the nervous system - definitions Flashcards
response
an action we take
stimuli
anything in our surroundings that causes an action
threshold
minimum level of stimulus required for impulse transmission
neuron
nerve cell
3 types of neurons
sensory
motor
interneurons
sensory (afferent)
neurons take messages from sense organs to CNS
motor (efferent)
neurons take messages from CNS to muscles or glands, causing a response
interneurons (relay)
carry information between sensory + motor neurons. only in CNS
parts of neurons (nerve cells)
Schwann cell
myelin sheets
dendrite
axon
nodes of Ranvier
cell body
neurotransmitters swellings
Schwann cell
secretes or maintains myelin sheets
myelin sheath
insulates
rises transmission rate
dendrite
transmits impulse to cell body
axon
transmits impulse away from cell body
nodes of Ranvier
gaps in the myelin sheath, speed up the passage of an impulse
cell body
produces neurotransmitter chemicals contains nucleus + cell organelles (mitochondria)
ganglion
group of cell bodies located outside CNS
another name of neurotransmitter swellings
synaptic knobs
synaptic knobs
release neurotransmitter chemicals that carry an impulse from one nerve cell to another
synapse
region where two neurons come into close contact
synaptic cleft
the gap between two neurons, bridged by chemicals (neurotransmitters)
describe the sequence of events that allows an impulse to be transmitted across a synapse from one neuron to the next
- the arrival of the impulse at the synapse, the synaptic vesicles secrete a neurotransmitter substance
- neurotransmitter diffuses across the synaptic cleft and combines with receptors on the post-synaptic neuron
- electrical impulse is then regenerated in the post synaptic neuron
- neurotransmitter is broken down by enzymes and is reabsorbed back into neurotransmitter swellings in the post synaptic neuron
suggest a possible role for a drug in relation to the events that you outlined in (i)
drugs can be used to inhibit (antagonists) or enhance (agonists) transmission of an impulse
