S1: Introduction to the Nervous System and Neurology (part I) Flashcards
What is the role of nerve cells?
- Generate electrical signals
- Form complex circuits
Describe the basic structure of a nerve cell (neurone)
- All contain a cell body that contain the machinery for life
- Dendrites (extentions of the cell body) provide a large surface area for receiving information. They make synaptic contact with other nerve cells
How does the axon of one neurone transmit information to another?
Action Potentials
What are synapses?
They are gaps between neurones where one cell passes information onto another.
What provides physical support for neurones?
- Skull
- Meninges
- CSF
How does the blood brain barrier support neurones?
Capillary bed forms “tight junctions”, that prevent free diffusion of ions and other polar substances from the body tissues into the cerebrospinal fluid. This maintains a stable environment for neurones.
How do blood vessels support neurones?
Dense capillary bed that provide all the nutrients needed for the nerve cells to function as they are very metabolically active
What are microglia?
They are phagocytic cells that are part of the immune system and they phagocytose damaged neural tissue and bacteria
What are glial cells?
They include:
- oligodendrocytes
- astrocytes
- neurolemmocytes
They provide biochemical, structural and other support for nerve cells
What is to role of astrocytes?
- Control biochemical enviroment of nerve cells
- They instruct capillaries to form the blood brain barrier
- Processes coming off astrocytes wrap around neurones. They maintain the concentration of fluid trapped between glial cells and neurones by pumping ions in and out.
- They soak up used signalling molecules and they transport nutrients and waster products between nerve cells and blood vessels.
What is the myelin sheath in the CNS made of?
Oligodendrocytes
What is the myelin sheath in the PNS made of?
Neurolemmocytes
How is a myelin sheath made?
The cells (oligodendrocytes or neurolemmocytes) form a sheath around each axon by wrapping themselves round the axon. They leave behind multiple layers of their membrane made of phospholipid which is fatty
What is the function of a myelin sheath?
- Good insulator
- Speeds up electrical transmission by insulating the axon
What does grey matter contain?
- Most of the nerve cell bodies densely packed together
- Dendrites
- Local axons forming complex circuits
- Astrocytes
