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Glucose Homeostasis/Energy Metabolism > Biochemistry Exam II > Flashcards

Biochemistry Exam II Flashcards

1
Q

Secreted by B-cells of pancreas

A

Insulin

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2
Q

Secreted by a-cells of pancreas

A

Glucagon

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3
Q

Insulin receptors

A

autophosphorylate themselves

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4
Q

Brings Glu into the cell

A

GLUT 4

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5
Q

Insulin-dependent gucose entry into cell is mediated by _____ which controls glucose uptake in _____ and _____

A

glucose transporters (GLUT4)
skeletal muscle
adipocytes

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6
Q

Most GLUT 4 reside

A

intracellularly (<10% on PM)

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7
Q

_____ Increases the expression of GLUT 4 independently of insulin

A

muscular contraction

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8
Q

____ decrease the expression of GLUT4 in the muscle

A

Fatty acids

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9
Q

Main contribution to type 2 diabetes

A

–Insulin resistance
Inadequate synthesis
Secretion
Unable to exert normal effect (most common)

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10
Q

Main cause of insulin resistance

A 
defect in signaling
-receptor binding
-mutation in receptor gene
-anti-receptor autoantibodies
Signaling defects
-IRS-phosphoiniositol kinase pathway
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11
Q

Anti-insulin hormone

A

Glucagon

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12
Q

Mobilizes glucose
Increases blood glucose
stimulates catabolism
Suppresses anabolism

A

Glucagon–breaks down glycogen (catabolic)

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13
Q

Catecholamine

  • secreted by AG
  • Inhibits glycolysis and lipogenesis
  • Stimulates gluconeogenesis
A

Epinephrine

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14
Q

Effect of Epinephrine

A

decrease glycolysis and lipogenesis

stimulate gluconeogenesis

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15
Q

Controlled by changes in plasma ratios of glucagon and insuin

A

Feed-Fast cycle

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16
Q

High insulin/low glucagon

A

fed state

17
Q

Low insulin/high glucagon

A

fasting between 6-12 hours state

18
Q

____ low insulin/high glucagon occurs during fasting of ___ or more hours, known as ____

A

Chronic
12
Starvation

19
Q

Tissues affected in Fed (absorptive state)

A 
Liver
Muscle
Adipose
--Storage tissues
Glucose utilization in brain = unaffected
20
Q

Decrease in glycogen synthesis
Increase in glycogenolysis
Liver switches from glucose usage to glucose production

A

Fasting (postabsorptive) state

21
Q

Gluconeogenesis key substrates

A

Lactate, alanine, glycerol

22
Q

During fasting ___% taken up by insulin-dependent tissues
__% glucose goes to brain
Remaining is divided among ____ _____ and ____

A

80
50
RBC, Muscle, Adipose

23
Q

after 12 hrs.
___% glucose comes from glycogen
Glucose contribution from ____ increases as it continues
-More ketone bodies present in this stage

A

Prolonged fasting (starvation)

24
Q

During prolonged fasting, ___ help by releasing ____ which goes to liver

A

Muscles

Lactate

25
Q

In liver, lactate—>

Glucose released goes to muscle =

A

pyruvate for gluconeogensis

Cori cycle

26
Q

In this stage:
Free fatty acids are major energy substrate
Oxaloacetate decreases in mito to fuel gluconeogenesis–limiting TCA activity
Acetyl CoA accumulates–used for ketogenesis causing inc. plasma ketone body levels

A

Prolonged fasting (starvation)

27
Q

During starvation, gluconeogensis occurs in

A

kidney and liver

28
Q

During starvation, muscle proteolysis increases, releasing

A

Alanine and Gln

29
Q

Anti-insuiln hormones

A

Epinephrine
Glucagon
Cortisol

30
Q

Metabolism is effected during stress:
Gluconeogenesis?
Glycogen breakdown?
Ketone body production?

A

Increases gluconeogenesis
Increases glycogen breakdown (glycogenolysis)
Increases ketone production by ketogenesis
—Stress response preserves glucose supply
—leaves more for brain utilization

31
Q

Stress induces insulin resistance
Cortisol decreases Glu4 expression
Cortisol induces expression of Glc-6-Pase and PEP carboxylase carrboxykinase genes which facilitate gluconeogenesis
Insulin-independent glu uptake increases

A

Outcomes of Stress Response

32
Q

develops before age 35
destruction of B-cells
Viral infection,toxins, food
Autoantibodies to insulin, glutamic acid decarboxylase and protein tyrosine phosphatase

A

Type I Diabetes

33
Q

Over age 40
Insulin resistance
Ketoacidosis rare
Obesity
normal glucose levels, hyper insulinemia
can be reversed with weighloss and exercise

A

Type 2 diabetes

Glucose Homeostasis/Energy Metabolism (1 decks)

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