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