6.9 Muscles - The Structure and Function of Muscle Tissue

Question 1

What are the functions of muscle?

Answer 1

• Motion
• Stability
• Organ volume regulation
• Soft tissue support
• Temperature maintenance
• Nutrient Storage

(MSNOTS)

Question 2

What is the name given to the type of control that enables the heart to contract as one coordinated unit?

Answer 2

Autorhythmic

Question 3

Does the heart need nervous innervation to function?

Answer 3

No; the sinoatrial node acts as the pacemaker, generating action potentials

Question 4

Which type of muscle is striated/not striated?

Answer 4

Striated: Cardiac, skeletal
Non-Striated: Smooth

Question 5

Describe the arrangement of smooth muscle nuclei

Answer 5

Single, centralised

Question 6

What are the two kinds of smooth muscle?

Answer 6

• Visceral (single-unit)
• Multi-unit

Question 7

Describe the defining characteristics of visceral smooth muscle

Answer 7

• Multiple muscle cells form one unit
• Gap junctions allow unison contraction

Question 8

Where can visceral smooth muscle be found?

Answer 8

Blood vessels, hollow organs

Question 9

Describe the defining characteristics of multiunit smooth muscle

Answer 9

• Each muscle has own nerve ending
• Contract independently

Question 10

Where can multiunit smooth muscle be found?

Answer 10

• Airways
• Arrector pili

Question 11

Can cardiomyocytes regenerate if injured (e.g. ischaemia)?

Answer 11

No. They heal via fibrosis (scarring; loss of function)

Question 12

Can smooth muscle cells regenerate? Can they grow in size and number?

Answer 12

Yes and yes (e.g. uterus thickening)

Question 13

What is the name of the junction between a bone and a skeletal muscle?

Answer 13

Tendinous-periosteal junction

Question 14

What are the types of fibres that give skeletal muscle its striated appearance?

Answer 14

Actin and myosin

Question 15

Are skeletal muscle cells uninucleated or multinucleated

Answer 15

Multinucleated

Question 16

Which type of nervous system innervates skeletal muscles?

Answer 16

Somatic; conscious control

Question 17

Describe the formation of skeletal muscle cells

Answer 17

Formed from 100s of embyronic myoblasts (stem cells) fusing to form one cell

Question 18

What are unfused myoblasts known as?

Answer 18

Satellite cells

Question 19

Can skeletal muscle cells divide/be replaced?

Answer 19

Divide: No
Replaced: Yes, by satellite cells (stem cells)

Question 20

What is a muscle cell membrane called?

Answer 20

Sarcolemma

Question 21

What is muscle cell cytoplasm called?

Answer 21

Sarcoplasm

Question 22

What are five things that are located in sarcoplasm?

Answer 22

• Mitochondria
• Glycogen
• Myoglobin
• Transverse (T) Tubules
• Sacroplasmic Reticulum

Question 23

List, from inside to outside, layers and connective tissue of muscle. Then draw a diagram

Answer 23

• Endomysium
• Fascicle
• Perimuysium
• Muscle
• Epimysium
• Tendons

Question 24

How many motor neurons innervate a single muscle fibre?

Answer 24

1

Question 25

Which of actin and myosin filaments are thick and thin?

Answer 25

Thick: Myosin
Thin: Actin

Question 26

How do myofibrils fit into the order of muscle organisation?

Answer 26

There are hundreds of myofibrils in the sarcoplasm of a single muscle cell

Question 27

What is the name of contractile units of muscle?

Answer 27

Sarcomeres