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15.1.414-15 · Homeostasis and Control

Sensory Receptor Cells — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

5 min read 6 parts Lesson 19 of 31 1 quiz

📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision
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Lesson summary

15.1.4 Sensory Receptor Cells — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Explain how receptor cells act as transducers and when they generate impulses.Definition — a cell that responds to a stimulus.Transducers — they convert energy in one form, such as light, …

  • Specialised cells
  • Neurone endings
  • Stimulation
  • Weak stimulus
  • Strong enough
  • Threshold potential

Section 1 of 6Receptor cells

Definition
  • Definition a cell that responds to a stimulus.
Transducers
  • Transducers they convert energy in one form, such as light, heat or sound, into electrical energy in a sensory neurone.
Location
  • Location often in sense organs, such as light receptors in the eye.

Section 2 of 6Types of receptor

Types of receptor
Specialised cells
  • Specialised cells for example light receptors in the eye and chemoreceptors in the taste buds, which detect one type of stimulus.
Neurone endings
  • Neurone endings some touch receptors are the ends of sensory neurones themselves.

Section 3 of 6Depolarisation and threshold

Stimulation
  • Stimulation receptor cells are depolarised when stimulated.
Weak stimulus
  • Weak stimulus the cell is not sufficiently depolarised and no impulses are sent.
Strong enough
  • Strong enough the sensory neurone is activated and sends impulses to the CNS.
Threshold potential
  • Threshold potential an impulse is sent only if the membrane potential rises above this value.

Section 4 of 6Stimulus strength

Receptor potential
  • Receptor potential increases as stimulus strength increases.
Frequency
  • Frequency beyond the threshold, the frequency of impulses increases, not their amplitude.
Adaptation
  • Adaptation thresholds often rise with continued stimulation, so a larger stimulus is needed.

Section 5 of 6Key terms

TermMeaning
Receptor cellCell that responds to a stimulus.
TransducerConverts one form of energy to another.
ChemoreceptorReceptor detecting chemicals.
Receptor potentialDepolarisation of a receptor cell.
Threshold potentialMembrane potential needed to trigger an impulse.

Section 6 of 6Exam technique

1
Saying receptors create energy — they transduce energy into an electrical signal.
2
Saying stronger stimuli give bigger impulses — they give more frequent impulses.
3
Saying every stimulus triggers an impulse — the threshold must be passed.
4
Thinking all receptors are specialised cells — some are neurone endings.

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