Topic 6 Muscle Contraction

Question 1

What is the order of the bands?
[In muscle contraction]

Answer 1

I A I
I band A band I band

Question 2

What colour are the bands?

Answer 2

Dark-a=A bands.
Light-I=I bands.

Question 3

What is in the middle of I bands?

Answer 3

Z line which is sarcomere

Question 4

What is the middle of A band?

Answer 4

H Zone.

Question 5

What filaments are present in A band?

Answer 5

In A band there is Actin and Myosin.
So thick and thin filaments together.

Question 6

What type of filament is present in I band?

Answer 6

I band has thin filaments only so only actin.

Question 7

What are the names of the thin and thick filaments?

Answer 7

Thin filaments are Actin.
Thick filaments are Myosin.

Question 8

What protein in present in Actin Filament?

Answer 8

Tropomyosin

Question 9

What binding site is in each Myosin head?

Answer 9

Each Myosin head has a binding site for Actin and binding site for ATP

Question 10

What is the sliding filament Hypothesis?

Answer 10

Thick and thin filaments do not change length.
A bands remain constant (A bands same length)
I bands decrease
Z line move together so sarcomere gets shorter

Question 11

What is the first thing that occurs in Sliding filament theory?

Answer 11

Action potential arrives at muscle fibre depolarising the Sacrolemma by T-Tubles causing release of Ca2+ from Sacrolemma Reticulm.

Question 12

What do Ca2+ ions do in Muscle contraction?

Answer 12

Ca2+ bind to tropomyosin which cause to expose myosin head binding site on the actin filament

Question 13

When Myosin head binds to the binding site on the Actin Filament what is formed?

Answer 13

Actin-Myosin cross bridge formed upon myosin and actin attachment this causes myosin to rotate to centre of Sacrolemma causing power stroke.

Question 14

What causes Myosin head to detach and what does this do?

Answer 14

ATP is then hydrolysed by ATP hydrolase and causes myosin head to detach and reattach on further binding sites shorting sacromere causing muscle contraction.

Question 15

When impulse stops in sliding filament theory occurs?

Answer 15

When impulse stops Ca2+ actively transported back into Sacrolemma Reticulm this allows tropomyosin to block myosin head binding sites on Actin Filament

Question 16

Where is Slow twitch located?
Where is Fast twitch located?

Answer 16

Slow twitch located in calf muscle.
Fast twitch located in biceps.

Question 17

What is the structure of Slow Twitch and what its general properties?

Answer 17

The structure is High concentration of myoglobin- so many Mitochondria and rich blood supply.

General properties-contracts slowly and respires Aerobically for long period of time.

Question 18

What is the structure fast twitch?
What is its general properties?

Answer 18

The structure is thicker so more myosin and High storage of Glycogen.

General Properties is it contracts faster in short bursts.

Question 19

What type of filament is present in H zone?

Answer 19

In H zone there is only myosin