5.3 Neuronal communication Flashcards
What is the purpose of sensory receptors? (1)
To detect change in environment
What is a transducer? (1)
Cell that converts energy from one form to another
How do pancinian corpuscles work? (3)
Pressure on skin
Deforms rings of connective tissue
Pushes against nerve ending, generating impulse
In the nervous system, what is the pathway in between the stimulus and response?
Stimulus Receptor sensory neuron Relay neuron Motor neuron Effectors Response
What is the speed of transmission of mylinated and non-mylinated neurons?
Mylinated- 100/120m/s-1
Non mylinated-2/20m/s-1
List 3 differences between motor and sensory neurons
Motor neuron longer axon
Motor neuron in CNS, sensory isn’t
Motor neuron from relay to effector, sensory from receptor to relay
Motor cell body at end, sensory cell body in middle
Describe a neuron “at rest”/resting potential
Sodium potassium pumps 3 na out, 2 k in
Potassium leaks out
Inside is negatively charged with respect to outside
Membrane is polarised
Potential difference across membrane -60mV
Describe how an action potential is generated (10)
starts at resting potential- high na inside, high k outside
na channels open some na diffuses in
membrane depolarises and reaches threshold potential (-50mV)
positive feedback cause na voltage gated channels open
k diffuses out making inside negative compared to outside again
the potential difference overshoots slightly- hyperpolarised membrane
origional potential difference is restored - cell returns to resting state
refractory period
Describe the transmission of an action potential (10)
action potential arrives at synaptic bulb
voltage gated calcium ion channels open, ca diffuses into bulb
causeing vesicles to move and fuse with membrane
acetylcholine is relased by exocytosis, diffuses across cleft
acetylcholine molecules bind to receptors on the na channels on post synaptic membrane
sodium ion channels open
if sufficient EPSP’s combine, threshold is reached
new action potential is created in post synaptic neuron
difference between convergence and divergence?
convergence- many to one
divergence- one to many
define summation.
when several EPSP’s are added together
What is meant by the all or nothing law? (1)
If threshold value isnt reached, action potential isnt generated
What is the role of synapses? (6)
allow neurons communicate convergence- many to one divergence- one to many one direction filter out low level stimuli summation- temporal or spatial habituation- reduce neural signalling following repeated stimulation because you run out of neurotransmitter memory/learning
How is strength/intensity of stimuli communicated to the brain? (2)
frequency of APs
more APs, the more intense the stimulus
