Muscle And Nerve

Question 1

What is muscle ?

Answer 1

It is a tissue specialised for contraction

Question 2

What are the functions of muscles ?

Answer 2

• force generation
• movement
• posture
• heat generation
• control of diameter of tubes
• heart beat

Question 3

What are the 2 types of muscle ?

Answer 3

• striated muscle
• smooth muscle

Question 4

What are the 2 types of striated muscle ?

Answer 4

• cardiac muscle
• skeletal muscle

Question 5

Where is smooth muscle found ?

Answer 5

It is widespread
Found in the viscera, blood vessels, skin and eye

Question 6

What is a fasicle ?

Answer 6

A bundle of muscle fibres

Question 7

What is endomysium ?

Answer 7

Connective tissue found around muscle fibres

Question 8

What is perimysium ?

Answer 8

Connective tissue which wraps around bundles of muscle fibres

Question 9

What is epimysium ?

Answer 9

Connective tissue which wraps around the whole muscle (around the perimysium)

Question 10

What are muscle fibres ?

Answer 10

They are very large and multinucleate cells
- may extend from 1 end of a muscle to the other

Question 11

What is the basal lamina ?

Answer 11

It is an extracellular matrix layer made by muscle fibres and it blends into the endomysium
All muscle cells are surrounded by a basal lamina

Question 12

What is a satellite cell ?

Answer 12

It is a muscle stem cell which is positioned against a muscle fibre membrane under the basal lamina

Question 13

Why is striated muscle striated ?

Answer 13

The contractile units are organised and in alignment with each other

Question 14

What is a sarcomere ?

Answer 14

It is a unit of contraction within a muscle fibre

Question 15

What is a myofibril ?

Answer 15

A collection of sarcomeres

Question 16

What happens when a muscle contracts ?

Answer 16

The sarcomere shortens and the actin filaments slide in between the myosin filaments

Question 17

What is the cytoplasm of a muscle cell known as ?

Answer 17

Sarcoplasm

Question 18

Describe the structure of the sarcoplasm

Answer 18

• contains many mitochondria
• contains a lot of glycogen
• contains myoglobin
• has a highly specialised endoplasmic reticulum
• contains many myofibrils

Question 19

What is a sarcoplasmic reticulum ?

Answer 19

A highly specialised endoplasmic reticulum

Question 20

What is a muscle plasma membrane known as ?

Answer 20

Sarcolemma

Question 21

Is cardiac muscle voluntary or involuntary ?

Answer 21

It is an involuntary muscle

Question 22

Describe the structure of cardiac muscle

Answer 22

• striated
• very different fibre structure from skeletal muscle
• branched fibres and the spaces are filled with connective tissue
• no epimysium or perimysium

Question 23

How do heart muscle fibres link together ?

Answer 23

The cells contain 1 or 2 centrally located nuclei and are linked end to end via intercalated discs

Question 24

Why can heart muscle not be repaired ?

Answer 24

Heart muscle doesn’t contain any satellite cells and so damaged heart muscle dies and is replaced with scarred connective tissue

Question 25

Describe the structure of smooth muscle

Answer 25

- long and thin spindle shaped fibres - fibres are linked by desmosomes, adherens junctions and gap junctions - not striated because the myofibrils are not parallel and in alignment

Question 26

Describe the innervation of smooth muscle

Answer 26

- most smooth muscle is poorly innervated - contractile signals spread from cell to cell via gap junctions

Question 27

How is smooth muscle repaired ?

Answer 27

Smooth muscle cells can divide and enlarge allowing generation of new smooth muscle so it can be repaired

Question 28

What is a peripheral nerve ?

Answer 28

Carries large numbers of axons

Question 29

Describe the structure of peripheral nerves

Answer 29

- structurally similar to skeletal muscle - epineurium, perineurium and endoneurium protects the nerve fibres

Question 30

What is epineurium made from ?

Answer 30

Collagen and fat

Question 31

What is perineurium made from ?

Answer 31

Dense collagenous layer

Question 32

Describe the properties of endoneurium

Answer 32

It is delicate and highly vascular

Question 33

What is the function of the smooth muscle in the small intestine ?

Answer 33

Allows for peristalsis so the gut contents can be moved along

Question 34

What are the general features of the skeletal muscle connective tissues ?

Answer 34

- allows for voluntary movement - harness for muscle contraction force - allows blood vessels and nerves in and out of the muscle at all levels

Question 35

What is the major difference in the cellular organisation of heart muscle and skeletal muscle fibres ?

Answer 35

- in heart muscle, the individual muscle fibres are linked end to end - in skeletal muscle, there is a fusion of thousands of cells to make multinucleate fibres

Question 36

What is the function of the connective tissue in a peripheral nerve ?

Answer 36

Protects the nerve and is also important in nerve regeneration