Chapter 15- Muscle structure and physiology (2)

Question 1

What are sarcomeres?

Answer 1

Groups of myosin, actin and elastic myofilaments within the myocyte arranged together.

Question 2

What is found at the end of each sarcomere?

Answer 2

A connective tissue called a Z disc.

Question 3

What is attached to the Z disc?

Answer 3

Thin actin filaments

Question 4

What interlocks between the actin filaments?

Answer 4

Myosin filaments anchored to the z disc by titin.

Question 5

What is the I band?

Answer 5

The region containing thin actin filaments.

It appears light

Question 6

What is the A band?

Answer 6

The area of overlapping actin and thicker myosin.

It appears dark

Question 7

What is the H zone?

Answer 7

The region of myosin only

Question 8

Why does a myofibril appear striped?

Answer 8

Because it consists of a repeating series of sarcomeres, arranged end to end in a line.

Question 9

What is found at the end of the sarcoplasmic reticulum?

Answer 9

A cisterna- a membranous sac filled with calcium.

Question 10

What is the transverse tubular system?

Answer 10

This is a continuation of the sarcolemma.

This system is crucial for excitation contraction coupling.

Question 11

FUNCTION OF SKELETAL MUSCLE IN DOC

Answer 11

FUNCTION OF SKELETAL MUSCLE IN DOC

Question 12

Fast twitch muscles contract…

Answer 12

quickly for rapid/brief motion.

Question 13

Slow twitch muscles contract…

Answer 13

slowly and are usually active for prolonged periods of time.

Question 14

Why do slow twitch muscles have many mitochondria and myoglobin?

Answer 14

Because these muscles are active for prolonged periods of time so uses a lot of energy, thus, have many mitochondria and myoglobin which stores oxygen

Question 15

Myoglobin gives muscle what colour?

Answer 15

A red colour

Question 16

What muscles are involved in maintaining posture and what muscle fibres do they contain?

Answer 16

Your soleus muscle in your lower leg and muscles in your back

Question 17

Why do fast twitch muscles have a large sarcoplasmic reticulum?

Answer 17

For rapid release and uptake of calcium.

Question 18

Why are fast twitch muscles less vascularised?

Answer 18

Because they rely on anaerobic respiration.

Question 19

Little myoglobin results in the fast twitch muscles being what colour?

Answer 19

White colour

Question 20

The extraocular muscles that move your eyes are made up what?

Answer 20

Fast twitch muscle fibres.

Question 21

The size of muscle contraction is controlled in two ways:

Answer 21

1- Spatial summation

2- Temporal summation

Question 22

How many motor neurons does a single muscle have and what does it come along with?

Answer 22

Each muscle has at least one motor neuron with a variable number of axon terminals.

Question 23

What does each axon terminal form?

Answer 23

Each axon terminal forms a neuromuscular junction with a single muscle fibre.

Question 24

What does a motor unit consist of?

Answer 24

A motor unit consists of one motor neuron and all the muscle fibres it innervates- to supply with nerves

Question 25

When a motor neuron transmits an action potential, what happens to the all the muscle fibres it innervates?

Answer 25

They contract