Nervous Communication Flashcards
Dendrins
To cell body
Axon
Away from cell body
Motor vs sensory
Motor cell body at end sensory in centre
Motor = no dendrimer Sensory= dendron
Motor cell body in cns sensory cell body in pns
Myelinated neuron
Insulated neuron impulse at faster speed
Node of ranvier electrical impulse jump from node to node saltatory process
Sensory receptor
Acts as transducer converts stimulus into nervous impulse
Pascinian corpuscle
Resting potential
Pressure -> Na channels change shape
Na channels open Na diffuse in
Depolarised -> generator potential
Action potential
Stimulus cause na + channels to open na+ diffuse in
Depolarisation if pd big enough reach threshold open vgscs and more Na+ diffuse in
Repolarisation Na channels close K channels open K+ let out
Hyperpolaristaion vgpcs close
Resting potential
Refractory period
K+ channels delayed close so AP doesn’t move backward unidirectional
Propagation
Movement of ap along neurone
Na diffuse sideways causing vgscs in adjacent region to open along neuron
Saltatory conduction
Depolarisation only occurs at nodes Ap jumps from node to node
Speedier reduce Na channels opening and closing
Less ATP
Synapses
Ap reaches end of synaptic knob depolarisation causes Ca channels to open
This causes vesicles containing neurotransmitter to fuse w membrane
Neurotransmitter diffuse across cleft
Bind w receptor opening Na channels
If threshold Ap generated
Somatic nervous system
Voluntary actions
Autonomic
Sympathetic fight or flight
Parasympathetic rest and digest
Brain responsible for controlling heart rate
Medulla oblongata
2 centres within medulla
Impulse through sympathetic - accelerator nerve
Impulse through parasympathetic- vagus nerve
Change in pH
Chemoreceptors
If CO2 increase carbonic acid forms decrease in pH - increase heart rate
Blood flows quicker to lungs
If blood pH increases - recept in aorta/carotid arteries reduction of impulses sent to medulla sent to SAN
Pressure changes
Baroreceptors in aorta/carotid arteries detect
If too high impulse to medulla oblongata then sends impulse along parasympathetic to SAN to decrease heart rate
If too low impulse sent to medulla oblongata which sends impulse down sympathetic neuron to incr heart rate
Neuron at rest
3 Na in
2K out
Potassium most permeable to facilitated diffusion
Electrochemical gradient exists
More positive ions outside the cell than inside - electrochemical gradient
Direction of ions during depolarisation
Na into the cytoplasm
