nervous system 15

Question 1

Structure of skeletal muscle cell

Answer 1

long, cylindrical, multi-nucleate cells
​- striations
​- light bands (called I bands) thick filaments made from myosin
​- dark bands (called A bands) thin filaments made from actin, tropomyosin, troponin

Question 2

What is muscle wrapped by?

Answer 2

Epimysium

Question 3

What is a bundle of nerves called and what is it wrapped around by?

Answer 3

Fascicle, wrapped by perimysium

Question 4

What is single muscle fibre wrapped by and called?

Answer 4

Endomysium , called myofibril

Question 5

What is cytoplasm membrane of muscle called?

Answer 5

Sacroplasm

Question 6

What does muscle contraction involve?

Answer 6

Thick and thin filaments living past each other

Question 7

Process of muscle activation

Answer 7

• when muscle is relaxed the receptors are covered by ​long tropomyosin molecule held in place by ​troponin molecules
  ​- tropomyosin stops ​myosin globular heads from attaching to the receptors ​on the actin molecules by covering binding site.
  ​- at neuromuscular junction an action potential is triggered ​which rushes in opposite directions along the muscle cell
  ​- the action potential is carried down deep narrow infoldings called transverse tubules

Question 8

Process of muscle contraction

Answer 8

-Muscle cell action potential causes release of calcium ions from sarcoplasmic reticulum
-Calcium ions attach to troponin causing a shape change which pulls tropomyosin away from receptors on actin
-Globular head on myosin is now able to bind to exposed receptor on actin
​- cross-bridge formation
​- head swivels, pulling with it the actin molecule (movement requires energy in form of ATP)
​- head detaches, swivels back and reattaches to receptor further ​along actin, etc…

Question 9

Are cardiac muscles and skeletal muscles striated or non-striated?

Answer 9

Striated

Question 10

Are smooth muscles striated or non-striated?

Answer 10

Non-striated = less orderly, more spaced out