Introduction to the nervous system

Question 1

how is the nervous system divided

Answer 1

CNS - brain and spinal chord

PNS - peripheral

Question 2

how is the peripheral nervous system split

Answer 2

sensory division - input eg sensors on nerve endings detect acidity
motor division - effector side

Question 3

describe the somatic PNS

Answer 3

controls motor and sensory function for the body wall

eg skin - sensory and skeletal muscle - motor neurons

Question 4

Describe the autonomic nervous system

Answer 4

visceral PNS, vegetative PNS and invol PNS
no conscious control
regulates function of viscera: smooth muscle, internal organs, sweating, blood vessels, bladder, intestine, glands, and controls heart contraction rate

Question 5

what is the sympathetic nervous system

Answer 5

fight/flight
increase heart rate
decrease digestion
spinal nerves only

Question 6

what is the parasympathetic nervous system

Answer 6

rest and digest 
controlled by cranial nerve 
more discrete anatomy than sympathetic
decrease heart rate 
increase digestion 
spinal nerves and cranial nerves

Question 7

what do the sympathetic and parasympathetic nervous systems make up

Answer 7

the autonomic nervous system

Question 8

what is the sensory division

Answer 8

afferent = arrive at CNS

signals from periphery to brain

Question 9

what is the motor division

Answer 9

efferent = exit CNS

CNS to periphery

Question 10

use an example to describe afferent and efferent

Answer 10

body knows what Bp is by sensory endings in aorta, baroreceptors recognise beat to beat pressure
send afferent signal to brain stem
through hypothalmus
change vascular tone - diameter of bv by efferent motor response

Question 11

describe the features of the gross anatomy of the brain

Answer 11

frontal - personality and conscious decision, front of brain, runs to the central gyrus
parietal - sensory for somatic, somatosensory cortex
occipital - visual cortex, back of brain
temporal - one each side, fear and anxiety - amygdala, primary auditory cortex,
cerebellum - little brain, fine motor skills like writing

Question 12

describe the features of the brain

Answer 12

cortex highly folded - increase SA to pack in neurons and process all info
gyrus - folds on top
brainstem - in charge of breathing, feeding, heart rate and Bp
corpus collosum - fibre allow communication between hemispheres

Question 13

what are the cranial nerves

Answer 13

there are 12 - originate from brain itself 
olfactory - smell
optic - sight - signal to back of 
oculomotor - move eyes
trochlear 
trigeminal 
abducens 
facial 
vestibulocochlear 
glossopharyngeal 
vagus - full of sensory and motor, efferent and afferent signal from stomach to vein, stomach stress signals - to brain show full, involved in heart rate 
Accessory 
hypoglossal

Question 14

what are the meninges

Answer 14

thick coverings that coat the outside of the brain

Question 15

describe the parts of the meninges

Answer 15

dura mater (inner and outer layer) - very strong, BV between layers - protects the brain
arachnoid
subarchnoid space
pia mater

Question 16

common head injury in meninges

Answer 16

subdural haemotoma - pool of blood between dura and arachnoid
increase intercranial pressure

Question 17

describe the spinal chord

Answer 17

grey matter - cell bodies of neurons - processing
white matter - axons of cells - fibres into brain and periphery
anterior (ventral) horn - spinal cord - body, efferent
posterior (dorsal) horn - into CNS, afferent
dorsal root and dorsal route ganglia - afferent, peripheral
dorsal root ganglia - cell bodies are

Question 18

describe a nerve cell

Answer 18

soma vary in size
dendrite pick up signals from other neurons
myelin sheath - speed up transmission of signals
length vary eg sciatic neuron reach from lower spinal chord to toes

Question 19

describe axons packing into nerves

Answer 19

nerves have afferent and efferent axons
bundled into fascicles surrounded by perineurium
whole nerve in epineurium capsule (tough)
axons wrapped in myelin and endoneurium - not all in myelin eg pain neurons
interjected with bv

Question 20

describe the action potential

Answer 20

baseline V -70mV 
Na channel open 
depolarisation 
\+40mV 
V gated K channel - out 
repolarisation

Question 21

describe synaptic transmission

Answer 21

distance 10nm - need chemicals

neurotransmitter bind to post synamptic neuron receptors

Question 22

how can we see nerve cells now

Answer 22

brainbow
transgenic mice
label neural cells with different colours

Question 23

what are the different brain cells and their functions

Answer 23

glia = 50% brain cells
microglia - immune cells - migrate to site of injury
oligodendrocytes and shwann cells (PNS) produce myelin
astrocytes - star, mop up neurotransmitter, form blood brain barrier - wrap around bv, sense chemicals in blood and shuttle to synapse

Question 24

describe regeneration of the nervous system

Answer 24

PNS - can regenerate partially - phagocytes stimulated - remove debris that would inhibit growth. non-specific - won’t get full recovery and can cause pain
CNS - won’t regenerate, glia inhibit regenerative force, scars form, there is an absence of guidance cues that stimulate axon growth

Question 25

describe the dorsal column-medial lemniscus pathway (sensory perception)

Answer 25

sensory organ detect signal
switches sides in the brain stem - contralateral
thalamus receives a lot of inputs and sends them to the right place
signal goes to primary somatosensory cortex
conveys fine touch, vibration and two-point discrimination

Question 26

describe the spinothalamic pathway (sensory perception)

Answer 26

signal enters spinal cord and immediately switches side

conveys pain and temperature sensation

Question 27

describe the lateral corticospinal tract (motor pathway)

Answer 27

from brain
in brain stem signal switch to the other side
down brain stem - ipsilateral ie down same side

Question 28

describe the vestibulospinal tract (motor pathway)

Answer 28

input from vestibular system - ear, not dizzy, know orientation
all ipsilateral - want ear to move same direction as body