Structure And Function

Question 1

What is a myocyte?

Answer 1

A muscle fibre which which is a cell and makes up muscle.

Question 2

What’s is the function of the muscular system?

Answer 2

Movement -muscular contraction and moving the bones, joints and muscles.
Posture - stabilising joints and balance
Heat production via thermogenesis. Shivering by muscular contractions
Glycogen store
Movement of substances such as sphincters, blood vessels, skeletal system, movement of food.

Question 3

What does contractility mean?

Answer 3

The ability of muscles to contract or shorten

Question 4

What does excitability mean?

Answer 4

The ability to generate an electrical current through action potentials.

Question 5

What does extensibility mean?

Answer 5

Ability to stretch muscles without being damaged

Question 6

What is elasticity?

Answer 6

The ability for something to return to its original length and shape after extension.

Question 7

What are the three types of muscles?

Answer 7

Cardiac, smooth and skeletal

Question 8

What does striated mean?

Answer 8

Cell aligned in parallel bundles so stripes are visible with a microscope

Question 9

What does non striated mean?

Answer 9

Randomly arranged cell with no stripes visible.

Question 10

What is skeletal muscle?

Answer 10

Voluntary movement which are striated and multi nucleated. Can not do mitosis but develop by hypertrophy.

Question 11

What is cardiac muscle?

Answer 11

Involuntary heart muscle which is striated and single nucleus in the cells. It is intercalated discs - fibres that mean contraction can spread like a wave. More and larger mitochondria which mainly use aerobic respiration.

Question 12

What does auto-rhythmic mean?

Answer 12

Contractions without nervous stimulation

Question 13

What is smooth muscle?

Answer 13

Involuntary, form the walls of hollow organs and blood vessel. Single nucleus and non striated. Filaments attach to structures called dense bodies which are pulled closer when muscle shortens.

Question 14

How are myocytes formed?

Answer 14

Embryonic fusion of myoblasts so each muscle skeletal fibre has many nuclei.

Question 15

Hypertrophy

Answer 15

Enlargement of existing fibres

Question 16

Atrophy

Answer 16

Wasting of muscles

Question 17

Fascia

Answer 17

Connective tissue that organises muscle, secures it to skin and provides stability.

Question 18

What is the skeletal muscle hierarchy?

Answer 18

Muscle is made of muscle fibre bundles which is made of muscle fibre which is made up of myofibrils. Myofibrils are made of myofilaments.

Question 19

Sarcolemma

Answer 19

Plasma membrane of muscle cell

Question 20

Transverse tubules

Answer 20

Tubes extending from sarcolemma into muscle cell

Question 21

Sarcoplasm

Answer 21

Muscle cell cytoplasm

Question 22

Sarcoplasmic reticulum

Answer 22

Tubular network that circulates cytoplasm and store terminal cisterns

Question 23

Terminal cisterns

Answer 23

Store calcium and attach on the SR.

Question 24

Myoglobin

Answer 24

Red coloured oxygen binding proteins in sarcoplasm

Question 25

What are myofilaments?

Answer 25

Made up of actin (thin) and myosin (thick) which overlap to form sarcomeres. A bands - dark area where myofilaments over lap I bands - light area with only actin filaments.

Question 26

What is epismyosium?

Answer 26

Wrapped around entire muscle.

Question 27

What is perimyosium?

Answer 27

Surround groups or bundles of 10-100 muscle fibres forming fascicles

Question 28

What is endomyosium?

Answer 28

Thing sheath around individual muscles.

Question 29

Explain how a neuromuscular junctions works.

Answer 29

Action potential travels down the moron neuron. This causes Ca to be to enter the axon terminal. Ca causes ACh to be release by exocytosis. ACh diffuses across the synapse and binds to receptors on sarcolemma. ACh binds to sodium potassium pump receptors cause them to open. Na enter the muscle cell and k leave muscles cell cause end plate potential. When ACh is broken down by acetylcholinesterase this ends the end plate potential.

Question 30

Explain sliding filament theory

Answer 30

Action potential arrives as neuromuscular junctions. Action potential spreads along sarcolemma and t tubules. Muscle cell releases Ca from storage (SR reticulum). Ca and adenosine triphosohate (ATP) trigger myosin to bind to actin so filament slide over each other and this shortens the fibre.

Question 31

What are the thee ways muscle fibres make ATP?

Answer 31

Creatine phosphate, aerobic and anaerobic respiration

Question 32

What is creatine phosphate?

Answer 32

Store excess ATP as creatine phosphate. During muscle contraction ATP is used up so creatine phosphate is used to regenerate ATP to make contraction longer or more sustained

Question 33

Occupitofrontalis

Answer 33

Raises eyebrows

Question 34

What's is the function of orbicularis oculi?

Answer 34

Closes eyes

Question 35

What's the function of orbicularis pro?

Answer 35

Closes or pouts lips

Question 36

Masseter

Answer 36

Elevates and protrudes mandible/closes jaw for chewing

Question 37

What is the temporalis?

Answer 37

For chewing

Question 38

What is sternocleidomastoid?

Answer 38

Tilting your head and rotating your head

Question 39

What is trapezium?

Answer 39

Pulls head backward, elevates, retracts and depressed shoulders

Question 40

What is supraspinatus?

Answer 40

Initial abduction of shoulder

Question 41

What is psoas?

Answer 41

Hip flexor: pull thigh towards trunk.

Question 42

What is latissimus dorsi?

Answer 42

extends, adducts and medially/internally rotates arms.

Question 43

What is quadrates lumborum?

Answer 43

bending backwards and sideways

Question 44

What is erector spine?

Answer 44

extension of vertebral volume, keep spine upright

Question 45

Pectoralis major

Answer 45

draws arms forward, shoulder flexion and adduction, medial rotation

Question 46

rectus abdominis

Answer 46

vertebrae flexion: bending forward

Question 47

transverse abdominis

Answer 47

compresses abdominal organs

Question 48

internal and external obliques

Answer 48

rotation, bending sideways

Question 49

deltoid

Answer 49

flexion, abduction and extension of shoulder joint.

Question 50

bicep branchii

Answer 50

stabilizes shoulder joint, flexion and supination of forearm

Question 51

tricep branchii

Answer 51

arm adduction and extends elbow

Question 52

flexor carpi ulnaris

Answer 52

flexes the hand at the wrist joint

Question 53

extensor carpi radialis

Answer 53

extend the hand at the wrist joint

Question 54

gluteus maximum

Answer 54

external rotation, abduction and extension of the hip joint

Question 55

gluteus medius

Answer 55

abducts leg, stabilises pelvis

Question 56

hamstring

Answer 56

bend knee

Question 57

rectus femoris

Answer 57

flexes hip, extends knee

Question 58

thigh adductors

Answer 58

squeezes thighs together

Question 59

tibialis anterior

Answer 59

dorsiflexion and inversion of foot

Question 60

soleus

Answer 60

plantar flexion of food at ankle, stabilises ankle

Question 61

gastrocnemius

Answer 61

flexes leg at the knee, plantar flexion of food

Question 62

What are the two smooth muscle types?

Answer 62

visceral/single unit and multi unit.

Question 63

What is a visceral/single unit of smooth muscle?

Answer 63

lines vessels and hollow viscera, auto-rhythmic, one stimulus causes contraction of many fibres together as a single unit.

Question 64

What is a multi unit of smooth muscle?

Answer 64

in large arteries and airways, iris and ciliary body. Fibres are stimulated individually and operate independently.

Question 65

What are the properties of smooth muscle?

Answer 65

slower and longer contractions, shorten and stretch more than skeletal muscle