Structure and function of the skin-2

Body Temperature

Heat always transfers from a hotter location to a colder location. The study of thermal energy motion rates is known as heat transfer. The three main ways the skin controls body temperature are as follows:

• Conduction
• Convection
• Radiation

Conduction

This is how heat is transferred through solids. Conduction is the transport of thermal energy from areas of greater temperature to areas of lower temperature, also known as thermal energy diffusion. This happens on a microscopic level as a result of energy transferring through molecule vibrations. Heat transfers from one end of a metal strip to the other when the metal strip is heated. The metal vibrates when it is heated, and these vibrations cause the nearby particles to vibrate as well. As a result, heat is transferred along the metal as well as the vibrations. Conduction is the term for this action. In gases and liquids, it barely ever happens. It is the slowest of the three processes when compared to convection and radiation.

Convection

The movement of materials causes convection, which is the transmission of heat energy. The transfer of heat energy in a flowing fluid is the focus of convection (liquid or gas). The transfer of energy caused by molecular vibrations and the motion of the bulk fluid are the two phenomena that control it. Convection is the movement of heated sections of a fluid; conduction is the movement of heat itself. Heat is transferred more quickly by mixing the hot and cold fluids than by conduction. While slower than radiation, convection is faster than conduction.

Radiation

Radiation is the exchange of heat energy via electromagnetic waves between two things. Radiation does not need a medium, in contrast to conduction and convection. It entails the transfer of energy from one location to another. This process takes place in a vacuum and with gases. Of the three methods, it is the fastest.

Color of the Skin

Three elements determine the hue of the skin.

• The presence of melanin, a dark pigment produced by the melanocyte, a specific type of cell
• The buildup of the carotene pigment, which is orange-yellow.
• The epidermis reflects the color of blood, which is determined by hemoglobin's oxygen content.

Accessory Structures of the Skin

The skin's auxiliary structure consists of:

• Hair
• Skin glands
• Nails

Hair

The epidermis gives rise to keratinized threads of cells that make up hair. Except for the lips, tip of the penis, and inner lips of the vulva, it covers the entire body.

Structure of Hair

The root and the hair shaft are its two components. The outermost layer of hair is called the shaft. The part of the hair that enters the dermis is known as the root. The hair follicle is located around the hair root. The bulbs, an onion-shaped structure, are formed when the lower portion of the root grows larger. The epithelial cell matrix that makes up the bulb. The papilla of the hair, an indentation that resembles a nipple and is filled with connective tissue rich in blood, is housed within this structure. About halfway down the follicle, a portion of the hair follicle is joined to the bundle of smooth muscle. These muscles are the arrector pili. Autonomic nerve terminals activate the arrector pili muscle in response to cold or fear. The follicles and hair are subsequently pulled to an upright position when it contracts, resulting in "goose bumps." When hair has finished growing, it sheds. The position of the hair affects how quickly it grows. Women between the ages of 16 and 24 see the fastest growth rate on their scalps. 0.4 mm of scalp hair grow per day. When hair growth is finished, it sheds. The matrix cell gradually becomes inactive and eventually dies just before a hair is about to fall out.

Functions of the Hair

• It insulates the scalp from the cold.
• It lessens the scalp's loss of heat.
• It shields the scalp from damage and UV rays. It prevents glare in the brows of the eyes.
• It filters out alien objects (eye lashes)
• Dust particles are caught in the nose and are breathed.
• It shields entrances from outside debris.
• It also works to detect light touches.

Skin Glands

Sebaceous and sudoriferous glands make up the majority of the skin's glands.

• Sweat is expelled from sudoriferous glands through the skin's pores by the cells of these sweat glands (sudor = sweat, ferous = bearing). Sweat glands can be divided into two categories: glands called eccrine and apocrine
• Eccrine glands are tiny, straightforward coiled tubular glands that are found almost everywhere on the body, with the exception of nail beds, vulvar lip borders, and penis points. Over the palms and soles, there are many eccrine glands. The deep dermis contains their secretary portion. They secrete a colorless, aqueous fluid called sweat that contains sodium chloride, neutral fats, albumin, urea, and lactic acid. Its excretion aids in controlling body temperature.
• Armpits, the shadowy area surrounding the nipples, the outer lips of the vulva, the anal and vaginal regions all have odorous apocrine glands. Compared to eccrine sweet glands, they are larger and located deeper. At puberty, an apocrine sweet gland starts to function. Stress, including sexual activity, affects how they react. The apocrine glands in female breasts have evolved to secrete and release milk rather than sweat. Apocrine skin glands also make up the ceruminous glands in the outer ear canal. On the exterior of the external ear canal, they secrete cerumen, a waxy lubricant.
• Sebaceous (Oil) glands: Sebaceous glands are straightforward, branched acinar glands that are located in the dermis. Sebace = greasy. Lubrication and protection are their primary purposes. They are linked to the oily secretion known as sebum and hair follicles. It is a completely lipid-based semi-fluid material. It serves as a permeability barrier, an emollient (skin softener), and an antibacterial and antifungal agent. There are glands of this kind all over the body, with the exception of the palms and soles. Sebum overproduction can cause acne vulgaris, which can enlarge the gland and clog the pore.

Nail

Similar to hair, nails are variations of the epidermis. They are created from tough keratin. The dorsal surface of the distal segment of the fingers and toes is where the flat, cornified plates that make up nails are located. The lunula, which makes up the proximal portion of the nail, is white in color because the capillaries beneath are shielded by a thick layer of epithelium. A nail body, a free edge, and a nail root make up each nail. The exposed portion is the body. The portion of the nail body that extends past the tips of the fingers is known as the free edge. The portion of the nail that is tucked away in a skin fold is called the root. Hyponychyem, or the nail bed on which the nail rests, is the epithelial layer that covers the area beneath the free edge. The nail matrix, which is the thicker layer of skin beneath the nail root, is where new cells are produced. A mm of nail growth occurs every week. The developing nail is initially covered by eponychium, which are very thin layers of epidermis.

Functions of the Nail

• Our fingers and toes are shielded from injury by the nails.
• It enables us to pick up and hold objects.
• Additionally, it enables us to itch various body parts.