Integumentary System

The human body is made up of several systems including the respiratory system, circulatory, system, nervous system and others, and each system includes one or more organs like the heart, lungs, brain, and several more. However, the system which claims the largest organ of the body is called the integumentary system, which includes the human skin, as well as the hair, nails, and exocrine glands.

The skin is the outer covering of the body and protects it from chemicals, disease, UV light, and physical damage. The hair and nails are extensions of the skin and help reinforce and protect the body from environmental damage as well. The exocrine glands produce sweat, and wax to keep the skin's surface cool, to protect it, and to moisturize its surface.

It has three main layers, and each layer has its own characteristics and functions for the body. The epidermis is the outer layer and the main purpose is for protection. New cells are constantly growing deep inside to replace the 30,000 to 40,000 dead skins cells that fall off the body every year. New skin cells come to the surface which contains keratin, helping to make the skin tough and waterproof. Other cells produce a pigment called melanin which darkens the skin and protects it from UV rays.

The second layer, the dermis, is thicker and more elastic and is home to hair follicles and glands, which are discussed below. There are also nerves and blood vessels inside the dermis layer. The nerves are sensors of the body for sending messages to and from the brain and is part of the nervous system. The blood vessels are part of the circulatory system and carry oxygen and nutrients to the cells in the body and carry away waste.

The final layer is the hypodermis and called the subcutaneous layer and is mostly made of fat. It helps keep the body warm and absorbs shocks to the body. The layer holds all the skin to the tissues beneath it, and it is the connection between the skin and the muscles and bones. The functions of the skin include temperature control, keeping your body typically at 98.6°F. It also helps warm the body when a person gets goosebumps from the cold.

The rest of the integumentary system includes the hair, nails, and glands, which are extensions or parts of the three main layers of skin. The first part is your hair, which covers nearly every region of the body. Hairless parts of the body include the palms of the hands, the soles of the feet, and lips.

The hair protects the body from UV radiation by preventing sunlight from hitting the skin and insulates the body by trapping warm air around the skin. The structure of hair is broken down into three parts: follicle, root, and shaft. The follicle begins in the dermis layer and cells reproduce to give the hair its color. The shaft is the part of the hair pushed up by the root and exits outside the epidermis layer of skin. The hair shaft and the root are made of three layers of cells called the cuticle, cortex, and medulla. Each cell layer has a responsibility for the hair such as how the hair points away from the body, its width, and the color of the hair.

Next are the nails found at the end of the fingers and toes. The fingernails and toenails reinforce and protect the digits and are used for scraping and handling small objects. The nails have 3 main parts: root, body, free edge. The root is the portion of the nail found under the skin's surface. The body is the visible extension of the fingernail or toenail, and the free edge is the part that has grown beyond the ends of the fingers or toes. They grow from the deep layer of epidermal tissue known as the nail matrix which surrounds the nail root. Under the body is a layer of dermis and epidermis called the nail bed, pink in color due to capillaries (tiny blood vessels) that support the cells of the nail body. The nails are places where bacteria and other infection-causing organisms grow and can cause problems for the body.

There are three main exocrine glands found in the dermis layer of skin and each has special functions. The sudoriferous glands, commonly known as sweat glands, include two major types. The eccrine is found in nearly every region of the skin & produce a secretion of water and salt used to lower the body's temperature through evaporative cooling. The apocrine is found mainly in the armpits and pubic regions of the body and extend into follicles of hair so sweat can exit the body along the surface of the hair shaft. The glands are inactive until a person reaches puberty. Sweat is consumed by bacteria on the skin and is the cause of body odor.

Sebaceous glands produce an oily secretion called sebum, a type of oil that helps keep your skin soft and waterproof, meaning water cannot get inside your body. They are found in every part of the skin except the palms of the hands and the soles of the feet.

Ceruminous glands are found in the dermis of your ear canals and produce a waxy secretion called cerumen (ear wax) to protect the canals and lubricate the eardrum. The ear wax traps dust and other airborne particles that enter the canal. It is made continuously and pushes the older ear wax out or it is removed

In summary, the integumentary system includes the skin and its three main layers, the hair, nails, and glands. All parts work together to provide a protective covering for the body and to help maintain the body's temperature.

A: Subcutaneous
B: Hypodermis
C: Dermis
D: Epidermis

A: Subcutaneous
B: Hypodermis
C: Dermis
D: Epidermis

A: Glands
B: Nails
C: Hair
D: Nerves

A: Sebaceous
B: Ceruminous
C: Sebum
D: Sudoriferous

A: Cerumen
B: Sebum
C: Melanin
D: Keratin

A: Follicle, shaft, root
B: Nail bed, root, shaft
C: Free edge, follicle, root
D: Root, body, free edge

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