Receptors are of many kinds those concerned with general bodily sensibility or somesthetic sensibility, touch, pressure, heat, cold, paid, temperature, position, movement, and those which form organs of special senses (smell, sight, taste, hearing and head position and movement). They may also be classified as exteroceptors, the receptors, affected by external stimuli (touch light, pressure cutaneous pain […]
Visceral efferent fibers are myelinated fibers terminating in cardiac muscle, smooth muscle of viscera, blood vessels, hairs and glands. The nerve fibres form plexuses around the muscle bundles. From these plexuses fine fibres pass to individual muscle fibre. In glandular epithelium, the nerve fibers from plexus beneath the basement membrane through which fibers pass to
Motor end plate (Somatic efferent fibers) Nerve fibre outer perimysium and branch to pass to individual muscle fibres where they end in structures called motor end plate. At the end plate region the myelin is lost and endoneurium becomes continuous with endomysium of muscle fibre. The axon devoid of its sheath divides to fine terminations which
Axons which form peripheral fibers terminate in some peripheral structure to which or from which they convey nerve impulses. Efferent fibers terminate in tissues which are excited into activity by the nerve impulses somatic efferent fibers in voluntary striated muscle and visceral efferent in smooth muscle or secretory epithelium. These are called effector organs. Afferent
The nerve fibre is essentially a highly irritable conductor. Along it the dynamic nervous excitation propagates in waves, faster in large than in small axons. During the conduction of excitation the activity of one portion of the axon, serves as a stimulate activating the next portion, and so on. As the nerve fibres become active
Nerves are profusely supplied by blood vessels. There are inter-fascicular, perineurial, intra-fascicular arteries and arterioles. Endoneurium contains a capillary network.
A cross section of a peripheral nerve shows that it is surrounded by a sheath of loose connective tissue called epineurium inside this wrapping several bundles of nerve fibres are seen and each of these is surrounded by a dense connective tissue sheath called perineurium. Inside these bundles are the nerve fibres. Each nerve fibre
Sometimes called fibers of Remak. There is no medullary or myelin sheath Axis cylinder is very slender and the thin neurolemma sheath contains scattered nuclei of Schwann cells. There are no nodes of Ranvier, up to a dozen or more of these nerve fibres are enclosed by the cytoplasm of the same sheath of Schwann
The medullated nerve fibers of the peripheral nervous system consist of the axon, myelin or medullary sheath and neurolemma. In the central nervous system, instead of the neurolemma, there is an irregular covering made of glial cells. Myelin forming the myelin sheath is glistening while when fresh, but with osmic acid fixation becomes grey or
Neurolemma or sheath of Schwann This is a thin tube like membranes or sheath, containing a nucleus surrounded by cytoplasm and is also known as schwann’s cell. The neurolemma forms sheath of the axon in all peripheral nerves and inside the central nervous system there is no neurolemma but the nerve fibres have a neurolemma and
