Regulation of Blood Flow through specific organs

If a substance was injected into an artery on the left side of the Circle of Willis how will it circulate

It will REMAIN on the same hemisphere

What is Virchow Robin space

Subarachnoid space that separates penetrating vessels from brain tissue

What is the effect of H+ on cerebral blood flow

Increased H+ depresses brain activity but increases blood flow

What happens when there is hypoxemia

Vasodilation → Returns brain blood flow and transport of O2 to cerebral tissue to near normal

What is the function of astrocytes and glutaminergic neurons in blood flow

Astrocytes support, protect and provide nutrients → Glutaminergic neuron causes Ca+ to increase → Vasodilation

What is the difference in the MAP of normal vs chronic hypertension patient

Chronic hypertension has right shift to protect against high BP → More vulnerable to ischemia

How does SNS affect cerebral blood flow

Very little effect; function is constrict large and intermediate size arteries to prevent high pressure in smaller vessels

How does CSF enter choroid plexus

Active transport of Na ions

What is external/communicating hydrocephalus

Large amounts of fluid accumulate when CSF reabsorption is decreased

What is internal/noncommunicating hydrocephalus

Fluid accumulation when there is a block/obstruction in the ventricular system

How does brain tumor affect ventricular system

Creates higher pressure and decrease reabsorption of CSF into blood

How does hemorrhage/infection affect ventricular system

Causes RBC/WBC to block the arachnoid villi

What is the Monro Kellie Doctrine

When there is high pressure the brain drains out some fluid (venous blood or CSF) → When the pressure is too high there is nothing else that can be drained

What is cerebral edema

Accumulation of extra edema fluid that compress vessel → Decreases blood flow and causes ischemia → More edema; O2 delivery is decreased → Permeability increase and ATP low → more edema

How does glucose enter the brain

Through GLUT1; babies without GLUT1 have normal plasma glucose with seizures and delayed development

What is the superficial system of venous return

Superior sagittal sinus → IJV and Cavernous sinus → IJV

What is the deep system of venous return

Internal cerebral vein → Great cerebral vein of Galen → Inferior sagittal sinus → Straight sinus → Confluence of sinus → Transverse sinus → Sigmoid sinus → Jugular foramen → IJV

What is the glymphatic system

Perivascular space between pia and each vessel that carries proteins and matter OUT of the brain

Function of LV muscle

Return to RA by coronary sinus → 75% of coronary blood flow

Function of RV muscle

Return through small anterior cardiac vein → RA NOT by coronary sinus

How does cardiac muscle compression change coronary blood flow

LV → Falls in systole → Blood fills in diastole phase; RV → Same but less extent

What controls coronary flow

Local muscle metabolism → Cardiac muscle nutrition need causes arteriolar vasodilation; more contraction = more blood flow

What is the effect of O2 demand on local coronary blood floe regulation

Regulated by O2 need → 70% of O2 is removed as it flows through the muscle → More O2 = more vasodilation

How does adenosine affect coronary artery

Causes DILATION; ATP degrades to AMP to adenosine in low O2

How does NS control blood flow

ACh → dilate vss, NE → constrict nss

How does sympathetic stimulation increase blood flow

HR increase → Contractility and metabolism increase → Coronary vessel dilation → Blood flow increase

How goes vagal stimulation cause vasoconstriction

Decrease HR and contractility → low O2 demand → Vasoconstriction

What is white reaction

Whitening of skin when stroked by blunt object caused by contraction of precapillary sphincter

What is Triple response of Lewis

Redness from capillary dilation → Swelling (local edema) from increased capillary permeability → Flare from arteriole dilation

What is axon reflex

Impulse from nerves at site of injury are antidromically relayed to other parts of body by substance P and CGRP

What is reactive hyperemia

Increase in blood after a period of occlusion → Rapidly increases oxygenation of that itssue

How does NS affect the blood vessels of the skin

NE nerve stimulation constrict vss, cold causes vasoconstriction (unless severe cold), in high temperature dilation overpowers NE constriction