Introduction to the Nervous System and Neurology Flashcards
What are the components of the nervous system?
Brain, spinal cord and nerve cells
What do nerve cells do?
They generate electrical signals
What is the cell body of a neuron?
It is what contains all the normal machinery of life
What is the function of the dendrites found on neurones?
To provide a large surface area for receiving information from other cells
What is the function of the axon of a neuron?
It transmits information to other nerve cells using action potentials
What is a synapse?
It is where one nerve cell passes information to another nerve cell by releasing neurotransmitters into the synaptic cleft which attach onto receptors and pass on the action potential
What is the function of the cerebrospinal fluid?
To act as a shock-absorber
What physical support/protection does the nervous system have?
- Meninges
- CSF
- Highly specialised capillaries with few gaps in their walls so nothing can diffuse through them
What defence does the nervous system have?
Microglia, blood-brain barrier and glial cells
What is the function of microglia?
It protects the brain against infection- part of the innate immune system
Where do glial cells come from?
The same stem cells as nerve cells
What is the function of glial cells?
To provide biochemical and structural support for nerve cells and helps control the activity of nerve cells
What is the function of astrocytes?
- Keeping the concentration of ions just right to allow optimal function of nerve cells
- Transport of nutrients and waste products between nerve cells and blood vessels
- Clear synaptic cleft for incoming action potentials
What is the structure of astrocytes?
They have long processes that come out of the cell body, processes form sheets that sheath the dendrites and cell bodies of nerve cells
What forms the blood-brain barrier?
The contact between astrocytes and capillaries
What are the 2 types of myelinated glial cells and what do they form?
Neurolemmocytes and oligodendrocytes
Form a sheath around each axon
Where is grey matter found?
Outside of white matter
What does grey matter contain?
- Cell bodies
- Dendrites
- Local axons
- Supporting astrocytes
What is white matter?
Bundles of axons linking different grey matter regions
What does white matter contain?
- Oligodendrocytes
- Astrocytes
What do afferent neurones do?
They carry information from sensory nerves to the CNS
What do efferent neurones do?
They carry signals from the CNS to motor nerve
What are pathways?
A chain of nerve cells that carry specific information
What are tracts?
Regions of white matter through which identified pathways run
What are the 2 main divisions of the nervous system?
Central and peripheral
What protects the CNS?
Cranium and vertebral column
Where do aneurysms mainly arise?
In the Circle of Willis
What is the name of the background potential that electrical signals are generated against?
Resting Membrane Potential (RMP)
What is the general value for RMP?
-60mV/-70mV
What produces RMP?
Generated as cell membranes are more permeable to K+ which means K+ diffuses out of cells
This leaves an excessive negative charge inside
What can increase the RMP and how?
- Kidney disease
- Major soft tissue damage
- Medication error
- All of these increase K+ concentration gradient
When does an action potential occur?
When there’s an increase in permeability to Na+
What happens as a result of increased permeability to Na+?
-Na+ diffuses into the cell making the inside more positive= depolarisation
How is RMP restored?
By the diffusion of extra K+ out of the cell, making the inside more negative again= repolarisation
Why does hyperpolarisation occur?
As the K+-voltage gated channels are slow to close so more K+ diffuses out of the cell
What causes the release of neurotransmitters from the pre-synaptic bouton into the synaptic cleft?
Depolarisation of the synaptic bouton
What does the effect of a neurotransmitter on a synapse depend on?
The receptor used
What can the different effects on a synapse be classified as?
- Excitatory/inhibitory
- Fast/slow
- Trasient/persistent
How do drugs effect synaptic transmission?
They interfere with:
- neurotransmitter production/release
- neurotransmitter receptors
- neurotransmitter removal
