Unit 3 -Sensory receptors

Receptors

Stimulated by stimuli and they in turn stimulate sensory neurons which send messages to the brain for interpretation. Grouped according to the kind of stimulus they receive

Photoreceptor

Respond to visible wavelength of light

Mechanoreceptor

Sensitive to mechanical energy

Thermoreceptor

Sensitive to heat and cold

Osmoreceptor

Detect changes in the concentration of solutes in body fluids

Chemoreceptor

Sensitive to specific chemicals such as the concentration of oxygen in the blood

Nociceptor

A pain receptor that is sensitive to tissue damage

Proprioceptors

Found in muscles, tendons and joints and provide information about body position to the brain

Taste

Tongue contains chemoreceptors called taste buds. 4 kinds of receptor cells in taste buds that correspond to 4 basic tastes: sour, sweet, salty, and bitter. Perception result of information received from parts of tongue and sensory neurons in nose. Info sent to parietal lobe of the brain

Smell

Olfactory cells are chemoreceptors. Different chemicals in air stimulate olfactory cells and trigger an action potential.

Free nerve endings

Simple receptors with little or not specialised structures at the end.

Encapsulated nerve endings

Nerve cells end in enclosed capsules of connective tissue.

Sense organs

Contain specialised receptors and sensory neurons. For example eyes, ears.