Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

12 Cards in this Set

  • Front
  • Back
What are the two strands of the actin filament?


- attached to what?
- initiates what?
Attached to tropomyosin

During contraction, what what bands shrink?
H band
I band
Z band (sarcomere)
Myosin heads attach to what?
Active sites on actin filament
Describe the transmission at the neuromuscular junction.
Nerve AP reaches axon terminal

Depolarization opens voltage-gated calcium channels

Calcium influx causes exocytosis of ACh into synaptic cleft

ACh binds to receptors on Post Junctional Membrane (PJM) or Post Synaptic Membrane

ACh-binded receptors will increase Na+ permeability via ligand-gated channels.

Influx of sodium will depolarize muscle cell membrane.
Describe the activity after the neuromuscular junction is activated?
Depolarization spreads along muscle membrane

Depolarization makes to T-tubules which are close to Sarcoplasmic reticulum (SR)

SR releases calcium

Calcium binds to Troponin C

Troponin C changes conformation which forces tropomyosin out of the way.

Now, myosin head is free to attach actin.

Sarcomere shortens
List energy resources for muscles

(in order of least efficient to most)
Cellular ATP (1-2 sec)

Phosphocreatine (5-8 sec)

Intramuscular Glycogen (1 min)

Oxidative Phosphorylation (hrs)
Fast fibers:

- size
- extensive what (why?)
- Lots of what?

Sarcoplasmic reticulum
(fast release of Ca2+)

Glycolytic enzymes
Slow fibers:

- size
- extensive what (why?)
- Lots of what?

Blood supply
(for large provisions of oxygen)

Mitochondria & Myoglobin
What happens after muscle denervation?

Degenerative changes in muscle
(after 2 months)

Most muscle fibers destroyed & replaced by fibrous fatty tissue.
(Final stages)
How does Poliomyelitis affect muscles?
Kills motor neurons
(lasts temporarily)

Surviving MACROmotor units sprout new axons.

No micromotor units, thus FINE MOTOR CONTROL IS LOST
How does Rigor Mortis affect the muscles?
After death, all muscles go into constant contracture

b/c there is NO ATP release myosin heads

and to pump out Calcium (via Calcium ATPase)