Muscle Structure And Function

Question 1

A muscle is a…

Answer 1

Group of specialised, elastic tissues.

Question 2

Muscle is made up from…

Answer 2

Water (75%), Proteins (20%), Fats (5%), Mineral Salts, and Glycogen

Question 3

Muscle is the most abundant body tissue in the body. True or false?

Answer 3

True

Question 4

Describe the structure of muscle tissue.

Answer 4

Muscle tissue bound together in bundles and contained in a sheath (fascia or epimysium), ends extend to form a tendon.

Question 5

What is the main function of a muscle?

Answer 5

To contract and start movement in surrounding structures (tendon, ligaments, bones).

Question 6

How does muscle tissue know to contract?

Answer 6

Contracts in reaction to a nerve stimulus sent by brain through motor nerve. Muscle shortens and becomes fatter at centre.

Question 7

What are the functions of muscle?

Answer 7

1. Contract to produce movement
2. Stabilise joints
3. Maintain postural tone
4. Aid in temperature control

Question 8

What are the three types of muscle tissue?

Answer 8

1. Skeletal
2. Smooth
3. Cardiac

Question 9

What is the function of Skeletal muscle?

Answer 9

Muscles that we consciously control to start movement.

Question 10

What is the structure of Skeletal muscle?

Answer 10

Cylindrical cells that make up fibres.
Multinucleate cells surrounded by a sheath (sacrolemma)
Striated (actin and myosin protein filaments).

Question 11

What is the sliding filament theory?

Answer 11

Muscle contraction = actin filament slides between myosin filament, which shortens and thickens fibres.

Question 12

What is the function of Smooth muscle?

Answer 12

Unconscious control found in the walls of blood and lymph capillaries, in respiratory, digestive, and genito-urinary systems.

Question 13

What is the structure of Smooth muscle?

Answer 13

Spindle-shaped cells with no distinct membrane, one nucleus.

Question 14

What is the function of Cardiac muscle?

Answer 14

Power the pump action of the heart

Question 15

What is the structure of Cardiac muscle?

Answer 15

Involuntary muscle tissue, striated muscle fibres, each cell has one nucleus.

Question 16

What is the smallest Skeletal muscle in the body?

Answer 16

Stapedius (middle ear) - sends vibrations from ear drum to inner ear

Question 17

What is the largest muscle in the body?

Answer 17

Latissimus Dorsi: flat back muscle that covers the central and lower back.

Question 18

What is the strongest muscle of the body?

Answer 18

Gluteus Maximus (main buttock) - lifts the torso after bending down or leaning over.

Question 19

What are the two forms of muscle contraction?

Answer 19

Isotonic & Isometric

Question 20

Isometric contraction is…

Answer 20

Muscle contraction where the length stays the same while tension increases.

E.g., holding a glass of water still in front of you.

Question 21

Isotonic muscle contraction is…

Answer 21

Muscle contraction where the length changes whilst the tension remains constant.

E.g., lifting a glass of water to mouth and lowering it back onto the table.

Question 22

What happens during contraction?

Answer 22

Fibres become shorter and thicker and the parts attached to the fibres (periosteum, bone, tendon, fascia) are pulled and move.

Question 23

What is the ‘all or nothing’ law?

Answer 23

When a muscle fibre contracts it contracts completely or not at all.

Question 24

The greater number of fibres that contract … =

Answer 24

Greater force produced

Question 25

How does movement happen?

Answer 25

Muscle passes over a joint to create movement. Muscle contraction pulls one bone towards another, moving the limb.

Question 26

Muscles usually work in pairs called:

Answer 26

Agonist (contracting muscle) and opposing Antagonist (relaxing muscle)

Question 27

How do nerve stimuli cause muscle contraction?

Answer 27

Motor nerves enter muscle and break into many nerve endings, each one stimulating muscle fibres.

Question 28

Where does a muscle get energy from?

Answer 28

Muscles receive nutrients and oxygen from arterial capillaries.

Question 29

What is the waste product produced during muscle contraction?

Answer 29

Lactic acid

Question 30

How is the waste products of muscle contraction removed?

Answer 30

Lactic acid is excreted into the venous blood system.

Question 31

What are the factors that affect the ability of a muscle to contract?

Answer 31

1. Energy availability 2. Strength of stimulus from nerve 3. Time muscle has been contracting 4. Adequate blood supply 5. Strength of inhibitory nerve supply 6. Temperature of muscle 7. Presence of waste products

Question 32

What does the state of contraction ‘tone’ mean?

Answer 32

Slight degree of contraction. Always will be some muscle fibres contracting to give normal body posture.

Question 33

What problems can occur with over-contraction?

Answer 33

Muscle tension & muscle fatigue

Question 34

Muscle tension is…

Answer 34

Over-stimulation of muscle fibres. More fibres contract than necessary to maintain postural tone.

Question 35

Muscle fatigue occurs when…

Answer 35

A muscle continues to contract without enough rest, muscle runs out of oxygen and lactic acid builds up.

Question 36

What is the ‘origin’ of a muscle?

Answer 36

Fixed end of a muscle. End that barely moves during muscle action.

Question 37

What is the ‘insertion’ of a muscle?

Answer 37

Moving end of a muscle. Muscle always works from insertion towards the origin.

Question 38

What is the ‘attachment’ of muscles?

Answer 38

At the origin or insertion attach to bone via tendons to produce movement of joints.

Question 39

What is the ‘belly’ of a muscle?

Answer 39

Thickest part or main body of muscle. Usually middle part.

Question 40

What is a tendon?

Answer 40

White fibrous cords with no elasticity that connect muscle to bone.

Question 41

What is fascia?

Answer 41

White fibrous connective tissue, found all over the body.

Question 42

What is the function of ‘superficial fascia’?

Answer 42

Facilitates the movement of the skin, medium for passage of nerves and blood vessels, helps retain body warmth, connects skin with deep fascia.

Question 43

What is ‘deep’ fascia?

Answer 43

Dense, inelastic, stiff membrane that forms a sheath for muscles and broad surfaces for attachment: