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BMD221 Biomedical Physiology > Week 4 Mean Arterial Pressure > Flashcards

Week 4 Mean Arterial Pressure Flashcards

1
Q

normal blood pressure

A

120/80 mmHg

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2
Q

hypertension

A

140/90 mmHg

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3
Q

hypotension

A

100/60 mmHg

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4
Q

Mean Arterial Pressure (MAP) =

A

diastolic pressure + 1/3(systolic pressure - diastolic pressure)

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5
Q

Pulse Pressure =

A

systolic pressure - diastolic pressure

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6
Q

on pressure time axis - SP and DP are

A

SP - peak
DP - lower point

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7
Q

systolic pressure

A

beginning of sounds

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8
Q

diastolic pressure

A

end of sounds

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9
Q

in terms of CO and TPR, Mean Arterial Pressure =

A

= cardiac output x total peripheral resistance

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10
Q

total peripheral resistance

A

the force needed to maintain blood flow from the aorta root to the venous exit

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11
Q

Cardiac Output =

A

= heart rate x stroke volume

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12
Q

what controls the heart rate, other than the heart itself

A

autonomic input

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13
Q

intrinsic firing rate of the heart

A

100 bpm

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14
Q

firing rate at rest + dominating system

A

parasympathetic dominates

75 bpm

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15
Q

firing rate during excitement + dominating system

A

sympathetic dominates

HR increases

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16
Q

what NT is used by the ANS to affect the SAN/AVN

A
  • ACh is used by parasympathetic and sympathetic nerves
  • in the final cardiac accelerator nerve - norepinephrine (NT) used
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17
Q

how does norepinephrine (NT) affect cardiomyocytes

A
  • cardiomyocytes are stimulated
  • they conduct APs faster
  • so rate of contraction can match rate of AP wave stimulation
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18
Q

chronotropic agents

A

affects heart rate by targeting the conduction system

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19
Q

in paraS - how does ACh act

A

ACh binds to a cholinergic receptor

different type of G proteins directly affect T type Ca channels

20
Q

what is the difference between positive and negative chronotropic effect

A

positive - funny channels open much quicker, putting pressure on T type calcium channels to open

L type Ca channels are unaffected

21
Q

what is the baroreceptor reflex

A

a rapid homeostatic mechanism

maintains blood pressure by change of heart rate

22
Q

what is the structure of arterioles

A
  • thinner walls
  • lack a tunica externa
23
Q

larger arterioles

A

extensive tunica media
thick layers of smooth muscle

24
Q

smaller arterioles

A

tunica media has a single layer of smooth muscle
arranged spirally around endothelium

25
Q

what is vascular tone

A

degree of constriction relative to dilated vessel

26
Q

why is control of radius of a vessel important to blood flow

A

radius strongly influences resistance
which controls blood flow

27
Q

effect of vasoconstriction

A

more contraction, smaller radius
increased resistance, decreased flow

28
Q

effect of vasodilation

A

less contraction, bigger radius
low contraction, increased flow

29
Q

what factors determine resistance to blood flow in a single vessel

A

vessel diameter, length and viscosity of blood

30
Q

Poi*Seuille’s law

A

volume flow rate is directly proportional to the pressure gradient

and to the fourth power of its internal resistance

31
Q

what is the effect of norepinephrine and epinephrine on adrenergic receptors

A

alpha receptors
- affected more by norepinephrine
- leads to smooth muscle contraction

beta receptors
- more epinephrine
- leads to smooth muscle relaxation

32
Q

increased blood flow effect on temp

A

increased BF = heat - vasodilation

33
Q

decreased blood flow effect on temp

A

decreased BF = cold - vasoconstriction

34
Q

metabolite changes in endothelial cells causing vasodilation

A

increase in adenosine
from AMP, CO2, H+, K+

35
Q

metabolite changes in endothelial cells causing vasoconstriction

A

increase in O2

36
Q

example of vasodilator substances

A

nitric oxide

histamine - inflammation/allergy

37
Q

examples of vasoconstrictor substances

A

endothelin

38
Q

what is vasopressin

A

ADH
from the posterior pituitary gland

maintain BP

39
Q

angiotensin II

A

from the kidney
by the RAAS system

increases blood pressure

40
Q

structure of veins

A

large diameter
small amount of smooth muscle
thin walls

41
Q

what is venous return

A

volume of blood that returns to the atria from veins

42
Q

effect of increased blood volume on venous return

A

increased BV = increased VR

43
Q

what is venomotor tone

A

constant excitatory influence on smooth muscle in veins

44
Q

effect of venomotor tone of venous return

A

norepinephrine stimulates contraction of smooth muscle

causing venous constriction

increases central venous pressure

decreases venous compliance

increases venous return

45
Q

how does norepinephrine increase MAP

A

increasing vascular tone (constriction) and heart rate

46
Q

why increase total peripheral resistance during exercise

A

increased TPR - local areas dilate - blood moves through arterioles faster

47
Q

during inspiration

A

diaphragm contracts
increased intrapleural volume = decreased pressure in the chest cavity

blood is squeezed from lower veins to chest veins
= increased central venous pressure + VR

BMD221 Biomedical Physiology (6 decks)

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