Physiology, Integument

Abstract

The integumentary system is the largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain. The integumentary system includes the epidermis, dermis, hypodermis, associated glands, hair, and nails. In addition to its barrier function, this system performs many intricate functions such as body temperature regulation, cell fluid maintenance, synthesis of Vitamin D, and detection of stimuli. The various components of this system work in conjunction to carry out these functions—for example, body temperature regulation occurs through thermoreceptors that lead to the adjustment of peripheral blood flow, degree of perspiration, and body hair. Hair is a component of the integumentary system and extends downward into the dermal layer, where it sits in the hair follicle. Humans have approximately five million hair follicles, which offer protection from cold and UV radiation, produce sebum, and can have a significant psychological impact when growth or structure is unbalanced. At a microscopic level, each hair's variety in length, color, diameter, and cross-sectional shape creates the characteristic profiles seen across ethnic groups and among individuals. This activity will discuss the physiology of hair, cellular components, mechanisms of growth and differentiation, and its clinical significance. After an injury, the skin attempts to restore its normal blood flow and function: this occurs through a very orderly three-phase process known as wound healing. The three steps or phases of wound healing are inflammation, proliferation, and maturation. A study by Dunkin et al. found permanent scars occur when the reticular dermis has been violated. Scars are a natural and normal part of healing following an injury to the integumentary system. Ideally, scars should be flat, narrow, and color-matched. Several factors can contribute to poor wound healing. These include but are not limited to infection, poor blood flow, ischemia, and trauma. Proliferative, hyperpigmented, or contracted scars can cause serious problems with both function and emotional well-being. 

Neurotransmitters

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