integumentary system

Epidermis

The outermost layer of the skin that protects the body from the outside, keeps skin hydrated, produces new skin cells, and determines skin color.

Dermis

The middle layer of skin containing collagen, blood vessels, glands, hair follicles, and nerve endings; it supports and protects the skin and deeper layers.

Hypodermis (subcutaneous)

The innermost layer of skin responsible for storing energy, connecting the dermis to muscles and bones, insulating the body, and protecting it from harm.

Dermal papillae

Protrusions of dermal connective tissue into the epidermal layer that regulate hair growth.

Melanocytes

Cells that produce and distribute melanin, the pigment responsible for skin color.

Stratum corneum

The most superficial layer of the epidermis, serving as the first line of defense against the environment.

Stratum lucidum

A thin, translucent layer of cells found in thickened parts of the epidermis, such as the palms and soles, lying above the stratum granulosum.

Stratum granulosum

A layer of the epidermis where cells accumulate keratohyalin granules forming a waterproof barrier to prevent fluid loss.

Stratum spinosum

The layer of the epidermis consisting mostly of keratinocytes held together by desmosomes that provide flexibility and strength.

Stratum basale

The deepest layer of the epidermis containing epidermal stem cells where skin cell proliferation occurs.

Sebaceous glands

Microscopic exocrine glands in the skin that secrete an oily substance called sebum into hair follicles.

Sudiferous (sweat glands)

Glands located in the dermis that transport sweat to the surface of the epidermis.

Eccrine glands

The most numerous type of sweat glands widely distributed over the body.