The change in hair color occurs when melanin ceases to be produced in the hair root and new hairs grow in without pigment. The stem cells at the base of hair follicles produce melanocytes, the cells that produce and store pigment in hair and skin. The death of the melanocyte stem cells causes the onset of graying.
Hereof, what are hair and nails made up of?
A nail is a horn-like envelope covering the tips of the fingers and toes in most primates and a few other mammals. Nails are similar to claws in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin. This protein is also found in the hooves and horns of different animals.
How is the growth of hair and nails similar?
Hair and Nails. Along with the skin, the integumentary system includes the nails and hair. Both the nails and hair contain the tough protein, keratin. Keratin is similar in toughness to chitin, the carbohydrate found in the exoskeleton of arthropods.
What type of cells produce melanin?
Melanin is a pigment that is produced by cells known as melanocytes in the skin of most animals. It comes in two basic forms: eumelanin (brownish color) and pheomelanin (reddish-brown color). The production of melanin is affected by UV exposure, genetic make-up, size of melanocytes, and disease conditions.
Which abbreviation stands for a cancerous tumor?
Which abbreviation stands for cancerous tumor. MM. Which procedure removes fat under skin.
What is not a component of sweat?
Sweat is composed of several components: Water, which is the primary component, and makes up 99% of sweat. Salts, which are released as part of the excretory, waste removal function of the skin. Urea, which is another waste product.
Where are the apocrine sweat glands located?
In humans, apocrine sweat glands are found only in certain locations of the body: the axillae (armpits), areola and nipples of the breast, ear canal, eyelids, wings of the nostril, perianal region, and some parts of the external genitalia.
How do the cells of stratum corneum and stratum Basale differ?
Grows from the hair follicle when epidermis cells divide and old cells move out and get keratonized. How do the cells of stratum corneum and stratum basale differ? Cells of the stratum basale are cuboidal to columnar and cells of the stratum corneum are made of keratin.
What does cyanosis?
Cyanosis is defined as the bluish or purplish discolouration of the skin or mucous membranes due to the tissues near the skin surface having low oxygen saturation. The name cyanosis literally means the blue disease or the blue condition.
Which vitamin is synthesized in the skin?
Only a few foods contain vitamin D. The major natural source of the vitamin is synthesis of cholecalciferol in the skin from cholesterol through a chemical reaction that is dependent on sun exposure (specifically UVB radiation).
What are the characteristics of cells in the epidermis?
Skin has three layers:
The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
The dermis, beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
Which type of sweat gland is most important in maintaining normal body temperature?
The eccrine sweat gland, which is controlled by the sympathetic nervous system, regulates body temperature. When internal temperature rises, the eccrine glands secrete water to the skin surface, where heat is removed by evaporation.
What is responsible for goosebumps?
Goose bumps are created when tiny muscles at the base of each hair, known as arrector pili muscles, contract and pull the hair erect. The reflex is started by the sympathetic nervous system, which is responsible for many fight-or-flight responses.
How do melanocytes and keratinocytes work together to protect the skin from UV damage?
Melanin protects melanocytes and keratinocytes against H2O2-induced DNA strand breaks through its ability to bind Ca2+. These compounds are highly reactive and can induce DNA lesions in epidermal cells. Melanin is considered to protect human skin against DNA damage by absorbing UV radiation.
What stimulates the secretion of sebum?
Sex steroids are known to affect the rate of sebum secretion; androgens such as testosterone have been shown to stimulate secretion, and estrogens have been shown to inhibit secretion. Dihydrotestosterone acts as the primary androgen in the prostate and in hair follicles.
Are stem cells found in the epidermis?
These stem cells are found in the basal layer of the epidermis. Hair follicle stem cells ensure constant renewal of the hair follicles. They can also regenerate the epidermis and sebaceous glands if these tissues are damaged. Hair follicle stem cells are found throughout the hair follicles.
What layer of skin is the hair follicle in?
The thick bottom layer of the dermis (the inner layer of the skin). The reticular dermis has blood vessels and connective tissue that supports the skin. Hair follicles, oil and sweat glands, and other structures are also found in the reticular dermis.
Where is the hair formed?
Hair is made of a tough protein called keratin. A hair follicle anchors each hair into the skin. The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft.
Where is the hair bulb located?
The bulge is located in the outer root sheath at the insertion point of the arrector pili muscle. It houses several types of stem cells, which supply the entire hair follicle with new cells, and take part in healing the epidermis after a wound.
Which layer of cells in the epidermis contains melanocytes?
The basal cell layer is also known as the stratum germinativum due to the fact that it is constantly germinating (producing) new cells. The basal cell layer contains cells called melanocytes.
What is the structure and function of the Hypodermis?
First is the hypodermis, which is subcutaneous (just beneath the skin) fat that functions as insulation and padding for the body. Next is the dermis, which provides structure and support. Last is the epidermis, which functions as a protective shield for the body.
What is the dermis largely composed of?
The dermis is composed largely of irregular dense connective tissue that includes tough collagenous fibers and elastic fibers in a gel-like substance. It has fingerlike projections called papillae that help form the fingerprints.