Neurons Flashcards
Dendrites are used for —– distance communication with ——– neurones
Dendrites are used for short distance communication with adjacent neurones
Dendrites conduct information ——- the cell body
dendrites conduct information towards the cell body
True or false? Axon is the longest connector that communicates with other neurones/effectors
TRUE
Which is the most common type of neuron?
Multipolar
What type of neurone are all motor neurones of skeletal muscle and ANS?
Multipolar
With multipolar the cell body is the the —
CNS
With unipolar the cell body is in the —
PNS
A collection of nerve cell bodies in the CNS is called what?
a Nucleus
A collection of nerve cell bodies in the PNS is called what?
a Ganglion
Myelin sheath in the CNS is made of what?
Oligodendrocytes
Myelin sheath in the PNS is made of what?
Schwann cells
What are the causes of nervous system injury?
- Hypoxia
- Trauma
- Toxic insult
- Metabolic abnormalities
- Nutritional deficiencies
- Infections
- Genetic abnormalities
- Ageing
What percentage of the body resting oxygen consumption is the brain?
20%
Central blood flow can increase only ——- to maintain oxygen delivery
twofold
In what situation does excitotoxicity occur?
Hypoxia (but also other acute neuronal injury events)
What is excitotoxicity?
- Large accumulation of glutamate in synaptic space
- Glutamate and oxygen free radical formation bring about calcium input
- This triggers protease activation, mitochondrial dysfunction and oxidative stress.
What is cytotoxic oedema?
Na+ and Cl- move into cells and take water with them
This does not cause swelling (as just shifting from extracellular to intracellular) but it does enhance ionic and vasogenic oedema
What are the 3 situations that ionic oedema occurs due to?
Cytotoxic Oedema
Hyponatraemia
Excess water intake e.g. SIADH
What is ionic oedema?
Na+ crosses BBB, drives ion transport, creates osmotic gradient for H20. SWELLING
When does vasogenic oedema occur?
Trauma, Tumours, Inflammation, Infection and hypertensive encephalopathy
What is vasogenic oedema?
Disruption of endothelial tight junctions
Plasma proteins e.g. albumin cross into extracellular space (H20 follows)
Disruption not severe enough to allow passage of RBC’s
Give an example of a potent osmotic factor
albumin
What is haemorrhage conversion?
Occurs when endothelial integrity is completely lost
Blood can enter extracellular space
In what percentage of ischaemic strokes does haemorrhage conversion occur?
30-40%
What are the two responses to damage to nerve cells?
Rapid necrosis
Slow atrophy
What is an example of when rapid necrosis occurs?
Stroke
What is an example of where slow atrophy occurs?
Age-related cerebral atrophy
What does red neurones represent?
A lethal injury to the neuron
When does red neuron become visible?
12-24h after an irreversible “insult” to the cell
What is the pattern of acute neuronal injury?
Shrinking and angulation of the nuclei
Loss of the nucleus
Intensity of the red cytoplasm
What are the 3 axonal reactions to injury/disease?
Increased protein synthesis
Chromatolysis
Degeneration of axon/myelin sheath distal to injury
3 examples of when you get inclusions (i.e. sub cellar alterations)
- Accumulate with age
- Viral infections affecting the brain
- Neurodegenerative disorders
Neurofibrillary tangles appear in which neurodegenerative condition?
Alzheimers disease
