Skeletal Muscle

Question 1

What are the 3 layers of muscle fibres?

Answer 1

Epimysium - perimysium - endomysium

Question 2

What is a sarcoplasmic reticulum?

Answer 2

Ca2+ reservoirs
Network of tubules
Wraps around myofibrils

Question 3

What’s a t tubule?

Answer 3

Invagination of membrane that’s activated during depolarisation

Question 4

What sits on top of actin, acts like a template, and regulates actins length?

Answer 4

Nebulin

Question 5

What acts as a spring, extends from z to m and contributes to passive elasticity of muscles?

Answer 5

Titin

Question 6

Describe the innervation of contraction?

Answer 6

Ach released- na enters cell - cell depolarises — depolarisation spreads via t tubules — ca released from sarcoplasmic reticulum — binds to troponin — pulls tropomyosin — contraction occurs

Question 7

What are the 5 stages of cross bridge formation?

Answer 7

1- attachment: myosin head stuck tight to actin
2- releases: atp binds to myosin … releases actin
3: bending: atp makes myosin bend, breaks down atp to adp
4- force generation: myosin binds to new part pd actin, increases binding affinity and causes power stroke bec myosin straightens
5- reattachment: release adp, myosin reattached to actin