S1L2 CV response to exercise

Question 1

How does the CV system acutely adapt to exercise?

Answer 1

increase O2 delivery to working muscles by increasing blood flow to muscles and reducing delivery to low activity tissues.

Question 2

How does the CV system chronically adapt to exercise?

Answer 2

delivers more O2 to active muscle mass: More effective O2 delivery during sub-max exercise and increased max O2 consumption (VO2max)

Question 3

What CV factors influence O2 uptake and VO2max?

Answer 3

• cardiac structure and function
• blood plasma volume
• blood flow distribution
• O2 extraction –> a-v difference

Question 4

What is Ficks Equation?

Answer 4

= how much O2 can be extracted from blood
VO2 = HR X SV X (a-v) O2 difference

Question 5

what is the a-v O2 difference and how does it change with training?

Answer 5

• the difference O2 content between arterial and venous blood. it represents the volume of blood extracted from blood by tissues
• more training = increased ability to extract O2 by tissues.

Question 6

how does training affect heart structure and ejection volumes?

Answer 6

more trained = heavier heart (more mass) and higher ejection volumes

Question 7

what is preload?

Answer 7

‘filling’. End diastolic volume - amount of blood in ventricle before contraction. Determined by venous return.

Question 8

what is afterload?

Answer 8

‘emptying’. resistance against ventricular ejection - pressure at which ventricle must contract. a high afterload (i.e pressure) means less blood ejected per heartbeat

Question 9

what is the frank-starling mechanism?

Answer 9

based on length-tension relationship within the ventricle. If EDV increased - ventricular fibre length increased - increased tension of muscle - increased contraction

Question 10

what is the Morganroth HYPOTHESIS?

Answer 10

1. Left Ventricle heavier in ENDURANCE athletes due to higher preload –> higher SV –> ECCENTRIC hypertrophy
2. Posterior wall and septal thickness larger in RESISTANCE athletes due to higher afterload –> decreased SV –> CONCENTRIC hypertrophy

Question 11

what is SV determined by?

Answer 11

• preload
• afterload
• contractility
  So, Q directly relation to venous return and vascular resistance.

Question 12

how does endurance training adapt SV?

Answer 12

• increased preload –> increased diastolic volume –> increased conractility –> increased maximal SV

Question 13

how does endurance training adapt HR?

Answer 13

• increased SV decreases HR for same Q
• Maximal HR unchanged

Question 14

How does endurance training adapt Q?

Answer 14

• higher Q = higher VO2max
• submax = decrease Q as higher O2 extraction

Question 15

what are the resting and exercise values for Q and muscle blood flow?

Answer 15

• resting Q = 5L/min
• Exercise Q = 20L/min
• resing muscle b. flow = 0.75L/min
• exercise muscle b.flow = 20L/min

Question 16

mechanisms of blood redistribution?

Answer 16

1. muscle metabolites and temp –> decreases in pH, O2, increases in H+, CO2 & temp - all cause vasodilation
   2.dilator substances –> NO - causes vasodilation
2. pressure changes in vessel –>decrease in pressure causes vasodilation
3. sympathetic activity –> decreased b.flow to low activity tissues

Question 17

what are the primary mechanisms of blood vol increases?

Answer 17

– Increase in plasma proteins, - albumin leads to osmotic effect – increases in water. So plasma increases.
– Increase in total body water via alterations in kidney function (reduced urine output and increased water retention)

Question 18

how does blood volume change during exercise?

Answer 18

• plasma increases in first 10 days
• RBC increases after months
• hematocrit decreased post training