Week 9: Muscle & Nerve 1

Question 1

Q1. Short Answer
Define afferent and efferent pathways in the nervous system.

Answer 1

A:

Afferent pathways carry sensory information toward the central nervous system (CNS).

Efferent pathways carry motor commands away from the CNS to muscles and glands​.

Question 2

Q2. Multiple Choice
Which part of the nervous system is responsible for voluntary control of skeletal muscles?
A) Autonomic nervous system
B) Parasympathetic nervous system
C) Somatic nervous system
D) Enteric nervous system

Answer 2

✅ Answer: C) Somatic nervous system​.

Question 3

Q3. Short Answer
Name two glial cells involved in myelination and state where they are located.

Answer 3

A:

Oligodendrocytes: Myelinate axons in the central nervous system.

Schwann cells: Myelinate axons in the peripheral nervous system​​.

Question 4

Q4. Short Answer
What are the three main phases of an action potential?

Answer 4

A:

Depolarization (membrane potential becomes more positive)

Repolarization (membrane potential returns toward resting)

Hyperpolarization (temporary overshoot, more negative than resting)​​.

Question 5

Q5. True/False
Action potentials can vary in size depending on the strength of the stimulus.

Answer 5

❌ Answer: False.
Action potentials are all-or-none; stimulus strength is encoded by frequency, not size​.

Question 6

Q6. Short Answer
What happens if myelin is lost in neurons?

Answer 6

A:

Signal transmission becomes slower or fails completely.

Diseases like multiple sclerosis show these effects​​.

Question 7

Q7. Short Answer
What neurotransmitter is used at all neuromuscular junctions with skeletal muscles?

Answer 7

A:
✅ Acetylcholine (ACh)​​.

Question 8

Q8. Application Question
How does myasthenia gravis affect the neuromuscular junction?

Answer 8

A:

It is an autoimmune disease causing loss of acetylcholine receptors.

Leads to muscle weakness and potential paralysis​​.

Question 9

Q9. Short Answer
Describe what happens at the neuromuscular junction during skeletal muscle activation.

Answer 9

A:

ACh is released by the motor neuron → binds to receptors on the muscle fibre → sodium influx → depolarization → action potential in muscle → contraction​​.

Question 10

Q10. Short Answer
What proteins are primarily responsible for skeletal muscle contraction?

Answer 10

A:

Actin (thin filament)

Myosin (thick filament; motor protein)​.

Question 11

Q11. Short Answer
What is a motor unit?

Answer 11

A:

A single alpha motor neuron and all the muscle fibres it innervates​​.

Question 12

Q12. Short Answer
What happens if a larger motor unit is recruited during contraction?

Answer 12

A:

A greater force is produced

Question 13

Q13. Short Answer
What are the two major proprioceptors and what do they detect?

Answer 13

A:

Muscle spindle: Detects stretch of muscle​.

Golgi tendon organ: Detects tension/force in tendons​.

Question 14

Q14. Short Answer
Explain the muscle spindle stretch reflex.

Answer 14

A:

Stretch of muscle → activation of Ia afferents → excitation of motor neurons to the same muscle (causing contraction) and inhibition of antagonist muscle​.

Question 15

Q15. Short Answer
Explain the Golgi tendon reflex.

Answer 15

A:

Tension increases → activation of Ib afferents → inhibition of the contracting muscle and activation of antagonist muscle → prevents damage from excessive force​.

Question 16

Q16. Fill-in-the-Blank
________ movements are involuntary, coordinated patterns elicited by peripheral stimuli.

Answer 16

✅ Answer: Reflexive​.

Question 17

Q17. Multiple Choice
Which movement type involves spontaneous or triggered rhythmic patterns like chewing or walking?
A) Reflexive
B) Rhythmic
C) Voluntary
D) Forced

Answer 17

✅ Answer: B) Rhythmic​.

Question 18

Q18. Short Answer
What are voluntary movements and how do they improve?

Answer 18

A:

Goal-directed actions initiated consciously.

Improve through practice, feed-forward, and feedback mechanisms