Sensory neurons

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)

---

The mechanism of the reflex arc

Sensory neurons (or afferent neurons or receptor neurons) are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical motor reflex loops and several forms of involuntary behavior, including pain avoidance. In humans, such reflex circuits are commonly located in the spinal cord.

The sensory neurons carry signals from a wide range of receptors which include:

• Baroreceptors
• Chemoreceptors
• Mechanoreceptors
• Nociceptors
• Photoreceptors
• Proprioceptors
• Taste buds
• Thermoreceptors

At the molecular level, these sensory receptors located on the cell membrane of sensory neurons are responsible for the conversion of stimuli into electrical impulses. The type of receptor employed by a given sensory neuron determines the type of stimuli it will be sensitive to. For example, neurons containing mechanoreceptors are sensitive to tactile stimuli, while olfactory receptors make a cell sensitive to odors.

In complex organisms, sensory neurons then relay their information to the central nervous system or in less complex organisms, such as the hydra, directly to motor neurons and sensory neurons also transmit information to the brain, where it can be further processed and acted upon. For example, olfactory sensory neurons make synapses with neurons of the olfactory bulb, where the sense of olfaction (smell) is processed. This information can be used by organisms to make decisions on whether to eat a particular piece of food, or whether a potential partner is ready to mate.

Types

Main article: Sensory fiber types

There are several types of sensory nerve fibers, depending on their modality etc. Examples are:

• GSA,
• GVA,
• SSA,
• SVA,
• fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain)

See also

• Afferent nerve
• Afferent pathways
• Auditory neurons
• Receptive fields
• Taste disorders
• Type Ia sensory fiber
• Nerve
• Pseudounipolar neuron