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In the nervous system, Afferent pathways are made of bundles of afferent neurons --otherwise known as sensory or receptor neurons-- which carry nerve impulses from receptors or sense organs toward the central nervous system.

This term can also be used to describe relative connections between structures. Afferent neurons communicate with specialized interneurons. (The opposite activity of direction or flow is efferent.)

In the nervous system there is a "closed loop" system of sensation, decision, and reactions. This process is carried out through the activity of afferent neurons, interneurons, and efferent neurons.

A touch or painful stimulus, for example, creates a sensation in the brain only after information about the stimulus travels there via afferent nerve pathways. Afferent neurons are pseudounipolar neurons, that have a single long dendrite and a short axon, and a smooth and rounded cell body. The dendrite is structurally and functionally similar to an axon, and is myelinated; it is these axon-like dendrites that make up the afferent nerves. Just outside the spinal cord, thousands of afferent neuronal cell bodies are aggregated in a swelling in the dorsal root known as the dorsal root ganglion. (See efferent nerve.)

Contents 1 Etymology and mnemonics 2 See also 3 References 4 External links

[edit] Etymology and mnemonics

Both afferent and efferent come from french, as evolution from latin (much used in medicine) of respectively ad ferentes (latin verb fero : I carry), meaning carrying into, and ex ferentes, meaning carrying away. Ad and ex give an easy mnemonic device for remembering the relationship between afferent and efferent : afferent connection arrives and an efferent connection exits.^[1]

[edit] See also

• Leminiscal system
• Spinalthalamic tracts
• Dorsal horns
• Efferent pathways
• Receptor fields

[edit] References

1. ↑ Mnemonic at medicalmnemonics.com 3502 3463 367 115

[edit] External links

• Dorlands/Elsevier n_07/12569826

v·d·e Histology: nervous tissue
Neurons (gray matter)	soma, axon (axon hillock, axoplasm, axolemma, neurofibril/neurofilament), dendrite (Nissl body, dendritic spine, apical dendrite, basal dendrite) types (bipolar, pseudounipolar, multipolar, pyramidal, Purkinje, granule)
Afferent nerve/Sensory nerve/Sensory neuron	GSA, GVA, SSA, SVA, fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain)
Efferent nerve/Motor nerve/Motor neuron	GSE, GVE, SVE, Upper motor neuron, Lower motor neuron (α motorneuron, γ motorneuron)
Synapses	neuropil, synaptic vesicle, neuromuscular junction, electrical synapse - Interneuron (Renshaw)
Sensory receptors	Free nerve ending, Meissner's corpuscle, Merkel nerve ending, Muscle spindle, Pacinian corpuscle, Ruffini ending, Olfactory receptor neuron, Photoreceptor cell, Hair cell, Taste bud
Glial cells	astrocyte, oligodendrocyte, ependymal cells, microglia, radial glia
Myelination (white matter)	Schwann cell, oligodendrocyte, nodes of Ranvier, internode, Schmidt-Lanterman incisures, neurolemma
Related connective tissues	epineurium, perineurium, endoneurium, nerve fascicle, meninges

This page uses content from the English-language version of Wikipedia. The original article was at Afferent nerve. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.