Lecture 3 – Integumentary System

These flashcards review skin functions, layers, appendages (hair, glands, nails), pigments, and thermoregulation as covered in Lecture 3 on the integumentary system.

What are two core protective functions of the integumentary system?

Acts as the first line of defense against pathogens and guards against physical injury.

Which skin function relies on sensory receptors detecting touch, pressure, heat, cold, and pain?

Sensation/Communication

How does skin prevent desiccation?

By minimizing fluid loss so cells remain hydrated and maintain homeostasis.

Name two mechanisms the skin uses for thermoregulation.

Capillary dilation/constriction and sweat gland secretion.

What vitamin is synthesized in the skin upon UV exposure?

Vitamin D

Which epidermal sublayer contains continuously dividing cells?

Stratum basale

What tough, waterproofing protein is produced by epidermal cells?

Keratin

Where are epidermal cells dead, flattened, and tightly packed for waterproofing?

Stratum corneum

What type of tissue dominates the dermis and allows stretching and recoil?

Dense connective tissue rich in collagen fibers

What structures in the dermal papillae aid in grip and form fingerprints?

Friction ridges

Which dermal structures deliver nutrients and assist in thermoregulation?

Capillaries within dermal papillae

What is another name for the subcutaneous layer?

Hypodermis or superficial fascia

List two key functions of adipose tissue in the hypodermis.

Shock absorption and thermal insulation (energy storage as well).

Which part of a hair is visible above the skin?

Hair shaft

What is the hair root?

The portion of hair located below the skin surface inside the follicle.

Define a hair follicle.

The hair root plus its surrounding epithelial and connective tissue sheath.

What happens when arrector pili muscles contract?

Hair stands up and the surrounding skin forms goosebumps due to cold or fear.

Which gland secretes sebum into hair follicles?

Sebaceous (oil) gland

State two functions of sebum.

Lubricates hair and skin, helps prevent water loss (also inhibits some bacteria/fungi).

What skin condition results from blocked sebaceous ducts?

Whiteheads, blackheads, or pimples

Which sweat glands are most numerous and vital for cooling the body?

Eccrine sweat glands

What primary substances do eccrine glands excrete?

Water, salts, and nitrogenous wastes such as urea

Where are apocrine glands concentrated and what produces their odor?

Armpits and genital areas; bacterial decomposition of their thick, milky secretion.

What pigment is produced by melanocytes in the stratum basale?

Melanin

Why do people with darker skin appear darker?

Their melanocytes are more active and produce more melanin.

What pigment contributes an orange-yellow hue to skin?

Carotene

What inherited condition results in an inability to produce melanin?

Albinism

How does melanin protect against ultraviolet radiation?

It absorbs and disperses UV rays before they damage nuclear DNA.

Excessive UV exposure can lead to what serious consequence in basal cells?

DNA mutations that may result in skin cancer

From which epidermal cells do nails develop?

Horny (keratinized) epidermal cells

Name the visible hard part of the nail.

Nail body

What is the nail bed and why is it pink?

Epithelial layer beneath the nail lacking stratum corneum; rich capillaries give it a pink color.

Identify the crescent-shaped whitish area at the nail base and its significance.

Lunula; it is the actively growing region of the nail (part of stratum basale).

How does sweating aid thermoregulation?

Evaporation of sweat absorbs body heat, cooling the skin surface.

Why are sports drinks recommended during heavy sweating?

They replenish salts (electrolytes) lost through eccrine sweat.