Skeletal and smooth muscle

Question 1

What is the name os a muscle cell membrnae?

Answer 1

Sarcolemma

Question 2

What is the name of a muscle cell cytoplasm?

Answer 2

Sarcoplasm

Question 3

Where are skeletal muscle fibres attached to?

Answer 3

Directly to bones - the periosteum

Question 4

What happens to the origin and insertion during contraction?

Answer 4

Origin remains stationary

Insertion is attached to a bone and moved

Question 5

Muscle fibres contain a lot of what?

Answer 5

Mitochondria

Question 6

What 2 structures make up myofibrils?

Answer 6

Myosin (thick filament) and actin (thin filament)

Question 7

What is the sliding filament theory?

Answer 7

Muscle contraction occurs when thick and thin filaments slide over each other

Question 8

What needs to happen to calcium levels for muscles to relax?

Answer 8

the conc of Ca2+ needs to return to basal levels. This is achieved by active pumping of calcium into the SR and out of cells through the sarcolemma.

Question 9

Where are calcium ions stored and released from?

Answer 9

Sarcoplasmic reticulum

Question 10

What causes a muscle twitch?

Answer 10

Single stimulus contraction-relaxation sequence in a muscle fibre

Question 11

What does an isotonic contraction cause?

Answer 11

Limb movement

Question 12

What does the force of contraction depend on?

Answer 12

Number of cross-bridges

Question 13

During muscle contraction, what is ATP required for?

Answer 13

Myosin ATPase and for calcium pumps

Question 14

What is a high energy store unique to skeletal muscle?

Answer 14

Creatine

Question 15

What is oxygen debt?

Answer 15

Amount of oxygen payment required after exercise in skeletal muscle to:

• replenish ATP stores
• Replenish creatine phosphate and myoglobin stores
• convert lactate back into pyruvate

Question 16

Does myoglobin have a greater or lesser affinity for oxygen than haemoglobin?

Answer 16

Greater (shift to the left0

Question 17

Why does the pH of skeletal muscle decreases during intense exercise?

Answer 17

Because pyruvate production also produces H+

Question 18

Where is smooth muscle found in the body?

Answer 18

• GI tract (peristalsis)
• Uterus
• Bladder
• Eye
• Blood vessels

Question 19

Compare smooth muscle structure to skeletal muscle

Answer 19

• similar amount of actin, less myosin
• Maximum contractile force similar to skeletal muscle
• Uses less energy than skeletal muscle to generate and maintain a given amount of force
• no neuromuscular junction
• no t-tubules
• no troponin
• less well-developed SR
• no sarcomeres

Question 20

What allows direct communication between smooth muscle cells?

Answer 20

Gap junctions

Question 21

Why does smooth muscle contract and relax much more slowly than cardiac and skeletal muscle?

Answer 21

Due to relative slow changes in sarcoplasmic [Ca]

Question 22

What are the roles of smooth muscle in vessels?

Answer 22

• changes resistance to flow
• changes blood pressure
• changes perfusion