the nervous system - definitions

Question 1

response

Answer 1

an action we take

Question 2

stimuli

Answer 2

anything in our surroundings that causes an action

Question 3

threshold

Answer 3

minimum level of stimulus required for impulse transmission

Question 4

neuron

Answer 4

nerve cell

Question 5

3 types of neurons

Answer 5

sensory
motor
interneurons

Question 6

sensory (afferent)

Answer 6

neurons take messages from sense organs to CNS

Question 7

motor (efferent)

Answer 7

neurons take messages from CNS to muscles or glands, causing a response

Question 8

interneurons (relay)

Answer 8

carry information between sensory + motor neurons. only in CNS

Question 9

parts of neurons (nerve cells)

Answer 9

Schwann cell
myelin sheets
dendrite
axon
nodes of Ranvier
cell body
neurotransmitters swellings

Question 10

Schwann cell

Answer 10

secretes or maintains myelin sheets

Question 11

myelin sheath

Answer 11

insulates
rises transmission rate

Question 12

dendrite

Answer 12

transmits impulse to cell body

Question 13

axon

Answer 13

transmits impulse away from cell body

Question 14

nodes of Ranvier

Answer 14

gaps in the myelin sheath, speed up the passage of an impulse

Question 15

cell body

Answer 15

produces neurotransmitter chemicals contains nucleus + cell organelles (mitochondria)

Question 16

ganglion

Answer 16

group of cell bodies located outside CNS

Question 17

another name of neurotransmitter swellings

Answer 17

synaptic knobs

Question 18

synaptic knobs

Answer 18

release neurotransmitter chemicals that carry an impulse from one nerve cell to another

Question 19

synapse

Answer 19

region where two neurons come into close contact

Question 20

synaptic cleft

Answer 20

the gap between two neurons, bridged by chemicals (neurotransmitters)

Question 21

describe the sequence of events that allows an impulse to be transmitted across a synapse from one neuron to the next

Answer 21

• 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

Question 22

suggest a possible role for a drug in relation to the events that you outlined in (i)

Answer 22

drugs can be used to inhibit (antagonists) or enhance (agonists) transmission of an impulse