Week 5 Flashcards

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1
Q

What is the role of Acetylcholine in Cardiac regulation ?

A
  • Slows heart rate by delaying sinus discharge
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2
Q

Name the two ways in which parasympathetic stimulation slows heart rate

A
  • Via Acetylcholine release

- Vagus Nerve stimulation

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3
Q

Sympathetic nerve fibres innervate the ________ and the ________

A

SA node

Ventricles

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4
Q

Sympathetic nervous system releases __________ and activates ___________ receptors in the heart

A

Noradrenaline

Beta-Adrenergic

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5
Q

Where is the cardiac control centre ?

A

Medulla Oblongata

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6
Q

What are the two factors affecting blood flow

A
  1. Pressure gradient between the two ends of the vessel

2. Inversely to the resistance encountered to fluid flow

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7
Q

What are the three factors determining resistance to blood flow ?

A
  1. Blood thickness/viscosity
  2. Length of the conducting tube
  3. Vessel radius
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8
Q

Name local factors causing vasodilation

A
  • decreases tissue O2
  • local increase in blood flow
  • Body temp.
  • CO2 levels
  • acidity
  • NO Production
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9
Q

Name three factors that stimulate NO production as a result from increased blood flow

A

Signal chemicals

Sheer stress

Vessels stretch

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10
Q

What is considered a reflection of the functional capacity of the CV system ?

A

Cardiac Output

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11
Q

At rest, why does CO vary ?

A

Emotional conditions that alter cortical outflow to Cardioaccelorator nerves

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12
Q

Name two factors decreases HR in Endurance athletes

A
  1. Increased Vagal Tone

2. Decreased sympathetic drive

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13
Q

Name 3 factors contributing to increased stroke volume in endurance athletes

A
  1. Increased blood volume
  2. Increased ventricular volume
  3. Increased compliance of left ventricle
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14
Q

What 2 mechanisms aid in venous return

A

Skeletal muscle pump

Respiratory (abdomino-thoracic) pump

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15
Q

Define Cardiovascular Drift

A

Gradual time-dependent downward drift in several CV responses

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16
Q

At rest, Roughly 80% of cardiac output is distributed to where?

A

Digestive tract, liver, spleen, brain, kidneys

17
Q

What type of muscle with receive most of the blood distribution during exercise

A

Fibres with higher oxidative capacity/tendencies

18
Q

What is blood O2 reserve and how much is there?

A

Extra O2 circulating above the requirement at rest

Roughly 750 ml

19
Q

A ____L increase in blood flow accompanies a ___L increase in O2 consumption

A

5-6 Litres

1Litre

20
Q

Aterial-Venous O2 difference during exercise = ?

A

50ml of O2 per litre of blood perfusing tissue-capillary bed

21
Q

Expanding a-VO2 functions to?

A

Increase O2 consumption for energy

22
Q

How is a-vO2 expanded

A

Extracting more O2 from blood

23
Q

How does arterial blood O2 concentration change during exercise

A

Varies little from the 200ml range

24
Q

How does the mixed-venous O2 content change with exercise

A

Decreases progressively with increased intensity

25
Q

Increased blood pressure functions to do what at the capillary?

A

Increased fluid, nutrient and O2 delivery

26
Q

List factors increasing O2 extraction at muscle tissue during exercise (5 factors)

A
  1. CO diverted to active tissue
  2. other tissue temporarily decrease blood supply
  3. Central circulation redirected to active muscle
  4. Increased capillary
  5. Increased muscle micro circulation
27
Q

True or false: arm exercise averages more O2 consumption than Leg exercise

A

False

28
Q

Upper body Submaximal exercise produces ______ O2 consumption

(Higher or lower)

A

Higher

29
Q

What responses are involved in CV Drift

A

Mainly Stroke

30
Q

The cardiovascular control centre continually receives input about what four things ?

A
  • BP
  • Core body temperature
  • muscle metabolism
  • muscle contraction
31
Q

Active muscle results in the opening of dormant capillaries, what is the function of this?

A
  1. Increase total muscle blood flow
  2. Large blood volume delivery with minimal increase in flow velocity
  3. Increase surface area for gas and nutrient exchange
32
Q

Three factors regulating SV

A
  • Preload
  • contractility
  • Afterload
33
Q

Three factors that enhance stroke volume during exercise

A
  1. Enhanced cardiac filling and pre load
  2. More complete systolic emptying
  3. Training adaptations that increase total blood volume and reduce resistance to flow