Lecture 12

Question 1

What is sarcolemma?

Answer 1

Plasma lipid bilayer, controls wat enters and exits the cell

Question 2

What is T-tubules?

Answer 2

plasma membrane with fold in or out tunnel that goes from one side of the cell to the other.

Question 3

What is Calcium important for contraction?

Answer 3

Actin = has other components (troponin and tropomyosin)

Calcium is released from SR and binds to the troponin which is the active site. When it binds calcium causes the shape of tropomyosin to change. Therefore exposes the binding site.

Myosin head binds to the binding site.
Myosin head come up and attach onto the actin then flex
and the sarcomeres drawn inwards, the heads detach and sent and go up and attach again.

Question 4

Muscle fibre activation and contraction

Answer 4

?

Question 5

What is the sliding filament theory?

Answer 5

During muscle shortening thin filaments draw towards each other over thick filaments. Z lines become closer together.
Microfilament does not change length the degree of overlap does.

Question 6

What is a motor unit?

Answer 6

Motor neuron, axon ,braches

all muscle it innervates

Question 7

What are the characteristics of a motor unit?

Answer 7

Size = more skeletal muscle fibres the greater the force of contractions

Number = recruit small motor units then get bigger

Rate of firing = higher ROF the higher the force

Question 8

What are the anatomical levers?

Answer 8

Bones = Levers
Joint = Pivot or Fulcrum
Muscle contraction = Pull
Load = External or Internal

Question 9

Types of levers within muscles attachments

Answer 9

First:
> stabilise joint position

Second:
> effective at overcoming loads

Third:
> large range of movement and speed

Question 10

Types of muscle action

Answer 10

Concentric
> muscle is active, develops tension
> change in joint position
> shortening of muscle

Isometric
> muscle is active, develops tension
> no change in joint position
> no change in length of muscle

Eccentric
> muscle is active, develops tension
> change in joint position
> lengthening of muscle

Question 11

Types of muscle role

Answer 11

Agonist
> muscle that creates the desired movement
> agonist act concentrically, muscle is contracting, tension is developed and the muscle is shortening

Antagonist
> muscle on the other side of the joint, oppose the desired movement
> antagonists act eccentrically, muscle is lengthening

Stabiliser
> when a muscle is active to hold a joint still
> e.g. holding a heavy book
biceps brachii role - stabiliser
biceps brachii action - isometric
no change in length of biceps Brach

Neutraliser
> muscle eliminates an unwanted movement caused by another muscle.
> e.g. biceps brachii
pronator muscles neutralise supinating effect of biceps brachii