Intro to the nervous system Flashcards
What are the divisions of the nervous system?
Central nervous system and peripheral nervous system.
Give an overview of the CNS.
- encephalon and spinal cord.
- Covered with a system of membranes (meninges).
- Suspended in the cerebrospinal fluid (CSF).
List the four parts of the central nervous system.
1) Spinal cord.
2) Brain stem (nuclei of all but the first two cranial nerves), also including the medulla, pons and midbrain.
3) Cerebellum.
4) Cerebrum, consisting of;
- Telencephalon (Cerebral hemispheres).
- Diancephalon (involved in the four F’s).
What makes up the PNS?
Cranial and spinal nerves and their ganglia.
What makes up the encephalon?
Brain stem, Cerebellum and Cerebrum.
What are neurons?
Excitable nerve cells which transmit information as electric signals or “action potentials”.
Describe the structure of a typical neuron.
A typical neuron has a cell body (soma) and neurites(s). Neurite is either a dendrite or and axon.
What is an axon?
Is a single extension, can be as long as 1M, usually covered with myelin or Schwann sheath
What is a dendrite?
Are multiple, thin, short extensions.
What are neuroglia?
Specialised cells which support neurons. (more neuroglia than neurons).
What is the function of satellite cells?
Support cell soma (to support neurons).
What is the function of Schwann cells?
Myelin production in PNS (Myelin helps speed up the impulse down a neuron).
What is the function of oligodendrocytes?
Myelin production in CNS (Same as the Schwann cell).
What is the function of the Astrocytes?
Important in maintaining the blood brain barrier.
What is the function of the microglia?
They are scavengers that float around the nervous system and scrounge up remnants and scraps etc.
What is the function of the Ependymal cells?
Cerebro-spinal fluid production.
What is the difference between the glial cells and the neurons they support?
They can regenerate quite well but the neurons cannot.
What are the properties of Myelin?
- Insulation material.
- Rich in lipid and protein.
- Makes conduction faster, requiring less energy.
What are the nodes of ranvier?
Nodes of Ranvier are gaps in the myelin sheath coating on the neural axon. The nodes of Ranvier allow for ions to diffuse in and out of the neuron, propagating the electrical signal down the axon.
describe the structure of the Myelin sheath in the peripheral nervous system.
Schwann cell envelops the axon and wraps the myelin sheath around it.
Describe the structure of the myelin sheath in the central nervous system.
Oligodendrocytes can myelenate multiple neurons and can also support un-myelenated neurons.