General Organisation of the Nervous System Flashcards
Describe the two functional divisions of the peripheral nervous system
Autonomic - involuntary nervous system. Supplies smooth muscle, glands and viscera.
Somatic - Voluntary nervous system. Supplies skeletal muscle and carries sensation.
What does the CNS consist of?
Spinal cord and brain
What does the peripheral nervous system (PNS) consist of?
axons, ganglia, and supporting cells
Name the 4 types of glial cells in the CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells
What is the function of an astrocyte?
Provides structural support to the neuron
What is the function of oligodendrocytes?
Wraps axons together/myelinates neurons
What is the function of microglia?
Macrophages of the brain
What is the function of ependymal cells?
They line chambers of the CNS. Play a key role in production of cerebro-spinal fluid
Name the two types of supporting cell in the PNS.
Schwann Cells
Satellite Cells
What is the function of schwann cells?
Myelinate axons to allow saltatory conduction to occur.
What is the function of Satellite cells?
Surround neurone cell bodies in ganglia. Regulate O2, CO2 and nutrient and neurotransmitter levels.
What is a ganglia?
A structure containing a number of cell bodies - typically synapsing. Supported by connective tissue.
Name the 3 layers of the meninges (coverings of the brain). Order the layers.
- Dura mater - outermost layer. Collagenous tough layer with inner specialised folds to support the brain. Outer layer fused to periosteum.
- Arachnoid mater - middle layer. Covers the surface of the brain.
- Pia mater - innermost layer. Tightly attached to the brain by astrocytes and follows its contours.
Where do sensory neurons have their cell bodies?
Outside the CNS in ganglia.
Name 2 similarities between the somatic and autonomic nervous system.
- Both initial cell bodies originate in the central nervous system.
- Both travel via the motor/sensory root
Name three differences between the somatic and autonomic nervous system.
- Somatic - has only one neurone, Autonomic has two which synapse at ganglion.
- Somatic nerves are fully myelinated, In motor nerves, only the first is myelinated.
- Somatic supplies skeletal muscle, autonomic supplies glands, smooth muscle and viscera.
Which segments of the spinal cord provide sympathetic innervation?
T1 to L2.
All thoracic and lumber 1 and 2.
Where to motor neurons of the sympathetic system originate?
In the spinal cord.
Where do motor neurons of the sympathetic nervous system synapse?
At sympathetic chain ganglia.
Some synapse further from the spinal cord e.g. in celiac ganglion for most nerves which innervate the liver/stomach.
Other than ganglia. Where can preganglionic neurons stimulate?
The adrenal medullae - causes the release of neurotransmitter into the circulation
Which segments of the spinal cord do parasympathetic neurons arise from?
Cranial nerves III, VII, IX and X.
Sacral spinal nerves S2,3,4
What is the distribution of parasympathetic stimulation?
Head and trunk ONLY.
What is the function of cranial nerve X (the vagus nerve)?
Provides innervation to all thoracic viscera and most of the GI tract.
Plexuses around the oesophagus.
Where does the sacral nerves S2, S3 and S4 supply?
The genito-urinary region.