Biochemistry Test Iii - Metabolism & Starvation

Front 1

1) Name the tissues of the body that are most dependent on glucose. Brain and Red blood

Back 1

Brain and Red

Front 2

2) What are the “favored” substrates of heart?

Back 2

• Heart muscle (aerobic metabolism): ketone bodies, fatty acid, and glucose

Front 3

2) What are the “favored” substrates of RBC’s?

Back 3

• RBC: glucose
o No mitochondria, and therefore cannot oxidize fats or ketones.

Front 4

2) What are the “favored” substrates of brain?

Back 4

• Brain: glucose
o except during low glucose/starvation  use ketone bodies for energy

Front 5

3) What is the role of adipose tissue?

Back 5

Store and regulate fatty acid release depending upon circulating glucose level (both directly and as it influences insulin). Insulin stimulates the synthesis of triglycerides in adipose.

Front 6

2) What are the “favored” substrates of skeletal muscle?

Back 6

• Skeletal muscle: fatty acids, glucose, and ketone bodies.
o @ rest: fatty acids
o Exercise: glycolysis

Front 7

5) What are the advantages of fat (triglycerides) over glycogen as an energy-storage form?

Back 7

Triglycerides represent the most concentrated energy source of the body.

Front 8

6) Which two hormones are most important for the control of energy metabolism in the body? What are their predominant effects?

Back 8

Fed state: High blood glucose causes Insulin to secreted by pancreatic β-cells promotes glucose transport in insulin responsive cells: stimulating glycogen synthesis in muscle, and triglyceride synthesis in adipose

Fasting state: Low blood glucose causes increases in glucagon produced by the α-cells and decreases in insulin. Liver glycogen is mobilized, and as stores are depleted, gluconeogenesis is effected at the expense of lactate and pyruvate. Later on, fats are mobilized (-oxidation). Insulin concentration decreases further (insulin/glucagon  ), and alanine is released from muscle tissue during proteolysis. The alanine is taken up by liver for GNG

Front 9

7) Which organs are responsive to insulin?

Back 9

Liver, muscle and adipose tissue.

Front 10

8) Discuss the importance of renal gluconeogenesis. What is the single most important determinant of length of survival of starvation?

Back 10

Renal gluconeogenesis has 2 functions:
1) Nitrogen is excreted as NH3 and save the use of ATP which is needed for urea synthesis.
2) Exceretion of ammonia facilitares correction of acidosis caused by the medabolism of ketones and fatty acids. Fat stores are important for survival during starvation.

Front 11

The goals of the Metabolic adaptation to fasting occurs in 2 major states

Back 11

1)Gluconeogenic :adequate fuel for brain (glucose&ketone bodies)
2)Protein sparing: minimum loss of lean muscle mass

Front 12

what is phase one of starvation?

Back 12

Gluconeogenic :
adequate fuel for brain (glucose&ketone bodies)

Front 13

what is phase one of starvation?

Back 13

Protein sparing: minimum loss of lean muscle mass

Front 14

if blood sugar is low, ___ is high

Back 14

glucagon

Front 15

if blood sugar is low, ___ is low

Back 15

insulin

Front 16

if blood sugar is high, ___ is high

Back 16

insulin

Front 17

if blood sugar is high, ___ is low

Back 17

glucagon

Front 18

What prevents muscle proteolysis

Back 18

ketonemia, insulin?

Front 19

during phase 2 of starvation, what organ increase gluconeogenesis

Back 19

renal cortex of the kidney

Front 20

what molecules are being use for the majority of energy by the brain in phase 2

Back 20

ketone bodies

Front 21

what does the decrese in insulin during phase one do to organs

Back 21

the lung, adipose. and muscle tissue start using fatty acids as energy and decrease their use of glucose

Front 22

Glucagon decreases what 2 pathways?

Back 22

fat synthesis (acetyl CoA decarboxylase) and glycolysis

Front 23

glucagon increases what 3 pathways?

Back 23

Beta-oxidation

glycogenolysis

lipolysis

gluconeogenesis

Front 24

why are ketones are good fuel in a pinch ?

Back 24

1)water soluble
2)transport to all tissues
3)inhibit glucose metabolism in most tissues

Front 25

what is the process that mobilizes fats?

Back 25

Beta-oxidation

Front 26

The cori cycle refers to

Back 26

metabolic interaction of the liver, skeletal muscle, and RBCs

exercise -->muscle--> lactate-->liver
liver: lactate + GNG-->replenish plasma and muscle glucose

Front 27

The Alanine cycle refers to

Back 27

muscle releases the GNG thereby shipping out nitrogen too

Front 28

what organ regulates fatty acid and carbohydrate levels in blood

Back 28

liver

Front 29

insulin is produced by

Back 29

beta cells

Front 30

glucagon is produced by

Back 30

alpha cells

Front 31

insulin stimulates the synthesis of what 3 things?

Back 31

1) glycogen
2) protein
3) fatty acids

Front 32

What 3 hormones antagonize insulin

Back 32

glucagon, epinephrine, cortisol

Front 33

What is the glucose sensor in the liver

Back 33

Glycogen phosphorylase a

Front 34

what does glucose do when it binds to Glycogen phosphorylase a?

Back 34

exposes the activating phosphate group so the phosphatase can dephospholyate and inactivate it to Glycogen phosphorylase b

Front 35

what happens to Glycogen phosphorylase b when blood sugar falls?

Back 35

Glycogen phosphorylase b is converted back to Glycogen phosphorylase a

Front 36

what is the hexosamine biosynthetic pathway?

Back 36

F-6-P --> G-6-P by GFAT

G-6-P is incorporated into UDP-N-acetylgucosamine which donates N-acetylgucosamine for modification of transcripion factors like SP-1

thought of as a fuel snsing system

Front 37

Protein can be used as fuel in emergencies, but it is not ____ as a fuel sorce

Back 37

stored

Front 38

Insulin increases glycogen, protein, and fatty acids T/F

Back 38

true

Front 39

Glucagon decreases glycogen, protein, and fatty acids T/F

Back 39

True

Front 40

what is cortisol secreted in response to?

Back 40

ACTH

Front 41

Hexosamine Biosynthetic pathway results in O-GlcNAc which are converted to

Back 41

proteins

Front 42

What does Renal GNG do?

Back 42

spares energy for urea

helps correct acidosis

Front 43

Renal GNG:

PEPCK activity is increased by

Back 43

acidosis

Front 44

Renal GNG:

what provides the carbon for glucose synthesis?

Back 44

glutamine

Front 45

What is Refeeding syndrome?

Back 45

severe electrolyte and fluid shifts associated with metabolic abnormalities in malnourished patients undergoing refeeding