Mammalian Sensory Receptors
- A cell that responds to a stimulus is called a receptor cell
- Receptor cells are transducers – they convert energy from one form (such as light, heat or sound) into energy in an electrical impulse within a sensory neurone
- Each receptor will only respond to a specific stimulus
Receptors of the body act as transducers
Receptors of the Body and their Stimuli Table
Pacinian corpuscles
- In any area of the skin, there are a range of different receptors present
- The different receptors have different structures and positions within the skin
- Pacinian corpuscles are a type of mechanoreceptor found deep in the skin
- They are present in the skin of fingers, soles of the feet as well as in joints, tendons and ligaments
- They respond to changes in pressure
- When these receptors are stimulated by pressure on the skin it leads to the establishment of a generator potential
Different skin receptors are found in different regions and have different structures
- Pacinian corpuscles connect to sensory neurones
- They consist of many layers of membrane around the end of the neurone
- The layers are separated by a gel
- The gel contains positively charged sodium ions (Na+)
- The section of neurone surrounded by layers of membrane contains stretch-mediated sodium ion channels which open when sufficient pressure is applied
- This allows (Na+) to flow into the neurone, so that an electrical potential difference is established across the cell membrane; this is a generator potential
The end of the sensory neurone is surrounded by layers of membrane
The process of converting mechanical pressure into a nervous impulse in a Pacinian corpuscle
Examiner Tip
Receptors can be cells, specifically adapted parts of a cell (e.g. the Pacinian corpuscle) or proteins on the cell surface membrane.Many sensory receptors are found in sensory organs such as the eye or ear.
