What is a sensory receptor?
A structure throughout the body, general or specialized, that converts specific stimuli (like heat or light) into electrical action potentials.
Why must stimuli be converted into action potentials?
Action potentials are the only type of information the central nervous system (CNS) can understand
What is transduction?
The process where a sensory receptor converts a stimulus into an action potential.
What is a sensation?
Information received by a sensory receptor, transduced into an action potential, and sent to the CNS.
What is perception?
The conscious awareness that results from the CNS interpreting a signal.
Why don’t we perceive every sensation?
The brain filters most sensations within the brainstem and thalamus and does not transmit them to the cerebrum.
What is adaptation?
The process where the brain ignores a baseline stimulus over time and only responds to changes. For example, we quickly adapt to smells and the feel of clothing, but not to pain.
What do Chemoreceptors sense?
Changes in chemicals dissolved in air or fluids (like saliva and blood)
What do Olfactory receptors sense?
Odorants carried in the air, which the brain perceives as smell. (They are a type of Chemoreceptor).
What do Gustatory receptors sense?
Molecules dissolved in saliva, which the brain perceives as taste. (They are a type of Chemoreceptor).
Where are Chemoreceptors found besides the nose and tongue?
In the stomach (monitor digestive juices) and the brain (monitor hormone, water, and carbon dioxide concentrations).
What do Thermoreceptors sense?
Changes in temperature. (They are free nerve endings ).
What do Nociceptors sense?
Pain. (They are free nerve endings ).
What do Photoreceptors sense?
Changes in light.
Where are Photoreceptors located?
Within the retina of the eye.
What do Mechanoreceptors sense?
Distortions of their shape
What are Rods and Cones?
Photoreceptors in the retina.
What are the key functions of Cones?
Found in the center of the retina (fovea); most sensitive to colorful stimuli and work best in bright light.
What are the key functions of Rods?
Found toward the edges of the retina; most sensitive to motion; adjust quickly to dim light but are easily bleached out by bright light.
What type of receptor is found in the ear?
Mechanoreceptors.
What stimuli do the ear’s receptors respond to?
Mechanical distortions caused by sound waves and the motion of the head.
What is a Corpuscle?
A capsulated mechanoreceptor where the nerve fibers are enclosed within a capsule that distorts when disturbed.
What are Tactile corpuscles (Merkel cells)?
Skin mechanoreceptors found in the basal layer of the epidermis that respond to fine touch and pressure stimuli.
What are Pacinian corpuscles?
Skin mechanoreceptors found deep in the subcutaneous layer that respond to deep pressure.
