Aδ fiber

(noun)

Carries sensory information related to muscle spindle secondary endings, touch, and kinesthesia.

Related Terms

Examples of Aδ fiber in the following topics:

  • Pain Sensation

    • The first phase is mediated by the fast-conducting Aδ fibers, and the second part is due to C fibers.
    • The pain associated with the Aδ fibers can be associated to an initial extremely sharp pain.
    • A delta fibers (Aδ fibers), a type of sensory fiber, are associated with the sensation of cold and pressure.
    • Aδ fibers are thinly myelinated; therefore, they conduct signals more rapidly than unmyelinated C fibers, but more slowly than other, more thickly myelinated "A" class fibers.
    • Aδ fibers terminate at Rexed laminae I and V (labeled I and V in the diagram).

  • Tactile Sensation

    • They are all innervated by Aβ fibers, except the mechanoreceiving free nerve endings, which are innervated by Aδ fibers.
    • A single afferent nerve fiber branches to innervate up to 90 such endings.

  • Dietary Fiber

    • Lignin, a major dietary insoluble fiber source, may alter the fate and metabolism of soluble fibers.
    • The term "fiber" is something of a misnomer since many types of so-called dietary fiber are not actually fibrous.
    • Dietary fiber is found in plants.
    • Fiber-rich plants can be eaten directly.
    • The plum's skin is a source of insoluble fiber while soluble fiber is in the pulp.

  • Characteristics of Connective Tissue

    • Connective tissue fibers provide support.
    • Three types of fibers are found in connective tissue:
    • Elastic fibers are long, thin fibers that form branching network in the extracellular matrix.
    • Reticular fibers are short, fine collagenous fibers that can branch extensively to form a delicate network.
    • Collagen fibers are the strongest and most abundant of all the connective tissue fibers.

  • Overview of Motor Integration

    • When a motor unit is activated, all of its fibers contract.
    • The number of muscle fibers within each unit can vary.
    • Motor units are generally recruited in order of smallest to largest (from fewest fibers to most fibers) as contraction increases.
    • These small motor units may contain only 10 fibers per motor unit.
    • These muscles may have as many as a thousand fibers in each motor unit.

  • Slow-Twitch and Fast-Twitch Muscle Fibers

    • Most muscles are made up of combinations of these fibers, although the relative number substantially varies.
    • Unlike slow-twitch fibers, fast twitch-fibers rely on anaerobic respiration (glycolysis alone) to produce two molecules of ATP per molecule of glucose.
    • As fast-twitch fibers generally do not require oxygenation, they contain fewer blood vessels and mitochondria than slow-twitch fibers and less myoglobin, resulting in a paler colour.
    • Muscles controlling eye movements contain high numbers of fast-twitch fibers (~85% fast-twitch).
    • Describe the different types of skeletal muscle fibers and their respective functions

  • Classification of Nerves

    • These classifications apply to both sensory and motor fibers.
    • The A group is further subdivided into four types (A-alpha, A-beta, A-delta, and A-gamma fibers) based on the information carried by the fibers and the tissues they innervate.
    • The primary role of B fibers is to transmit autonomic information.
    • C fiber axons are grouped together into what is known as Remak bundles.
    • A-delta and C fibers both contribute to the detection of diverse painful stimuli.

  • Parasympathetic (Craniosacral) Division

    • The motor root carries presynaptic parasympathetic nerve fibers (general visceral efferent fibers) that terminate in the ganglion by synapsing the postsynaptic fibers traveling to target organs.
    • The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without synapsing.
    • The sensory root carries general sensory fibers (general somatic afferent fibers) that also do not synapse in the ganglion.
    • Some ganglia also carry special sensory fibers (special visceral afferent) for taste sensation.
    • Pre- and post-ganglionic fibers and targets are depicted.

  • Preganglionic Neurons

    • In the autonomic nervous system (ANS), nerve fibers that connect the central nervous system to ganglia are known as preganglionic fibers.
    • In the autonomic nervous system (ANS), fibers from the central nervous system to the ganglion are known as preganglionic fibers.
    • Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord while parasympathetic preganglionic fibers tend to project to and synapse with the postganglionic fiber close to the target organ.
    • Another major difference between the two ANS systems is divergence, or the number of postsynaptic fibers a single preganglionic fiber synapses with.
    • Pre- and post-ganglionic fibers and targets are depicted.

  • Structural Elements of Connective Tissue

    • Elastic fibers (or yellow fibers) are bundles of proteins (elastin) found in extracellular matrix of connective tissue and produced by fibroblasts and smooth muscle cells in arteries.
    • These fibers can stretch up to 1.5 times their length and snap back to their original length when relaxed.
    • Elastic fibers include elastin, elaunin, and oxytalan.
    • Reticular fibers or reticulin is a histological term used to describe a type of fiber in connective tissue composed of type III collagen.
    • Reticular fibers crosslink to form a fine meshwork (reticulin).