Physiology

Question 1

define a motor unit

Answer 1

single alpha motor neurone and all the skeletal muscle fibres it innervates

Question 2

which part of the nervous system are muscles controlled by?

Answer 2

somatic nervous system

Question 3

what is secreted across the NMJ

Answer 3

ACh

Question 4

how does an AP initiate a muscle contraction?

Answer 4

AP spreads down T-tubules which are close to lateral sacs of SR which contain Ca2+
Ca2+ binds to troponin on actin leading to movement of tropomyosin to uncover an actin binding site which myosin forms cross bridges with

Question 5

how can muscle twitches be summated?

Answer 5

AP is shorter than the twitch

Question 6

what happens if there is no opportunity for the muscle to relax?

Answer 6

tetanus is produced

Question 7

two types of movement

Answer 7

isotonic (movement)

isometric (posture)

Question 8

metabolic pathways for ATP used by muscles

Answer 8

creatine phosphate
oxidative phosphorylation
glycolysis

Question 9

three types of muscle fibre

Answer 9

1. slow oxidative type 1 (aerobic)
2. fast oxidative type IIa (moderate)
3. fast glycolytic type IIb (anaerobic)

Question 10

what do slow oxidative fibres have a lot of?

Answer 10

mitochondria and myoglobin so are resistant to fatigue

Question 11

define a reflex

Answer 11

stereotyped response to a specific stimulus

Question 12

describe the monosynaptic spinal reflex

Answer 12

• muscle spindle (sensory receptor) activated by stretch causes firing in afferent neurones
• gamma motor neurones adjust tension in muscle spindle
• synapse at spinal cord with alpha-motor neurones

Question 13

3 types of joints

Answer 13

1. fibrous (synarthrosis)
2. cartilaginous (amphiarthrosis)
3. synovial (diarthrosis)

Question 14

describe fibrous joint

Answer 14

bones are united by fibrous tissue causing no movement

Question 15

example of fibrous joint

Answer 15

in the skull

Question 16

describe cartilaginous joint

Answer 16

bones united by cartilage causing limited movement

Question 17

example of cartilaginous joint

Answer 17

primary= physis
secondary= vertebrae

Question 18

describe a synovial joint

Answer 18

bones are separated by cavity containing synovial fluid and united by fibrous capsule with synovial membrane

Question 19

what are bones covered with in synovial joints

Answer 19

hyaline

Question 20

role of synovial fluid

Answer 20

lubricates joint

supplies chondrocytes with nutrients while removing waste

Question 21

what makes synovial fluid

Answer 21

synovial membrane which contains vasculature, lymphatics and fibroblasts

Question 22

role of articular cartilage

Answer 22

low friction

distributes pressure to subchondral bone

Question 23

what is articular cartilage ECM made up of?

Answer 23

water
collagen (type II)
proteoglycans (GAGs)

Question 24

is cartilage avascular?

Answer 24

yes

Question 25

markers of cartilage degradation

Answer 25

serum keratin sulphate

type II collagen