Chapter 15- Muscle structure and physiology (1)

Question 1

What is a muscle?

Answer 1

a soft tissue composed of myocytes which contracts to produce force and motion.

Question 2

Muscle is responsible for many tasks including:

Answer 2

1- Posture

2- Generating heat

3- Movement

4- Regulating sight and hearing

Question 3

Is the skeletal muscle voluntary or involuntary?

Answer 3

Voluntary (somatic)

Question 4

Is the cardiac muscle voluntary or involuntary?

Answer 4

Involuntary (autonomic)

Question 5

Is the smooth muscle voluntary or involuntary?

Answer 5

Involuntary (autonomic)

Question 6

What does the myocyte contain?

Answer 6

1- A myocyte has a membrane called the sarcolemma

2- Contains a cytoskeleton which is densely packed with myofilaments of actin, myosin and titin.

3- A cytoplasm called the sarcoplasm which is rich in mitochondria

4- Has mitochondria called a sarcosome

5- Has a smooth endoplasmic reticulum which is called the sarcoplasmic reticulum which is full of calcium.

Question 7

Skeletal muscle is composed of what 4 tissues:

Answer 7

1- Muscle tissue
2- Connective tissue
3- Blood vessels
4- Nerve tissue

Question 8

What is a fascicle?

Answer 8

Bundles composed of many densely packed myocytes in the skeletal muscle.

Question 9

Why are myocytes known as fibres?

Answer 9

Because they are elongated in one direction.

Question 10

What tissue includes tendons that attach muscle to bone?

Answer 10

Connective tissue

Question 11

Another form of connective tissue are 3 types of sheaths which compartmentalise the muscle and transport blood:

Answer 11

1- Epimysium wraps the muscle as a whole

2- Perimysium wraps each fascicle

3- Endomysium extends between individual myocytes

Question 12

Muscle metabolism requires what?

Answer 12

A plentiful supply of oxygen and glucose

Question 13

Is muscle tissue highly vascularised?

Answer 13

Yes. There is lots of blood vessels to get the blood in and carry the waste back out.

Question 14

Each skeletal muscle is innervated by what?

Answer 14

A single motor axon

Question 15

What is a myocyte generally made up of?

Answer 15

Multiple myofibrils

Question 16

What is a myofibril generally made up of?

Answer 16

Myofilaments

Question 17

What are myofilaments?

Answer 17

Strands of proteins involved in muscle contraction

Question 18

What are the three types of proteins in myofilaments?

Answer 18

1- Myosin- made up of large proteins that make up thick myofilaments

2- Actin- Smaller proteins that make up thin myofilaments

3- Titin- elastic proteins

Question 19

What is the general structure of myosin?

Answer 19

Myosin is an elongated protein molecule composed of a heavy tail and 2 light heads.

The junction of the heads and tail acts as a hinge.

Question 20

An actin filament is made up of 3 components:

Answer 20

1- A helix of two strands of globular actin

2- Thin rod like tropomyosin molecules in a helix

3- Troponin at regular intervals along tropomyosin and is attracted to calcium ions

Question 21

Elastic filaments are composed of what?

Answer 21

Titin- a long, stripy protein

Question 22

What do elastic filaments aid in?

Answer 22

It aids in preventing overstretching of the thick filament.