(3) The types and functions of receptor cells linked to the central and peripheral nervous systems

Cells called receptors can detect stimuli (changes in the environment outside the organism).

Receptor cells and the stimuli they detect include:

Light receptor cells in the eyes that are sensitive to light, the light energy creates electrical signals that are sent to the brain for 'processing'.

Light receptor cells, like most animal cells, have a nucleus, cytoplasm and cell membrane.

 

Sound receptors in the ears fine hairs that are sensitive to sound vibrations in the air

There are also balance receptors in the ears that are sensitive to changes in position and enable us to keep our balance.

 

The receptors on the tongue are sensitive to chemicals and enable us to taste, and therefore detect, a wide variety of different foods (bitter, salty, sour, sweet chemical stimuli etc.) or anything else in contact with the tongue - good or bad!

 

The receptors in the nose are also sensitive to chemicals and enable us to smell all sorts of different things which may be a pleasant or unpleasant experience.

 

The receptors in the skin that are sensitive to touch, pressure, pain and to temperature changes.

Receptors are sometimes grouped and function as one unit i.e. a sense organ.

A summary of human senses

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Key points and more details about receptor cells of the central and peripheral nervous systems

Source of information is based on textbooks and syllabus-specifications for students taking the AQA GCSE, Edexcel GCSE and OCR GCSE level biology examinations (~US grades 9-10)

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Receptor Cells – Structure, Types & Functions

1. What Are Receptor Cells?

Receptors are specialised cells or proteins that detect stimuli—changes in the environment. They are found in sense organs and are the starting point for nervous responses.

Receptors are essential for the nervous system to gather information and respond appropriately.

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2. Types of Stimuli and Receptors

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3. How Receptors Are Linked to the Nervous System

a) Peripheral Nervous System (PNS)

• Receptors are connected to sensory neurons in the PNS.

• These neurons carry electrical impulses from receptors to the CNS.

b) Central Nervous System (CNS)

• The brain or spinal cord receives the signal.

• The CNS processes the information and decides on a response.

• A motor neuron carries the signal from the CNS to the effector (a muscle or gland).

Together, this forms part of a stimulus → receptor → CNS → effector pathway.

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4. Importance in Human Biology

Understanding receptor cells helps to explain:

• How the nervous system interacts with the environment.

• The role of sensory input in maintaining homeostasis and survival.

• Conditions such as nerve damage, loss of sensation, or sensory disorders.

• How reflexes protect the body (e.g. withdrawing from pain).

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5. Exam Tips

• Learn the different types of receptors and the stimuli they detect.

• Know the pathway from receptor → sensory neuron → CNS → motor neuron → effector.

• Be able to label receptor locations in a diagram of the body.

• Revise examples like pupil reflex, knee-jerk reflex, or withdrawal from heat to show how receptors trigger responses.

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Keywords, phrases and learning objectives for this part on the functions and types of receptor cells and our senses link to the CNS

Know the functions and types of receptor cells and how our senses are linked to central nervous system CNS.

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