The Nervous System Flashcards
What is a nerve fascicles ensheathed by?
Perineureum
What is an entire nerve ensheathed by?
Epineureum
How many axons do all neurones have?
1
What are neurones with multiple dendrites called?
Multi-polar
What are neurones called with 1 dendrite and 1 axon?
Bi-polar
What are neurones with no dendrites called?
Unipolar
Where are multipolar neurones found?
They make up most neurones
Where are bi-polar neurones found?
In the retina of the eye
Where are uni polar neurones found?
Primary sensory neurones
What maintains the myelin coating of an axon?
Oligodendrocytes
Does the autonomic system and somatic system contain myelinated or unmyelinated neurones?
Autonomic - both
Somatic - all myelinated
Why does demyelination slow down conduction?
Impulse has further to travel as salutatory propagation is inhibited.
What happens in multiple sclerosis?
Myelin sheath is destructively removed from the axon and is replaced by scar tissue.
Oligodendrocytes and axons can also be damaged.
Conduction velocity is slowed down.
Scar tissue doesn’t permit conduction so the axon is useless
What is Nissl substance made up of?
RER
What do astrocytes do?
Form the blood brain barrier
Assist in the transfer of nutrients and waste
What is produced in Nissl bodies?
Neurotransmitter
What are dendrites specialised to do?
Receive stimuli from the environment or other neurones
Conducts them towards the cell body
What does the cell body consist of and what does it do?
Nucleus and cytoplasm containing Nissl substance.
Maintains the cell
What is the axon specialised to do?
Generates or conducts nerve impulses AWAY from the cell body to other cells
Where are neuroglial cells found and what do they do?
In the spaces between neurones in the central nervous system
Provide structural and metabolic support for neurones
Name the four types of neuroglial cells
Oligodendrocytes
Astrocytes
Microglia
Ependymal cells
What does grey matter contain?
Neuronal cell bodies and their associated fibres
What does white matter contain?
Nerve fibres
Why does white matter appear white?
Myelin
What stain is used to allow myelin to show up?
Osmium tetroxide
What is a ganglion?
An accumulation of neurone cell bodies, outside of the central nervous system.
In the CNS, where are the cell bodies of sensory neurones found?
Spinal or cerebral ganglia at the dorsal root of spinal nerves
