Peripheral Nervous System Flashcards Preview

Neuromuscular Section > Peripheral Nervous System > Flashcards

Flashcards in Peripheral Nervous System Deck (30)
Loading flashcards...
1

What is the PNS?

Peripheral nervous system contains nerves that originate in the brain and spinal cord but end peripherally.

Consists of motor, sensory, and autonomic neurons that innervate end-organs That include sensory receptors, muscles, and glands

2

T or F: The PNS consists 8 cranial nerves and 20 pairs of spinal nerves and all associated with ganglia and sensory receptors

False: the PNS consists of 12 cranial nerves and 31 pairs of spinal nerves and all associate with ganglia and sensory receptors

3

Where do sensory nervers originate?

Dorsal root ganglia

4

where do motor nerves originate?

Anterior horn of the spinal cord

5

What is the autonomic system divided into?

Sympathetic and parasympathetic nerves.

6

Where do the sympathetic nerves originate ?

Lateral horn of the thoracic spinal cord

7

Where do the parasympathetic nerves originate?

From the lateral gray matter of the sacral level of the spinal cord and from the brain stem itself

8

How are peripheral nerves typically classified?

By axon diameter and speed of conduction

9

List teh Sensory End-organ Receptors.

1. Thermoreceptors

2. Nociceptors

3. Mechanoreceptors: Merkel’s disc, Ruffini’s corpuscle, Pacinian corpuscle, muscle spindle, free nerve endings, Golgi tendon organ (GTO)

4. Chemoreceptors

5. Photoreceptors

10

Axon

Projection of a nerve AWAY from the cell body that conducts impulses

11

Dendrite

An extension of the cell body that receives signals from other neurons

12

Endoneurium

Innermost covering of a peripheral nerve that surrounds each individual axon

13

Epineurium

Outermost covering of a peripheral nerve that surrounds the entire nerve and provides a buffer for the peripheral nerve

14

Motor unit

Single motor neuron and all of the muscle fibers that it innervates

15

Myelin

Proteins and lipids that form to crate a sheath around particular nerves; increases conductivity of the nerve impulse

16

Nerve conduction velocity

Measures the speed of a nerve impulse along the axon of a nerve

17

Neurons

Nerve cells that receive and send signals to other cells; comprised of a cell body, acon, and dendrites

18

Nodes of Ranvier

Brief gaps in myelination of an axon; serves to facilitate rapid conduction of a nerve impulse via jumping from gap node to gap node

19

Perineurium

Middle layer of covering surrounding hte peripheral nerve that envelopes fascicles or groups of axons and maintains the blood-nerve barrier

20

Saltatory conduction

An action potential moving along an axon in a jumping fashion from node to node; decreases the use of sodium potassium pumps and increases the speed of conduction

21

Schwann cell

Cells that cover the nerve fibers within the peripheral nervous system and fore the myelin sheath

22

Describe A Fibers.

- Large fibers

- Myelinated

- High conduction rate

23

What are the types of A Fibers?

Alpha

Beta

Gamma

Delta subsets

24

Describe an Alpha fiber.

(A fiber)

Alpha motor neurons, muscle spinal primary endings, GTOs, touch

25

Describe a Beta fiber.

( A fiber)

Touch, kinesthesia, muscles spindle secondary endings

26

Describe a gamma fiber

(A fiber)

Touch, pressure, gamma motor neurons

27

Describe a delta fiber.

(A fiber)

Pain, touch, pressure temperature

28

The sensory components of an A fiber include?

1. Muscle spinal (primary afferent endings): primary for low-threshold stretch

2. Muscle spinal (secondary afferent endings): receptors that respond to changes in length

3. Golgi Tendon organ: responds to tension/stretch of a tendon

29

Describe B fibers.

- Medium fibers

- Myelinated

- Reasonably fast conduction

- preganglionic fibers of the autonomic nervous system

30

Describe C Fibers.

- Small fibers

-poorly Myelinated or unmyelinated

-slowed conduction rate

-postganglionic fibers of the sympathetic system

-exteroreceptors for pain, temperature, and touch