Review

Question 1

Primary function of muscle is to:

Answer 1

Generate force or movement in response to a physiological stimulus

• body movement
• maintenence of posture
• Respiration
• production of body heat
• communication
• constriction of organs and vessels (smooth muscle mostly)
• Heart beat (cardiac muscle)

Question 2

Functional properties of muscle

Answer 2

Contractility:
-ability to shorten with a force
Excitability
-capacity of muscle to respond to stimulus
Extensibility
-muscles can be stretched to its normal resting length and beyond to a limited degree
Elasticity
-ability of muscle to recoil to its original resting length.

Question 3

Skeletal muscle

Answer 3

40% of total body weight
15-60% of daily expenditure
Generate heat and contribute to homeostasis of temperature control (shivering)
Commonly attached to bones by tendons
When focused around a joint, muscles usually occur in antagonist pair:
-flexor brings bones closer together
-extensor moves bones away from one another

Question 4

Skeletal muscle:

Parts of the sarcomere

Answer 4

Myosin- thick filament
Actin- thin filament
A-band: area of actin and myosin
H-band: just myosin
I-band: just actin
z-discs: attachment site of actin

Question 5

Initiation of skeletal muscle contraction

Answer 5

• A single motor neuron and all the muscle fibres it innervates is known as a motor unit.
• The area where the motor neuron makes synaptic contact with the muscle fibre is known as the neuromuscular junction

Question 6

Alpha-motor neuron and motor units

Answer 6

Large, myelinated axon, 15-120m/sec
Each axon branches and innervates muscle fibers (cells)
All muscle fibers/ motor unit varies
- < 10 for delicate precise work
- >100 for powerful, less precise contractions
Determine contractile / metabolic properties of muscle cells) depending on the movement, fine movements will have less muscle fibres innervated

Question 7

Action potential

Answer 7

1. An action potential reverses the charge across the membrane
2. the action potential is a stimulus that causes the productions of another action potential in the adjacent plasma membrane.
3. the action potential propagates along the plasma membrane.

-an all or none charge i