Introduction to the nervous system Flashcards
how is the nervous system divided
CNS - brain and spinal chord
PNS - peripheral
how is the peripheral nervous system split
sensory division - input eg sensors on nerve endings detect acidity
motor division - effector side
describe the somatic PNS
controls motor and sensory function for the body wall
eg skin - sensory and skeletal muscle - motor neurons
Describe the autonomic nervous system
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
what is the sympathetic nervous system
fight/flight
increase heart rate
decrease digestion
spinal nerves only
what is the parasympathetic nervous system
rest and digest controlled by cranial nerve more discrete anatomy than sympathetic decrease heart rate increase digestion spinal nerves and cranial nerves
what do the sympathetic and parasympathetic nervous systems make up
the autonomic nervous system
what is the sensory division
afferent = arrive at CNS
signals from periphery to brain
what is the motor division
efferent = exit CNS
CNS to periphery
use an example to describe afferent and efferent
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
describe the features of the gross anatomy of the brain
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
describe the features of the brain
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
what are the cranial nerves
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
what are the meninges
thick coverings that coat the outside of the brain
describe the parts of the meninges
dura mater (inner and outer layer) - very strong, BV between layers - protects the brain
arachnoid
subarchnoid space
pia mater
common head injury in meninges
subdural haemotoma - pool of blood between dura and arachnoid
increase intercranial pressure
describe the spinal chord
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
describe a nerve cell
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
describe axons packing into nerves
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
describe the action potential
baseline V -70mV Na channel open depolarisation \+40mV V gated K channel - out repolarisation
describe synaptic transmission
distance 10nm - need chemicals
neurotransmitter bind to post synamptic neuron receptors
how can we see nerve cells now
brainbow
transgenic mice
label neural cells with different colours
what are the different brain cells and their functions
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
describe regeneration of the nervous system
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
describe the dorsal column-medial lemniscus pathway (sensory perception)
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
describe the spinothalamic pathway (sensory perception)
signal enters spinal cord and immediately switches side
conveys pain and temperature sensation
describe the lateral corticospinal tract (motor pathway)
from brain
in brain stem signal switch to the other side
down brain stem - ipsilateral ie down same side
describe the vestibulospinal tract (motor pathway)
input from vestibular system - ear, not dizzy, know orientation
all ipsilateral - want ear to move same direction as body
