The skin, the accessory structures, and the subcutaneous tissue form the integumentary system .
Oxygen and nutrients diffuse into the lower epidermis from the richly nourished dermis. In which layers are the blood vessels found? The blood vessels are found in the dermis and subcutaneous. Where are the statum germinativum and stratum corneum found? Both are layers of epidermis; the statrum germinativum is the deeper of the two.
As the cells of the stratum germinativum divide, they push the older cells toward the surface of the epithelium. To what do the terms exfoliation and desquamation refer? These terms describe the sloughing off of the stratum corneum. What are dander and dandruff? Individual dead cells are called dander; when clumped together by oil, they are dandruff.
What role do the collagen and elastin fibers of the dermis play? These fibers make the dermis stretchable and strong. What accessory structures are embedded in the dermis? The hair, nails, and certain glands are embedded in the dermis. The sensory receptors that detect pain, temperature, pressure, and touch are also located in the dermis.
Is the subcutaneous layer considered to be part of the skin? No, it is not. Why are many drugs injected subcutaneously (SC)? The hypodermis has a rich supply of blood vessels. The blood vessels absorb the drug and distribute it throughout the body.
What are some drugs that can be given transdermally? Examples are nitroglycerin and contraceptive patches. What are some toxins that can be absorbed through the skin? Examples are pesticides, dry cleaning fluid, acetone, and mercury. Distinguish between transdermal and topical applications of drugs. Transdermal applications enter the bloodstream; topical applications remain on the skin’s surface.
What is the physiological basis of the summer tan? UV radiation boosts melanin production, beginning with a tan, and potentially leading to permanent damage. Moles are abnormal but harmless concentrations of melanin. What are signs that a mole may be becoming a melanoma? Signs of possible melanoma are asymmetrical shape, irregular borders, change in color, and diameter larger than a pencil eraser.
Jaundice can be a sign of liver disease; the liver is unable to excrete bilirubin, so it is deposited in the skin. In light-skinned people, bronze skin can signal poor adrenal function. A bruise, or ecchymosis, is clotted blood under the skin. Fear can make a person look white as a sheet. Physiologically, what is going on? Vasoconstriction is part of the fear response.
What role do the arrector pili muscles play? When the arrector pili muscles contract, they cause the hair to stand up on end. The hair follicle is surrounded by epidermal tissue. Distinguish between hirsuitism and alopecia. The former can be caused by steroid therapy and the latter can be caused by cancer or chemotherapy.
Nails are thin plates of stratified squamous epithelial cells. They contain a very hard form of keratin and slide over a layer called the nail bed, which is part of the epidermis. Clubbing is an indication chronic lung or heart disease; it results from chronically poor oxygenation of the nail and fingertip.
What is the role of the vernix caseosa? This cream cheese–like covering found on the fetus protects it from maceration. What happens when the sebaceous glands become blocked? When accumulated sebum blocks a sebaceous gland and is exposed to air and dries out, it turns black and forms a blackhead. If it becomes infected with staphylococci, it becomes a pustule, or pimple.
There are two types of sweat glands, apocrine and eccrine. Apocrine sweat glands are found in the axillary and genital areas. These glands develop during puberty. When broken down by bacteria on the skin surface, sweat from these glands cause body odor. The eccrine glands are active at birth and located throughout the body. Crucial for temperature regulation, eccrine gland sweat cools the body as it evaporates from the skin surface.
What is the “normal” body temperature? Normal body temperature can range from 97 to 100 F. What are excessive decrease and increase in body temperature? Excessive decrease is hypothermia; excessive increase is hyperthermia. How can core and shell temperature be measured? Core temperature is measured rectally and shell temperature is measured at the axillary site.
Heat is produced by metabolizing cells. The amount of heat is affected by food consumption, physical activity, and hormonal secretion (as in thyroid gland disorders).
Why do most people feel so uncomfortable on a hot and humid day? Humidity prevents evaporation, so less heat is carried away from the skin. A cooling blanket to treat hyperthermia is an example of conduction. An example of convection is the use of a fan to cool the body.
Pyrogens reset the hypothalamus at a higher temperature. Intense heat can cause heat syncope, heat cramps, heat exhaustion, or heat stroke. In heat stroke, thermoregulatory mechanisms fail. Core temperature exceeds 104° F, and hallucinations or altered mentation may occur. With slower metabolisms and thinner skin, older adults are more prone to hypothermia.
Neonates wear hats in the nursery because so much heat loss happens through their large, bald skulls. Preterm infants have less capacity to thermoregulate, so they are often in incubators.
What type of burn is sunburn? It is a first-degree burn. Third-degree burns are pain-free, but the areas of first- and second-degree burns that often surround the more severe burn will still hurt.
What is the extent of a burn on the front and back of an adult’s limbs? According to the rule of nines, 36% of the body is burned. Why is eschar removed as part of postburn therapy? Eschar can act like a tourniquet, cutting off blood supply or preventing chest expansion. It becomes a breeding ground for bacteria and secretes toxins into the blood.
Both the sun and tanning beds expose people to UV radiation. In older adults, frequent bathing with soap dries the skin.
1. The Human Body in Health
and Illness, 4th edition
and Body Temperature