consists of the skin and its accessory structures, including the hair, nails, sebaceous glands, and sweat glands.
INTEGUMENTARY SYSTEM
- the exterior covering of the body.
- It weighs more than 6 pounds in the average adult, and covers more than
3,000 square inches. - It is the largest organ of the body.
- It is supplied with blood vessels and nerves.
SKIN
FUNCTIONS OF SKIN
- provides protection.
- It protects against invasion by bacteria and other harmful agents.
- It protects delicate cells beneath the surface from injury.
- It inhibits excessive loss of water and electrolytes.
- It produces a protective pigmentation to protect the body against excessive exposure from the sun.
- It helps produce the body’s supply of Vitamin D.
- regulates body temperature.
When the body is too cold, the skin’s blood vessels ______. This allows more heat-carrying blood to circulate to the muscles and organs.
constrict
When the body is too hot, the blood vessels in the skin ____. That brings more blood to the surface for cooling by radiation. At the same time, sweat glands secrete more sweat that cools the body when it evaporates.
dilate
It contains millions of nerve endings that act as receptors for pain, heat, cold, and pressure.
SKIN
When stimulation occurs, nerve impulses are sent to the ______ of the brain.. and the brain triggers any necessary response.
cerebral cortex
two layers of skin
EPIDERMIS
DERMIS
4 Strata of Epidermis
- STRATUM CORNEUM
- STRATUM LUCIDUM
- STRATUM GRANULOSUM
- STRATUM GERMINATIVUM
- is the outermost strata of the epidermis.
- It is mostly dead cells, filled with a protein substance called keratin.
- It is thicker on the soles of the feet than on the eyelids where there is less presumably
STRATUM CORNEUM
- is a translucent layer lying directly beneath the corneum.
- It may not even exist in thinner skin.
- Cells in this layer are also dead or are in the process of dying.
stratum lucidum
- is one or more layers of cells starting to die and become hard.
- They are in the process of keratinization becoming fibrous protein similar to that in hair and nails.
stratum granulosum
- is composed of several layers of living cells capable of cell division.
- It is the innermost layer of the epidermis, and contains melanin
- Damage to this layer, such as in severe burns, requires skin grafts.
stratum germinativum
beneath the epidermis and is composed of connective tissue.
DERMIS
TWO LAYERS OF DERMIS
- PAPILLARY LAYER
- RETICULAR LAYER
contains the lymphatics, nerves, nerve endings, blood vessels, sebaceous and sweat glands, elastic fibers, and hair follicles.
DERMIS
arranged into microscopic structures that form ridges. These are the finger- and footprints
PAPILLARY LAYER
beneath the papillary layer; it is a white fibrous tissue that supports the blood vessels
RETICULAR LAYER
The subcutaneous tissue or hypodermis is composed of ____ and _____. It supports, nourishes, insulates, and cushions the skin.
adipose and connective tissue
- threadlike structure formed by a group of cells that develop within a hair follicle or socket.
- has a shaft that is visible and a root that is embedded in the follicle.
HAIR
is attached to the side of each follicle. It is stimulated by skin irritants, emotional arousal, or cold temperatures, and reacts by contracting. This causes goose flesh or goose pimples.
PILOMOTOR MUSCLE
a bulb enclosing a loop of capillaries. It provides nourishment to the hair. It is one of the few living parts of the hair, and is responsible for hair growth.
HAIR PAPILLA
covers the hair shaft like shingles on a roof, protecting it from the elements and chemicals, and from losing moisture.
CUTICLE
provides most of the hair’s weight. It contains melanin which provides color to the hair, stores oils, provides flexibility and elasticity, and adds shape to the hair.
CORTEX
