HESI A2 Exam: Integumentary System
• What are the two types of sweat glands?
• What functions as a barrier to infection?
• What is the innermost layer of skin?
• What is the body’s response to hyperthermia?
Intro
The integumentary system is comprised of the largest organ in the human body, which is the skin. Additionally, this system includes hair, nails, and accessory glands. The integumentary system is in constant contact with the external environment and offers protection from the body’s surroundings.
Anatomy/Physiology
The skin forms a waterproof protective barrier that prevents germs and foreign material from entering the body.
The outermost layer of the skin is the epidermis, the middle layer is the dermis, and the innermost layer is the hypodermis.
The epidermis functions as a barrier to infection.
The dermis is the location of sweat glands and nerve endings. The hair follicles, along with sweat glands and nerve endings, are found in the dermis.
The hypodermis contains blood vessels and adipose tissue.
Sudoriferous glands are the sweat glands, of which there are two types:
1.Eccrine glands are the primary sweat glands of the body.
2.Apocrine glands become active after puberty and are located in the armpits, nipples, and groin.
Sebaceous glands secrete sebum, a mixture of fats and proteins that prevents the skin and hair from drying out.
Hair follicles in the skin have a large dose of keratin producing cells. These cells form the hair. The pigmentation in hair comes from melanin producing cells.
Nails are developed by keratin producing cells at the ends of the fingers and toes.
Collagen maintains the firmness of skin.
Fibroblasts secrete collagen as well as other components of the extracellular matrix.
Macrophages are phagocytic cells that engulf potential pathogens. They destroy bacteria and other harmful organisms. Macrophages are part of the immune system.
As its name suggests, keratinocytes produce keratin. Keratinocytes are the most common type of cell in the epidermis. They arise from stem cells in the stratum basale and die as they move towards the surface of the skin.
Melanocytes produce melanin, which gives skin its color and protects against UV radiation.
Thermoregulation
Hyperthermia means body temperature is too high. In response, the body dilates blood vessels in the dermis to increase heat loss at the skin. The body also increases excretion of sudoriferous glands to cool the body through the endothermic evaporation of water.
Constriction of blood vessels, shivering, and contraction of hair follicle muscles occur during hypothermia to decrease heat loss.
Shivering generates heat and reduces heat loss. Increased blood flow to the skin, increased evaporative cooling, and sweating all increase heat loss.
The role of sweat is to aid in evaporative cooling.
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