Anatomy, Physiology and of the Integumentary and Lymphatic Systems In Conjunction with the Immune System - Essay Example

The inner core is keratin, while the outer layer is a single layer of overlaid flat cells (Gale, 2005, Hair section). All integumentary external cells, of nails, hair, and skin, are dead cells. This is because new cells are generated beneath the surface; this process pushes the dead cells towards the outside. This process is easiest to discuss through an anatomical dissection of the skin into it's three layers: the epidermis, the dermis, and the subcutaneous layers. The epidermis is composed of multiple layers of epithelial cells, which are extremely flat and range from two extremes.

The outermost layer is entirely dead and made entirely of keratin, which is tightly joined so as to be waterproof. The innermost layer, consists of basal and melanocyte cells: the former produces keratin; the latter, melanin. Beneath these layers lies the live cells of the dermis, which produces all of the accessory features, contain the nerve fibers and blood vessels, and is constructed of fibrous proteins of collagen combined with connective tissue. The dermis is much thicker than the epidermis and is anchored to the muscles by the subcutaneous layer (Gale, 2005, Epidermis and Dermis sections).

Farabee ( 2001a) notes that "Skin functions include protection, regulation of body temperature, sensory reception, water balance, synthesis of vitamins and hormones, and absorption of materials." The external layer both prevents excessive water loss while allowing the body to cool itself via sweat glands and the process of evaporation. The glands contract when the body has cooled. Other glands secrete acidic solutions to the skin surface to prevent fungus growth. Sebaceous (oil) glands secrete a mixture of fatty proteins both through hair follicles and directly to the skin surface.

These oils prevent the dead hair and skin cells from drying out, while simultaneously killing bacteria on the skin surface (Gale, 2005, Sebaceous glands section). The epidermal melanocytes help prevent harm from UV radiation by producing melanin - it is this pigment which gives the skin both it's coloring and it's ability to darken (Gale, 2005, Epidermis section). The dermis sends nutrients to the epidermis through extended capillaries into the basal cells called dermal papillae. The dermal papillae result in looped ridges on the outer surface, i.e. fingerprints and similar markings.

The sweat glands of the dermis are divided into two categories: the eccrine and the apocrine (Gale, 2005, Dermis section). The first are the sweat gland found all over the body, the second refers particular sweat glands found in the armpit, groin, and nipple area. The apocrine are normally larger glands which empty out into hair follicles; their production attracts a bacteria which produces what is generally termed 'body odor'. The dermis layer also contains the hair follicles (attached to pili muscles), and sensory receptors, which communicate information of temperature or pressure to the brain, thus allowing the brain to process external information (Gale, 2005, Hair and Sensory Reception sections).

The lymphatic system mimics the circulatory system: it is a system of tubes that spread throughout the body anywhere the blood is carried. Plasma from the blood washes