The Dermis and Hypodermis

Dermis

The middle layer of skin, which contains collagen, blood vessels, glands, hair follicles, and nerve endings that support and protect the skin.

Hypodermis

The innermost layer of skin, which stores energy, connects the dermis to muscles and bones, and provides insulation.

Dermal papillae

Protrusions of dermal connective tissue into the epidermal layer, aiding in the connection between the epidermis and dermis.

Melanocytes

Cells in the skin that produce and distribute melanin, contributing to skin pigmentation.

Sebaceous glands

Microscopic exocrine glands in the skin that secrete sebum, an oily substance that lubricates hair and skin.

Sudiferous glands

Sweat glands located in the dermis; they regulate body temperature and excrete water and electrolytes.

Eccrine glands

The most numerous type of sweat glands that secrete water and electrolytes directly onto the skin surface.

Body temperature regulation

The process by which the skin and hypothalamus work together to maintain a stable internal temperature through sweating and blood vessel adjustments.

Arrector pili muscles

Bands of smooth muscle attached to hair follicles, causing hair to stand up during sympathetic nervous system activation.

Sebum

An oily substance secreted by sebaceous glands that helps to keep hair and skin moisturized.

Apocrine glands

Sweat glands that secrete into hair follicles, primarily found in the axillary and genital regions, often causing odor.

Hypothalamus

The brain region responsible for regulating body temperature by controlling sweat glands and muscle contractions.

Hypothermia

A condition resulting from excessive drop in body temperature, leading to shivering, confusion, and potential loss of consciousness.

Hyperthermia

A condition resulting from excessive increase in body temperature, with symptoms including lightheadedness, dizziness, and fatigue.

Nail matrix

The area from which the nail grows, located underneath the proximal portion of the nail.

Nail bed

The skin beneath the visible part of the nail, supplying nutrients and blood.