Mini-Test 1

Question 1

Factors affecting mean arterial pressure

Answer 1

• Downstream resistance changes
• compliance

Question 2

Def: Compliance

Answer 2

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

Question 3

How does compliance change

Answer 3

• Decrease with age, sedentary and hypertension
• increase with exercise

Question 4

Purpose of compliance

Answer 4

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

Question 5

Def: Total peripheral resistance

Answer 5

the resistance of all downstream vessels

Question 6

Factors affecting TPR

Answer 6

• vasculature anatomy (diameter)
• blood viscosity

Question 7

Poiseuille’s law

Answer 7

R= 8uL/pir^4

Question 8

Def: Vascular resistance (tone)

Answer 8

How difficult it is for blood to flow through a vessel

Question 9

Ohm’s Law

Answer 9

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

Question 10

Def: Augmented Pressure

Answer 10

The increase in peak blood pressure due to reflective waveforms

Question 11

Isolated Systolic Hypertension

Answer 11

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

Question 12

Def: Pulse Pressure

Answer 12

the difference between DBP and SBP

Question 13

What are the effects of exercise on vascular compliance

Answer 13

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

Question 14

What lines all vessels

Answer 14

Endothelium

Question 15

Smooth muscle and vessels

Answer 15

• Surrounds in rings
• Causes vasodilation and vasoconstriction

Question 16

Elastin and vessels

Answer 16

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

Question 17

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

Answer 17

• 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

Question 18

Steady state conditions vascular control

Answer 18

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

Question 19

Pulsatile Flow vascular control

Answer 19

HEART LEVEL
1. Vascular Compliance

Question 20

Variables which determine VO2 (equation)

Answer 20

Q*(aO2 - vO2)

Question 21

How does local blood flow increase with workload

Answer 21

linearly

Question 22

Def: Functional/exercise hyperemia

Answer 22

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

Question 23

Variables affecting stroke volume

Answer 23

• Venous Return
• Cardiac Mechanisms

Question 24

Variables affecting heart rate

Answer 24

• Neural Control

Question 25

Variables affecting TPR

Answer 25

- Vascular constriction - Vascular dilation

Question 26

Role of Cardiac output compared to vascular conductance during exercise

Answer 26

- 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

Question 27

Mechanical constraints of on SV of the Pericardium

Answer 27

- ridged structure limits distension - shown through increase in SV, CO and VO2 in a heart with the pericardium removed

Question 28

How does the pattern of blood flow increase during exercise

Answer 28

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

Question 29

Factors involved in vasomotor control

Answer 29

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

Question 30

Muscle Pump

Answer 30

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

Question 31

Myogenic Mechanism

Answer 31

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

Question 32

Effect of potassium on vasodilation

Answer 32

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

Question 33

Effect of adenosine originating form the skeletal muscle

Answer 33

Metabolite leads to vasodilation through the stimulation of receptors

Question 34

Effect of lumen originating metabolites and ACh

Answer 34

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

Question 35

How does shear force cause vasodilation?

Answer 35

- 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

Question 36

Def: Reactive Hyperemia

Answer 36

Increased blood flow due to muscle ischemia

Question 37

Def: Flow mediated dilation

Answer 37

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

Question 38

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

Answer 38

- 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

Question 39

How can the rate and % change following reactive hyperemia change

Answer 39

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

Question 40

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

Answer 40

Rest and Heavy exercise

Question 41

Red Blood cell Hypothesis

Answer 41

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