Drew Pusey Period 7
The Integumentary System
The Integumentary System is the structure of organs that protect the body from various kinds of damage, such as loss of water or wearing down from the environment. This encompasses the skin, hair, nails, and exocrine glands.
The skin is the largest and most important organ in the body. As the first defense, skin makes up the body’s outer covering and forms a boundary to protect the underlying muscle and organs from chemicals, disease, UV light, and physical damage. It also has nerves to sense different textures and temperatures. Since it is an interface with the surroundings, it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation, sensation, and vitamin D and B synthesis.
The Epidermis is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main function is protection, absorption of nutrients, and homeostasis.
Parts of the
The Dermis is the middle layer of skin, composed of dense irregular connective tissue and areolar connective tissue such as collagen with elastin arranged in a diffusely bundled and woven pattern. The dermis has two layers. One is the papillary layer which is the superficial layer and consists of the areolar connective tissue. The other is the reticular layer which is the deep layer of the dermis and consists of the dense irregular connective tissue. These layers serve to give elasticity to the integument, allowing stretching and conferring flexibility, while also resisting distortions, wrinkling, and sagging. The dermal layer provides a site for the endings of blood vessels and nerves. Many chromatophores are also stored in this layer, as are the bases of integumental structures such as hair, feathers, and glands.
The Hypodermis is the innermost and thickest layer of the skin. It invaginates into the dermis and is attached to the latter, immediately above it, by collagen and elastin fibres. It is essentially composed of a type of cell specialised in accumulating and storing fats, known as adipocytes. These cells are grouped together in lobules separated by connective tissue.
Mostly for insulation, hair is another branch of the integumentary system. It keeps humans warm by trapping warm air near the skin. It also defends the body by helping to protect the skin from UV rays in sunlight. Hair is primarily made of three parts: the follicle, root, and shaft. The hair follicle is an indent of epidermal cells deep inside the second layer of skin. Stem cells in the follicle reproduce to create the keratinocytes which form the hair, and melanocytes which produce pigments that gives the hair its color. Within the follicle is the hair root, the part of this organ below the skin’s surface. As the follicle produces new hair, the cells in the root push up to the surface until they exit the skin.
Functions of the
The integumentary system has multiple roles in homeostasis. All body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body. The skin has an important job of protecting the body and acts as the body’s first line of defense against infection, temperature change, and other challenges to homeostasis. Functions include protecting the body’s internal living tissues and organs, protect against invasion by infectious organisms, protect the body from dehydration, protect the body against abrupt changes in temperature, maintain homeostasis, help excrete waste materials through perspiration, act as a receptor for touch, pressure, pain, heat, and cold, protect the body against sunburns by secreting melanin, generate vitamin D through exposure to ultraviolet light, store water, fat, glucose, and vitamin D, maintenance of the body form, formation of new cells from stratum germanium to repair minor injuries, protect from UV rays.