Test 1, Deck 4

Question 1

what determines coronary blood flow? what regulates it?

Answer 1

• determines: aortic pressure

- regulates: metabolic activity/changes in arteriolar resistance

Question 2

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

Answer 2

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

Question 3

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

Answer 3

diastole

Question 4

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

Answer 4

• endo to ALL

Question 5

What compress endo/epicardium vessles?

Answer 5

Diastolic pressure and contraction

Question 6

what is the relationship between blood flow and metabolic activity?

Answer 6

linear

* increased metabolism, decreased resistance, increased blood flow

Question 7

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

Answer 7

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

Question 8

how does the heart get more oxygen?

Answer 8

it is flow limited- must vasodilate

Question 9

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

Answer 9

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

Question 10

which factors affect myocardial oxygen supply?

Answer 10

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

Question 11

which factors create largest O2 demand?

Answer 11

• afterload
• heart rate
• contractility

Question 12

what is ischemia, considering O2?

Answer 12

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)

Question 13

what is coronary steal?

Answer 13

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

Question 14

when would coronary steal present clinically?

Answer 14

• exercise-induced ischemia
• stress testing
• peripheral arterial disease

Question 15

What happens to skeletal muscle circulation during exercise?

Answer 15

• the flow oscillates

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

Question 16

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?

Answer 16

20
active hyperemia
largest
tonic

Question 17

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

Answer 17

adenosine

Question 18

Skeletal muscle vasculature is primarily innervated by _____ fibers

Answer 18

sympathetic adrenergic

Question 19

Ach causes ___ by acting on ___ coupled to ___

Answer 19

vasodilation
muscarinic (on endothelials)
NO production

Question 20

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

Answer 20

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

Question 21

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

Answer 21

aerobic metabolism of glucose

most metabolically active tissue in the body

Question 22

What is the BBB due to? What can cross?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

what is the monroe-kellie doctrine?

Answer 24

brain volume + cerebral vascular volume + CSF volume= constant

Question 25

What happens as CSF pressure rises?

Answer 25

- 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

Question 26

Cerebral blood flow is very sensitive to which metabolite?

Answer 26

PCO2

Question 27

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

Answer 27

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

Question 28

mechanism for nitric oxide

Answer 28

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

Question 29

what is the cushing response?

Answer 29

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

Question 30

when does the cushing response occur?

Answer 30

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

Question 31

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

Answer 31

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

Question 32

Pulmonary arteries are ___ compliant than regular arteries because____

Answer 32

7x more; they lack smooth muscle

Question 33

Pulmonary capillaries represent ___ of the vascular resistance

Answer 33

40%

Question 34

T/F Pulmonary vessels autoregulate

Answer 34

F

Question 35

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

Answer 35

distends; increases | net effect- no change!

Question 36

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

Answer 36

bottom | waterfall effect

Question 37

what happens in zone 1?

Answer 37

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

Question 38

what happens in zone 2?

Answer 38

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

Question 39

what happens in zone 3?

Answer 39

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

Question 40

primary function of cutaneous circulation

Answer 40

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

Question 41

what is apical skin?

Answer 41

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

Question 42

what is nonapical skin?

Answer 42

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

Question 43

neural control of apical skin

Answer 43

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

Question 44

neural control of nonapical skin

Answer 44

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

Question 45

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

Answer 45

core body temperature; hypothalamus

Question 46

fetal circulation pathway

Answer 46

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

Question 47

valves close, pressure changes, pipes shut

Answer 47

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

Question 48

difference between HbF and HbA and why?

Answer 48

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

Question 49

umbilical artery umbilical vein ductus venosus ductus arteriosus

Answer 49

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

Question 50

what happens with skin circulation and exercise?

Answer 50

sympathetics want to vasoconstrict | internal metabolic heat stimulates cutaneous vasodilation

Question 51

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

Answer 51

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

Question 52

What ist he portal system?

Answer 52

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

Question 53

metabolic control of splanchnic circulation

Answer 53

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

Question 54

hormonal control of splanchnic circulation

Answer 54

cholecystokinin & neurotensin increase vasodilation

Question 55

neural control of splanchnic circulation

Answer 55

- 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

Question 56

what is postprandial hyperemia?

Answer 56

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