Nerve Transmission Flashcards
Clusters primarily composed of axons
CNS: Tract
PNS: nerve
Glia
Smaller than neurons but more numerous
Don’t transmit info across long distances
Astrocytes
Synchronize activity of neurons
Remove waste materials
Microglia
Remove waste materials and microorganisms (viruses, fungi)
Oligodendrocytes and Schwann cells
Build the myelin sheaths
Radial glia
Glide migration of neurons and growth of their axons
What protects the NS?
Skull (brain)
Backbone (spinal cord)
Meninges (membranes surrounding brain and spinal cord)
What does a blood brain barrier do?
Prevents viruses as harmful chemicals from entering the brain
Stops large molecules and electrically charged molecules
What passes the barrier?
ACTIVELY Small uncharged molecules Water Fat soluble molecules PASSIVELY glucose Amino acids Certain vitamins
Speed that neurons conduct info via electric impulses
1 meter/second to 100 m/s
Explain resting potential (neurons)
Neurons more negative inside
Voltage difference
70MV (typical)
4 interacting factors of resting potential
Homogenizing factors: 1. Concentration gradients 2. Electrical gradient These are counteracted by two properties 3. Membrane permeability at rest 4. Sodium potassium pump
Explain action potential
Response of a neuron to stimulation above a certain threshold
Prepares neuron to respond quickly
Results in depolarisation - neuron becomes less negative
Then returns to RP value (repolorization)
What is the refractory period?
Immediately after action potential, another cannot happen
What is absolute refractory period?
No action potential can be produced
What is relative refractory period
Stronger than usual stimulus can produce action potential
Synapse
Side at which info flows from one neuron to another
Small gap between neuron has 3 main parts;
- presynaptic terminal
- synaptic cleft
- post synaptic neuron
What are ionotropic receptions
Post synaptic receptors
Effect is fast and short
Glutamate and GABA
for vision, hearing
What are metabotropic receptors?
Post synaptic receptor Effect is slow and long NT activates G-protein This can bind to ion channels Relevant for hunger, thirst, fear, anger
Reuptake of NT?
NT is taken up and reused by presynaptic neuron
What is temporal summation?
Depends of size, time and threshold of postsynaptic neuron
What is spatial summation
Summation of several simultaneous EPSP
Cocaine
Dopamine and norepinephrine agonist
Blocks their reuptake
Effects - euphoria, loss of appetite, insomnia and addiction
Benzodiazepines?
Diazepam
GABA agonists increases binding of GABA
Effects - reduce anxiety, induce sleep and reduce seizures
Clusters contain
CNS: nucleus
PNS: ganglion
