Chapter 6 The Muscular System

Question 1

Characteristics of skeletal muscle

Answer 1

Skeletal muscle is a type of striated muscle, which usually attaches to tendons. Skeletal muscles are used to create movement, by applying force to bones and joints; via contraction. They generally contract voluntarily (via somatic nerve stimulation), although they can contract involuntarily through reflexes. The whole muscle is wrapped in a special type of connective tissue, epimysium.”

Question 2

Characteristics of smooth muscle

Answer 2

No striations
Spindle shaped cell
One nucleus, uninucleate
Involuntary
Walls of hollow organs like the stomach and intestinal walls

Question 3

Describe the microscopic structure of skeletal muscle

Answer 3

There is a blood vessel, perimysium, perimysium, muscle fiber, fascicle, endomysium, tendon, bone

Question 4

What is actin

Answer 4

Major component of thin filaments, part of the contractile apparatus in muscle cells.

Question 5

What is myosin

Answer 5

ATP dependent motor proteins

Question 6

What are the events of muscle contraction?

Answer 6

1 brain generates action potential down motor neuron

2 AP reaches the end of neuron to release acetylcholine from axon terminal

3 acetylcholine crosses the synaptic cleft and binds to receptor of sarcolemma

4 channels in sarcolemma open and sodium enters muscles where action potential is generated

5 action potential moves along the sarcolemma Into t tubules

6 sarcoplasmjc reticulum releases calcium

7 calcium binds to troponin

8 troponin changes shape, causing tropomyosin to slide

9 myosin binding sites on actin are uncovered

10 myosin binds to actin

11 myosin pulls on actin from the energy of ATP, causing them to slide over each other many times, sacrilege shortens and muscle contracts

Relaxation
12 ap stops, acetylcholine destroyed, calcium back in sarcoplasmic reticulum
13 tropomyosin covers binding sites on actin
14 myosin releases hold on actin
15 actin and myosin slide apart and the muscle relaxes

Question 7

3 events of muscle contraction

Answer 7

1 direct phosphorylation: muscle cells contain creating phosphate, cp. transfers it’s phosphate to adp producing ATP
2 aerobic respiration, oxidative phosphorylation, occurs in mitochondria, glucose broken down to carbon dioxide, releases energy to be used to attach phosphate to adp producing 36 ATP/ glucose
3 anaerobic respiration
Glucose broken down, lactic acid stored in liver, no oxygen

Question 8

Describe muscle fatigue and soreness

Answer 8

Results from lack of ATP and buildup of lactic acid, oxygen must be supplied to remove lactic acid from the liver. This oxygen that is repaid is called oxygen debt.