Which cells detect stimuli

During hearing, mechanoreceptors in hair cells of the inner ear detect vibrations conducted from the eardrum. During taste, sensory neurons in our taste buds detect chemical qualities of our foods including sweetness, bitterness, sourness, saltiness, and umami savory taste.

During smell, olfactory receptors recognize molecular features of wafting odors. During touch, mechanoreceptors in the skin and other tissues respond to variations in pressure. Adequate stimulus can be used to classify sensory receptors.

Somatic sensory receptors near the surface of the skin can usually be divided into two groups based on morphology:. A tonic receptor is a sensory receptor that adapts slowly to a stimulus, while a phasic receptor is a sensory receptor that adapts rapidly to a stimulus. Learning Objectives Differentiate among the types of stimuli to which receptors respond. Key Points Chemoreceptors detect the presence of chemicals.

Thermoreceptors detect changes in temperature. Mechanoreceptors detect mechanical forces. Privacy Policy. Skip to main content. Peripheral Nervous System. Search for:. Sensory Receptors. Classification of Receptors by Stimulus Sensory receptors are primarily classified as chemoreceptors, thermoreceptors, mechanoreceptors, or photoreceptors. Learning Objectives Differentiate among the types of stimuli to which receptors respond.

Key Takeaways Key Points Chemoreceptors detect the presence of chemicals. Thermoreceptors detect changes in temperature. Mechanoreceptors detect mechanical forces. Photoreceptors detect light during vision. More specific examples of sensory receptors are baroreceptors, propioceptors, hygroreceptors, and osmoreceptors. Sensory receptors perform countless functions in our bodies mediating vision, hearing, taste, touch, and more.

Key Terms photoreceptor : A specialized neuron able to detect and react to light. Classification of Receptors by Location Some sensory receptors can be classified by the physical location of the receptor. Learning Objectives Differentiate among sensory receptors by location. Key Takeaways Key Points Sensory receptors that share a common location often share a related function. Free nerve endings can be stimulated by several different stimuli, thus showing little receptor specificity.

For example, pain receptors in your gums and teeth may be stimulated by temperature changes, chemical stimulation, or pressure. The first step in sensation is reception: the activation of sensory receptors by stimuli such as mechanical stimuli being bent or squished, for example , chemicals, or temperature. The receptor can then respond to the stimuli. Think for a moment about the differences in receptive fields for the different senses.

For the sense of touch, a stimulus must come into contact with body. For the sense of hearing, a stimulus can be a moderate distance away. For vision, a stimulus can be very far away; for example, the visual system perceives light from stars at enormous distances.

Visual sensory system : This scheme shows the flow of information from the eyes to the central connections of the optic nerves and optic tracts, to the visual cortex. Area V1 is the region of the brain which is engaged in vision. Transduction is the process that converts a sensory signal to an electrical signal to be processed in a specialized area in the brain. The most fundamental function of a sensory system is the translation of a sensory signal to an electrical signal in the nervous system.

This takes place at the sensory receptor. The change in electrical potential that is produced is called the receptor potential. How is sensory input, such as pressure on the skin, changed to a receptor potential? As an example, a type of receptor called a mechanoreceptor possesses specialized membranes that respond to pressure.

Disturbance of these dendrites by compressing them or bending them opens gated ion channels in the plasma membrane of the sensory neuron, changing its electrical potential. Receptor potentials are graded potentials: the magnitude of these graded receptor potentials varies with the strength of the stimulus. If the magnitude of depolarization is sufficient that is, if membrane potential reaches a threshold , the neuron will fire an action potential.

In most cases, the correct stimulus impinging on a sensory receptor will drive membrane potential in a positive direction, although for some receptors, such as those in the visual system, this is not always the case. Mechanoreceptor activation : a Mechanosensitive ion channels are gated ion channels that respond to mechanical deformation of the plasma membrane. A mechanosensitive channel is connected to the plasma membrane and the cytoskeleton by hair-like tethers.

When pressure causes the extracellular matrix to move, the channel opens, allowing ions to enter or exit the cell. When a sound causes the stereocilia to move, mechanosensitive ion channels transduce the signal to the cochlear nerve. Sensory receptors for the various senses work differently from each other.

They are specialized according to the type of stimulus they sense; thus, they have receptor specificity.