Energy And Skeletal Muscle

Front 1

What are the 3 different systems for muscles to regenerate ATP for continuous muscle contraction?

Back 1

1) Phosphogen System
2) Glycogen-Lactic System
3) Aerobic System

Front 2

Phosphogen System - what are the 2 enzymes involved in this system?

Back 2

Creatine Kinase and AMP Kinase. Creatine Kinase is the only one that works throughout the contraction

Front 3

What is the reaction involving Creatine Kinase

Back 3

ADP -----> ATP via CK. In this process, Cr-P is converted to Cr. This P is used to rephosphorylate ADP once an ATP is used. This rxn provides 6-8 seconds more of muscle contraction. Its a very important backup system

Front 4

What is the reaction involving AMP Kinase

Back 4

2 ADP ---> ATP + AMP via AMP kinase (myokinase). So one of the phosphates comes off one ADP and goes onto the other.

Front 5

Glycogen-Lactic System - takes place where, structure of glycogen, ends of glycogen called?

Back 5

Occurs in Muscle Cell.
Glycogen is highly branched. made up of alpha1-4 and alpha1-6 linkages. all of the ends of the glycogen branches are called the Non-reducing ends

Front 6

What enzyme breaks down glycogen and how?

Back 6

Glycogen Phosphorylase uses inorganic phosphates to split the glucose molecules from the non-reducing ends via phosphorylation.

Front 7

What is the rxn?

Back 7

Glyc --> G-1-P --> G6P (via mutase) --> Pyruvate (via glycolysis) --> Lactic Acid (via LDH)

Front 8

What are the enzymes (4) used in conversion of G6P to Pyr and what are their modulators? Which ones supply the ATP for muscle contraction?

Back 8

1) PFK-1: uses an ATP. ATP is negative modulator while AMP is positive modulator

2) G3PDH: uses NAD+

3) PK: uses an ADP to MAKE ATP! ATP is a negative modulator.

4) 3PG-Kinase: Uses an ADP to MAKE ATP!

So 3PG-Kinase and PK make the ATP in this system for muscle contraction

Front 9

What is the key enzyme in this system and how can it be activated? (2)

Back 9

GP is the key enzyme here.
It exists in several forms. To activate it, use GPK to make GP-P from GP.

OR

Can use AMP with the GPK to activate the GP

Front 10

How do you activate GPK? (2)

Back 10

GPK itself is not very active. So use Ca++ to activate it (Ca++ is a + mod.)

OR

Can use PKA on the GPK to make it GPK-P - also activated (P is a + mod)

Front 11

What is unique about the Ca++

Back 11

Ca++ is the trigger for muscle contraction and also the signal for the breakdown of glycogen

Front 12

Aerobic System - what does it use?

Back 12

Using all the storage forms of energy in the body. The muscle cell starts taking up Fatty Acids. This system provides energy for a LONG time. THe key thing here is that the O2 is used (aerobic)

Front 13

Reaction of Uptake of FA's in this system?

Back 13

FA ---> FA-CoA --> Acetyl CoA (via B-Oxidation and Carn. Shuttle) --> CO2 (via TCA)

Then ADP ---> ATP using O2 via Complex V

Muscle Cells can also use ketone bodies or pyruvate if necessary

Front 14

When do the 3 systems take place and which organ uses which system (heart, brain, liver, resting muscle)

Back 14

All 3 start as muscle starts to contract.
Resting muscle cell primarily uses FA
Heart generates lots of its E from FA
Brain relies on aerobic glucose
Brain and heart can use ketone bodies, but dont prefer to
Liver gets most of its E from FA, cannot use ketone bodies

Front 15

Why are red muscle fibers red? (2)

Back 15

1) have good vascular system
2) have hemoglobin

Front 16

What type of exercise are red muscle fibers built for and what kind of twitch are they?

Back 16

endurance, they are slow twitch. lots of mitoch.

Front 17

What type of exercise are white muscle fibers built for and what kind of twitch are they? what system are they using?

Back 17

fast twitch, used for quick short response. can do aerobic or anaerobic metabolism. are probably using phosphogen system

Front 18

Why can't you use the glycogen-lactic system for long?

Back 18

b/c then lactic acid builds up, pH goes down, PFK-1 becomes unhappy and leads to a bad effect on glycolysis