autoregulation?
Positive feedback
How does Myogenic autoregulation compare to Metabolic?
-Less precise - not a sensor of changes in metabolism
-Positive vs Negative feedback - more dangerous
What are 2 results of decreasing Resistance at the Precapillary Sphincter?
1. Release of vasodilator substances
2. Shear stress
What is the effect of Shear stress on endothelial cells?
They produce Nitric Oxide
What does NO do?
Vasodilates large vessels PROXIMAL to the precapillary sphincter to increase BF more
What is NO produced from?
What enzyme converts Arg into NO?
NOS - nitric oxide synthase
What is the action of NO?
-Activates Guanylyl cyclase
-Activates cGMP formation
-cGMP causes vasodilation
What happens to myogenic autoregulation in the long term?
It stretches out to keep BF constant even in extremely high BP.
How do vessels keep BF low even in high arterial pressure if R can't change anymore?
By remodeling the vessel wall - hypertrophy.
What law is exhibited by vascular remodeling?
Laplace's law:
T = Pr/M
M (muscle thickness) increases to keep Wall Tension from going too high.
What is the drawback to vascular remodeling?
It increases resistance which makes BP increase even more - a vicious cycle.
What is the 4th way to regulate bloodflow at the local level?
What are 3 important angiogenic factors?
What induces angiogenic factors?
Shear stress or oxygen decrease
What do angiogenic factors do?
Act on the basement membrane to induce sprouting of endothelial cords.