Module 5 overview OCR A Level Biology EXAM
COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS)
|ALREADY GRADED A+
,Neurone - ✔✔ANSWER✔✔-A cell that transmits electrical
impulses in the nervous system
Structure of a neurone - ✔✔ANSWER✔✔-Cell body,
dendrons, axons
Cell body - ✔✔ANSWER✔✔-Contains the nucleus
surrounded by cytoplasm, which also contains rough
endoplasmic reticulum and mitochondria for
neurotransmitter synthesis
Dendron - ✔✔ANSWER✔✔-Extensions coming from the
cell body which branch off into dendrites; transmit
electrical impulses towards the cell body
Axon - ✔✔ANSWER✔✔-Elongated nerve fibre which
transport electrical impulses away from the cell body
which is surrounded by a very thin layer of cytoplasm
(often 1 micrometre) and a cell membrane
Sensory neurone - ✔✔ANSWER✔✔-Carries impulses
from the sensory organs/receptors to somewhere else
(relay neurone, motor neurone, CNS); often have one
dendron and one axon
Relay neurone - ✔✔ANSWER✔✔-Carries impulses from
sensory neurone to motor neurone; short axon and
dendron
, Motor neurone - ✔✔ANSWER✔✔-Carries impulses from
sensory/relay neurone to the effector; long axon and many
short dendrites
Examples of effectors - ✔✔ANSWER✔✔-Muscles and
glands
Common nerve pathway - ✔✔ANSWER✔✔-Receptor ⮕
sensory neurone ⮕ relay neurone ⮕ motor neurone ⮕
effector cell
Myelination - ✔✔ANSWER✔✔-Production of the myelin
sheath around a neurone's axon, allows saltatory
conduction
Saltatory conduction - ✔✔ANSWER✔✔-The jumping of
action potentials from node to node; faster than a 'normal'
impulse speed (100m/s vs 1m/s)
Schwann cells - ✔✔ANSWER✔✔-Cell that wraps around
the axon many times to form the myelin sheath, mostly
lipid based
Node of Ranvier - ✔✔ANSWER✔✔-Gaps in the myelin
sheath of a nerve, between adjacent Schwann cells
Pacinian corpuscles - ✔✔ANSWER✔✔-Located in skin;
example of a mechanoreceptor
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