Metabolism Flashcards

1
Q

The control of metabolism is directed primarily toward

A

1.maintaining blood [glucose] sufficiently high for nervous tissue to function, and 2. insuring that other cells of the body have adequate substrates

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2
Q

name 6 hormones that influence metabolism

A

Insulin

Glucagon

Epinephrine

Norepinephrine

Growth Hormone

Cortisol

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3
Q

name 3 stored forms of energy

A

glycogen

protein

fat (triglycerides)

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4
Q

name 3 forms of energy in the blood

A

glucose

fatty acids

ketones

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5
Q

what is a difference between keto acids and ketones?

A

keto acids are intermediates of tricarboxylic acid cycle (Krebs cycle) ketones are derived from fatty acids

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6
Q

name 4 tissues controlling body metabolism

A

Liver

Skeletal muscle

Adipose tissue

Brain

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7
Q

list the functions of liver hepatocytes

A
  1. GLUCOSE <–> GLYCOGEN
  2. Release Glucose to blood
  3. Gluconeogenesis
  4. Formation of triglicerides
  5. Release triglycerides to blood
  6. TRIGLYCERIDES –> FATTY ACIDS
  7. FATTY ACIDS –> KETONE BODIES
  8. Releases Ketone Bodies to blood
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8
Q

Describe the process of export of triglycerides by hepatocytes

A
  1. synthesis of apoprotein, phosphotidylcholine, triacylglycerol, cholesterol in ER
  2. assembly into prelipoprotein in ER then transfer to Golgi
  3. Golgi processes
  4. Formation of secretory vesicle
  5. VLDL is released into circulation
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9
Q

describe 6 functions of the liver

A
  1. capable of gluconeogenesis (in common with kidney)
  2. high capacity for storing glucose as glycogen (muscle 3X better)
  3. capable of releasing glucose into the blood (unique to liver)
  4. can synthesize and catabolize fat (in common with adipose tissue)
  5. can export TG into the blood (unique to liver)
  6. can synthesize and export ketones (unique to liver)
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10
Q

why is skeletal muscle important to overall metabolism?

A

it constitutes a large percentage of body weight (20%)

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11
Q

Where do the long term and short term energy supply in skeletal muscle come from?

A

long term: protein

short term: glycogen

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12
Q

why is adipose tissue important for metabolism?

A

is important in metabolism because it is the great “energy depot” of the body

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13
Q

Fat supplies ___% of daily calories, carbohydrate ___%.

A

55%

45%

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14
Q

why is the brain important for metabolism?

A
  1. its need for a constant supply of metabolic fuels 2. controls the secretion of important hormones (catecholamines, growth hormone and cortisol) that insure the availability of substrates during acute hypoglycemia and and chronic starvation
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15
Q

the brain is only ___% of body mass but is responsible for ___% of total body metabolism

A

2%

15%

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16
Q

the brain burns what percent of all glucose used/day?

A

burns 45% of all of the glucose used/day.

17
Q

what happens when the brain is without glucose for >10 mins?

A

coma and death

18
Q

after 4 days postabsorptive the brain gets 70% of its energy from _____.

A

ketones

19
Q

Whether we are in an anabolic or a catabolic state depends on ….

A

whether we are in the absorptive phase, having just eaten a meal or in the postabsorptive phase, having completely absorbed the nutrients of the last meal we consumed

20
Q

During the absorptive phase we obtain nutrients from _________ sources

A

exogenous (external)

21
Q

name Three forms of energy currency that become available from endogenous stores

A

glucose

fatty acids from adipocytes

ketones from hepatocytes

22
Q

_____ is the most important hormone regulating daily metabolic transitions

A

insulin

23
Q

The rate of insulin secretion is maximal when blood glucose is _________

A

about 25 mM

24
Q

The ability of skeletal muscle fibers to take up glucose is nearly absolutely dependent upon ____

A

insulin

25
Q

insulin (increase/decreases) in the absorptive phase and (increase/decreases) in the postabsorptive

A

increases decreases

26
Q

The effect of insulin on blood sugar is to

A

lower blood sugar

27
Q

Lowering blood sugar below 5 mM _____ glucagon secretion

A

enhances

28
Q

Hour by hour maintenance of blood glucose near 90mg/dl (5 mM) is due to the balance between the influences of blood _______ and ______.

A

glucagon and insulin

29
Q

______ elevate blood substrates when plasma glucose falls below 70 mg/dl

A

Catecholamines

30
Q

_______ is secreted when blood glucose falls below 70 mg/dl for a sustained period

A

Growth hormone

31
Q

Growth Hormone functions:

A
  1. increases sensitivity of adipocytes to lipolytic stimuli
  2. increases gluconeogenesis in liver hepatocytes
  3. reduces effect of insulin to stimulate glucose uptake in muscle and adipose tissue.
32
Q

____ is secreted when blood glucose falls below 60 mg/dl for a sustained period

A

Cortisol