seminar 5

Question 1

In the cycle of muscle contraction, two molecules have to form a crossbridge to enable contraction. What is the name of these two molecules?

Answer 1

Myosin and actin

Question 2

Muscle contraction depends on an action potential and excitation-contraction mechanisms. 1. What is the name of the neurotransmitter to trigger an action potential in skeletal muscle and 2. what is the molecule that is released by the sarcoplasmatic reticulum to trigger the sliding of filaments to contract muscle?

Answer 2

1. Acetylcholine 2. calcium

Question 3

What is not a characteristic of a skeletal muscle fibre

Answer 3

can divide

Question 4

Fast twitch/type II have a larger fibre diameter than slow twitch/type I fibres true or false

Answer 4

true

Question 5

The concentration of citrate synthase is higher in slow twitch/type I fibres than fast twitch/type II fibres. true or false

Answer 5

true

Question 6

At which of the below exercise intensities (%VO2max) is the relative and absolute concentration of carbohydrates as fuel source the highest?

Answer 6

80%

Question 7

At which of the following exercise intensities (%VO2max) is fat oxidation as fuel source the highest relatively?

Answer 7

less than 20%

Question 8

At which of the following exercise intensities (%VO2max) is fat oxidation the highest in absolute terms?

Answer 8

21-75%

Question 9

True or false: eating carbohydrates before exercise will reduce the body’s ability to utilise fat as a fuel source?

Answer 9

true

Question 10

During exercise, we can derive glucose for substrate oxidation from two sources: muscle glycogen and blood glucose (derived from liver). Which one contributes more to energy production?

Answer 10

muscle glycogen

Question 11

Which of the following answer options are a physiological mechanism that explains why fat oxidation declines at high exercise intensities (>70% VO2max)?

Answer 11

Reduced blood flow to adipose tissue
Reduced carnitine availability inside skeletal muscle

Question 12

Acetyl-CoA increases due to higher rates of ______. Subsequently, the enzyme ______ forms Malonyl-CoA. Malonyl-CoA _______ CPT1 activity, and thus ______ fatty acids are transported into the mitochondria

Answer 12

Glycolysis; ACC; Inihibits; less

Question 13

With increased exercise duration (at a fixed exercise intensity), a shift in substrate selection takes place by increasing the reliance on fat and reducing the contribution of CHO. What is/are the mechanism(s) underpinning this shift?

Answer 13

glycogen depletion and increased lipolysis

Question 14

What sort of molecule is AMPK?

Answer 14

an enzyme

Question 15

Which of the below statements is Not correct with regards to AMPK

Answer 15

Decreases CD36 in the plasma membrane