Chapter 5.1.3: Neuronal communication Flashcards
What’s one difference between relay neurones and motor neurones?
Relay neurones don’t have a myelinated sheath as faster transmission is not needed (Schwann cells minimise electrical loss)
What do the specialised cells on receptor organs do?
Detect energy changes in the surroundings - known as energy transducers
What are the axon and the axon hillock?
Axon = carries nervous impulses away from the cell body
Axon hillock = specialised region of tissue which triggers the production of nervous impulses
How are neurons specialised to their function?
They’re long so they can transmit messages over long distances, they’re surrounded by a fatty sheath to insulate neurones and they have numerous dendrites to connect to other neurones
What is the name of the receptor cell for touch and what form of energy is it received in?
Meissners corpuscles - kinetic
What is the name of the receptor cell for smell and what form of energy is it received in?
Olfactory cells - chemical
What is the name of the receptor cell for temperature and what form of energy is it received in?
Ruffins ending - thermal
What is the name of the receptor cell for pressure and what form of energy is it received in?
Pacinian corpuscles - kinetic
What is the name of the receptor cell for placement of limbs and what form of energy is it received in?
Proprioceptors - mechanical displacement
What is the name of the receptor cell for balance and what form of energy is it received in?
Semicircular canals hair cells - kinetic
What’s the resting potential of the neurone’s membrane?
-65mv
Define spatial summation
two or more presynaptic neurones converge and release their NT at the same time onto the same post synaptic membrane
Define temporal summation
two or more action potentials arrive in quick succession from the same presynaptic neurone
In six steps, outline the process of synaptic transmission
- action potential arrives = voltage gated calcium ion channels open
- Influx of calcium ions = presynaptic vesicles to move toward the membrane and fuse - releasing NT into synaptic cleft.
- NT diffuses across cleft and binds to subunits that bind to the receptor - opens sodium ion channels on post synaptic membrane.
- Sodium ions flood into post synaptic membrane - excitatory post synaptic membrane.
- NT broken down so that continual simulation of the PSM does not happen by enzyme
- Broken down NT re enter presynaptic membrane by diffusion - using ATP they are recombined in secretory vesicles
Define inhibitory
Hyperpolarise post-synaptic membrane - prevents AP being generated
Define excitatory
Depolarise post- synaptic membrane - trigger AP
Describe the 3 ways that drugs and poisons affect the synapse
- Blocking NT receptors so AP’s aren’t generated
- Preventing the removal of NT from the synaptic cleft
- Destroying enzymes which breakdown the NT