CV 3 Flashcards

1
Q

At each level, arteries have (compared to veins): (3)

A

thicker walls
more elastic tissue
more smooth muscle

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2
Q

Vascular Tone

= Level of

A

Vascular Smooth Muscle Contraction

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3
Q

Vascular Tone (4)

A

 Determines radius of vessel lumen
 increase Tone increase vasoconstriction and decrease lumen diameter
 decrease Tone increase vasodilation and increase lumen diameter
Δ vascular tone > ΔR > Δ Blood Flow through vessel

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4
Q

Q=

R=

A

ΔP/R

8Ln/Πr^4

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5
Q

Vascular Tone is Modified by: (2)

A
  1. Paracrines from Endothelial Cells

2. Autonomic NS

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6
Q
  1. Paracrines from Endothelial Cells (2)
A

NO and Prostacyclin (decreases tone; relaxes smooth
muscle)
Enothelin-1 (increases tone; contracts smooth muscle)

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7
Q
  1. Autonomic NS (2)
A

Sympathetic NS (influence depends on NT rec., typically increase)
*Parasympathetic NS (Decreases tone)

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8
Q

Arteries/Arterioles (2)

A

 Basal Tone

 Vasodilate or Vasoconstrict from rest

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9
Q

Veins/Venules (2)

A

 No Basal Tone

 Only vasoconstrict from rest

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10
Q

Artery Basal Tone

 Mediated by: (2)

A

 Paracrines secreted by endothelial cells

 Tonic activity of sympathetic motor neurons

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11
Q

Abnormal Arterial Tone =

A

hypertension

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12
Q

Compliance =

A

how easily a structure stretches

= ΔVolume/ΔPressure

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13
Q

High compliance vessels can have large changes in volume with little
change in pressure; —

A

Veins

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14
Q

Low compliance vessels will have large changes in pressure with
small changes in volume; —

A

Arteries

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15
Q

The pressure gradient throughout the circulatory system is the
driving force for

A

blood flow

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16
Q

Pressure in the arterial vessels is —, producing (2)

A

pulsatile

systolic and diastolic pressures.

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17
Q

Damping α (R)(Compliance)

A

Pulsation disappears by the capillaries smoothing out due to
decreasing elastic/collagen tissue and increasing R as you move through arteries to capillaries

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18
Q

Mean Arterial Pressure (MAP)

A

Average driving pressure in systemic arteries
= Diastolic P + 1/3(Systolic P – Diastolic P)
= 80 + 1/3(120-80) = 93 mmHg

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19
Q

Elastic recoil prevents

A

arteriole diastolic pressure from dropping to ventricular diastole pressure

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20
Q

Elastic recoil is essential to maintain

A

driving pressure in systemic circulation

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21
Q
Pulse Pressure (PP)
Felt as a
A

pulsation or throb in the arteries of the wrist or neck with
each heartbeat.

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22
Q

PP =

A

(SP – DP) : (120 – 80 = 40 mmHg in the example)

23
Q

The most important factors determining the magnitude of the

pulse pressure are: (2)

A

(1) Stroke volume

(2) Arterial compliance

24
Q

PP α

A

SV/C

25
Q

MAP

A

 Average driving pressure in systemic circulation to
move blood through the blood vessels
= Diastolic P + 1/3 (Systolic P – Diastolic P)
= 80 + 1/3 (120 – 80)

26
Q

Hypertension
Increased —
Caused by (2)
Affects ≈

A

MAP
increased Systolic and/or Diastolic Pressure
70 million Americans (1 in 3)

27
Q

Factors Influencing MAP

1. Flow In and Out of Systemic Arteries (5)

A

 Flow In = CO (HR x SV)
 Flow Out = Total Peripheral Resistance (TPR)
 TPR = ΣRArterioles (vasoconstriction of arterioles)
 If: Flow in > Flow out (due to increase CO or increase TPR) > increase MAP
 If: Flow in < Flow out (due to decrease CO or decrease TPR) > decrease MAP

28
Q

MAP =

A

CO x TPR

29
Q

F =

A

ΔP/R

30
Q

CO =

A

MAP/TPR

31
Q

Factors Influencing MAP

2. Total Blood Volume (2)

A

 Total Blood Volume increase > increase MAP (ex. Increased NaCl
intake)
 Total Blood Volume decrease > decrease MAP (ex. Hemorrhage)

32
Q

Factors Influencing MAP

3. Distribution of Blood in Circulatory System (2)

A

 Normally 11% of blood volume in arteries and 60%
in veins
 Blood can be shifted from veins to arteries to
increase MAP

33
Q

Regulation of TPR (2)

A

TPR α ΣRArterioles

Factors that change arteriolar diameter > RArterioles > ΔTPR

34
Q

Arteriolar Diameter Regulation (3)

A
  1. Autoregulation
  2. Local Control
  3. Reflex Control
35
Q
  1. Autoregulation (2)
A

 Function of blood vessel wall

 Assures blood flow to tissues matches tissue demands.

36
Q
  1. Local Control (3)
A

 Match tissue blood flow to metabolic demands
 FTissue= MAP/RTissue
 Function of Paracrines

37
Q
  1. Reflex Control (4)
A

 Maintain MAP to assure adequate blood flow to brain and heart
 MAP = CO x TPR
 Systemic Homeostatic Reflex
 Function of NS and ES

38
Q

Factors Regulating Systemic
Arteriolar Resistance
1. Myogenic Autoregulation (3)

A
 Function of arterioles
 Nearly all organs tend to keep their 
blood flow constant despite 
variations in arterial pressure 
(F=MAP/RTissue )
 Reflex arteriolar constriction in 
response to increased MAP
39
Q

skipped
Myogenic Autoregulation
Mechanism:

A
increase MAP
increase arteriolar blood flow 
arteriolar stretch 
open mechanically gated sodium channel in VSM
depolarizes membrane 
opens voltage gated a channels in VSM
ca entry and binds to calmodulin
activates myosin light chain kinase 
increase myosin ATPase activity 
VSM contraction
vasoconstriction
decrease r
increase R
decrease F tissue
40
Q

Factors Regulating Arteriolar Resistance

2. Paracrines (2)

A

 Matches tissue blood flow to metabolic demands (F=MAP/RTissue )
 Interstitial concentration of paracrine substances changes as cells
become more or less metabolically active

41
Q

Increased Tissue Metabolism >

A

decrease O2 , increase CO2, increase H+, increase K+ (Vasodilation of
Arterioles)

42
Q

Decreased Tissue Metabolism >

A

increase O2 , decrease CO2 (Vasoconstriction of

Arterioles)

43
Q

Active Hyperemia -

A

Process in which an increase in tissue blood flow

accompanies an increase metabolic activity

44
Q

Reactive Hyperemia-

A

Increased in tissue blood flow following a period

of low perfusion (blood flow)

45
Q

If blood flow to a tissue is occluded, paracrines accumulate in
interstitial space: (3)

A

decrease O2
increase CO2
increase H+

46
Q

Hypoxia stimulates endothelial cells to (2)

A
secrete NO (potent 
vasodilator) and NO also accumulates in interstitial space
47
Q

Once occlusion removed, paracrines cause (2)

A

vasodilation and
increase in tissue blood flow until paracrines washed away and
arteriolar diameter returns to resting state.

48
Q

Vasodilating Paracrines (7)

A
CO2
H+ (lactic acid)
Adenosine (ATP→Adenosine)
K+ (multiple action potentials)
Prostaglandins
Bradykinin
Nitric oxide (NO)
49
Q

Vasoconstricting Paracrines (3)

A

O2
Endothelin
Thromboxanes

50
Q

Factors Regulating Arteriolar Resistance

3. Reflex Control (4)

A

 Maintain MAP so have adequate blood flow to brain and heart
 MAP = (CO)(TPR)
 Reflex control can override local control
 Function of NS and ES

51
Q

Other Hormones

Vasoconstrictors (2)

A

ADH

ANG II

52
Q

Other Hormones

Vasodilators (1)

A

ANP

53
Q

Local Control

Qtissue=

A

MAP/Rarterioles

54
Q

Reflex Control

MAP =

A

CO x TPR