1.28 Biochemistry of the muscles

Question 1

List the types of muscle fibre

Answer 1

1. Slow twitch, Type-I
2. Fast twitch, Type-IIA
3. Intermediate fast, Type-IIB
4. Cardiac muscle (Aerobic)

Question 2

Slow Twitch muscle:

• Contraction speed
• Myoglobin content
• Glycogen content
• Mitochondria
• Fatigue
• Respiratory activity
• Example

Answer 2

• Contraction speed: Slow
• Myoglobin content: High
• Glycogen content: Low
• Mitochondria: Many
• Fatigue: Slow
• Respiratory activity: High
• Example: M. gluteus

Question 3

Fast Twitch muscle:

• Contraction speed
• Myoglobin content
• Glycogen content
• Mitochondria
• Fatigue
• Respiratory activity
• Example

Answer 3

• Contraction speed: Quick
• Myoglobin content: Low
• Glycogen content: High
• Mitochondria: Few
• Fatigue: Quick
• Respiratory activity: Low
• Example: M. gastrocnemius

Question 4

Intermediate fast Twitch muscle:

• Contraction speed
• Myoglobin content
• Glycogen content
• Mitochondria
• Fatigue
• Respiratory activity

Answer 4

• Contraction speed: Quick
• Myoglobin content: Low
• Glycogen content: High
• Mitochondria: Intermediate
• Fatigue: Intermediate
• Respiratory activity: Low

Question 5

Cardiac muscle:

• Contraction speed
• Myoglobin content
• Glycogen content
• Mitochondria
• Fatigue
• Respiratory activity

Answer 5

• Contraction speed: Continuous
• Myoglobin content: High
• Glycogen content: Stable
• Mitochondria: Many
• Fatigue: Continuous function
• Respiratory activity: High

Question 6

Draw the source of ATP for muscle contraction

Answer 6

Question 7

Adipose tissue composition

Answer 7

• Fat: 80%
• Protein: 20%
• Carb: <1%

Question 8

Function of brown adipose tissue

Answer 8

Heat production, instead of ATP

(Thermogenin)

Question 9

Fat as an energy source in a marathon runner

Answer 9

• Glycogen: Energy for 15 mins
• Later: Fat is oxidised

Question 10

Give the biochemical pathways in the white adipose tissue

Answer 10

• FA synthesis
• Lipogenesis
• Lipolysis
• FA beta-oxidation
• Glycolysis
• Ketolysis

Question 11

What can pass the blood brain barrier?

Answer 11

• O₂, CO₂, NH₃
• Glucose
• Ketone bodies
• Some Amino acids
• Short, unsaturated fatty acids

Question 12

What can’t pass the blood brain barrier?

Answer 12

Proteins + Fatty acids

Question 13

Biochemistry of the brain

Answer 13

α-ketoglutarate is removed from the citrate cycle → bound to NH₃ to form glutamate

Ammonia detoxification is the reason for neural symptoms

Question 14

The brain consumes …% of the bodies oxygen

Answer 14

20

Question 15

The brain consumes …% of glucose released from the liver

Answer 15

60-75%

Question 16

List the biochemical pathways in the brain

Answer 16

• Glycolysis
• Ketolysis
• Fat synthesis
• Non-essential amino acid + protein synthesis

Question 17

Glucose is taken up by the kidney using which transporters?

Answer 17

• SGLT-1
• SGLT-2

Question 18

Which biochemical pathways exist in the kidney

Answer 18

• Glycogenesis
• Glycogenolysis
• Glycolysis
• GNG
• Ketolysis
• Beta oxidation

Question 19

Give the glutaminase activity of the kidney

Answer 19

Gln + H₂O → Glu + NH₃

→NH₄ is then excreted by the urine