Physiology

Question 1

Name the 3 types of muscle in the body

Answer 1

Skeletal
Cardiac
Smooth

Question 2

Which of the 3 types of muscle lack striation?

Answer 2

Smooth muscle

Question 3

Which of the 3 types of muscles are under voluntary control?

Answer 3

Skeletal muscle

Somatic NS innervation

Question 4

What is a skeletal muscle motor unit?

Answer 4

One alpha motor neurone

+ all the skeletal muscle fibres it innervates

Question 5

How does the number of muscle fibres within a motor unit affect overall function?

Answer 5

Greater number = more power but less precision

Fewer number = finer control but less power

Question 6

In skeletal muscles, where does Ca come from to initiate contraction?

Answer 6

ENTIRELY from sarcoplasmic reticulum

Question 7

Where must action potential spread before Ca can be released by the SR?

Answer 7

Down transverse T tubules

Released from lateral sacs of SR

Question 8

What are the 4 sarcomere zones?

Answer 8

A-band
H-zone
M-line
I-band

Question 9

Which ion is required for cross-bridge formation during muscle contraction?

Answer 9

Ca++

Question 10

How does Ca cause cross-bridge formation?

Answer 10

Binds to troponin

Question 11

What is the transmitter of impulses at the neuromuscular junction?

Answer 11

Acetylcholine

Question 12

What is ATP used for in muscle contraction?

Answer 12

Power cross bridges

Question 13

What is ATP used for in muscle relaxation?

Answer 13

Release cross bridges

Pump Ca back into the SR

Question 14

How does the duration of action potential in skeletal muscles relate to that of the resulting twitch?

Answer 14

AP is much shorter than the twitch

- allows summation for stronger contraction

Question 15

What is tetanus of a skeletal muscle?

Answer 15

Maximal sustained contraction

Question 16

How is a muscle tetanised?

Answer 16

Rapid action potentials to muscle fibres do not allow opportunity for relaxation, so summation occurs to its highest (constant) level

Question 17

Is tetanus possible in cardiac muscle?

Answer 17

No

- long refractory period prevents constant/summative twitches

Question 18

When might you get maximal tetanic contraction?

Answer 18

When muscle is at its optimal length before contraction

- for skeletal muscle, this is its resting length

Question 19

What are the 2 types of skeletal muscle contraction?

Answer 19

Isotonic

Isometric

Question 20

What is isotonic contraction?

Answer 20

Tension in muscle remains constant but its length changes

e.g. during movement

Question 21

What is isometric contraction?

Answer 21

Muscle tension develops at a constant muscle length

e.g. maintaining posture, holding objects

Question 22

How is muscle tension transmitted to bone?

Answer 22

Via elastic components of the muscle

Question 23

What is the relationship between velocity of muscle shortening and its load?

Answer 23

Inverse

• max vel. at zero load
• zero vel. at max load (isometric contraction)

Question 24

Describe the stretch reflex

Answer 24

Negative feedback

Resists passive change in muscle length to maintain its optimal length

Question 25

What are the sensory receptors of the stretch reflex?

Answer 25

Muscle spindle - aka intrafusal fibres - collection of specialised muscle fibres

Question 26

What are annulospiral fibres?

Answer 26

Sensory nerve endings of muscle spindles

Question 27

What are the efferent neurones that supply muscle spindles?

Answer 27

Gamma motor neurones | - sense that the muscle has been stretched beyond optimum length

Question 28

Name 3 metabolic sources of ATP to the muscle fibre

Answer 28

Transfer of phosphate from creatine phosphate to ADP Oxidative phosphorylation Glycolysis

Question 29

What are the 3 types of muscle fibres?

Answer 29

Type I - SLOW oxidative Type IIa - Intermediate Type IIx - FAST glycolytic

Question 30

Which activities are Type I muscle fibres more suited for?

Answer 30

- slow twitch - for prolonged, low intensity, aerobic work e. g. walking, maintaining posture

Question 31

Which activities are Type IIa muscle fibres more suited for?

Answer 31

- use both aerobic and anaerobic metabolism - for prolonged mod. intensity work e. g. jogging

Question 32

Which activities are Type IIx muscle fibres more suited for?

Answer 32

- fast twitch - anaerobic metabolism - for short-term high intensity activities e.g. jumping

Question 33

Which 3 investigations can be used to detect neuromuscular disease?

Answer 33

Electromyography (EMG) Nerve conduction studies Muscle enzyme checks e.g CK

Question 34

Name 3 types of joints. Examples?

Answer 34

Synovial e.g. knee Fibrous e.g. between skull bones Cartilaginous e.g. between vertebrae

Question 35

What is the synovial membrane?

Answer 35

Vascular connective tissue with lymphatics | - contains fibroblasts which produce the fluid

Question 36

What are the 2 types of synovial joints?

Answer 36

Simple: one pair of articular surfaces Compound: more than one pair

Question 37

Name 3 extra-articular structures of the synovial joint which contributes to support

Answer 37

Ligaments Tendons Bursae

Question 38

Give features of synovial fluid

Answer 38

High viscocity because of mucin Clear and transparent Replenished and absorbed by cells of the synovial membrane