The peripheral nervous system

Question 1

Peripheral NS
General overview

Answer 1

-co ordinates transmission of impulses to and from CNS
-consists of 31 pairs spinal nerves, 12 cranial nerves, ANS

Question 2

Function neurones

Answer 2

-control muscular activity
-regulate glands
-support and protect NS

Question 3

Which way does the nerve impulse flow

Answer 3

dendrites to axon

Question 4

Schwann cells

Answer 4

-produce and secrete neurilemma
-this forms outer layer of myelin sheath

Question 5

Boutons

Answer 5

-small end bulbs at axon terminals

Question 6

Acetylcholine

Answer 6

-released mainly from outside brain/ spinal cord
-used in parasympathetic NS, to slow things down

Question 7

Adrenaline and noradrenaline

Answer 7

-found in brain and some neuro-muscular junctions
-leads to excitation

Question 8

Transmitters that lead to excitation

Answer 8

Serotonin- stabilizes mood, wellbeing, sleep
Dopamine- pleasure hormone
Histamine- contraction of smooth muscle tissues in lungs, uterus, stomach; dilation of blood vessels

Question 9

How fast do impulses travel via Na/ K pump

Answer 9

130m per second

Question 10

What can alter synaptic conduction

Answer 10

Alkalosis- pH 7.8 can cause cerebral convulsions
Acidosis- pH 6.5 depresses neural activity causing coma

Question 11

Afferent-
Efferent-

Answer 11

-sensory nerve fibres
-motor nerve fibres

Question 12

Efferent neurones

Answer 12

Divided into:
Somatic- voluntary
Autonomic- involuntary
-convey info from CNS to voluntary muscles and involuntary glands
-usually multipolar neuron

Question 13

Afferent neurones

Answer 13

-sensory
-usually unipolar
-convey info from receptors in periphery eg. skin to the CNS or connector neurone in reflex arc

Question 14

Spinal nerves

Answer 14

-31 pairs of spinal nerves
(from top to bottom)
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal
-extend from medulla oblongata to lower border of 1st lumbar vertebra

Question 15

5 things reflexes require

Answer 15

-receptor
-sensory neurone
-associated neurone/ relay
-motor neurone
-effector

Question 16

Reflexes-

Answer 16

-specific responses to a sensory stimulus with no conscious control

Question 17

Types of reflexes

Answer 17

-Spinal- sensory impulse for quick action
-Cortical- overrides spinal reflex under conscious control eg. when somethings hot but you don’t want to drop it and break it
-Coordinating- modifies movement and coordinates
-Autonomic- immediate reaction to situation, overrules conscious decision

Question 18

ANS

Answer 18

-involuntary
-controls the functions of the body carried out automatically
-initiated in the brain below the level of the cerebrum
-effects are mainly glandular secretions and contraction of cardiac/ smooth muscle
-sympathetic= fight or flight, adrenaline
-parasympathetic= rest and digest, acetylcholine

Question 19

Nociception

Answer 19

perception or sensation of pain

Question 20

Transduction of pain

Answer 20

-begins when free nerve ending (nociceptors) of afferent neurones respond to a noxious stimuli
-due to tissue damage
-causes inflammation

Question 21

Transmission of pain
3 stages

Answer 21

-site of transduction along nociceptor fibres to the dorsal horn in spinal cord
-from spinal cord to brain stem
-through connections between thalamus, cortex and higher levels of brain

Question 22

Responses to pain

Answer 22

Reticular system
-autonomic and motor response to pain, affective-motivational response
Somatosensory cortex
-perception and interpretation of sensations, identifies intensity, location of pain, identifies nature of stimulus before triggering response
Limbic system
-emotional and behavioural response to pain
-attention, mood, motivation

Question 23

Modulation of pain

Answer 23

Analgesics
-relieve pain without loss of consciousness
-block pathway that transmit pain to brain
Anaesthetics
-depress CNS
-cause absence of perception of sensory modalities including loss of consciousness