Annoying DSA Flashcards
What do arteries contain?
Stressed volume of blood
What do venules and veins contain?
Unstressed volume of blood and largest amount of blood at any time.
What are veins innervated by?
a1 adrenergic receptors
When does turbulent flow occur?
When laminar flow is disrupted
When can bruits be heard?
When turbulent flow occurs in an artery or other vascular channel and may indicate stenosis
What is the site of highest resistance and largest drops in pressure?
Arterioles
Where is compliance greatest?
Veins
When does compliance drop?
In arteries and then arteries with aging
What decreases the compliance of veins? What happens as a result?
Venoconstriction. Blood moves from unstressed to stressed.
Where does the largest pressure drop occur in the vasculature?
Arterioles, due to the high resistance to flow
What is pulse pressure?
The difference between systolic and diastolic pressures
2 formulas for MAP
= 2/3(DBP) + 1/3(SBP)
= DBP + 1/3 (pulse pressure)
What two pathological conditions with alter arterial pressure?
- ) arteriosclerosis
2. ) Aortic stenosis
How does arteriosclerosis alter arterial pressure?
plaque deposits decrease compliance and diameter of vessel walls. This will increase SBP, pulse pressure, and MAP, without changing DBP
How does aortic stenosis alter arterial pressure?
A narrowing of the aortic valve decreases SBP, pulse pressure, and MAP
What can cross the capillary wall by simple diffusion?
O2 and Co2
What do the pores in capillary allow through?
Water soluble substances (water, glucose, amino acids)
In the brain, are the capillaries tighter?
Yes, BBB
Where are continuous capillaries located?
Most places in the body.
ex. Muscle, brain, peripheral nerves, exocrine glands
Where are fenestrated capillaries located?
Endocrine glands, sites of absorption (gallbladder, kidney)
Where are discontinuous/sinusoidal capillaries located?
bone marrow, liver, spleen, (intestines?)
Where can proteins cross in capillaries?
In capillaries with fenestrations (kidneys and intestines)
What special process allows proteins to move through capillaries
pinocytosis
What is the starling equation?
Jv = Kf [(Pc-Pi)-(πc-πi)}
When Jv is positive, what is the net movement of fluid?
Out of the capillary, filtration
When Jv is negative, what is the net movement of fluid?
Into the capillary, absorption
Where is Pc the greatest?
At the arterial end, it decreases towards the venous end
What does Pc favor?
Filtration out of the capillary
What does Pi do?
Opposes filtration out of the capillary. It is normally negligible
What does πc do?
Opposes filtration.
What is πc due to?
Protein concentration in the blood (especially albumin).
What does πi do?
Favors filtration due to protein in interstitial fluid
3 mechanisms of local (intrinsic) control of BP?
- ) Autoregulation
- ) Active hyperemia
- ) Reactive hyperemia
What is auto regulation? Where does it occur?
maintenance of a constant blood flow in face of changing arterial pressure. Brain, heart, kidney
What is active hyperemia?
Blood flow to an organ is proportional to its metabolic activity. Ex. Increased blood flow to exercising skeletal muscle
What is reactive hyperemia?
Increase blood flow in reaction to a period of decreased blood flow. (ischemia - reperfusion)
Myogenic hypothesis?
Vascular smooth muscle contracts when it is stretched
Metabolic hypothesis?
Tissue supply for O2 is matched to the tissue demand for o2. If o2 consumption is increased, vasodilatory metabolites are released to dilate smooth muscle
What does histamine cause?
arteriolar dilation and venous constriction. This leads to increase Pc and increased filtration out of the capillaries, resulting in local edema
What does bradykinin cause?
Arteriolar dilation and venous constriction
What does serotonin cause?
Arteriolar constriction, released in response to vascular damage
What does prostacyclin cause?
Vasodilation
What are E-series prostaglandins?
Vasodilators
What are F-series prostaglandins?
Vasoconstrictors
What is thromboxane A2?
Vasoconstrictor
