Lecture 34: Absorptive and Postabsorptive Nutrient Utilization-2

Question 1

What happens to glucose and glucagon during the postabsorptive phase

Answer 1

Blood glucose decreases, stimulates glucagon and inhibits insulin secretion

Question 2

Describe the liver transition from absorptive to postabsorptive phase

Answer 2

Liver switches from glucose utilization to glucose production by glycogen and gluconeogenesis

Question 3

What tissues are using glucose during postabsorptive phase

Answer 3

All tissues, including brain. Muscle and adipose tissue at a diminished rate

Question 4

How does the liver mobilize its stores during postabsorptive phase

Answer 4

Decrease glucose stimulates glucagon secretion

Glucagon stimulated glycogenolysis and gluconeogenesis

Question 5

How long does glycogen depot last during rest/moderate ecercise

Answer 5

8-12 hrs

Question 6

How long does glycogen depot last during high demand/severe exercise

Answer 6

30 minutes

Question 7

How does glucagon act on adipose tissues

Answer 7

Stimulates lipolysis

Question 8

__ and ___ stimulate lipolysis and FA release through B-adrenoreceptors

Answer 8

Epi and NE

Question 9

___ peptide from the heart stimulate lipolysis during exercise

Answer 9

Natriuretic

Question 10

__ and ___ reinforce increased lipolysis during and after prolonged exercise

Answer 10

Growth hormone and cortisol

Question 11

How are FA mobilized and released from adipose tissue

Answer 11

1. Epi or Glucagon bind B-adrenergic receptor
2. Activate hormone sensitive lipase
3. NEFA are transported out as free FA, bound to albumin or VLDL
4. Taken up by liver and skeletal muscle

Question 12

NEFA’s are used for synthesis of ___ and ___

Answer 12

Ketones and VLDL

Question 13

Why are there multiple transport mechanisms for NEFA’s

Answer 13

Albumin decreases during long phases of nutrient deficiency. VLDL’s are independent of AA availability

Question 14

What transporters FA into cells

Answer 14

CD36

Question 15

Describe the steps in transportation of FA into cells—> kreb cycle

Answer 15

1. NEFA’s bind albumin and are transported
2. CD36 transporters NEFA’s into cell
3. After absorption enter B-oxidation in Krebs cycle

Question 16

How does the absorption of fatty acids and glucose in the absorptive phase vs postabsorptive (what receptors are used)

Answer 16

Absorptive: GLUT4
Post-absorptive: CD36

Question 17

How are muscle stores/proteins utilized during postabsorptive phase

Answer 17

1. Decrease AA entry into AA pool
2. Degrade and use AA pool for energy

Question 18

During the postabsorptive phase what enzymes does glucagon activate and deactivate

Answer 18

Deactivate: glycogensynthase and phosphofructokinase
Activate: fructose-1,6 biphosphate and glycogenophosphorylase

Question 19

Without food for 24 hrs or more the body forms ___

Answer 19

Ketone bodies

Question 20

After 24 hours without food all glycogen stores are exhausted and the body utilized ___ for energy

Answer 20

FA (which get converted to ketones)

Question 21

Brain can’t use __ too large so for first 48hrs without food the brain uses ___

Answer 21

FA, glucose

Question 22

> 48hrs without food the liver metabolizes FA to ___ which can be used by the brain

Answer 22

Ketone bodies

Question 23

How does the fuel oxidation shift in prolonged energy deficiency

Answer 23

Carbs to mainly lipids as oxidative source

Question 24

During prolonged energy deficiency what happens to lipolysis

Answer 24

Increases to provide body with FA—> TG and ketone bodies

Question 25

during prolonged energy deficiency __ are released from adipose tissue

Answer 25

NEFA’s

Question 26

What are the three mechanisms by which liver utilizations NEFA’s

Answer 26

1. Oxidation
2. Triglycerides
3. Ketones

Question 27

During the prolonged energy deficiency phase, the goal is to preserve ___ and ___ and utilize ___

Answer 27

Glucose, AA and utilize fat

Question 28

Liver can produce FA from glucose and AA during absorptive phase or consume fatty acids and channel them to krebs or into ketogenesis. What determines pathway to use

Answer 28

Levels of malonyl Co-A, decreased levels enter ketogenesis

Question 29

During the absorptive phase (insulin high) malonyl CoA suppresses ___

Answer 29

CPT-1

Question 30

During postabsorptive phase and prolonged deficiency malonyl-CoA is __ because glugacon inhibits glycolysis

Answer 30

Low

Question 31

When malonyl CoA is low what happens to FA

Answer 31

1. FA are released from adipose tissues and transported to mitochondria via CPT-1
2. FA into mitochondria-> B oxidation and ketone body synthesis

Question 32

What is happening during hepatic lipodosis

Answer 32

Can’t convert NEFA to VLDL because hepatocytes become overwhelmed by NEFA

Question 33

Hepatic lipodosis leads to build up of TG’s which results in ___

Answer 33

Fatty liver

Question 34

What diseases are associated with hepatic lipodosis

Answer 34

Old age, obesity, DM, pancreatitis, DKA, IBD, cholangitis, hepatitis, cancer

Question 35

What are some symptoms of hepatic lipodosis in cats

Answer 35

Anorexia, obesity, icterus, liver enlargement, vomiting

Question 36

What is the treatment for H. Lipodosis

Answer 36

High protein diet

Question 37

How doe s a ruminant maintain glucose homeostasis

Answer 37

Production of propionate which results in gluconeogenesis

Question 38

What is negative energy balance in dairy cows

Answer 38

Usually occurs post calving and during lactation when they start spending lots of energy to produce milk and not gaining enough energy via feed3

Question 39

What happens to electrolytes during starvation (clinical correlation: refeeding)

Answer 39

Shift from intracellular space to extra cellular space

Question 40

What causes refeeding syndrome

Answer 40

Surge of insulin movement of electrolytes back to intracellular space and overwhelm, leading to severe hypokalemia

Question 41

What effect does insulin play in electrolyte homeostasis in regards to refeeding syndrome

Answer 41

Activates Na/K+ pump, movement of K+ to intracellular space—> hypokalemia—> effects on membrane potential for nervous tissue and cardiac muscle

Question 42

What is the therapy strategy for refeeding syndrome

Answer 42

Low carb/high fat diet
Adequate K, PO4, MG