Chapter 8 - Flashcards Preview

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Flashcards in Chapter 8 - Deck (21)
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1
Q

How do muscles contract?

A

A nerve must stimulate skeletal muscle or it will not contract. CNS - Motor nueron - Muscle

2
Q

What does a neuron do?

A

It transmits electrical signals from the CNS to the muscle

3
Q

What is a motor unit?

A

The motor neuron and all of the muscle fibers it innervates

4
Q

How does the size of a motor unit change for fine movements versus gross movements?

A

Neuromuscular junction - the site where the motor neuron and muscle cell meet.
Synaptic Cleft - Space between the end of the motor neuron and muscle fiber.
Motor end plate - “the pocket” formed on the sarcolemma at the neuromuscular junction.

5
Q

How do nerves initiate the signal to begin muscular contractions?

A

Stimulation from motor neutrons initiates contraction process

6
Q

What is the charge of cells?

A

Cells are positively charged on the outside and negatively charged on the inside

7
Q

Why does sodium stay outside of the cell?

A

Proteins within the membrane close the gates.

8
Q

What is the resting membrane potential?

A

-70 mV

9
Q

What is the resting membrane potential ?

A

At rest all cells are negatively

10
Q

How do nerves initiate the signal to begin muscular contractions?

A

Stimulation from motor neurons initiates contraction process.

11
Q

At rest, cells are positively charged on the outside and negatively charged on the inside. Why does sodium stay outside of the cell?

A

Proteins within the membrane close the gates

12
Q

What is the resting membrane potential?

A

At rest cells are negatively charged, the cell is polarized and the charge difference is called the resting membrane potential.

13
Q

When a stimulus of sufficient strength reaches the neuron, sodium gates open and sodium enters the cell.

A

This makes the cell more positive

14
Q

When is threshold reached and what happens when threshold is reached?

A

Sodium gates open and action potential (nerve impulse) is formed and transmitted.

15
Q

Explain “all or none” principle

A

A muscle cell contracts normally or not at all

16
Q

What happens when the nerve and muscle meet?

A

The muscle and nerve come together at the neuromuscular junction but the nerve does not actually touch the nerve: there is a gap between them

17
Q

What is the name given to the space between the nerve and muscle?

A

Synaptic Cleft

18
Q

What is the motor end plate?

A

The end of a motor neuron that transmits neural impulses to a muscle.

19
Q

What are the small sacks called at the end of the motor nerve?

A

Synaptic Vesicles

20
Q

What is in the synaptic vesicles?

A

Acetylcholine

21
Q

What are the 7 steps that happen when an action potential arrives at the neuromuscular junction?

A
  1. When an action potential arrives at the neuromuscular junction, it causes the release of calcium
  2. The calcium triggers the synaptic vesicles to release acetylcholine into the synaptic cleft
  3. The acetylcholine binds to receptors on the sarcolemma.
  4. This results in the opening of sodium channels
  5. Na+ enter the cell, it depolarizes, and an action potential occurs.
  6. The wave of depolarization spreads across the sarcolemma in all directions and deep into the muscle in the transverse tubules.
  7. This causes calcium to be released from the sarcoplasmic reticulum.