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Cardiovascular Physiology > Mini-Test 1 > Flashcards

Mini-Test 1 Flashcards

1
Q

Factors affecting mean arterial pressure

A
  • Downstream resistance changes
  • compliance
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2
Q

Def: Compliance

A

Ability for a vessel to change in volume for a given change in pressure

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3
Q

How does compliance change

A
  • Decrease with age, sedentary and hypertension
  • increase with exercise
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4
Q

Purpose of compliance

A

-Buffers the change in pressure
- acts as an intermittent pump due to the recoil of elastin (windkessel effect)

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5
Q

Def: Total peripheral resistance

A

the resistance of all downstream vessels

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6
Q

Factors affecting TPR

A
  • vasculature anatomy (diameter)
  • blood viscosity
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7
Q

Poiseuille’s law

A

R= 8uL/pir^4

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8
Q

Def: Vascular resistance (tone)

A

How difficult it is for blood to flow through a vessel

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9
Q

Ohm’s Law

A

Ohms (vascular resistance) = Voltage (change in pressure) / amperes ( blood flow)

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10
Q

Def: Augmented Pressure

A

The increase in peak blood pressure due to reflective waveforms

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11
Q

Isolated Systolic Hypertension

A

Systole: with age, stiffer aorta and large arteries do not expand as much with the injection of blood volume into the vascular space (less damping)
Diastole: Decrease in compliance = decrease in recoil - blood not pushed along the vascular tree & DBP decreasesDe

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12
Q

Def: Pulse Pressure

A

the difference between DBP and SBP

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13
Q

What are the effects of exercise on vascular compliance

A
  • Greater compliance in endurance trained individuals compared to sedentary individuals of same age
  • Increase in compliance following training intervention
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14
Q

What lines all vessels

A

Endothelium

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15
Q

Smooth muscle and vessels

A
  • Surrounds in rings
  • Causes vasodilation and vasoconstriction
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16
Q

Elastin and vessels

A
  • Runs parallel to vessel
  • involved in mechanical dilation that results from shear force produced by increased blood flow
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17
Q

Are vessels closer or further away from the heart more compliant and how does that affect reflective wave forms

A
  • Vessels become less compliant the further you move away from the aorta
  • need to accommodate less significant changes in pressure
  • reflect waves because not all energy can be transferred
18
Q

Steady state conditions vascular control

A

DOWNSTREAM VASCULATURE
1. Vascular resistance to flow
2. Resistance, CO, MAP
3. Resistance vs conductance

19
Q

Pulsatile Flow vascular control

A

HEART LEVEL
1. Vascular Compliance

20
Q

Variables which determine VO2 (equation)

A

Q*(aO2 - vO2)

21
Q

How does local blood flow increase with workload

A

linearly

22
Q

Def: Functional/exercise hyperemia

A

The increase in blood flow (decrease in vascular resistance) in response to muscle contraction

23
Q

Variables affecting stroke volume

A
  • Venous Return
  • Cardiac Mechanisms
24
Q

Variables affecting heart rate

A
  • Neural Control
25
Q

Variables affecting TPR

A
  • Vascular constriction
  • Vascular dilation
26
Q

Role of Cardiac output compared to vascular conductance during exercise

A
  • Q increases with exercise
  • Mechanical constraints on heart limit Q (Pericardium)
    -Skeletal muscle blood flow increases linearly with workload
    -Q cannot provide enough blood flow to exercising muscles - requires changes in local vascular conductance to direct blood flow
27
Q

Mechanical constraints of on SV of the Pericardium

A
  • ridged structure limits distension
  • shown through increase in SV, CO and VO2 in a heart with the pericardium removed
28
Q

How does the pattern of blood flow increase during exercise

A
  1. Redistribution of blood flow in body
    - Muscle takes most of CO
    - More CO going to the heart with exercise
    -less going to viscera
  2. Rapid blood flow/vasodilation response
    - Single contraction causes immediate increase in muscle blood flow
  3. Ascending vasodilation
29
Q

Factors involved in vasomotor control

A
  1. Mechanical
    - Muscle Pump
    - Myogenic
  2. Neural
    - SNS (Vasoconstriction)
  3. Biochemical
    - Metabolic
    - endothelium
    - neural
30
Q

Muscle Pump

A

Mechanically changing the pressure gradient across the capillary bed
- Collapse of vein during exercise changes the venous pressure from 40 mmHg at rest to 0 during muscle contraction
- increases venous return back to heart

31
Q

Myogenic Mechanism

A
  1. increase in arterial pressure due to increased Q
  2. Natural cause increase in arterial radius
  3. constriction due to detection of stretch
  4. returns capillary pressure to baseline
    Mechanism used to protect capillaries - form of local flow autoregulation in response to changes in pressure
32
Q

Effect of potassium on vasodilation

A
  • K released rapidly from skeletal muscle ( release related to workload)
  • outside smooth muscle because more positive
  • hyperpolarization leads to vasodilation
33
Q

Effect of adenosine originating form the skeletal muscle

A

Metabolite leads to vasodilation through the stimulation of receptors

34
Q

Effect of lumen originating metabolites and ACh

A
  1. ACh, ATO and adenosine bind to receptors on endothelial cell
  2. Cause an increase in Ca+ in endothelial cell
  3. Leads to the upregulation of COX and NOS
  4. increase in prostacyclin and NO production
  5. PGI2 and NO more into SMC
  6. Activates cAMP and cGMP which causes a decrease in Ca+ leading to SM relaxation
35
Q

How does shear force cause vasodilation?

A
  • Shear force causes phospholipid breakdown of the glycocalyx which line the endothelial cell
  • Phospholipid breakdown causes an increase in Ca+ increasing NOS activity and produces arachidonic acid
  • arachidonic acid then produces prostaglandins via the enzyme cyclooxygenase
  • Both leading to dilation
36
Q

Def: Reactive Hyperemia

A

Increased blood flow due to muscle ischemia

37
Q

Def: Flow mediated dilation

A

the conduit vessel dilation due to shear stress typically following an increase in blood flow

38
Q

how can flow-mediated vasodilation be used to assess how well the endothelium is working

A
  • We inflate cuff
  • release it to cause a shear stress stimulus on an artery
  • Measure dilation in artery
  • 10-15% dilation is normal
  • <5% = bad
39
Q

How can the rate and % change following reactive hyperemia change

A
  • normally there is a delay between increase in shear and % change in diameter
  • Age effects the time it takes
  • training effects the % change
40
Q

What conditions does endothelial control of blood flow have the greatest effect on

A

Rest and Heavy exercise

41
Q

Red Blood cell Hypothesis

A
  1. ATP released, binds into P2Y receptors on endothelium
  2. Cascade of events leads to eNOS activation
  3. NO production increases
  4. NO diffuses to smooth muscle cell

Cardiovascular Physiology (1 decks)

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