Structure of a Sarcomere

Question 1

Types of muscle contractions

Answer 1

Concentric - muscle shortens
eccentric - muscle lengthens
isometric - muscle doesnt change length

Question 2

Structure of a sarcomere

Answer 2

The length of a muscle changes when myofibril length changes
myofibril is the smallest unit of a skeletal muscle that can contract
Each myofibril comprises many sarcomeres joined end to end
When a muscle contracts the fibres attach and grow closer and when they relax they let go and drift apart

Question 3

Sarcomere diagram

Answer 3

see onenote (Functional anatomy) 2 and 3

Question 4

What a sarcomere contains

Answer 4

Actin
Myosin
Z-line
Cross bridges
H-zone
I band
A band

Question 5

Sarcomere

Answer 5

Comprises the unit between the two Z lines and makes up the functional unit of a muscle fibre.

Question 6

Actin

Answer 6

is the thin protein filament that is attached to the z line
Cross bridges on the myosin attaches to the actin when stimulated with calcium

Question 7

Myosin

Answer 7

The thick filament contains cross bridges
The myosin cross bridges attach to the actin when stimulated with calcium

Question 8

Z-line

Answer 8

Is found at either end of the sarcomere
They come closer together when contracting and further apart when relaxing

Question 9

Cross bridges

Answer 9

Tiny projections from myosin filaments that attach temporarily to actin filaments, which pulls the actin towards the midline. This makes the H-zone disappear
(THESE ARE THE OARS THAT PUSH ACTIN AND MYOSIN TOGETHER)

Question 10

H-zone

Answer 10

Space between actin filaments
This gets longer or shorter as the sarcomere changes in length

Question 11

I band

Answer 11

The light band that contains the thin actin filament
(WHERE THE SARCOMERES CROSS OVER)

Question 12

A band

Answer 12

It contains both thick and thin filaments and is the centre of the sarcomere that spans the H-zone
(IS BETWEEN THE EDGES OF THE MYOSIN IN THE MIDDLE)