Lecture 39

Question 1

True or False:

There is always a high metabolic demand for ATP use?

Answer 1

False: there is variable metabolic demand for ATP

Question 2

What happens to insulin and glucagon as blood glucose levels rise (after a meal)?

Answer 2

Insulin is increased and Glucagon is decreased

-Insulin:glucagon ratio increases

Question 3

Because ruminants convert CHO in their diet to VFA’s they require _____ to make glucose to fuel brain and RBCs.

Answer 3

Gluconeogenesis

*In these animals glucagon is released after a meal

Question 4

How is insulin secretion different in ruminants from other mammals? What is it maintained by?

Answer 4

• Insulin secretion in ruminants continues after the meal has been digested (maintained)
• amino acids, glucagon, GI hormone stimulation

Question 5

In the well-fed state what happens to the glucose once it reaches liver?

Answer 5

-Either stored as glycogen or converted to fat through lipolysis

Question 6

What organs require glucose for energy?

Answer 6

Brain, Kidney, Liver, RBC, Muscle

Question 7

___ works to drive liver glucose uptake when blood glucose is ____

Answer 7

• Glucokinase

- High

Question 8

What happens to glucose in adipose tissue following a meal?

Answer 8

-Used for glycerol 3-phosphate production for TG storage

Question 9

Following a meal the Insulin driven anabolic pathways are ____, while the glucagon-driven catabolic pathways are ____.

Answer 9

Active

-Inactive

Question 10

Following a meal protein phosphatases are ____ and protein kinases are ____

Answer 10

• active

- inactive

Question 11

Indicate increase/decrease or on/off following a meal:

1. GLUT4 translocation
2. Glycogenesis
3. Glycogen Synthase
4. Glycogen phosphorylase
5. Glycolysis
6. PFK II
7. PDH
8. Fructose 2,6 bisphosphate
9. Gluconeogenesis

Answer 11

1. Increased
2. Increased
3. On
4. Off
5. On
6. actively phosphorylating Fructose 2,6 P2
7. On
8. On
9. Off

Question 12

What is responsible for delivering lipids to tissues for use and storage?

Answer 12

Chylomicrons

Question 13

Indicate what effect high insulin is having on the following pathways:

1. Lipogenesis
2. Acetyl CoA carboxylase
3. Lipoprotein Lipase
4. Hormone Sensitive lipase
5. Lipolysis

Answer 13

1. On
2. On –> convert excess glucose to lipid
3. On –> deliver FA for storage
4. Off –> prevents TG breakdown
5. Off

Question 14

True or False:

Liver metabolizes aromatic amino acids and non-hepatic tissue metabolizes branched chain amino acids.

Answer 14

True

Question 15

Please indicate whether the rate of the pathway would be increased or decreased when the two conditions are compared.

1. Glucagon secretion in a Fasted state is ___ relative to the well fed state
2. Liver glycogen synthase activity in the well-fed state is ___ relative to a fasted state
3. Liver glycogen phosphorylase activity in a fasted state is ___ relative to the well-fed state
4. Muscle protein synthesis in the well-fed state is ___ relative to a fasted state
5. Adipose tissue lipolysis in a fasted state is ___ relative to a well-fed state.

Answer 15

1. Decreased
2. Increased
3. Increased
4. Increased
5. Increased

Question 16

Is there more energy in stored glycogen or stored triglyceride?

Answer 16

Triglyceride

Question 17

In the early fasting state what does the liver release?

Answer 17

Glucose from the glycogen supply

Question 18

In early fasting liver glycogenolysis ____

Answer 18

Increases.

-Brain and RBC need glucose!

Question 19

In general what is the glycogenolysis pathway?

Answer 19

Glucagon –> PKA –> activated phosphorylase kinase –> Glycogen phosphorylase –> Breakdown glycogen

Question 20

When the insulin:glucagon ratio falls sufficiently during mid fasting liver ___ is increased as well as adipose tissue ____

Answer 20

• gluconeogenesis

- lipolysis

Question 21

How does the liver promote gluconeogenesis during mid fasting?

Answer 21

-Glucagon activates liver PFK II phosphatase which decreases fructose 2,6 P2, turning gluconeogenesis on

Question 22

How is lipolysis activated during mid fasting?

Answer 22

-Glucagon and epinephrine activate hormone sensitive lipase

Question 23

What is the significance of lipolysis activation during mid fasting?

Answer 23

-Provides FFA for tissues to oxidize and allow diminished glucose oxidation

Question 24

During late fasting/early starvation where is the glycerol coming from for gluconeogenesis?

Answer 24

-Glycerol is released from adipose tissue lipolysis which is activated by catecholamines and cortisol

Question 25

How does the glucose requirement change during early and intermediate-late starvation?

Answer 25

Early on glucose requirement is high but later the brain can switch to using ketones so gluconeogenesis decreases and ketogenesis increases

Question 26

True or False: | The liver is the only organ that can perform gluconeogenesis?

Answer 26

False. | The kidney can perform gluconeogenesis during prolonged fasting/starvation.

Question 27

___ declines over time while ____ increases

Answer 27

- gluconeogenesis | - ketogenesis

Question 28

Where is the glucose coming from throughout a fast?

Answer 28

- Early-exogenous - As this is digested glycogen stores are broken down. - As Glycogen is diminished gluconeogenesis kicks in - After several days gluconeogenesis slows and ketogenesis increases

Question 29

What happens in a starved state?

Answer 29

- Increased muscle protein breakdown - Loss of digestive and nutrient processing enzymes - Increased AA oxidation - Increased gluconeogenesis - Increased urea production - Increased ammonia production

Question 30

Indicate whether the rate of the pathway would be increased or decreased: 1. Liver gluconeogenesis in the fasted state is ___ relative to well-fed state. 2. Adipose tissue triglyceride synthesis in the well-fed state is ___ relative to the fasted state 3. Adipose tissue hormone-sensitive lipase activity in the fasted state is ___ relative to the well-fed state. 4. Liver ketone synthesis in the well-fed state is ___ relative to the fasted state 5. Red blood cell glycolysis is the well-fed state is ___ relative to the fasted state.

Answer 30

1. Increased 2. Increased 3. Increased 4. Decreased 5. No change