ToB - Neurones, Nerves And ANS Flashcards
What are the meninges made of and what order do they go in?
Squamous epithelia
Skull/spinal vertebrae Dura mater Arachnoid mater Pia mater Brain/spinal cord
What makes up the gross nervous system?
1). The brain and its 12 pairs of cranial nerves and the spinal cord and its 31 pairs of spinal nerves.
OR
2). The brain, spinal cord and nerves.
What form the leptomeninges and what is their function?
The arachnoid mater and pia mater.
Cerebrospinal fluid flows in between them.
What is CSF formed by and what is its function?
Formed by the choroid plexus of the arteries. It takes nutrients and O2 to the neurones of the CNS and removes waste. It also exerts CSF pressure.
What is nissl substance and what does it contain?
It is found inside a neurone cell body. It has aggregations of RER and many golgi to be able to synthesise and package neurotransmitters.
What type of neurone are dendrites normally found on?
Motor neurones
What are spines of a dendrite linked to?
These are linked to the ability to learn.
What are the 2 classes of dendrite and their function?
Function is to increase s.a. For which an input can be received.
Proximal - a dendrite stems from the axon body
Distal - a dendrite stems from another dendrite
How can the arrival of an input at a dendrite be summated?
Temporal summation - with respect to the time it arrived (how many times the axon fired)
Spatial summation - with respect to where on the neurone the input arrived (how many axons fired at that one neurone together)
What is the function of the nodes of ranvier on an axon?
1) . Allow nutrients in and out of the axon between myelination
2) . Allows saltatory conduction of the impulse via de/repolarisation = much quicker
What is the axonal hillock?
It isn’t always present but it is where the action potential summated from and fires down the axon (often at the base of the cell body)
What is the effect of demyelination of an axon and what disorder does this occur in?
No saltatory propagation can occur = much slower transmission of impulse.
Occurs in MS where myelinated tissue is replaced by scar tissue
What are the usual neurotransmitters released at excitatory synapses?
Glutamate and aspartate
What are the usual neurotransmitters released at inhibitory synapses?
GABA and glycine
What are the 3 ways in which synapses can occur?
1) . Lightly - 1 to 1
2) . Diverge - 1 to 10
3) . Converge - 10 to 1