12/30/2023 0 Comments Ruffini endings![]() This results in the formation of small or large depigmented patches on the skin. Leucoderma: It is an abnormal condition of skin pigmentation in which the melanin is lost from any of the localised areas of the skin. There are the following two abnormal conditions of skin pigmentation:ġ. Melanin is responsible for the pigmentation of the skin. There should be a balanced production of melanin in our skin as too much melanin interferes with the production of vitamin D.Ībnormal conditions of melanin production Beyond providing pigmentation, melanin also plays an important role in the protection of the DNA of epidermal cells from UV ray damage. Exposure to the sun’s UV rays stimulates the keratinocytes to secrete chemicals that stimulate the melanocytes to produce more melanin that leads to the darkening of the skin. People having dark skin produce more melanin compared to pale skin members. Melanin occurs in the following two primary forms: The pigment is further transported and delivered into the cytoplasm of the keratinocytes. Melanocytes: These cells produce a pigment called melanin that is produced by an amino acid tyrosine found in the cellular vesicles called melanosomes.The insoluble keratin protein present in the superficial cells makes the epithelium impervious to water and highly resistant to mechanical abrasion. Keratinocytes: These cells form about 95 % of the total epidermal layer.The thickness of the epidermis varies at different body sites.Ĭells of the epidermis: There are the following four types of cells found in the epidermis: The epidermis consists of stratified keratinised squamous epithelium. The epidermis is a Greek word that means ‘over’ or ‘upon.’ It is the outermost avascular (without blood vessels) layer of the skin. The cross-section through the skin represents the following layers: Epidermis ![]() Human skin remains covered with the hair follicle. Skin is part of the integumentary system. Pacinian corpuscles are located deeper in the dermis and determine heavy pressure. Ruffini endings: These receptors are located in the dermis sense for heavy and continuous pressure. Meissner’s corpuscles: These are found in the superficial layer of the dermis and detect light touch and vibrations. Merkel’s cells are located in the epidermis and possess senses for softness. These are named Merkel’s cells, Meissner’s corpuscles, Ruffini endings, and Pacinian corpuscles. Mechanoreceptors: There are four different types of tactile mechanoreceptors located in the human skin.These receptors are found in the dermis around the base of the hair follicle. Pain receptors: These receptors detect any extreme mechanical stimuli that induce pain.These receptors are located in the dermis layer of the skin. Thermoreceptors: These receptors detect the change in the temperature of the external environment.A few receptors found in the skin can be discussed as follows: Different types of sensory receptors are specialised for different types of senses in our body. It possesses a number of sensory receptors. Skin serves as a sense organ and is also the largest sense organ. Nerve Terminations - CATS program of the University of Vermont College of Medicine.Fig: The Cross-Section Through the Skin Receptors in the Skin.Daley of North Carolina Wesleyan College. Stretch-sensitive muscular-free nerve endings. Neural mechanisms underlying the clasp-knife reflex in the cat. Textbook in Medical Physiology And Pathophysiology: Essentials and clinical problems.Difference in responses of free nerve endings and Ruffini-type endings innervating the cat mandibular periosteum to square wave pressure stimuli, ramp mechanical stimuli and triangular vibrations. Free nerve ending terminal morphology is fiber type specific for A delta and C fibers innervating rabbit corneal epithelium. ![]() Aδ fibres are fast-adapting, while C fibers are slow-adapting. The majority of Aδ (A delta) fibers (group III) and C (group IV) fibers end as free nerve endings.ĭifferent types of FNE can be fast-adapting, intermediate, or slow-adapting. Some FNEs can also detect stretch stimuli. These nerve endings are responsible for detecting temperature, mechanical stimuli (such as pressure), pain (nociception), and information about touch. They penetrate the epidermis and end in the stratum granulosum. They are the most common type of nerve ending, and are most frequently found in the skin. Free nerve endings are unencapsulated and have no complex sensory structures, unlike those found in Meissner's or Pacinian corpuscles. A free nerve ending ( FNE) is an unspecialized, afferent nerve ending, meaning it brings information from the body's periphery to the brain.
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