General Organisation of the Nervous System Flashcards
Name the X2 primary divisions of the nervous system and what each contains.
Central
= brain
= spinal cord
Peripheral
= nerves and ganglia outside of the brain/spinal cord
Neural tissue consists of:
1) neurons
2) supporting cells
What is the role of the neurons?
To transmit electrical impulses along their axons.
Neural tissue consists of:
1) neurons
2) supporting cells
What is the role of the supporting cells?
To structurally support the neurons, bring nutrients and regulate the interstitial fluid.
What can be said about a neurons capacity for cell division?
They have none, and have limited capacity for repair after damage also.
What is the name of a neuronal cell body?
Neuronal cell body’s are highly branched, what are these branches called?
What is the name of the singly long projection from the cell body why terminates at other neurons?
Soma.
Dendrites.
Axon.
What is the name of the connection between the axon of one neuron and the soma of another?
What is the name of the end point of the axon?
What is the name of the gap between the two structures?
Synapse.
Synaptic terminal = the end of the axon
(Synaptic cleft = the space between the two structures)
What is the name given to the connection between a neuron and an effector cell?
The neuro-effector junction.
What is another name for the supporting cells of the nervous system?
Neuroglial cells.
How many types of glial cells are found within the CNS?
What are the called?
X4:
1) Astrocytes
2) Microglia
3) Ependymal cells
4) Oligodendrocytes
What is the role of Astrocytes in the CNS?
They are in contact with both the neurons and capillaries and therefore work to maintain the blood-brain barrier.
They provide structural support for the CNS.
They produce scar tissue following injury.
They control interstitial environment and help recycle neurotransmitters.
What is the role of Microglia in the CNS?
They are the macrophages of the CNS.
They can are not fixed in position therefore can mobilise around the CNS to move to where they are needed.
What is the role of Ependymal cells in the CNS?
These line the ventricles of the brain and any structure containing CSF.
They branch inwards to connect with other glial cells, but their function is not fully known. It is suggested they may help with the monitoring of CSF composition.
What is the role of Oligodendrocytes in the CNS?
These have many processes which wrap around axons to myelinate them.
X1 Oligodendrocytes can myelinate multiple axons in order to improve the neurons conduction velocity.
How many types of glial cells are found within the PNS?
What are the called?
X2:
1) Schwann cells
2) Satellite cells
What is the role of Schwann cells in the PNS?
These surround all axons in the PNS and either act to:
1) Structurally group up to 20 small diameter neurons (non-myelinate from Schwann cells)
2) Myelinate a single axon with a single cell (myelinating Schwann cells)
What is the role of Satellite cells in the PNS?
These surround neural somas when they are grouped in ganglia for structural support, as well as regulating nutrient levels around them.
What is a ganglion?
A group of neuron cell bodies in a cluster located outside of the CNS.
What type of neurons are found in sensory ganglia?
Pseudo-unipolar.
= no synapses, one end is in the CNS, the other in the PNS at the receptor.
= has a soma with an axon that bifurcates into X2 that travel in opposite directions.
What type of neurons are found in autonomic motor ganglia?
Multipolar
= X1 axon from the soma
= with have individual pre- and post-ganglionic neurons which synapse at the ganglia.
What are the X2 structures protecting the brain & spinal cord?
1) cranium and vertebrae
2) meninges
What are the X3 layers of the meninges from most to least superficial?
1) Dura mater
2) Arachnoid mater
3) Pia mater
What further X2 layers is the dura mater split into?
1) periosteal layer = fuses with the inside of the skull
2) meningeal layer = deep to the periosteal layer and against the arachnoid mater
In which space does the CSF exist?
The subarachnoid space.
What is a dermotome?
An area of skin supplied by a single spinal nerve.
What is a myotome?
A group of muscles that a single spinal nerve innervates.
Which spinal nerves form plexuses?
Name some plexuses.
The anterior rami of all spinal nerves (excluding T2-T12).
- cervical
- brachial
- lumbar
- sacral
Which is dorsal and which is ventral in terms of posterior and anterior?
Ventral = anterior
Dorsal = posterior
What is the advantage of plexuses?
The criss-crossing and redistribution of spinal nerves to the point where each branch of a plexus contains fibres from multiple spinal nerves is a benefit as it means damage to a single nerve may cause muscle weakness but NOT paralysis.
