Cardio 4 Flashcards
blood flow (Q) =
Q=∆P/R
* Q=flow rate in an artery (mL/min)
* ∆P=the ∆ pressure across the artery or system (mmHg)
* R=resistance to flow in the artery
assume delta P is MAP for our calculations
blood flow will only occur when there is a difference in
pressure
R=8Lη/πr^4
-considering this equation, what happens to blood flow when the radius increases by one unit?
the blood flow increases to the radius^4
ex:
Q = 1/R = 1 x 14 = 1
Q = 1/R = 1 x 24 = 16
Q = 1/R = 1 x 44 = 256
*increases exponentially to the 4th power
-increasing by 16 folds each time radius doubles
-this is why radius is * for flow
- main 3 factors that affect blood flow
length, viscosity and radius- main 3 factors
-pressure and resistance too
-resistance is primarily driven through the..
-resistance is primarily driven through diameter
BP is modulated by …
-hint baroreceptors detect stretch
extrinsic regulation
blood flow is regulates by..
intrinsic regulation
vasocontrictor and vasodialtor signals, compete to signal …
vasocontrictor and vasodialtor signals, compete to signal relax or contract
Myogenic (mechanical) changes in vessels can help regulate fluctuations in
BP
Endothelial shear stress (mechanical)
explain
def: Shear stress is the tangential force per unit area exerted by the flowing blood on the endothelial cells. It is a result of the blood’s viscosity and velocity as it moves through the vessels
-signal to ‘open’ the highway in preparation of high blood volume passing through
- promotes relaxation
- Helps maintain tone
- Helps enhance blood flow delivery
- Respond to external environment
- Produces dilation in most arteries
- Produces constriction in brain
- Relays signal to VSM
Metabolic/Neurogenic (intrinsic):
at neuromuscular junction, what is released?
at neuromuscular junction, Ach is released
at neuromuscular junction, Ach is released and acts on neighboring muscarinic receptors on vessels to stimulate..
vasodilation
Metabolic/Neurogenic (intrinsic) is Predominantly in X and X
brain and muscle
- disproportionate delivery of blood based on where the Ach is released and where the vessels are actively dilating –> allows direction of blood towards active fibers
active tissues will receive more blood.
this is what kind of regulaiton?
Metabolic/Neurogenic (intrinsic) regulation
breakdown of X causes dilation of vessels
breakdown of metabolites causes dilation of vessels
Endothelial regulation mechanism
receptors respond to release of peptides and hormones through production of NO
1. Redistribution of blood flow
2. Responds to & produces dilators
3. Responds to & produces constrictors
4. Relays signal to VSM
5. (note on NO) *causes vessel dilation/relaxation
note on feedback, NO vs. ET1 status:
production of ET1 causes vessel constriction. this competes W X to maintain vessel diameter
NO
-negative feedback mechanism occurs when ET1 is activated where receptors are bound in the endothelium to produce NO as a means of regulating constriction and creating a buffer system
review final slide
- and mechanisms bc i got lost
there are many types of X that are on smooth muscle cells to determine contraction or relaxation
–> depends on the balance between them
receptors
