Exam 5 lecture 30.5 and 31

Question 1

Vertebrate skeletal muscle

Answer 1

-Each myofibril is surrounded by sarcoplasmic reticulum that stores Ca2+
-Transverse tubule relays signal to all parts of cell

Question 2

Myofibrils are made up of myofilaments

Answer 2

Thin filaments: Actin regulatory proteins. Includes regulartoy proteins, troponin and tropomyosin
(Troponin has to move off binding site for tropomyosin to bind)

Thick filaments: Staggered arrays of myosin molecules. Has gobular head with actin binding site.

Question 3

Intracellular Ca2+

Answer 3

Muscle contraction

Question 4

ATP

Answer 4

Goes to ADP and Pi which is stored energy

Question 5

Sarcomere

Answer 5

Repeating units of actin/myosin

Myosin is longer

Question 6

Sliding filament theory

Answer 6

-Actin and myosin filaments slide past eachother, producing more overlap

1. Myosin binds
   2.Hinge pivots

Question 7

The neuromuscular junction

Answer 7

-Voluntary control: alpha motor neuron stimulates muscle cell
1. AP cause Ach release
2. Ach binds receptors
3. Ion channels open (ligand gated), sodium influx
4. Muscle cell depolarizes

Question 8

Motor end plate

Answer 8

Part of muscle cell under axon terminal

Question 9

Cross bridge formation

Answer 9

5. Muscle cell depolarizes along T tubule
6. Causes release of intracellular Ca2+
7. Ca2+ binds to troponin
8. Troponin moves tropomyosin
9. The myosin binding sites are exposed
10. Cross bridge forms

No calcium = no cross bridge (muscle relaxed)

Question 10

Cross bridge formation 2

Answer 10

11. Hinge pivots
12. Actin slides over myosin
13. Myosin head detatches
14. Myosin head resets
15. Myosin head binds new subunit
16. Think filaments move toward center
17. Break down of ATP powers cycling process

Repeats as long as there is Ca2+

Question 11

Muscle relaxation

Answer 11

-Motor neuron stops firing AP
-Ca2+ unbinds troponin
-Tropmyosin covers myosin binding sites
-Ca2+ is resequesterd into SR
-Acting and myosin slide back apart