Metabolism

Question 1

The control of metabolism is directed primarily toward

Answer 1

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

Question 2

name 6 hormones that influence metabolism

Answer 2

Insulin

Glucagon

Epinephrine

Norepinephrine

Growth Hormone

Cortisol

Question 3

name 3 stored forms of energy

Answer 3

glycogen

protein

fat (triglycerides)

Question 4

name 3 forms of energy in the blood

Answer 4

glucose

fatty acids

ketones

Question 5

what is a difference between keto acids and ketones?

Answer 5

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

Question 6

name 4 tissues controlling body metabolism

Answer 6

Liver

Skeletal muscle

Adipose tissue

Brain

Question 7

list the functions of liver hepatocytes

Answer 7

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

Question 8

Describe the process of export of triglycerides by hepatocytes

Answer 8

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

Question 9

describe 6 functions of the liver

Answer 9

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)

Question 10

why is skeletal muscle important to overall metabolism?

Answer 10

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

Question 11

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

Answer 11

long term: protein

short term: glycogen

Question 12

why is adipose tissue important for metabolism?

Answer 12

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

Question 13

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

Answer 13

55%

45%

Question 14

why is the brain important for metabolism?

Answer 14

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

Question 15

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

Answer 15

2%

15%

Question 16

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

Answer 16

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

Question 17

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

Answer 17

coma and death

Question 18

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

Answer 18

ketones

Question 19

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

Answer 19

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

Question 20

During the absorptive phase we obtain nutrients from _________ sources

Answer 20

exogenous (external)

Question 21

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

Answer 21

glucose

fatty acids from adipocytes

ketones from hepatocytes

Question 22

_____ is the most important hormone regulating daily metabolic transitions

Answer 22

insulin

Question 23

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

Answer 23

about 25 mM

Question 24

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

Answer 24

insulin

Question 25

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

Answer 25

increases decreases

Question 26

The effect of insulin on blood sugar is to

Answer 26

lower blood sugar

Question 27

Lowering blood sugar below 5 mM _____ glucagon secretion

Answer 27

enhances

Question 28

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

Answer 28

glucagon and insulin

Question 29

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

Answer 29

Catecholamines

Question 30

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

Answer 30

Growth hormone

Question 31

Growth Hormone functions:

Answer 31

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.

Question 32

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

Answer 32

Cortisol