The Nervous System Flashcards
3 examples of stimuli
Temperature
Chemicals
Light intensity/wavelength/ duration
What is a receptor
Specialised sensory cell
Detects internal or external stimuli
Converts one form of energy into electrochemical energy
What is the coordinator
The CNS
Processes info
Initiates appropriate response
What is an effector
Muscles or glands
Bring about the response
What’s the difference between depolarisation and action potentials
Axon membrane depolarises when above -70mV
Action potential is when the inside of the axon becomes positively charged
What is the refractory period
Na+ channels are inactivated
Inward movement of Na+ ions is prevented
Another action potential cannot be generated
Why is there a refractory period
Action potentials can only go in one direction
A second action potential is separated from the first
What 3 factors affect the speed of the impulse
Temperature
Diameter of the axon
Presence or absence of myelin sheath
How does the diameter of the axon affect the speed
Increasing the diameter of the axon reduces the resistance of the axoplasm. Lower resistance causes the current to flow further
What causes acetylcholine to be released
Synaptic vesicles fuse with the presynaptic membrane
What depolarises the postsynaptic neurone
Acetylcholine
What hydrolyses acetylcholine
Acetylcholinesterase
What are the resulting molecules of acetylcholine hydrolysed
Choline and ethanoic acid
What do the resulting molecules do
Choline and ethanoic acid
What happens to choline and ethanoic acid
Diffuse back across the synaptic cleft
Reform to acetylcholine using ATP
