Neurochem + Neurophysiology Of Nerve Transmission Flashcards
(29 cards)
Cells of nervous system
Neurons and Glia
Neurons role:
Receive + transmitted info to other cells
Lots of neurons
Glia role:
Support neurons
Smaller, but more numerous than neurons
Don’t transmit info across long distances
Neuron structure
Soma- contains nucleus
Dendrites- branching fibre, receive info via synaptic receptors
Axon- info sender of neuron
Myelin sheath- insulates neuron
Presynaptic terminal- point axon transmits info from
Types of axon (2)
Afferent- bring info TO structure (sensory neuron)
Efferent (eff off)- carries info AWAY from structure (Motor neuron)
Glia structure
Astrocytes— help synch activity of neurons/ remove waste material
Microglia— remove waste material (bacteria, viruses)
Olygodendrocytes— build myelin sheath
Radial glia— guide migration of neurons…. Grow axons
What protects nervous system
Skull— protects— brain
Backbone— protects— spinal cord
Blood-Brain Barrier — prevent virus and bacteria entering brain
Blood-brain barrier - what it depends on
Endothelial cells
Cells closely spaced— nothing passes
What is sipped by blood-brain-barrier
Viruses
Harmful bacteria
Electrically charged molecules
What passes blood-brain barrier
Uncharged molecule (O2 and CO2)
Vitamin A and D
Water
Resting potential
At rest, neurons more negative inside than out
Results from unequal distribution of negatively- positively charges particles
Restin gpotential maintained by 4 interacting factors
- Concentration gradient— ions move from height concentration area to low concentration area
- Electrical gradient— charges repelled by like charges, attracts unlike charges
- Meme ran permeability at rest— Cl and K pass, protein does not
- Sodium-potassium pump— transports Na and K out, requires energy
Action potential
Repsonce of neurone to stimulation above threshold
Prepares neuron to respond to QUICK to stimulus
Depolarisation
Results from stimulation
Neuron becomes less negative
Beyond threshold = massive depolarisation
After depolarisation: potential returns to RP
Molecular basis of action Potential
Ion and molecules responsible for its generation
1. Sodium enters cell
2. Potassium later leaves cell, makes negative
3. Sodium, potassium then restored OG ion distribution
Refactory period
Right after AP, membrane area cant produce another AP
Results in refactory period
Determined direction of propagation
Absolute refectory period
No AP can be produced
Relative refactory period
Stronger than usual stimulus
Can initiate AP
AP conduction speed
Depend on axon diameter
Myelin sheath increases speed
AP jumps from node-to-node= saltatory conduction
This increases speed + saves energy
Synapse
Side info flows from on neuron to another
Main parts of synapse (3)
- Presynaptic terminal
- Synaptic effect
- Postsynaptic neuorn
Events at the synapse
AP arrrives at Presynaptic terminal
Neurotransmitters (NT) release into synaptic cleft
NT attach to receptors
NY separate from receptors
Nt taken by Presynaptic cell to diffuse away
Iontropic receptors
Effect = fast and short
NT opens/closes channel directly
Relevant for vision, hearing (quick changing info)
Metabotropic receptors
Effect= slow and long
NT activated G protein
G protein stimulates synthesis of second messenger
Relevant for hu her, thirst, fear (long-term behaviour changes)
