Physiology

Question 1

What is the largest tissue type in the body?

Answer 1

Muscle

Question 2

All muscle in the body is striated. True/False?

Answer 2

False

Smooth muscle is not striated

Question 3

Which division of the nervous system - autonomic or somatic - innervates skeletal muscle?

Answer 3

Somatic

Question 4

Skeletal muscle fibres are organised into motor units. What are motor units?

Answer 4

Motor neuron + all the muscle fibres innervated by that single motor neuron

Question 5

What determines the number of muscle fibres per motor unit?

Answer 5

The function of the muscle (whether it is concerned with powerful or precise movement)

Question 6

Give examples of muscles that have few muscle fibres per motor unit

Answer 6

External eye muscles
Muscles of facial expression
Intrinsic hand muscles

Question 7

What is contained within a muscle fibre?

Answer 7

Myofibrils and sarcomeres

Question 8

Skeletal muscle contraction is brought about by myogenic initiation. True/False?

Answer 8

False

Neurogenic (nerve stimulated first)

Question 9

Are there gap junctions between muscle fibres?

Answer 9

No

Question 10

Which substance is released in response to action potential generation + presence in the T-tubule of the muscle fibre?

Answer 10

Calcium

Question 11

What does calcium release by the sarcoplasmic reticulum cause?

Answer 11

Calcium binds to troponin, causing conformational change in tropomyosin complex to expose myosin-binding-site on actin to allow cross-bridge formation between actin and myosin

Question 12

List the 4 zones of a sarcomere

Answer 12

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

Question 13

What does the A-band consist of?

Answer 13

Myosin + portion of actin that overlaps with myosin

Question 14

Where is the H-zone?

Answer 14

Lighter area within A-band where actin doesn’t reach

Question 15

Where is the M-line?

Answer 15

Extends vertically down the middle of the A-band within the centre of the H-zone

Question 16

What does the I-band consist of?

Answer 16

Remaining portion of actin that is not part of the A-band

Question 17

What 2 primary factors determine gradation of skeletal muscle tension?

Answer 17

Number of muscle fibres contracting within the muscle

Tension developed by each muscle fibre

Question 18

What is meant by “motor unit recruitment”?

Answer 18

Stimulating numerous motor units to contract elicits stronger contraction

Question 19

Tetanic contractions of skeletal muscle are not possible. True/False?

Answer 19

False

Question 20

How is tetanic contraction of skeletal muscle brought about?

Answer 20

Generation of numerous action potentials one after the other amplify the contraction/skeletal muscle twitch

Question 21

When can maximum tetanic contraction of skeletal muscle be achieved?

Answer 21

At rest (optimal length of muscle at this point)

Question 22

Name the 2 main types of skeletal muscle contraction

Answer 22

Isotonic

Isometric

Question 23

What is isotonic skeletal muscle contraction used for?

Answer 23

Body movements

Moving objects

Question 24

Muscle length changes in isotonic skeletal muscle contraction. True/False?

Answer 24

True

Muscle tension remains constant

Question 25

What is isometric skeletal muscle contraction used for?

Answer 25

Maintaining fixed positions

Question 26

Muscle length changes in isometric skeletal muscle contraction. True/False?

Answer 26

False | Muscle length is constant to allow tension to develop

Question 27

Velocity of muscle length shortening increases/decreases with increasing load

Answer 27

Decreases

Question 28

What is the stretch reflex?

Answer 28

Negative feedback mechanism that resists passive change to muscle length by contracting the muscle

Question 29

Once a muscle is stretched, how does the stretch reflex elicit contraction?

Answer 29

Afferent fibres fire and synapse with alpha motor neurons which, when stimulated, contract the stretched muscle

Question 30

What are the special sensory receptors for the stretch reflex, that, when stretched, elicit the reflex?

Answer 30

Muscle spindles AKA intrafusal fibres

Question 31

What are extrafusal fibres?

Answer 31

Ordinary muscle fibres

Question 32

Is the activity of the myosin ATP-ase fast or slow in type I muscle fibre? What effect does this have on resistance to fatigue?

Answer 32

Slow activity of myosin ATP-ase | High resistance to fatigue

Question 33

Is the speed of the myosin ATP-ase fast or slow in type II muscle fibre?

Answer 33

Fast activity of myosin ATP-ase

Question 34

What is the difference between simple and compound synovial joints?

Answer 34

``` Simple = one pair of articular surfaces Compound = more than one pair of articular surfaces ```

Question 35

What is the fluid secreted by the synovial membrane in the joint capsule of synovial joints?

Answer 35

Synovial fluid

Question 36

What are the functions of synovial fluid?

Answer 36

Joint lubrication, reduce friction Minimise wear-and-tear Provides nutrition for chondrocytes

Question 37

What 3 main things provide joint lubrication?

Answer 37

Interstitial fluid Synovium-derived hyaluronic acid Synovium-derived lubricin

Question 38

How does rapid movement affect the properties of the synovial fluid?

Answer 38

Fluid becomes thinner and elasticity increases to aid movement

Question 39

Normal synovial fluid is milky in colour. True/False?

Answer 39

False | Normally it is colourless

Question 40

Inflammatory synovial fluid is thin, orange, translucent and has a high white blood cell count. True/False?

Answer 40

False | All correct apart from colour - inflammatory SF is yellow

Question 41

Which type of cartilage is usually articular cartilage?

Answer 41

Hyaline

Question 42

What is the extracellular matrix of hyaline cartilage made up of?

Answer 42

Water 70% Collagen 20% Proteoglycans 10%

Question 43

The collagenous component of hyaline cartilage is mainly type 2 collagen. True/False?

Answer 43

True

Question 44

Which cells synthesise, organise and degrade the extracellular matrix of hyaline cartilage?

Answer 44

Chondrocytes

Question 45

What catabolic factors influence hyaline cartilage ECM breakdown?

Answer 45

TNF-alpha IL-1 Stimulate proteolytic enzymes

Question 46

What anabolic factors influence hyaline cartilage ECM replacement?

Answer 46

TGF IGF Stimulate proteoglycan synthesis

Question 47

What markers indicate cartilage degradation?

Answer 47

Increased serum/synoval keratin sulphate | Increased type 2 collagen in synovial fluid