Flashcards - Integumentary System

Main components of the integumentary system

Skin, hair, nails, and glands.

3 main layers of the skin

Epidermis, dermis, hypodermis (subcutaneous layer).

Main function of the epidermis

It protects deeper layers and provides a waterproof barrier.

Main cell types in the epidermis

Keratinocytes, melanocytes, Langerhans cells, and Merkel cells.

Function of keratinocytes

Produce keratin; make skin tough and water-resistant.

Function of melanocytes

Produce melanin, protecting skin from UV rays.

Function of Langerhans cells

Detect and fight pathogens.

Function of Merkel cells

Detect light touch; connected to nerves.

5 layers of thick epidermis (palms, soles)

Stratum basale → spinosum → granulosum → lucidum → corneum.

What happens in the stratum basale

Cell division; contains stem cells, melanocytes, Merkel cells.

What happens in the stratum spinosum

Keratinocytes with desmosomes and Langerhans cells.

What happens in the stratum granulosum

Keratinocytes produce waterproof granules and start dying.

What is the stratum lucidum

Clear, dead cells; only in thick skin.

What is the stratum corneum

Flattened, dead keratinocytes that are shed regularly.

Two layers of the dermis

Papillary layer and reticular layer.

What is the papillary layer

Upper dermis with dermal papillae; nutrients & sensation.

What is the reticular layer

Deeper layer with dense connective tissue, blood vessels & nerves.

What is the hypodermis made of

Areolar and adipose tissue.

Functions of the hypodermis

Connects skin to muscle/bone, stores fat, insulates.

Three parts of a hair

Follicle, root, shaft.

Layers of a hair shaft

Cuticle (outer), cortex (middle), medulla (inner).

Functions of hair

Protection from UV light and insulation.

Three parts of the nail

Root, body, free edge.

What is the lunula

Crescent-shaped white area of the nail.

What is the nail matrix

Produces keratinocytes for nail growth.

What are eccrine glands

Sweat glands all over body; regulate temperature.

What are apocrine glands

In axillary/pubic regions; activate at puberty, cause odor.

What are sebaceous glands

Produce sebum to lubricate and waterproof skin/hair.

What are ceruminous glands

In ear canals; produce cerumen (earwax) for protection.

What is keratinization

Keratinocytes accumulate keratin as they move to surface.

What happens during apoptosis in skin

Keratinocytes die, leaving a tough keratin shell.

How does the skin cool the body

Sweating and vasodilation.

How does the skin retain heat

Goosebumps (arrector pili) and vasoconstriction.

How is Vitamin D produced in the skin

UV light converts 7‑dehydrocholesterol to Vitamin D3 in epidermis.

How does the skin protect the body

Prevents pathogen entry, blocks UV via melanin, repairs quickly.

What pigments determine skin colour

Melanin, carotene, hemoglobin.

What causes tanning

Increased melanin production from UV exposure.

What do Merkel cells detect

Shapes and textures.

What do lamellar corpuscles sense

Pressure and vibration.

What do free nerve endings detect

Pain, heat, or cold.

What is excreted in sweat

Water, sodium, chloride, urea, lactic acid, ammonia, sometimes alcohol.