Chapter 6 pt.1: Integumentary

What are the two distinct regions of the skin?

Epidermis and Dermis.

What is the primary characteristic of the epidermis?

It consists of epithelial tissue and is avascular.

What is the function of the hypodermis?

It anchors skin to underlying structures, absorbs shock, and insulates.

How many layers does thick skin have, and where is it found?

Thick skin contains five layers and is found in high-abrasion areas like hands and feet.

What are the five layers of the epidermis?

Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum (only in thick skin), and Stratum corneum.

What is the role of the stratum basale?

It is the deepest layer, where stem cells actively divide and produce new cells.

What percentage of the stratum basale is composed of melanocytes?

10-25%.

What characterizes the stratum spinosum?

It is several cell layers thick, with spiky keratinocytes and contains melanosomes and dendritic cells.

What occurs in the stratum granulosum?

Cells flatten, nuclei disintegrate, keratinization begins, and they accumulate keratohyaline and lamellar granules.

What is the stratum lucidum and where is it found?

A clear layer found only in thick skin, consisting of flat, dead keratinocytes.

What is the function of the stratum corneum?

It protects deeper cells, prevents water loss, and acts as a barrier against environmental assaults.

What are dermal papillae?

Fingerlike projections from the dermis into the epidermis containing capillary loops and touch receptors.

What are cleavage lines and why are they important?

They are caused by collagen fibers running parallel to the skin surface and are important for surgical incisions.

What are flexure lines?

Dermal folds at or near joints that cause deep creases due to the skin's inability to slide easily.

What causes stretch marks (striae)?

Extreme stretching of the skin can cause dermal tears.

What is carotene and where does it accumulate?

A yellow to orange pigment that accumulates in the stratum corneum and hypodermis.

What gives fair skin its pinkish hue?

Lower levels of melanin and the transparency of the skin allowing hemoglobin to show through.

What does the ABCDE mnemonic help diagnose?

Early-stage melanoma.

What are the signs of melanoma according to the ABCDE mnemonic?

Asymmetry, Borders, Color, Diameter, Evolving.

What are some additional signs of nodular melanoma?

Elevated, Firm, Growing.

What are some effects of excessive sun exposure on the skin?

Clumping of elastic fibers, leathery skin, immune suppression, and potential DNA alterations.

What does cyanosis indicate?

Low oxygenation of hemoglobin, resulting in blue skin color.

What is the significance of bruises?

They are clotted blood beneath the skin, changing color as they heal.

What are the three parts of a hair shaft?

Medulla, Cortex, and Cuticle.

What causes gray or white hair?

Decreased melanin production and replacement by air bubbles.

What are the two types of hair?

Vellus hair (fine body hair) and Terminal hair (coarse, long hair).

What is alopecia?

Hair thinning in both sexes after age 40.

What causes male pattern baldness?

Follicular response to dihydrotestosterone (DHT).