Muscular System

Question 1

What does the muscular system consist of?

Answer 1

Muscular System consists of the named skeletal muscles, as well as smooth muscle and cardiac muscle.

Question 2

What are two functions of the muscular system include?

Answer 2

1. Facilitate movement and posture (with the skeletal system)
2. Generates heat – this helps maintain a constant body temperature which then contributes greatly to homeostasis.

Question 3

What are the three types of muscle tissue?

Answer 3

Skeletal, Cardiac and Smooth

Question 4

What does skeletal muscle look like?

Answer 4

Skeletal muscle is striated, it has long thin multinucleated fibres.

Question 5

What does smooth muscle look like?

Answer 5

Smooth muscle has no stripes or striations when looking at it under a microscope.

It consists of narrow spindle shaped cells with single nuclei.

Question 6

What does cardiac muscle look like?

Answer 6

The cardiac muscle contains sarcomeres – similar to skeletal muscle.

Question 7

What is the function of skeletal muscle?

Answer 7

Skeletal muscle enables the body to produce movement.

It is also involved in resisting movement or posture

Question 8

What is the functional unit of skeletal muscle?

Answer 8

The sarcomere

Question 9

At each end of the sarcomere where it connects to the next sarcomere there are lines called what?

Answer 9

Z-disks/Z-lines

Question 10

The sarcomere is composed of thin filament containing what?

Answer 10

The thin filament contains actin and the troponin-tropomyosin complex

Question 11

The sarcomere contain thick filament made of what?

Answer 11

Myosin

Question 12

What happens when sarcomere contracts?

Answer 12

The muscle contracts

Question 13

During a muscle action potential what gates open during the depolarisation phase?

Answer 13

Na+ (Sodium)

Question 14

During a muscle action potential what gates open during the repolarisation phase?

Answer 14

K+ (Potassium)

Question 15

What does filament interaction lead to?

Answer 15

Muscle contraction

Question 16

When does the sliding occur as described by the sliding filament model?

Answer 16

The sliding can only occur when the myosin binding sites on the actin are exposed.

Question 17

What do we need for muscle contraction?

Answer 17

ATP (energy)

Question 18

When is ATP not present?

Answer 18

Rigor mortis

Question 19

What is the force generated by contraction of skeletal muscle involving the shortening of sarcomeres called?

Answer 19

Tension

Question 20

What are the two main types of skeletal muscle contraction called?

Answer 20

1. Isotonic

2. Isometric

Question 21

Describe Isotonic Contractions

Answer 21

o When the tension in the muscle stays constant and a load is moved as the length of the muscle changes

Question 22

What are the two types of isotonic contraction?

Answer 22

Concentric (muscle shortening) and eccentric (muscle lengthening).

Question 23

Describe isometric contractions

Answer 23

Muscle produces tension without changing the angle of the joint, or when the load does not move.

Question 24

What is the motor unit?

Answer 24

The motor unit is the motor neuron and all the muscle fibres that it innervates.

Question 25

Describe fast twitch muscle fibres.

Answer 25

Rapid energy generation for quick powerful actions.

Less fatigue resistant – fatigue quickly but produce energy quickly for powerful actions.

Question 26

Describe slow twitch muscle fibres.

Answer 26

Large numerous mitochondria for greater reliance on oxidative metabolism.

Highly fatigue resistant – don’t produce energy as quickly but don’t tire so quickly.

Question 27

Where is cardiac muscle found?

Answer 27

The heart

Question 28

How are cardiac muscle fibres connected?

Answer 28

The cardiac muscle fibres are extensively branched, and they’re connected by and intercalated discs.

Question 29

What are gap junctions?

Cardiac

Answer 29

Gap junctions are the channels between the fibres that allows the current to flow from one cell to another. This allows the heart to function as a muscle pump.

Question 30

What are desmosomes?

Cardiac

Answer 30

Desmosomes are sealed structures that anchor the ends of the fibres to one another so that when contraction occurs, the cells don’t pull away from one another

Question 31

What are varicosities?

Smooth

Answer 31

A series of neurotransmitter filled bulges

Question 32

Where does the varicosity release a neurotransmitter to?

Smooth

Answer 32

The synaptic cleft.

Question 33

What causes smooth muscle fibre to contract?

Answer 33

The dense bodies and intermediate filaments that are networked through the sarcoplasm

Question 34

Where does muscle tissue arise from?

Answer 34

Embryonic mesoderm

Question 35

What are satellite cells?

Answer 35

• Satellite cells are muscle stem cells that help to repair skeletal muscle cells. They are also involved with muscle growth

Question 36

What are satellite cells required for?

Answer 36

The regeneration of skeletal muscle.

Question 37

Where are satellite cells located?

Answer 37

o They are located underneath the basal lamina of the myofibre.

Question 38

When are satellite cells activated?

Answer 38

Muscle damage/muscle growth

Question 39

What are the three stages of regeneration for skeletal muscle?

Answer 39

1. Inflammatory phase.
2. Satellite cell activation/differentiation phase.
3. Maturation phase (remodelling of newly formed myofibers).

Question 40

What does the term ‘Insertion’ mean?

Answer 40

Insertion refers to the moveable end of the muscle that attaches to the bone

Question 41

What does the term ‘origin’ mean?

Answer 41

Origin refers to the end of the muscle attached to a fixed (stabilised) bone.

Question 42

What does the term ‘prime mover (agonist)’ mean?

Answer 42

Prime mover refers to the principal muscle involved in the action.

Question 43

What does the term Antagonist mean?

Answer 43

Antagonist refers to muscle with the opposite action of the prime mover (agonist)