Neurons w3 Flashcards
multiple sclerosis
autoimmune disease to attack own myelin - protective sheath:
- poor coordination
importance of synapses
- to impose breaks in neutrons to reduce neural system overload
Acetylcholine (ACh)
mobility issues, memory impairment- influences muscle activity &memory - Alzheimers: underproduction of ACh
Neuro-modulators
brains own opioids - opium like chemicals
biggest group: endorphins
endorphines
- inhibit pain transmission
- increase pleasure
3 types of neurones
sensory neurones
motor neurones
inter-neurones
sensory neurones
imput from sense organs to spinal cord & brain
motor neurones
output from brain & spinal cord to muscles & organs
inter-neurones
connective/ associative functions relays info between neurones.
withdrawal reflex
subcontious act - bypasses brain, only through spinal chord - brain after. noxious stimulus - sensory neurones- excitatory info- interneurones- spinal chord-
autonomic nervous system
sympathetic:
parasympathetic:
Homeostasis:
Action Potential (nerve impulse)
1) Resting state inside axon: -70mv, Na, K channels closed
2) Pressure/ sensory imput disturbs membrane: -55mv - threshold voltage, triggers Na channels to open, Na+ diffuses in, more +ve charge inside than out, +30mv (Depolarisation)
3) Impulse passes, K+ channels open to go out, inside -ve voltage (depolarisation)
4) Some K+ channels rain open, more -ve charge than resting (hyperpolarisation)
5) in “refractory period”sodium-potassium pumps return 2 K+ to inside, 3 Na+ returned to outside = back to resting potential -70mv
Facilitated diffusion
passive unless agains conc. grad.
used by
Carrier Proteins: change shape to allow certain large or polarised ions/molecules to move across membrane
will only move molecules against conc. grad. when ATP present, slow transportation rate
Channel proteins: stay same shape, can close or open in response to certain stimuli, cannot move molecules against conc. grad., faster transportation rate
neuron components
soma: cell body
Axon: conducts electrical impulses away from the cell body to other neurons, muscles, or glands
Dendrites: specialized receiving units that collect messages from neighboring neurons and send them on to the cell body
psych resting potential:
- Neuron is separated from surrounding fluid by a cell membrane; substances pass through ion channels
- Inner ions are more negatively charged than outer ions, resulting in a net negative charge for the resting neuron (polarization)
psych Action potential:
- Positive sodium ions enter the neuron, causing brief depolarization
- It begins at one end of the axon & moves down along it
absolute refractory period
- happens at each point along axon after action potential passed
- During this period the membrane is not excitable & cannot discharge another impulse.
Graded Potentials:
changes in the negative resting potential that do not reach the action potential threshold
neurotransmitter stages:
1) synthesis
2) storage
3) release
4) Binding
5) deactivation
neurotransmiter synthesis
the transmitter molecules are formed
1 - storage
transmitter molecules are stored in synaptic vesicles (in axon terminals)
2- release
action potential causes transmitter molecules to move from synaptic vesicles across the gap
3- Binding
transmitter molecules bind themselves to receptor sites embedded in the receiving neuron’s cell membrane
4- neurotransmitter deactivation
occurs in two ways:
- Transmitter can be broken down by other chemicals
- Reuptake: transmitter molecules are taken back into the presynaptic axon terminals
