Functions of the Integumentary system
- Protection
a) Chemical factors in the skin:
Sebum (or oil) from the sebaceous glands is slightly acidic, retarding bacterial colonization on the skin surface.
Sweat from the sudoriferous glands is slightly hypertonic and can flush off most bacteria on the skin surface.
Melanin (skin pigment) from melonocytes avoids excessive ultraviolet radiation from penetrating the skin layers
b) Physical factors in the skin:
Stratified squamous epithelium in the epidermis layer provides a large number of layers of cells, preventing most bacteria invasion. Keratinized cells in the stratum corneum layer of the epidermis provides a physical barrier against most invasion.
c) Biological factor in the skin:
White blood cells such as macrophages destroy most invaded bacteria and other foreign substances.
- Excretion
Waste materials such as ammonia, urea, and excessive salt are eliminated from sweating.
- Body temperature regulation
Sweating by the sweat glands promotes evaporation , resulting in a loss of excessive body heat.
Vasoconstriction by arterioles (small arteries) in the dermis layer provides a smaller surface area in the blood vessels, resulting in less heat loss .
Vasodilatation by arterioles in the dermis layer provides a larger surface area in the blood vessels, resulting in greater heat loss.
- Sensation
Nerve receptors in the dermis layers detect sensations such as heat, cold, pain, pressure, and touch, allowing the body to be aware of these stimuli.
- Vitamin D Synthesis
Ultraviolet radiation in the sunlight activates a series of chemical reactions in the epidermis layer, resulting in the synthesis of vitamin D (cholecalciferol) from the modification of cholesterol for the absorption of calcium.
- Blood reservoir
Dermis houses an extensive network of blood vessels carrying 8-10% of total blood flow in a resting adult.