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level: Level 1 of The Nervous system

Questions and Answers List

level questions: Level 1 of The Nervous system

QuestionAnswer
Reflex arcstimulus - receptor- (sensory neurone) -CNS (Relay neurone) - (motor neurone)- effector response
the receptor for the following stimuli light- sound- temp- smell -pressure blood pressure blood co2photoreceptors -ear -thermoreceptors - nose -panincal corpuscle -pressure receptors -chemoreceptos
Features of the structure of a neurone-cell body -axons conduct implulses - myelin sheath - eletrical insulation contains many lipids -nodes of ranvier - gaps in myelin -synaptic knob - communication to other nuerones
resting potentialsodium potassium pump in the axon membrane actively transports 3 NA+ out of the axon for every 2K+ transported in. Potassium chanels in axon membrane diffuse K+ ions of the axon from high to low by facitlilated diffusion making the charge -70mv
Action potentialDepolarisation occurs when sodium gated channels open sodium diffuses in by FD stimulating others to topen passing a threshold 40mv repolarisation Na+ channels CLOSE K+ chanells open so K+ diffuses out of the axon lowering membrane potential to -70mv
All or nothing principleall - sodium gated channels pass threshold impulses travel nothing - weak stimulus threshold not passed
what is a refractory periodthe time when time in when action potential occurs
why are refractory periods occurproduces discrete impulses in one direction limits the freq of impulses action potentials are unidirectional
Factors affecting speed of transmission-myelin sheath insulates - nodes of ranvier are where depolarisation occurs , impulses jump from node to node called saltatory conduction -axon diamter - bigger = less resistance -temp diffusion faster
diffusion across synaspesAction potential arrives at the pre synaptic knob stimulates calcium channels to open diffusing calcium in causing vesicles containing neurotransmitters to fuse with pre synaptic membrane realasing ach ach diffuses across synaptic cleft ach binds with receptor proteins trigerring sodium gated channels to open so sodium diffuses in by FD , if enough sodium diffuses in , threshold is passed. impulses continue
How are synapses unidirectionalvesicles containing neurotransmitters are only found in the pre synpatic knob receptors receptors are only found in post synaptic knob so neurotransmitters cam only go from pre to post
What are excitatory and inhibitory synapsesexcitatory - synaptic synapses inhibitory - prevent transmission
differences in inhibitory synapsesPotassium channels open and K+ DIFFUSES OUT CL channels open and CL- diffuses in so more negative so threshold not passes
what is spatical summationmultiple pre synaptic neurones - lots of ach - threshold
what is temporal summationone after the other in the same place ach - threshold