Biochem

Question 1

Type 1 Fibers

Answer 1

Slow, oxidative
Red fibers, slow to fatigue
Maintain prolonged low intensity contracture

Question 2

Type 2A Fibers

Answer 2

Fast oxidative glycolytic

Red fibers that produce ATP by both aerobic and anaerobic metabolism

Question 3

Type 2B Fibers

Answer 3

Fast glycolytic
White fibers, fast to fatigue
ATP produced mainly by anaerobic

Question 4

Cardiac Muscle Metabolism

Answer 4

Red fibers with aerobic metabolism

High mitochondria and myoglobin

Question 5

Preferred Substrate for Cardiac Muscle

Answer 5

Fatty Acids

Question 6

Smooth Muscle Metabolism

Answer 6

Most energy is from glycolysis
Less oxidative capacity then cardiac muscle
Can also use lactate as substrate

Question 7

What is the immediate source of ATP in muscles?

Answer 7

Myosin ATPase

Question 8

What enzymes maintain ATP equilibrium?

Answer 8

Creatine kinase and Adenylate kinase (2 ADP create ATP and AMP)

Question 9

How can we measure kidney function using creatine?

Answer 9

The spontaneous breakdown of phosphocreatine into creatine is normally at a constant level so excretion in the kidneys is at regular rate

Question 10

Role of AMP in ATP replenishment during contraction

Answer 10

Rising levels of AMP causes activation of glycogen phosphorylase b that stimulates glycogenolysis to make more glucose available for ATP production, It also activates phosphofructokinase-1 to stimulate glycolysis

Question 11

Three methods of that stimulate glycogenolysis pathway

Answer 11

1) High AMP from adenylate cyclase
2) Nerve impluse release of Ca
3) Epinephrine stimulating cAMP to turn on PKA

Question 12

McArdle’s Disease

Answer 12

Glycogen storage disease where glycogen phosphorylase is deficient. Increased lactate production for energy during exercise

Question 13

Carb Metabolism in FED State of Skeletal Muscle

Answer 13

BLood glucose rises causing increased insulin which leads to increased GLUT-4 transporters membrane.
Glycogen synthesis in Type 2B fibers if stores depleted

Question 14

Fat Metabolism in Skeletal Muscle

Answer 14

FA released from chylomicra and VLDL, fat oxidation less important process until glucose levels fall

Question 15

Metabolism of BCAA in Skeletal Muscle

Answer 15

Amino acids produced via protein synthesis as required

Question 16

Advantages of carbs over fat

Answer 16

Catabolism switches on faster, maxium rate of ATP formation greater, and yeild slightly more ATP per oxygen molecule

Question 17

Disadvantage of carbs

Answer 17

Produce about 7 times less energy per gram because it is stored hydrated

Question 18

Oxygen Dept

Answer 18

The continued consumption of oxygen after vigorous sustained exercise is over

Question 19

Cori Cycle

Answer 19

RBC lack mitochondria and use anaerobic glycolysis solely for ATP production and waste product is lactate that is converter back to glucose in liver

Question 20

Causes of Muscular Fatigue

Answer 20

Increase in Pi and fall in pH

Question 21

Glucose-Fatty Acid Cycle

Answer 21

When glucose is high insulin is high too and inhibits release of FA, when glucose/insulin are low FA is not inhibited and released

Question 22

What amino acids largely released by muscle during starvation?

Answer 22

Alanine and Glutamine

Question 23

Starvation

Answer 23

Glucose reserved for brain
Muscle uses FA and ketone bodies
Muscles provide C-skeleton for liver to make glucose

Question 24

Cardiac Muscle in FED State

Answer 24

Oxidative catabolism mostly of FA, very little glycogen stored

Question 25

Cardiac Muscle in Fasting State

Answer 25

Oxidize FA and ketone bodies

Question 26

Metabolism during Myocardial Infarction

Answer 26

ATP levels fall and AMP levels increase and anaerobic glycolysis stimulated

Question 27

X-Linked Muscular Dystorphies

Answer 27

Duchenne Muscular Dystrophy

Becker Muscular Dystrophy

Question 28

Duchenne MD

Answer 28

Dystropin virtually absent
Frameshift mutation
Cower’s Sign

Question 29

Becker’s MD

Answer 29

Reduced or modified dystrophin

Non-frameshift mutation

Question 30

Myotonic MD

Answer 30

Autosomal Dominant
Expansion Repeat Mutation
Most common form of MD
Anticipation more likely in female offspring
Myotonia (difficulty relaxing muscles)

Question 31

Limb-girdle MD

Answer 31

Mutation in genes encoding sarcoglycans

Dystrophy in extremities/girdles

Question 32

Oculopharyngeal MD

Answer 32

Expansion Repeat Mutation

Drooping eyelids, weakness in facial and pharyngeal muscles

Question 33

Congenital MD

Answer 33

Autosomal Recessive

Deficiency usually in laminin-2

Question 34

Bethlem Myopathy

Answer 34

Autosomal dominant

Mutation affecting Type 4 collagen

Question 35

Malignant Hyperthermia

Answer 35

Pathogenic release of Ca in response to anesthesia, hypermetabolic state with muscular rigidity