9.4 Regulation Of Contraction

Question 1

Calcium is sometimes referred to as a

Answer 1

Second messenger. Powerful intracellular signal

Question 2

Intracellular calcium levels in most cells is

Answer 2

Very low, released when stimulated by AP

Question 3

Calcium stored in

Answer 3

Organelle Sarcoplasmic reticulum

Question 4

Ca2+ ATPase

Answer 4

Uses ATP to pump Ca into the sarcoplasmic reticulum

Question 5

Tropomyosin covers what and does what

Answer 5

Covers actin preventing myosin from binding

Question 6

Troponin binds to what and does what

Answer 6

Calcium ions causing Tropomyosin to move over

Question 7

Binds, releases, reaches, grabs

Question 8

Summary of contraction

Answer 8

• somatic motor neuron has AP that reaches terminal
• NT ACH released into cleft
• muscle fiber receptors bind ACH
• Sodium channel opens allowing depolarization EPSP
• AP reaches Sarcoplasmic reticulum releasing Calcium into cell (Ca AtPase attempting to bring Ca back in)
• Ca causes troponin/Tropomyosin complex to shift allowing myosin to reach actin
• space between Z-discs decreases (sarcomere shrinks)
• myofibril contracts
• fiber contracts
• fascicles contract
• muscle contracts