Histology - Muscle

Question 1

Name the 4 types of contractile cells

Answer 1

1. Muscle
2. Myoepithelial cells
3. Myofibroblasts
4. Pericytes

Question 2

Name the 3 types of muscle cells

Answer 2

1. Skeletal/voluntary
2. Cardiac
3. Smooth/involuntary

Question 3

What % of your body weight is made up of skeletal muscle

Answer 3

About 40%

Question 4

What is muscle tissue formed of

Answer 4

Muscle cells and associated connective tissue

Question 5

Describe what fibres are, and their size

Answer 5

1. They are long cylinders
2. 10-100 micrometres in diameter
3. 1,000-200,000 micrometres in length

Question 6

What is the longest muscle in the body

Answer 6

The saratoris muscle (within the thigh)

Question 7

Within the mesenchyme of the mesoderm, what do cells lose and what do they form

Answer 7

Lose their supporting cell membranes and form multinucleate myotubes

Question 8

What is a fascicle

Answer 8

These are the bundles that muscles are grouped into; muscle contains several

Question 9

What is the connective tissue that surrounds the muscle as a whole

Answer 9

Epiymysium

Question 10

What is the connective tissue that surrounds a single fascicle

Answer 10

Perimysium

Question 11

What are fascicles made up of and what connective tissue surrounds them

Answer 11

1. Muscle fibres

2. Endomysium

Question 12

What is each muscle fibre made up of

Answer 12

Myofibril which is composed of many sacromeres placed end-to-end

Question 13

What is the motor unit

Answer 13

The motor neuron and all of the muscle fibres that it innervates

Question 14

Describe the relationship between muscles fibres in the motor unit

Answer 14

The fewer the number of muscle fibres in a motor unit, the finer the control of movement

Question 15

What terminates at a neuromuscular junction and was released causing an initation

Answer 15

1. Motor axons terminate at a motor end-plate

2. Action potentials arriving, cause the release of acetylcholine, and initiate an action potential in the sacrolemma

Question 16

What surrounds each myofibril and, roughly, where does this happen

Answer 16

T-tubules; roughly at the A-I junction of each sacromere

Question 17

What is the sacroplasmic reticulum

Answer 17

A labyrinth of specialised smooth ER within each muscle cell

Question 18

Where are muscles attached to bone, using a tendon

Answer 18

The myotendinous junction

Question 19

What information do muscle spindles provide to muscles

Answer 19

The amount of stretch in the muscle and the amount of tension in the muscle

Question 20

What does cardiac muscle form

Answer 20

1. Part of the walls of the heart chambers

2. Origins of the great vessels

Question 21

How long are the cardiac muscle fibres

Answer 21

50-100 micrometres

Question 22

Where are satellite cells located

Answer 22

Pressed against the outer surface of the sacrolemma of the muscle cell, under the surrounding basal lamina

Question 23

What is the function of satellite cells

Answer 23

Following damage they become activated and proliferate to form new muscle fibres

Question 24

Why is smooth muscle considered ‘smooth’

Answer 24

It contains no visible striations

Question 25

Name 4 areas smooth muscle can be found

Answer 25

1. Gut
2. Respiratory tract
3. Uterus
4. Blood vessels

Question 26

Describe the rough size of smooth muscle fibres

Answer 26

About 5 micrometres in diameter and 20-500 micrometres in length

Question 27

What allows smooth muscle cells to contract

Answer 27

They contain many actin and myosin filaments