How many neurones does the brain contain?
86 billion neurones
Describe three cell properties
Cell excitability
Conductivity
Secretia
Describe myelination
Insulates the neurone for more rapid conduction
Saltatory conduction across nodes of ranvier
Schwann cells myelinate peripheral axons
Oligodendrocytes myelinated CNS axon
Describe Multiple sclerosis
Myelination of central nerve cells = targeted
Describe guillan barré syndrome
Myelination of peripheral nerves = targeted
Describe postsynaptic response
- Excitatory post synaptic potential caused by excitatory neurotransmitter receptors e.g. glutamate, ACh
- Inhibitory post synaptic potential caused by inhibitory neurotransmitters e.g. GABA, Glycine
Describe inhibitory GABAergic Synapse
Action potential triggers GABA release which crosses synapse
Receptors trigger opening of CL- and influx of inhibitory post synaptic potential therefore less likely to reach threshold
Describe an agonist
Chemical that binds to a receptor thus activating the receptor to produce a molecule/response
Describe an antagonist
Chemical that intercepts with a receptor to inhibit the action of an agonist
- competitive binds to active site
- non-competitive binds to allosteric site
Describe 5 drugs altering receptor activity
Nicotine - agonist of nicotinic ACh receptors
Antipsychotics - olanzapine = antagonist of dopamine
Buprenophine - partial agonist of the opioid receptor
Benzodiazepines - CNS depressant increase GABAa receptor activity
Alcohol - alters GABAa activity channel = open for longer
Describe three antidepressants
- Selective serotonin re-uptake inhibitors
- Monoamine oxidase inhibitors
- Nerve agents VX gas
Describe Glia (6 types )
- Ependymal cells - form permeable barrier between CFS + tissue fluid
- Microglial cells - forms permeable barrier between CFS and tissue fluid
- Astrocytes - star shaped cells with increased branches, provide mechanical support and supply CNS neurones with nutrients maintain extracellular environment - have perivascular feet
- Oligodendrocytes - myelinated CNS neurones
- Satellite cells - surround cell bodies in PNS ganglia to give physical support
- Schwann cells - Myelinate PNS fibres
What are the 4 main transmitters in somatic nervous system?
- ACh
- Nicotinic
- Muscarinic
- NA
Describe the cerebrum and Diencephalon
Cerebrum = high brain functions Diencephalon = low brain functions
Describe the two cerebral hemispheres
4 lobes joined by corpus callosum
- frontal lobe
- temporal lobe
- parietal lobe
- occipital lobe
What is gyrification?
Characteristic folds increase surface area of cortex
What is the grey and white matter in the brain?
Grey = cell bodies White = axons
Describe the cerebrum
Covered in the neural cortex
Comprised of ridges (gyri) to increase surface area and grooves (sulk) and large grooves (fissures)
Describe the frontal lobe
-Pre frontal cortex
High level of thought and decision making
Inhibiting impulse and actions
Personality
-Motor cortex
Process and transmit information with position and movement
Plans and coordinates fine movements via basal ganglia
Describe the parietal lobe
-Sensory association
primary sensory Cortex - detects sensations - touch and pressure
-Spatial orientation and processing
- Memory for numeracy and spelling
Describe the occipital lobe
- Sensory
- Main vision centre of the brain
- Visual information from eyes processed
Describe Diencephalon
- thalamus, hypothalamus
- integration of nervous and endocrine systems
- structural and functional link between hemispheres + brain stem
- filters sensory information
- involved in memory + autonomic function
Describe the hippocampus memory
Cerebullum - movements and sensations
Basal ganglia - regulation of movement
Brain stem - mid brain, medulla oblongata controlling vital functions
