This Chapter contain :
Basic Anatomy of skin
- The integumentary system is an organ system consisting of the skin, hair, nails, and exocrine glands.
- This extraordinary organ system protects the internal structures of the body from damage, prevents dehydration, stores fat, and produces vitamins and hormones.
- It also helps to maintain homeostasis within the body by assisting in the regulation of body temperature and water balance.
- The integumentary system is the body’s first line of defense against bacteria, viruses, and other pathogens.
- It also helps to provide protection from harmful ultraviolet radiation.
- The skin is a sensory organ in that it has receptors for detecting heat and cold, touch, pressure, and pain.
LAYERS OF THE SKIN
- Epidermis – outermost layer of the skin composed of squamous cells. This layer is characterised into two distinct types: thick skin and thin skin.
- Dermis – thickest layer of skin that lies beneath and supports the epidermis.
- Hypodermis (Subcutis) – innermost layer of the skin that helps to insulate the body and cushion internal organs.
- stratum corneum – top layer of dead, extremely flat cells. Cell nuclei are not visible.
- stratum lucidum – thin, flattened layer of dead cells. Not visible in thin skin.
- stratum granulosum – rectangular-shaped cells that become increasingly flattened as they move to the surface of the epidermis.
- stratum spinosum – polyhedral-shaped cells that flatten as they get closer to the stratum granulosum.
- stratum basal – innermost layer of elongated columnar (column-shaped) cells. Consists of basal cells that produce new skin cells.
Dermis Skin Layer
Components of the dermis include:
- Blood vessels – transport oxygen and nutrients to the skin and remove waste products.
- Lymph vessels – supply lymph to skin tissue to fight microbes.
- Sweat glands – regulate body temperature by transporting water to the skin’s surface where it can evaporate to cool down the skin.
- Sebaceous (oil) glands – secret oil that helps to waterproof the skin and protect against microbe build-up. They are attached to hair follicles.
- Hair follicles – tube-shaped cavities that enclose the hair root and provide nourishment to the hair.
- Sensory receptors – nerve endings that transmit sensations such as touch, pain, and heat intensity to the brain.
- Collagen – generated from dermal fibroblasts, this tough structural protein holds muscles and organs in place and gives strength and form to body tissues.
- Elastin – generated from dermal fibroblasts, this rubbery protein provides elasticity and helps to make the skin stretchable.
Hypodermis Skin Layers
The innermost layer of the skin is the hypodermis or subcutis. Composed of fat and loose connective tissue.
Basic Anatomy of Nail
Interesting facts about nails
- Nails grow throughout our whole lives, but they grow slowest during the first four years of life, and fastest between the ages of 4 and 30 years.
- Fingernails grow more rapidly than toenails.
- Nail growth is fastest in the longer fingers and on people who bite their nails.
- Nails grow faster in summer compared to winter.
- Our nails are made up of keratinised cells.
- These cells make up the nail plate, which is the structure that covers the nail bed and the matrix underneath it.
- The nail plate curves slightly, which allows it to embed in the nail folds in the fingers.
- The hyponychium is located where the sterile matrix of the nail bed meets the skin of the fingertip under the nail.
- The hyponychium is an area of heightened immune activity, where large amounts of immune cells such as lymphocytes are found.
The paronychium contributes to the stability of the nail and its adherence to the fingertip, and is located where the skin of the finger comes into contact with where the nail curves into the finger.
Basic Anatomy of Breast
The breast is the tissue overlying the chest (pectoral) muscles. Women’s breasts are made of specialised tissue that produces milk (glandular tissue) as well as fatty tissue. The amount of fat determines the size of the breast.
The female breast is mostly made up of a collection of fat cells called adipose tissue. This tissue extends from the collarbone down to the underarm and across to the middle of the rib cage.
Lobes, Lobules, And Milk Ducts
A healthy female breast is made up of 12–20 sections called lobes. Each of these lobes is made up of many smaller lobules, the gland that produces milk in nursing women. Both the lobes and lobules are connected by milk ducts, which act as stems or tubes to carry the milk to the nipple. These breast structures are generally where the cancer begins to form.