Physiology- regulation of blood flow
T/F: Circulation of the skin is almost entirely controlled by the central nervous system.
T
T/F: Products of tissue metabolism play an important role in regulating blood flow
T
T/F: The left ventricular blood flow is weird compared to other organs because it gets its blood supply during diastole
T (other organs = greatest blood flow during systole. LV compresses its arteries during contraction --> increases resistance --> not as much flow)
ACTIVE/REACTIVE hyperemia is also known as functional hyperemia
active
ACTIVE/REACTIVE hyperemia is increased blood flow to tissues with increased activity
active
During ACTIVE/REACTIVE hyperemia, metabolites accumulate because the blood flow is insufficient to remove the increased production (due to increased tissue activity)
active
Oxygen regulating blood flow in ACTIVE/REACTIVE hyperemia: increased tissue activity -> increased metabolism --> decreased oxygen --> vasodilation --> increase blood flow --> oxygen restored to normal
active
In ACTIVE/REACTIVE hyperemia, increased tissue activity (increased metabolism), causes metabolites to accumulate because normal blood flow is insufficient to remove them --> this leads to vaso DILATION/CONSTRICTION --> LESS/MORE blood flow to the area
active, dilation, more (metabolites are vasodilators)
What are the 7 important vasodilator metabolites?
adenosine, atp, adp, amp, CO2, lactic acid, K ions
Epi and NE interact with alpha and beta adrenergic receptors. The ALPHA/BETA receptors mediate vasoconstriction
alpha
NE has greater affinity for BETA/ALPHA receptors
alpha (so NE has more affect on periphery than heart)
At high concentrations, epi activates ALPHA/BETA receptors, thus causing vaso DILATION/CONSTRICTION
alpha, constriction
Long term regulation of blood flow: Increasing the number of blood vessels is done by process of _____
angiogenesis
______: capacity of blood vessels to oppose changes in blood flow that are imposed by change in BP
autoregulation
Epi and NE interact with alpha and beta adrenergic receptors. The ALPHA/BETA receptors mediate vasodilation
beta
At low concentrations, epi activates ALPHA/BETA receptors, thus causing vaso DILATION/CONSTRICTION
beta, dilation
The blood flow & metabolic need relationship is not linear because tissues have a ___ ___ ___. When there is increased metabolism they draw upon this without having to increase blood flow significantly. *HOWEVER, as blood flow continues to increase, the rate of blood flow increases to match the demand.*
blood flow reserve
Vasopressin -oligopeptide -At high levels, *constricts* ARTERIES/VEINS/BOTH in the ____ area. -Regulates ARTERIAL PRESSURE/PLASMA VOLUME/BOTH -directs kidneys to INCREASE/DECREASE during output
both, GI, plasma volume, decrease
Angiotensin: -oligopeptide that *constricts* ARTERIES/VEINS/BOTH -Regulates ARTERIAL P/PLASMA VOLUME/BOTH -directs kidneys to INCREASE/DECREASE urine output
both, both, decrease
_____ (polypeptide) and ____ (biogenic amine) are vasoactive agents that are vasodilators and are released by cells of the immune system to *increase capillary permeability*
bradykinin, histamine
During exercise, blood flow to the ____ stays the same
brain (stays at 750 the whole time)
The role of the myogenic control in autoregulation is via stretch-activated _____ channels
ca
Important local metabolites for _____ circulation regulation are CO2, adenosine, nitric oxide, PG and Non-PG arachidonic acid metabolites
cerebral
Prostaglandin Thromboxane is a vaso DILATOR/CONSTRICTOR
constrictor
Vasopressin is a vaso DILATOR/CONSTRICTOR
constrictor
angiotensin 2 is a vaso DILATOR/CONSTRICTOR
constrictor
What blood vessels are sparsely innervated by the sympathetic NS?
coronary, cerebral
What blood vessels are heavily innervated by the sympathetic NS?
cutaneous, renal, GI, skeletal muscle
Skin blood flow regulation temperature is increased --> central & peripheral receptors cause a(n) INCREASE/DECREASE in sympathetic activity which CLOSES/OPENS the anastomoses --> blood FILLS/LEAVES venous plexus --> heat is lost and body temp drops
decrease, open, fills,
Long term regulation of blood flow can be done by INCREASING/DECREASING the size of the vascular lumen
decreasing (hypertrophic vascular remodeling)
It is important for ventricular pressure to remain low during SYSTOLE/DIASTOLE so the heart can be perfused during this period
diastole (heart gets its blood supply during diastole due to reactive hyperemia)
At low levels, epi causes vaso CONSTRICTION/DILATION and at high levels, it causes vaso CONSTRICTION/DILATION
dilation (via beta 2 receptors), constriction (as concentration increases, it also activates alpha 1 receptors)
Bradykinin is a vaso DILATOR/CONSTRICTOR
dilator
Prostaglandin PGE2 is a vaso DILATOR/CONSTRICTOR
dilator
Prostaglandin PGI2 is a vaso DILATOR/CONSTRICTOR
dilator (prostacyclin)
Blood flow is DIRECTLY/INVERSELY related to metabolism
directly (increase one, increase the other)
Humoral factors that regulate blood flow are ____ and _____
epi, NE
When regulating coronary blood flow, nitric oxide dilates EPICARDIAL/RESISTANCE arteries
epicardial
Cutaneous, renal, splanchnic, and skeletal muscle vascular beds are SPARSELY/HEAVILY innervated by sympathetic NS
heavily
______ - increased blood flow
hyperemia
_____ ____ ___ is the process used to decrease the size of vascular lumen. The walls of blood vessels thicken --> reduce radius --> increase resistance
hypertrophic vascular remodeling
Atrial netriuretic peptide is an oligopeptide released by atrial myocytes that directs the kidneys to DECREASE/INCREASE urine output
increase (lose more water)
Ischemia induces a DECREASE/INCREASE in the number of blood vessels
increase (low oxygen --> need more blood vessels)
Blood flow is DIRECTLY/INVERSELY related to oxygen tension
inversely (lower arterial oxygen concentration --> greater blood flow)
At low levels of sympathetic activity, a small increase in sympathetic activity will cause a SMALL/LARGE increase in vascular resistance
large
In poiseuille's law, determinants of resistance in laminar flow are ____, _____, and _____
length, viscosity, radius
Rapid regulation of resistance is done by: 1. Regulating _____ factors 2. Regulating the _______ NS 3. Regulation by _____ factors
local, sympathetic, humoral
Autoregulation via METABOLIC/MYOGENIC mech: increase pressure --> increased flow --- increased oxygen OR decreased metabolite --> increase vascular resistance --> decrease flow
metabolic
____ and ____ control are 2 physiological mechanisms that explain autoregulation
metabolic, myogenic
METABOLIC/MYOGENIC autoregulation control: increase flow --> increase Pressure --> increase stretch --> increase ca channel activity --> increase cytoplasm calcium --> increase force --> decrease radius --> decrease flow
myogenic
The role of the METABOLIC/MYOGENIC control in autoregulation is via stretch-activated calcium channels
myogenic
Which vasoactive agent? Regulates blood flow by decreasing intracellular calcium levels --> induce vasodilation is large vessels, upstream of hyperemic tissues
nitric oxide
___ ____ is a potent vasodilator derived from arginine. In normal tissues its generated by endothelial cells, but extracellular ATP and increased shear stress induce its release
nitric oxide
what are the 6 vasoactive agents?
nitric oxide, ANP (atrial natriuretic peptide), angiotensin 2, vasopressin, bradykinin, PGs
SLOW/RAPID regulation of resistance is done by regulating local factors, sympathetic nervous system, humoral factors
rapid (occurs in seconds to minutes)
Long term regulation of blood flow: Decreasing the number of blood vessels is done by process of _____
rarefaction
ACTIVE/REACTIVE hyperemia is increased blood flow above original resting level that follows reduction of blood flow to a specific tissue
reactive
ACTIVE/REACTIVE hyperemia: Constriction of arteries --> decreased blood flow --> release constriction --> increased blood flow (magnitude and duration of blood flow after constriction release depends on the duration of the ischemic episode)
reactive
During ACTIVE/REACTIVE hyperemia, metabolites accumulate only because of reduced removal of metabolites
reactive
Oxygen regulating blood flow in ACTIVE/REACTIVE hyperemia: Decreased blood flow --> decreased O2 -> vasodilation --> increased blood flow --> Oxygen restored
reactive (doesnt relate to metabolism like seen in active hyperemia)
It makes more sense to alter blood flow by altering PERFUSION PRESSURE/RESISTANCE due to physical arrangement of the vascular system.
resistance
When regulating coronary blood flow, NE dilates EPICARDIAL/RESISTANCE arteries
resistance
SLOW/RAPID regulation of resistance is done by reducing blood vessel lumen side (hypertrophy) or change in number of blood vessels per tissue (vascularity)
slow (occurs in weeks to months)
Cerebral and coronary vasculatures SPARSELY/HEAVILY innervated by sympathetic NS
sparsely
Arteriovenous anastomoses (skin circulation) is controlled by the SYMPATHETIC/PARASYMPATHETIC NS, which is controlled by the hypothalamus
sympathetic
Blood flow to some organs (kidneys, GI) decreases during exercise in order to decrease demands on heart. This is done by increased PARASYMPATHETIC/SYMPATHETIC activity in organs not experiencing increased function during exercise
sympathetic
Innervation of blood vessels is via the _____ nervous system vasoconstrictor fibers, and _____ is the major NT
sympathetic, NE
NE dilating coronary arteries via beta 2 receptors contributes to ___% of exercise-induced vasodilation
25
EPI/NE interacts with both alpha and beta (doesnt show preference)
Epi
T/F: Increased rates of metabolism = increased blood flow is shown in a linear relationship
F (NOT a linear relationship!)
T/F: NE plays a small role in regulating coronary blood flow
F (Nitric oxide. NE is a big role)
T/F: Small changes in radius only lead to small changes in resistance
F (Small change in radius = large change in resistance bc resistance is related to the inverse of the 4th power of the radius)
T/F: All blood vessels are innervated, including capillaries, and innervation density is constant throughout all vascularization
F (capillaries are NOT innervated, and density varies!)
T/F: In humans, angiogenesis occurs at high levels, especially in neoplastic tumors.
F (doesnt occur at high levels except in neoplastic tumors)
T/F: In reactive hyperemia, the longer the ischemic episode --> the magnitude of blood flow during hyperemia is increased by the duration remains the same
F (greater magnitude and duration as ischemic episode is increased)
T/F: In autoregulation, as you increase pressure you increase flow and vise versa for decrease.
F (increase pressure --> decrease flow)
T/F: The brain has very strong autoregulatory control, but only by the myogenic component.
F (metabolic and myogenic)
T/F: The most important factors regulating coronary blood flow are nitric oxide and NE
F (metabolic end products and altered oxygen)
T/F: The relationship between metabolism and blood flow is not linear, while the relationship between oxygen tension and blood flow is.
F (neither are linear)
T/F: The vasodilatory effect of epi on beta2 receptors is more powerful than its vasocontrictive effects at alpha 1 receptors
F (opposite! more effect on vasoconstriction via alpha1)
T/F: An increase in sympathetic activity will cause a decrease in vascular resistance
F (small increase in symp. activity = large increase in resistance)
T/F: There is no sympathetic activity at rest
F (there is tonic activity which allows increases and decreases in sympathetic activity)
T/F: Because the brain has sympathetic and parasympathetic innervation, they predominate the control of cerebral circulation
F (they do both innervate brain, but *local control is predominant*)
Based on _____ law, blood flow may be regulated by altering perfusion pressure or by altering resistance to perfusion (or both).
Ohm's
______ are vasoactive agents derived from arachidonic acid
PGs
T/F: Blood flow to each organ can be independently regulated by altering resistance
T
