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PSIO202 > PSIO202 Exam 1 Lecture 6-7 > Flashcards

PSIO202 Exam 1 Lecture 6-7 Flashcards

1
Q

What is the basic reason that blood flows instead of sitting still?

A

pressure differences

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2
Q

What is the term for the pressure difference that causes bloodflow?

A

driving pressure

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3
Q

Where is BP pulsatile?

A

Elastic arteries near the heart

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4
Q

When does BP rise and fall? What happens to the arteries at these times?

A

rises during systole so the arteries expand, and falls during diastole so the arteries recoil to push blood through

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5
Q

Where is BP lower, arteries, capillaries, or veins? Why is this important?

A

Lowest in veins, which favors blood return to the heart

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6
Q

What is the equation for mean arterial pressure?

A

MAP = DBP + 1/3 (SBP-DBP)

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7
Q

What two factors does arterial blood pressure reflect?

A

amount of blood and arterial compliance

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8
Q

What is compliance? What is the equation? What does this equation mean?

A

Ability of arteries to stretch and recoil (opposite of stiffness)
C = dV/dP
C = change in volume / change in pressure
If it takes a lot of pressure to change the volume of an artery, compliance is low. If it doesn’t take much pressure to change the volume, compliance is high.

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9
Q

Are elastic arteries generally compliant or not?

A

Compliant

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10
Q

What are the two factors that ensure blood is propelled through the cardiac cycle?

A

expansion and recoil (arterial compliance and elasticity)

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11
Q

Waves of expansion and recoil result in a pressure wave called…

A

pulse pressure

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12
Q

How do you calculate pulse pressure?

A

SBP-DBP

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13
Q

How are pulse pressure and stroke volume related?

A

PP reflects SV if compliance is constant

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14
Q

When arteries are stiff or non-compliant, what must happen for them to eject blood?

A

The pressure has to increase

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15
Q

Are pressures in the pulmonary circuit low or high? How does this relate to compliance?

A

low, because it is highly compliant

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16
Q

What is the MAP for the pulmonary artery? What is the mean left atrial pressure? What does this cause?

A

pulmonary artery: 14 mmHg
left atrium: 5 mmHg
Pressure gradient for atrial filling from the pulmonary artery is 9 mmHg

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17
Q

What is the relationship between CSA (cross sectional area) and flow velocity?

A

more CSA = slower flow velocity

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18
Q

What structures allow blood to NOT be sent to certain areas?

A

precapillary sphincters

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19
Q

Do the capillaries have smooth muscle?

A

No, only arteries and veins

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20
Q

What term is the same as “blood flow”?

A

cardiac output

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21
Q

What is the relationship between blood flow, resistance, and driving pressure? Explanation and equation.

A

Blood flow is proportional to driving pressure and inversely proportional to resistance.
CO=MAP/resistance

22
Q

What is resistance? What is a common cause?

A

Anything that slows flow, such as friction between the molecules and with the walls of the tube.

23
Q

What is the equation for resistance?
**not based on Ohm’s Law

A

R = (viscosity x vessel length) / r^4
resistance radius

24
Q

What happens when you halve or double radius?

A

2 r = 1/16 R
1/2 r = 16 R

25
Q

What impacts viscosity in the resistance equation?

A

hydration, temperature (think honey)

26
Q

What is Ohm’s Law? What is the “blood pressure” translation?

A

V= I x R
voltage = current x resistance
blood pressure = flow x resistance
BP = CO x resistance
BP = (SV x HR) x resistane

27
Q

What is the simplified equation for systemic resistance?

A

resistance = BP/Flow
OR
resistance = (DBP + 1/3 (SBP-DBP)) / CO

28
Q

What are the three regulations of blood flow?

A

neural, humoral, and local/metabolic

29
Q

What is neural regulation of blood flow?

A

nervoussystemrespondstobloodflow

30
Q

What is humoral regulation of blood flow?

A

change in blood flow due to circulating hormones

31
Q

What is local regulation of blood flow?

A

change in blood flow due to other substances released by the cells related to their metabolic activity

32
Q

Is sympathetic, parasympathetic, or both involved in neural regulation of blood flow?

A

Only sympathetic for correcting low BP, but parasympathetic can be involved too

33
Q

Where do cardiovascular neurons receive input from for blood flow regulation?

A

higher brain structures: cortex, limbic system, hypothalamus
peripheral afferent input: baroreceptors, chemoreceptors, proprioceptors
Baroreceptors and chemoreceptors are most important in cardiovascular regulation

34
Q

Where are baroreceptors located? What takes the signals back to the cardiovascular center?

A

High pressure:
carotid sinus: cranial nerve IX (glossopharyngeal)
aortic arch: cranial nerve X (vagus)

Low pressure:
walls of right atrium and vena cava: cranial nerve X (vagus)

35
Q

Explain the baroreceptor reflex response for blood pressure homeostasis. Assume BP is dropping.

A

BP dops
less stretch is sensed by baroreceptors
signal sent to medulla CV center via CN IX and X (glossopharyngeal and vagus)
triggers sympathetic vasomotor response, sympathetic cardioaccelatory response, and inhibits parasympathetic response
sympathetic vasomotor —> vasoconstriction, more vascular resistance, increase BP
sympathetic cardioaccelatory —> NE released and HR and contractility increase, increase cardiac output, increase BP

36
Q

Where are chemoreceptors located? How do the signals reach the CV center?

A

carotid sinus: glossopharyngeal IX
aortic arch: vagus X

37
Q

What do chemoreceptors respond to (specifically)?

A

reduced O2 (hypoxia) and increase CO2 or hydrogen ion content

38
Q

What happens if chemoreceptors sense increase CO2 or decrease O2?

A

signals sent via cranial nerves, sympathetic vasomotor and sympathetic cardioaccelatory are activated while parasympathetic is inhibited.
Vasomotor—-> vasoconstriction, increases resistance, therefore increase BP
Cardioaccelatory—>increase HR and contractility, increase cardiac output, increase BP

39
Q

How does increase of catecholamines impact blood pressure? What are the two catecholamines in humoral regulation?

A

increase HR, SV, and vasoconstriction which increases BP
NE and Epi

40
Q

Where do the arteries NOT vasoconstrict? Do they have SNS or humoral regulation? How do they manage blood pressure?

A

brain and heart (little smooth muscle), no SNS or humoral regulation, instead they autoregulate

41
Q

What are the five other hormones in humoral regulation that we know?

A

antidiuretic hormone, angiotensin II, aldosterone, histamine, and ANP (atrial natriuretic peptide)

42
Q

What does antidiuretic hormone do? Where is it released from?

A

vasoconstriction for extremely low BP, water retention by the kidneys
produced in the hypothalamus

43
Q

What does angiotensin II do?

A

Causes intense vasoconstriction when renal perfusion is inadequate

44
Q

What does aldosterone do?

A

water retention (so increase blood volume)

45
Q

Explain the renin-angiotensin-aldosterone system through the point that AT II is produced.

A

low BP sensed by juxtaglomerular cells in kidney causes release of renin by the kidney
angiotensinogen converts renin to Angiotensin 1
Angiotensin converting enzyme (ACE) in the endothelium of the lung converts angiotensin 1 to angiotensin II

46
Q

What does angiotensin II cause once it is produced in the renin-angiotensin-aldosterone system?

A

—>increase sympathetic activity
—> increase water retention, Na+ reabsorption, and K+ excretion
—> vasoconstriction, increase vascular resistance and therefore BP
—> triggers aldosterone secretion by the adrenal cortex which promotes salt and water re-absorption (increase blood volume and raise blood pressure)
—> cause pituitary gland to release ADH which prompts water absorption

47
Q

What substances from humoral regulation lower blood pressure? How?

A

atrial natriuretic peptide (ANP) release from the atria when BP is high
inhibits the release of renin (effectively stop the entire renin-angiotensin-aldosterone process)
vasodilation, excretion of salt by kidneys, vascular permeability
reduce blood volume and lower blood pressure

histamine: released by mast cells, causes vasodilation by relaxing smooth muscle

48
Q

When is histamine especially improtant?

A

Increasing blood flow to inflamed or damaged tissue

49
Q

What cells in the kidney detect blood pressure and can kickstart the renin-angiotensin-aldosterone system?

A

juxtaglomerular cells

50
Q

What other hormones does angiotensin cause to increase?

A

aldosterone and antidiuretic hormone (ADH)

PSIO202 (27 decks)

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