Test 1, Deck 4 Flashcards by Kelly A

what determines coronary blood flow? what regulates it?

determines: aortic pressure

- regulates: metabolic activity/changes in arteriolar resistance

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when do you see a reversal in the blood flow of the left- but not right- coronary artery?

during max systolic pressure (isovolumetric contraction- rapid ejection) aka early systole

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60-65% of coronary blood perfusion to LV muscle occurs during ______

diastole

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Vessels in the endocardium or epicardium are more compressible?
Which vessels are more dilated?
Which is more at risk for ischemia?

endo to ALL

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What compress endo/epicardium vessles?

Diastolic pressure and contraction

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what is the relationship between blood flow and metabolic activity?

linear

* increased metabolism, decreased resistance, increased blood flow

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what are the metabolic substrates for the heart, and what is the largest consumer of O2?

fatty acids (LARGEST O2), carbs, ketones/lactate/proteins

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how does the heart get more oxygen?

it is flow limited- must vasodilate

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what is the equation for cardiac work, and which factor matters more?

cardiac work= MAP x systolic stroke volume
(W=F*D)
- pressure is more important

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which factors affect myocardial oxygen supply?

diastolic perfusion pressure
coronary vascular resistance (external vs intrinsic (metabolites))
O2 carrying capacity

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which factors create largest O2 demand?

afterload
heart rate
contractility

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what is ischemia, considering O2?

imbalance in the ratio of oxygen supply to oxygen demand; creates a relative lack in blood flow
- excessive O2 demand is NEVER the primary cause (always too little supply)

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what is coronary steal?

an increase in blood flow to one region can cause a decrease in flow to another-
* problematic with vasodilation if there is a stenosis *

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when would coronary steal present clinically?

exercise-induced ischemia
stress testing
peripheral arterial disease

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What happens to skeletal muscle circulation during exercise?

the flow oscillates

- overall, there is a significant reduction in resistance to blood flow to vasodilation

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Skeletal flow can increase ___ time during exercise, which is called _____. It constitutes the ____ vascular bed in the body. Which type of muscle has more vascular supply- tonic or phasic?

20
active hyperemia
largest
tonic

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What is the main vasodilator- working against sympathetics- in skeletal muscle?

adenosine

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Skeletal muscle vasculature is primarily innervated by _____ fibers

sympathetic adrenergic

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Ach causes ___ by acting on ___ coupled to ___

vasodilation
muscarinic (on endothelials)
NO production

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Epinephrine from ____ causes ____ at low concentrations through activating _____, but _____ at high concentrations through activating ____

adrenal medulla
vasodilation
beta-2 adrenergic receptors
vasoconstriction
alpha adrenergic receptors

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The brain primarily uses _____ metabolism of _____. How metabolically active is it?

aerobic metabolism of glucose

most metabolically active tissue in the body

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What is the BBB due to? What can cross?

endothelial tight junctions
basement membrane
neuroglial processes
metabolic enzymes
lipid soluble substances- O2, CO2, ethanol, steroids, glucose

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What is CPP? If CPP falls, what happens? What reduces CPP?

cerebral perfusion pressure
CPP= MAP- intracranial venous pressure
vasodilation
reduced by decrease in MAP or increase in intracranial pressure

what is the monroe-kellie doctrine?

brain volume + cerebral vascular volume + CSF volume= constant

What happens as CSF pressure rises?

- increase CSF pressure - cerebral blood flow decreases (veins compressed) - metabolic autoregulation dilates the arteries - this only works up until a certain pressure, where the arteries become compressed

Cerebral blood flow is very sensitive to which metabolite?

PCO2

An increase in pH (hyperventilation) causes what? This helps with what clinical scenario?

- vasoconstriction & decreased blood flow | - cerebral edema (high intracranial pressures)

mechanism for nitric oxide

- causes vasodilation of smooth muscle - increases cGMP and PKG - increases phosphorylation of MLCK - decreases phosphorylation of myosin light chain

what is the cushing response?

with elevated intracranial pressure, you see - high blood pressure (medulla sympathetics) - low heart rate (parasympathetics)

when does the cushing response occur?

when CSP (cerebral spinal pressure) is greater than the mean arterial pressure

Pulmonary circulation is a ____ pressure, ____ volume system, ___ resistance; mean pressure gradient= ____

low pressure, high volume, low resistance | mean pressure gradient 6 mm Hg

Pulmonary arteries are ___ compliant than regular arteries because____

7x more; they lack smooth muscle

Pulmonary capillaries represent ___ of the vascular resistance

40%

T/F Pulmonary vessels autoregulate

During inspiration, negative pressure ______'s extra-alveolar vessels and _____ resistance in alveolar vessels - net effect on resistance = ?

distends; increases | net effect- no change!

intravascular (hydrostatic) pressure is greatest at which part of the lung? what does this cause?

bottom | waterfall effect

what happens in zone 1?

alveolar pressure exceeds arterial and veous pressures, causing capillaries to collapse - exists w/ hypotension or positive pressure mechanical ventilation

what happens in zone 2?

alveolar pressure exceeds venous pressure but does not exceed arterial pressure; capillaries are partially collapsed, is the upper 1/3rd of lung

what happens in zone 3?

arterial and venous pressures exceed alveolar pressure; flow depends on AV pressure gradient

primary function of cutaneous circulation

maintain a constant body temperature | - provides transport of heat to the body surface for exchange with the environment

what is apical skin?

- high surface-volume ratio that favors heat loss | - has lots of AV anastomoses called glomus bodies

what is nonapical skin?

- lacks AV anastomoses | - innervated by sympathetic fibers- postganglionics release Ach; vasodilation

neural control of apical skin

sympathetic adrenergic nerves that produce vasoconstriction of cutaneous vessels (withdrawal produce passive vasodilation)

neural control of nonapical skin

- sympathetic vasoconstriction (NE) | - active vasodilation via cholinergic fibers via bradykinin

temperature regulation (what kind?) is primarily controlled by major sensory sites in the ______ and less by receptors in the spinal cord

core body temperature; hypothalamus

fetal circulation pathway

fetal branch villi- umbilical vein- ductus venosus- IVC- RA- foramen ovale- LA-LV- aorta some blood goes RA- RV-pulm artery- ductus arteriosis- systemic circulation

valves close, pressure changes, pipes shut

valves close- foramen ovale pressure changes- atria pipes shut- ductus venosus & ductus arteriosus

difference between HbF and HbA and why?

HbF has greater affinity for O2 due to DpG shifting O2 dissociation curve left- more saturation at lower pressures

umbilical artery umbilical vein ductus venosus ductus arteriosus

umbilical artery- medial umbilical ligament umbilical vein- ligamentum teres ductus venosus- legamentum venosus ductus arteriosus- ligamentum arteriosum

what happens with skin circulation and exercise?

sympathetics want to vasoconstrict | internal metabolic heat stimulates cutaneous vasodilation

what does the arrangement of vessels within the intestinal villus form?

contercurrent flow system; arteries and venules run parallel to each other- solutes such as sodium dissolve from the arteries back to the venules to increase osmolarity/blood flow

What ist he portal system?

1- portal vein- blood from intestine/stomach/pancreas (only a few mmHg higher than IVC) 2- liver capillaries- blood from portal vein 3- hepatic vein- liver capillaries 4- IVC

metabolic control of splanchnic circulation

``` increase metabolism O2 decreases metabolites (CO2, H+, adenosine) increase vasodilation (moderate autoregulation) ```

hormonal control of splanchnic circulation

cholecystokinin & neurotensin increase vasodilation

neural control of splanchnic circulation

- sympathetic vasoconstriction via NE acting on alpha adrenergic receptors on vascular smooth muscle (also have beta receptors) - parasympathetics act indirectly by contacting sympathetics in intestinal wall & stimulates motility

what is postprandial hyperemia?

after eating, get increase in intestinal blood flow due to metabolic/hormonal/neural/mechanical influences