Integumentary System: Key Parts, Functions, and Skin Layers

Main parts of the integumentary system

Skin, hair, nails, glands, and sensory receptors.

Key functions of the integumentary system

Sensory input, protection, vitamin D synthesis, water retention, and thermoregulation.

Three layers of skin

Epidermis, dermis, and hypodermis.

Cells that make up the epidermis

Stratified squamous epithelial cells (mostly keratinocytes).

Thick skin

Skin with extra layers of cells, found on palms and soles.

Epidermal cells as they move upward

They fill with keratin and die.

Surface skin cells

They are too far from blood supply for oxygen and nutrients.

Keratin

A tough protein that waterproofs and protects skin.

Melanocytes

Cells that produce melanin, which gives skin color and UV protection.

Vitamin D

A hormone made when UV light converts precursors in the skin; helps absorb calcium.

Dermis composition

Connective tissue with collagen, blood vessels, and nerves.

Capillaries in the dermis

They dilate to release heat and constrict to retain it.

Collagen in the dermis

Provides strength and elasticity.

Parts of a hair

Shaft (visible) and root (below skin).

Arrector pili muscles

Tiny muscles that make hair stand up ('goosebumps').

Pacinian corpuscle

Detects deep pressure and vibration.

Meissner's corpuscle

Detects light touch.

Fibroblasts in the dermis

Make collagen and connective tissue.

Sebaceous gland function

Secretes sebum (oil) to lubricate skin and hair.

Eccrine sweat glands

Produce watery sweat for cooling.

Apocrine sweat glands

Produce thicker sweat that causes body odor.

Sebum

Oily secretion that keeps skin soft and waterproof.

Hypodermis composition

Fat (adipose) and connective tissue (fascia).

Pigments affecting skin color

Melanin, carotene, bilirubin, and iron.

1st-degree burns

Affect epidermis; redness and mild pain.

2nd-degree burns

Affect epidermis and dermis; blistering and pain.

3rd-degree burns

Destroy all layers; may appear white or charred.

Rule of nines

Divides body into sections (9%) to estimate burn area.

Clotting process

Platelets form a plug and fibrin seals the wound.