Muscle Metabolism

Question 1

Percentage of muscle in body that is skeletal?

Answer 1

40%

Question 2

Sarcomeres

Answer 2

Functional contractile segment

Question 3

Aerobic metabolism in muscle

Answer 3

. Requires O2

. Myoglobin in muscle imparts ability to store O2

Question 4

Anaerobic metabolism in muscle

Answer 4

. Depends on availability of glucose

Question 5

Type 1 aerobic fibers

Answer 5

. Favor aerobic metabolism
. Contain more mitochondria/lipid stores
. Less glycogen

Question 6

Type 2 anaerobic muscle fibers

Answer 6

. More glycogen

. Less mitochondria/lipid stores

Question 7

One’s ability to do anaerobic/aerobic is largely ____

Answer 7

Genetic

Question 8

Hormonal regulation of muscle in fed state

Answer 8

. Insulin stimulates transport of nutrients and glucose into muscle
. Glucose enters via GLUT4
. Amino acids transported into muscle
. Insulin binds to phosphatase that removes phosphate to turn on or off metabolic pathways

Question 9

Carb metabolism in muscle fed state

Answer 9

. Glucose enters muscle cells
. Used to replenish muscle glycogen stores
. Used in glycolysis to generate ATP

Question 10

Fat metabolism in muscle fed state

Answer 10

. FA released from TAGs assoc. w/ lipoproteins by lipoprotein lipase
. Lipoproteins tat are primary targets VLDL and chylomicrons
. FAs taken up into muscle and oxidized

Question 11

Amina acid metabolism in fed muscle state

Answer 11

. Dietary AA taken up by muscle

. Used to synthesize proteins degraded since last meal

Question 12

Well fed resting skeletal muscle oxidizes ____

Answer 12

50% glucose

50% FAs

Question 13

Well fed cardiac muscle oxidizes ____

Answer 13

. Primarily FAs

. Some glucose

Question 14

Hormonal regulation of skeletal muscle in starved state

Answer 14

. Insulin falls

. Counter regulatory hormones (glucagon, epinephrine, cortisol) inc.

Question 15

Carb metabolism in starved muscles

Answer 15

. Dec insulin causes dec. glucose transport into muscle
. Muscle glycogen degraded during periods of activity to generate glucose for glycolysis
. When active muscle can take up glucose from blood

Question 16

Lipid metabolism in staved muscles

Answer 16

. In first 2 weeks of starvation, muscle uses FA from adipose AND ketones from liver
. After 3 weeks the muscle only uses FAs

Question 17

Amino acid metabolism in starved muscle

Answer 17

. During first days of starvation, muscle proteolysis inc. to provide AAs for liver to use in gluconeogenesis
. After several weeks starvation: muscle proteolysis dec. slightly because brain switches to using ketones and not FAs

Question 18

60% of AAs released from muscle from fasting person are what AAs?

Answer 18

Ala and Gln

. Derived from catabolism of BCAAs

Question 19

Why are Ala and Gln released from skeletal muscle?

Answer 19

. Both AAs carry amino groups to liver (Gln brings 2, Ala makes 1) to make urea
. Used in liver to make glucose
. Gln used in intestine and kidney

Question 20

Glucose-Ala cycle

Answer 20

. Ala released into blood as glucose goes into muscle

. NADH used in ETC to make ATP and Ala carries an amino group to liver

Question 21

Starved muscles loses ___ over time

Answer 21

Mass