fiber1(redirected from A f's)
an elongated threadlike anatomical structure.
myelinated fibers of the somatic nervous system having a diameter of 1 to 22 μm and a conduction velocity of 5 to 120 meters per second.
accelerating f's, accelerator f's
adrenergic fibers that transmit the impulses which accelerate the heartbeat.
nerve fibers that liberate epinephrine-like substances at the time of passage of nerve impulses across a synapse.
motor and proprioceptive fibers of the A type having conduction velocities of 70 to 120 meters per second and ranging from 13 to 22 μm in diameter.
any of the bow-shaped fibers in the brain, such as those connecting adjacent gyri in the cerebral cortex, or the external or internal arcuate fibers of the medulla oblongata.
nerve fibers that interconnect portions of the cerebral cortex within a hemisphere. Short association fibers interconnect neighboring gyri; long fibers interconnect more widely separated gyri and are arranged into bundles or fasciculi.
myelinated preganglionic autonomic axons having a fiber diameter less than 3 μm and a conduction velocity of 3 to 15 meters per second.
the fibers holding staples of wool in a fleece together so that the fleece can be handled as a unit.
touch and temperature fibers of the A type having conduction velocities of 30 to 70 meters per second and ranging from 8 to 13 μm in diameter.
unmyelinated postganglionic fibers of the autonomic nervous system; also, the unmyelinated fibers at the dorsal roots and at free nerve endings having a diameter of 0.3 to 1.3 μm and a conduction velocity of 0.6 to 2.3 meters per second.
nerve fibers that liberate acetylcholine at the synapse.
fibers running in a circle, e.g. in the ciliary muscle of the eye around the corneoscleral junction.
collagen f's, collagenic f's, collagenous f's
the soft, flexible, white fibers that are the most characteristic constituent of all types of connective tissue, consisting of the protein collagen, and composed of bundles of fibrils that are in turn made up of smaller units (microfibrils) that show a characteristic crossbanding with a major periodicity of 65 nm.
nerve fibers which, when stimulated reflexly, cause a diminished vasomotor tone and thereby a decrease in arterial pressure.
yellowish fibers of elastic quality traversing the intercellular substance of connective tissue.
fibers that conduct touch and pressure impulses and innervate the intrafusal fibers of the muscle spindle; they conduct at velocities of 15 to 40 meters per second and range from 3 to 7 μm in diameter.
unmyelinated nerve fibers found largely in the sympathetic nerves.
modified muscle fibers which, surrounded by fluid and enclosed in a connective tissue envelope, compose the muscle spindle.
auxiliary conduction fibers from the atrium to the ventricle that bypass the A-V bundle. See also mahaim fibers.
muscle fibers poor in sarcoplasm and more transparent than dark fibers.
see mahaim fibers.
fibers of the ciliary muscle of the eye, running in an anterior-posterior direction.
nerve fibers transmitting motor impulses to a muscle.
grayish-white nerve fibers encased in a myelin sheath.
a slender process of a neuron, especially the prolonged axon which conducts nerve impulses away from the cell; classified on the basis of the presence or absence of a myelin sheath as myelinated or unmyelinated.
osteogenetic f's, osteogenic f's
precollagenous fibers formed by osteoblasts and becoming the fibrous component of bone matrix.
nerve fibers passing to involuntary muscle and gland cells, the cell bodies of which lie in the autonomic ganglia.
nerve fibers passing to the autonomic ganglia, the cell bodies of which lie in the brain or spinal cord.
nerve fibers which, when stimulated reflexly, cause or increase vasomotor tone.
bundles of axons that connect the cerebral cortex with the subcortical centers, brainstem and spinal cord.
modified cardiac muscle fibers in the subendothelial tissue concerned with conducting impulses in the heart.
fibers in the roots of the spinal nerves.
immature connective tissue fibers, staining with silver, forming the reticular framework of lymphoid and myeloid tissue, and occurring in interstitial tissue of glandular organs, the papillary layer of the skin, and elsewhere.
1. collagenous fibers that pass from the periosteum and are embedded in the outer circumferential and interstitial lamellae of bone.
2. terminal portions of principal fibers that insert into the cementum of a tooth.
the microtubules radiating from the centrioles during mitosis and forming a spindle-shaped configuration.
nerve fibers that lack a myelin sheath.
extensions of the ciliary processes attaching to the lens suspending it around its periphery.