nervous system Flashcards
draw out the organisation of the nervous system
draw structure of a typical CNS neuron :
what are excitatory neurotransmitters - what do they do?
give some examples?
cause depolarisation
e.g.
acetylcholine
glutamate
what are inhibitory neurotransmitters - what do they do?
give some examples?
cause hyperpolarisation
e.g.
GABA and glycine
what is gray matter
nucleus - a cluster of neuron cell bodies and their dendrites
what is white matter
White matter is bundles of myelinated axons that form fibre tracts connecting nuclei
Grey matter connected by white matter
how is the spinal cord divided into grey and white matter
what are the 3 distinct regions of the spinal cord
- Grey matter in butterfly space
- Divided into 3 distinct regions
- Dorsal horn
- Closest to back
- Intermediate zone
- Ventral horn
- Closest to internal organs
- Dorsal horn
- Divided into 3 distinct regions
- White matter surrounding
- Axons of neurons in the grey matter
describe motor neurons in the spinal cord
- found in ventral horn
- has single basal axon
- leaves through grey matter
- leaves through ventral root
- coalesces with dorsal root
- gives rise to segmental spinal nerve
describe sensory neurons in the spinal cord
- found outside spinal cord but associated
- in dorsal root ganglia
- neuron cell bodies are pseudo unipolar
- have two projections / axons
- one to spinal nerve
- one to dorsal horn / passes through
- neuron cell bodies are pseudo unipolar
what are interneurons
Neurons which relay information between neurons
types of interneurons :
- Local circuit interneurons
- Axons remain within the nucleus
- Carry out complex computation to integrate information
- Projection interneurons
- Send their axons along fibre tracts to other nuclei
- Can be over a metre long
how many glial cells are there in the nervous system
many more than neurons
what types of glial cells are there?
Three types of glial cell
- Oligodendrocytes
- Astrocytes
- Microglia
what are oligodendrocytes
- myelinating cells
- form myelin sheath that wraps around axons
- have processes which project from them
- wrap around axons
- nodes of ranvier - ares of no myelination
- in PNS - called schwann cells
what are astrocytes
Large star shaped cells
Multiple processes
Multiple functional roles
what are the roles of astrocytes
- regulation of extracellular ion concentrations
- essential for establishing resting potential of neurons
- Astrocyte processes enclose synapses and regulate synaptic activity
- Regulate neurotransmitter uptake and degradation
- structural support
- regulation of integrity of the blood-brain barrier
- neurotrophic support/nutritive role
how do astrocytes regulate the integrity of the blood-brain barrier
astrocytes have end feet which support integrity of the tight junctions
what are microglia?
Small glial cells with numerous structure forms (depending on their activation state)
Play an equivalent role within the brain to white blood cells in the periphery
Immune system of the brain
what can occur when microglia are activated?
can :
- Release inflammatory cytokines
- Attach disease organisms
- Phagocytose damaged cells
what can occur when microglia are ‘inappropriately’ activated
what can this lead to?
Role in generation of neuropathic pain conditions
Role in some neurodegenerative diseases
- Alzheimers & parkinsons
organisation of the peripheral nervous system
- Peripheral sensory neurons
- The majority of the body receives sensory innervation from Dorsal Root Ganglion (DRG) neurons.
- Autonomic neurons
- Neurons of the sympathetic, parasympathetic and enteric nervous systems.
which parts of the body do not receive sensory information from the dorsal root ganglion neurons?
what are they innervated by?
Head, neck and some internal organs are innervated by cranial sensory ganglia that are associated with cranial nerves
what do segmental spinal nerves carry?
Carry axons of
- DRG neurons
- Sympathetic neurons (postganglionic)
- Spinal cord motor neurons
how are segmental spinal nerves formed?
from coalescence of the dorsal roots and ventral roots
- Ventral contain axons of
- motor neurons
- Sympathetic neurons
- Dorsal contains axons of
- DRG neurons
what are dermatomes
Area of skin supplied by each segmental spinal nerve
- Sensory innervation
draw mid-sagittal section of the brain and label
Corpus callosum
- Fibre tract containing axons of neurons
- Where axons cross across the hemispheres
cerebellum
- mostly balance
draw coronal brain section and label
function of basal ganglia
controlling movement
- Regulate output from motor and premotor areas of the cortex
- Initiation of movement
what does the basal ganglia comprise of
Dorsal striatum = Caudate nucleus and Putamen
Globus pallidus
Subthalamic nucleus
Substantia nigra
what is the substantia nigra divided into?
2 subnuclei
- substantia nigra pars reticulata
- substantia nigra pars compacta
how are the motor symptoms of parkinson’s caused?
- substantia nigra pars compacta
- contains dopeminergic neurons
- these project to dorsal striatum
- degeneration of these axons and dopeminergic neurons leads to symptoms
how are the motor symptoms of huntington’s caused?
Dorsal striatum contains medium spiny neurons
-
Degeneration of medium spiny neurons
- = motor symptoms of huntingtons disease
