CVM Week 9 - Exercise and the ageing heart

Question 0

What does chronotropic mean?

Answer 0

Increases the heart rate and therefore speed of the cardiac cycle

Question 1

What does dromotropic mean?

Answer 1

Affects the conduction speed of the AV node, which helps increase the rate of the heat

Question 2

What does inotropic mean?

Answer 2

Increasing the force of the contraction of the heart

Question 3

What does lustitropic mean?

Answer 3

Refers to the relaxation of the myocardium

Question 4

What changes occur in the heart during exercise?

Answer 4

Increased SNS vs PNS tone
Increased cardiac output - up to 5x greater than resting
Heart rate increase
Ejection fraction increased ( % of end diastolic volume ejected)
Better venous return to heart via skeletal muscle pump action allows greater greater CO despite shorter time for ventricular filling

Question 5

What changes occur in the blood vessels during exercise?

Answer 5

30x more flow to into skeletal muscles
100x more consumption of oxygen in skeletal muscles
Vasodilation in vessels supplying muscles
Arterioles dilate and increased surface area of capillary beds
Restriction of blood flow to organs that aren’t essential in exercise

Question 6

What causes the vasodilation in vessels supplying muscles during exercise?

Answer 6

Decreased pH
Decreased PO2, increased PCO2
Higher temperature

Question 7

Why is decreased velocity of blood flow thought capillary beds beneficial in exercise?

Answer 7

It allows for better oxygen delivery as the RBCs are moving through the capillaries more slowly and able to release oxygen more efficiently

Question 8

Which organs is blood most notably directed AWAY from during exercised?

Answer 8

Kidneys and again tract (both going from over 20% blood flow down to 1%)

Question 9

What happens to fluid movement in interstitial spaces during exercise?

Answer 9

Increases into the interstitium, and lymph flow also increases

Question 10

What changes occur in the lungs during exercise?

Answer 10

Breathing deeper a and more rapid
Alveolar ventilation increase 20x
Blood flow in lungs increase from 5-25L or more (must accept what the heart pumps)

Question 11

Why does oxygen delivery to tissues increase with exercise?

Answer 11

Decreased pH and increased CO2 in tissues leads to Hb releasing more oxygen at the tissues as binding of H+ on Hb favours oxygen unloading

Question 12

What is oxygen debt?

Answer 12

Where short term energy demands are my by anaerobic respiration and lactate builds up. It requires oxygen to restore back to normal pH and is why you breath deeply after a sprint.

Question 13

What is a stitch in your chest an indicator of? What is it caused by?

Answer 13

Hypoxia to diaphragm, due to a lagging behind of the cardiopulmonary system supply of oxygen, and the demand for oxygen.

Question 14

What is the major effect of aerobic/dynamic exercise?

Answer 14

Increased cardio respiratory fitness. More ability to provide oxygen rich blood to the tissues over a sustained period

Question 15

What does flexibility exercise achieve?

Answer 15

Improve full range and motion of muscles and joints

Question 16

What effects do resistance/static exercise achieve?

Answer 16

Increases muscle strength. Not so much impact on increasing stroke volume as this type of exercise doesn’t greatly increase venous return.

Question 17

What happens to resting heart rate in someone who performs endurance/aerobic training?

Answer 17

Lower resting heart rate due to increased stroke volume supplying the same cardiac output

Question 18

What happens to blood volume in aerobic athletes?

Answer 18

Increases

Question 19

What is physiological hyper Trophy?

Answer 19

The increase muscle thickness of ventricular walls as a result of increased preload as a result of exercise

Question 20

What cardiac output can be achieved in an elite athlete?

Answer 20

35-40 litres per minunte

Question 21

On a cellular level, what happens to the mitochondria of skeletal muscle cells in aerobic athletes?

Answer 21

Increase in number to facilitate increased metabolism allowing for better oxygen extraction

Question 22

What is the lactate threshold?

Answer 22

Maximal rate of oxygen consumption before blood lactic acid levels rise.

Question 23

If training doesn’t affect heart rate, how does cardiac output increase with training?

Answer 23

CO = SV x HR
So if HR stays the same, stroke volume must increase. This is due to the physiological hyper trophy along with increased SNS tone that has a positive inotropic action. Essentially causes a stronger contraction which ejects more blood from each beat

Question 24

In what two states does cardiac remodelling occur?

Answer 24

Physiological (exercise) and pathological state

Question 25

What is remodelling triggered by?

Answer 25

The volume of blood attempting to fill the ventricles, the neurohumoral and local regulatory factors (endothelin, nitric oxide)

Question 26

Distinguish between eccentric a concentric hypertrophy?

Answer 26

Eccentric is improved compliance and myocardial energetics (exercise)
Concentric is where increased stiffness and energy demand occur (pathological)

Question 27

What is a major functional difference in the healthy hypertrophy and the pathological hypertrophy?

Answer 27

Presence of fibrosis. Healthy heart has none and the diseased heart will have mild to extensive fibrosis which will affect cardiac output

Question 28

What factors determine the extent of physiological hypertrophy in exercise?

Answer 28

The type of exercise (mixed aerobic I.e. Rowing is highest)
Age (older than 16 can develop bigger hearts)
Gender (women generally don’t)
Size (bigger body means bigger ability to increase heart size)
Ethnicity

Question 29

If the baroreceptor reflex gets slower in old age, what effects does this have?

Answer 29

There is postural hypotension (low blood pressure when you get up too quickly)
Spontaneous changes in blood pressure

Question 30

Why are older people prone to dyspnea during exertion?

Answer 30

Elevated LA and LV pressures are associated with have to pump blood above high afterload. This can lead to ineffective delivery of oxygen rich blood to skeletal muscle.

Question 31

Why is hypertension common in old age?

Answer 31

Atherosclerosis, loss of arterial elasticity and nicotine induced vascular damage

Question 32

What effect does fibrosis/calcification have on a heart valve?

Answer 32

Predisposed patient towards stenosis/regurgitation

Causes cardiac workload to increase and predisposed towards heart failure