Skeletal muscle as a target for nervous system control

Question 1

What is the transmitter at the neuromuscular junction (NMJ)?

Answer 1

Acetylcholine

Acetylcholine is crucial for transmitting signals at the NMJ.

Question 2

Name the components of the postsynaptic membrane at the NMJ.

Answer 2

• Closed K+ channel
• Open Na+ channel
• ACh-containing synaptic vesicle
• Na+
• Ca2+
• Synaptic cleft
• K+
• Action potential
• Wave of depolarization
• Graded local potential

These components are essential for the generation of action potentials in muscle cells.

Question 3

List the structural components of muscle anatomy.

Answer 3

• Epimysium
• Tendon
• Perimysium wrapping a fascicle
• Endomysium
• Muscle fibre

These structures contribute to the organization and function of muscle tissue.

Question 4

Define the term ‘sarcolemma’.

Answer 4

The membrane surrounding a muscle fiber

The sarcolemma plays a critical role in muscle contraction and action potential propagation.

Question 5

What does the term ‘Excitation-Contraction Coupling’ refer to?

Answer 5

The process by which a signal arrives at the contractile machinery

This involves the interaction between T tubules and the sarcoplasmic reticulum.

Question 6

Identify the components of the triad in muscle fibers.

Answer 6

• Sarcolemma
• T tubule
• Terminal cisternae

The triad is crucial for the release of calcium ions during muscle contraction.

Question 7

List the structural components of a sarcomere.

Answer 7

• Sarcomere
• I band
• A band
• Z disc
• H zone
• M line

These components are fundamental to the contraction mechanism of muscle fibers.

Question 8

Describe the state of a fully relaxed sarcomere.

Answer 8

• M-line
• Titin
• Myosin
• Actin
• Z-line (disk)

This configuration is essential for understanding muscle contraction dynamics.

Question 9

What happens during rigor mortis?

Answer 9

• ATP synthesis stops
• SR calcium pumps stop
• Actin/troponin complex activated
• No ATP for cross-bridge detachment
• Muscle stiffens

Rigor mortis typically develops 3-12 hours post-mortem and can only be reversed by enzymatic breakdown of proteins.

Question 10

What are the five components of a reflex arc?

Answer 10

• Stimulus
• Receptor
• Sensory neuron
• Integration center (Interneuron)
• Motor neuron
• Effector

Understanding these components is crucial for studying reflex actions.

Question 11

True or False: The withdrawal reflex requires conscious input.

Answer 11

False

The withdrawal reflex operates automatically without the need for conscious thought.

Question 12

What is the role of gamma motor neurons in muscle reflexes?

Answer 12

Innervate intrafusal fibers linked to alpha motor neuron activity

This is essential for muscle spindle function and reflex actions.

Question 13

Fill in the blank: The tendon reflex is also known as the _______.

Answer 13

Inverse Myotatic Reflex

This reflex helps regulate muscle tension.

Question 14

What are some contributing factors to sarcopenia?

Answer 14

• Myosin production
• Mitochondrial malfunction
• Motor axon atrophy
• Atrophy of muscle fibers

Sarcopenia is associated with aging and leads to muscle loss.

Question 15

What does the term ‘frequency coding’ refer to in motor unit functionality?

Answer 15

The process of recruiting motor units with larger and larger cells to improve smoothness of motor actions

This is key for coordinated muscle movements.