Lecture 12 - metabolic integration part 1

Question 1

Metabolic integration of protein

Answer 1

intermediates with 3-6 carbons can be used to make glucose
once you form acetyl CoA you can no longer use the building blocks to make glucose

Question 2

What must metabolic maintain?

Answer 2

1. blood glucose between 60-100 mg/dL
2. blood pH near neutrality (related to amino group handling)

Question 3

Where is blood glucose required in the body?

Answer 3

1. by red blood cells as an energy substrate (because they have no mitochondria)
2. by the central nervous system (although gradual adaptation to ketones possible)
3. to maintain an active Kreb’s cycle

Question 4

In the fed state, what is the predominant source of blood glucose

Answer 4

dietary CHO (if high carb diet)
dietary protein (if high protein diet)

Question 5

In the post-absorptive state, what is the predominant source of blood glucose?

Answer 5

glycogen from liver (glycogenolysis)

Question 6

In the fasting (no glycogen) state, what is the predominant source of blood glucose?

Answer 6

gluconeogenesis from protein catabolism

Question 7

In the starvation state, what is the predominant source of blood glucose?

Answer 7

gluconeogenesis from glycerol produced by TAG breakdown;some protein catabolism

Question 8

What is the nature of the insulin hormone?

Answer 8

anabolic

Question 9

What is the nature of the glucagon hormone?

Answer 9

catabolic

Question 10

What is the nature of corticosteroids (cortisol)?

Answer 10

catabolic

Question 11

What is the nature of catecholamines (epinephrine)?

Answer 11

catabolic

Question 12

What is insulin produced by?

Answer 12

pancreas (beta cells)

Question 13

What is glucagon produced by?

Answer 13

pancreas (alpha cells)

Question 14

What are corticosteroids (cortisol) produced by?

Answer 14

adrenal cortex

Question 15

What are catecholamines (epinephrine) produced by?

Answer 15

adrenal medulla

Question 16

What are the main effects of insulin?

Answer 16

raise glucose and AA uptake in muscle and liver
raise glycogen and protein synthesis in muscle and liver
raise TAG synthesis and storage in adipose

Question 17

What are the main effects of glucagon?

Answer 17

raise breakdown of glycogen, protein and fat
raise gluconeogenesis from AAs and glycerol

Question 18

What are the main effects of corticosteroids (cortisol)?

Answer 18

raise muscle protein catabolism
raise gluconeogenesis from AAs

Question 19

What are the main effects of catecholamines (epinephrine)?

Answer 19

raise glycogenolysis and lipolysis

Question 20

What are some characteristics of the brain metabolism?

Answer 20

• constantly working
• brain cells need glucose
• low carb diet - brain cells aren’t getting what they need

Question 21

What are the brains requirements for oxidative metabolism?

Answer 21

• high requirement - needed to support continuous electrical activity
• 100-120 g per day required

Question 22

Why can’t the brain use FA’s for energy?

Answer 22

FA can’t cross the blood-brain barrier enough to provide sufficient energy

Question 23

What are some characteristics of the energy requirements of adipose tissue?

Answer 23

• low energy requirements, therefore not a lot of oxidative fuel consumption
• mostly just storage

Question 24

What is glucose used for in adipose tissue?

Answer 24

• for de novo lipogenesis and TAg synthesis
• to provide energy for FA uptake

Question 25

What does the adipose tissue release?

Answer 25

non-esterified FA (NEFA), into circulation from lipolysis

Question 26

How much of total body weight does skeletal muscle represent?

Answer 26

40%

Question 27

What are the two regulators of muscle fuel consumption?

Answer 27

nutritional status and exercise

Question 28

What are the two different fibres of the skeletal muscle?

Answer 28

slow twitch
- used for long duration activity slow concentration
- FA are the predominant source of energy
fast twitch
- used for short duration activity, quick contraction
- local glycogen stores provide energy

Question 29

What are some characteristics of fed to starvation phase in the body?

Answer 29

• glucose is used quickly
• glycogen reserves are sufficient for 24 hrs and then depleted
• protein breakdown occurs initially releasing glucogenic AA
  
  • this will then slow down to preserve protein function, but small amounts continue to be broken down to maintain the activity of the krebs cycle
• FA breakdown occurs to spare protein eventually used to make ketone bodies

Question 30

What are the trends of energy source from fed to starvation?

Answer 30

glucose - decreases
glycogen - peaks 24 hrs and then is zero
AA (protein) - raises after 24 hrs and then slowly decreases
FA - raised after 24 hrs and maintains consistently high
ketones - raised after 3 days and maintains high