nervous system Flashcards
AP transmission across synapse
AP arrives
axon terminal depolarised causing Na channels to open
causes Ca channels to open and Ca influx
releases acetylcholine into cleft
interacts with Na channels on post SN membrane
Na channels open and move in (depolarised)
causes voltage heated Ca open and in
causes increase Ca from SR
AP stops
golgi tendon organs
senses tension
has an inhibitive afferent neurone
large forces generated, feedback from it activates muscle to decrease
muscle spindle
encapsulated muscle fibres positioned parallel to normal muscle fibres
sense change in length
afferent wraps around it
efferent causes it to contract to maintain tension in middle
4 types of neurone
anaxonic
bipolar
unipolar
multipolar
anaxonic neurone
in brain and special senses
very small
no anatomical features distinguish dendrites from axon
bipolar neurone
2 processes
1 dendrite
1 axon with cell body between
rare
in special senses
unipolar neurone
dendrites and axon continuous
cell body off to one side
most sensory PNS neurones
multipolar neurone
2+ dendrites
1 axon
most common CNS
all motor neurones controlling skeletal muscle
what is the spinal cord
passage for sensory and motor impulses
integrates info on its own and controls reflexes and automatic motor responses
spinal cord structure
grey matter = unmyelinated neurones
31 segments with pair of dorsal root ganglia (contains cell bodies of sensory neurones)
ventral roots in spinal cord
contain axons of motor neurones
what do dorsal roots do
bring sensory info to spinal cord
what does grey and white matter do
grey = contains cell body and neuroglia
white = myelinated and uunmyelinated axons
how are the 31 pairs of spinal nerves grouped
according to region of vertebral column
what’s the name for specific regions of the body spinal nerves monitor
dermatome
3 layers of the brain
reptilian brain (stem) = involuntary
mammalian brain (limbic system) = emotion
higher brain (cerebral cortex) = logic and creativity
6 areas of the brain
cerebrum
diencephalon
midbrain
pons
medulla oblongata
cerebellum
cerebellum functions
complex somatic motion eg balance
voluntary and involuntary contractions
white and grey matter
what is in the diencephalon
thalamus
hypothalamus
pituitary gland
pineal gland
epithalamus
hypothalamus functions
controls emotion
autonomic function
hormone production
thalamus functions
relays and processes sensory info
what is in the mid brain
mesencephalon
mesencephalon functions
process auditory and visual info
maintain consciousness
generation of reflective somatic motor responses
pons functions
links all together
relays signals from cerebrum to cerebellum
subconscious
r/s, sleep, bladder control
medulla oblongata function
links brain stem and spinal cord relay sensory info to thalamus
autonomic function eg hr
what provides physical protection of brain
bones
cranial meninges
cerebrospinal fluid
biochemical insulation of brain
blood brain barrier
cranial meninges layers
- dura mater (outer tough layer)
- arachnoid mater (web like delicate)
- pia mater (fragile close to surface)
cerebrospinal fluid
surrounds all CNS exposed surfaces
same density as brain = shock absorb
transport nutrients and waste
how many cranial nerves are there
12
cranial nerves
olfactory
optic
occulomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
accessory
hypoglossal
olfactory
chemoreceptors for smell
sensory
optic
in retina
destination = diencephalon
occipital lobe
sensory
occulomotor
movements in the eye - lens shape
originates midbrain
motor
trochlear
lateral and down movement of eye
motor
trigeminal
largest
many destinations
how face feels
chewing action
sensory and motor
abducens
lateral eye movement
motor
facial
taste receptors on tongue
facial expressions
salivary and tear glands
sensory and motor
vestibulocochlear
balance and hearing
cochlear branch = hearing
vestibular branch = motion
sensory
glossopharyngeal
taste and motor response for swallowing
sensory and motor
vagus
many functions
digestive muscles
sensory and motor
accessory
originates in motor nuclei of neck and upper back
motor
hypoglossal
destination in tongue controlling its movement
motor
graded potentials
affect limited portion of membrane \too small area to effect activity of cells
in response to environmental stimulus
is chemical or electrical gradient stronger
chemical
process of continuous AP propagation
ap in segment 1 depolarised to +30
local current = na spread away from channel and depolarised
second segment generates ap while first refractory period
repeat
speed of unmyleinted axon vs myelinated
1m/s
18-140ms
graded vs action potentials
g = depolarise or hyperpolarise
a = only depolarise
g = no threshold
a = threshold before ap starts
g = depends on intensity of stimulus
a = all or none (identical)
g = passive spread from site
a = one site depolarises adjacent
g = effect decreases with distance from stimulus
a = along entire membrane equally
g = no refractory
a = refractory
g = most plasma membrane
a = only excitable membranes
excitatory NT
depolarisation of neurone = promotes AP
inhibitory NT
hyper polarisation of neurone = suppress AP
where are all neurones cholinergic
pns
norepinephrine
excitatory
adrenergic synapses
broken by monoamine oxidase
dopamine
excitatory or inhibitory
dopaminergic synapses
serotonin
sleep wake cycle
serotonergic synapses
