Tissues & Muscular Tissues: Sliding filament theory.

Question 1

What is the sliding filament theory?

Answer 1

explains how muscles contract by describing the process where thin actin filaments slide past thick myosin filaments within a sarcomere, causing the sarcomere to shorten and thus contracting the muscle fiber, while the filaments themselves remain relatively constant in length

Question 2

State the preparation of myosin head.

Answer 2

ATP binds with myosin head and immediately gets broken down into ADP and a phosphate group

• However has a temporary stored energy within the now Primed myosin head. (from the hydrolysed ATP)

Question 3

What happens at the Neuromuscular Junction.

Answer 3

The nerve impulse arrives at the neuromusclar junction (when asked to contract.) This causes calcium to be released after the sacroplasmic reticulum where it is needed to trigger muscle fibres.

Question 4

Explain how calcium ions bind with troponin?

Answer 4

When calcium ions are released into the sarcoplasm due to a nerve impluse. they bind with troponin proteins. this causes troponin to change shape consquently pulling tropomyosin (membrane-like structure) out of the way as they are connected.
this exposes the binding site.

Question 5

What happens if no calcium ions are released from the sarcoplasm.

Answer 5

troponin & tropomyosin (protein) - looks like jelly. does not move, meaning no contraction can occur.

Question 6

How do Cross bridges form and power strokes occurs,

Answer 6

when actin and myosin bind there are many bridges between the two.

Power stroke occurs when the stored energy from the breakdown of ATP is used to pivot the myosin head.

Question 7

What happens to the sacromere as the power stroke occurs

Answer 7

pivoted myosin head connects to the actin and pulls actin towards the mid-line which makes the sacromere get smaller

Question 8

What happens when the stored energy of in myosin head is used up?

Answer 8

Energy from respiration is used to combine with ADP + Pi to create more ATP molecules

Question 9

How does myosin head detach.

Answer 9

temporal energy in myosin head used up so will detach to bind to the new ATP molecule to start the process again.

• process repeated 1000s of times every second to make sarcomere contract & retract: so long as there are calcium ions present in the sacroplasm.