Lesson 1: Integumentary System

Lesson 1– Integumentary System It performs these functions: Protects body Maintains body temperature Eliminates waste Helps respond to touch sensations Absorbs substances Helps produce vitamin D Integumentary System The integumentary system refers to the skin that covers the body. The skin is the largest organ of the body. It performs these functions: Protects the body by screening the sun’s ultraviolet rays and keeping out pathogens Maintains proper body temperature Eliminates waste through perspiration Helps respond to touch sensations through the nerves in the skin Absorbs certain substances, including some medications Helps produce vitamin D using sunlight Temporarily stores fat, glucose, water, vitamins, and salts

Lesson 1– Layers of Skin Epidermis Dermis Hypodermis Layers of Skin The skin consists of three basic layers: the epidermis (outermost), dermis (middle), and hypodermis (innermost). The epidermis contains no blood vessels or nerve cells. It is made up of five smaller layers. The cells of the outermost layer, the stratum corneum, are continually shed and replaced with new cells from the innermost layer, the stratum germinativum. The dermis is also called the corium, or “true skin.” This layer is made of elastic connective tissue. It contains blood vessels, lymph vessels, nerves, involuntary muscle, sweat and oil glands, and hair follicles. Patterns of ridges are formed between the top of the dermis and the epidermis that create unique fingerprints and footprints for each person. The hypodermis is the innermost layer of skin. This layer is made of elastic and fibrous connective tissue as well as fatty tissue. It connects the skin to underlying muscles and protects body organs.

Lesson 1– Pigmentation Skin color is inherited Melanin Carotene A person’s basic skin color is inherited. It is determined by pigments in the epidermis. Melanin is a brownish-black pigment that can result in a black, brown, or yellow tint to the skin. This pigment can absorb ultraviolet light to tan the skin, and small concentrations of it form freckles. Carotene is a yellowish-red pigment that also influences the color of the skin.

Lesson 1– Glands of the Skin Sudoriferous glands Sebaceous glands Glands of the Skin The integumentary system has two main types of glands, sudoriferous and sebaceous. Sudoriferous glands are known as sweat glands. From their coiled bases, tubes extend through the dermis and form pores on the surface of the skin. Perspiration excreted through these pores eliminates excess water, heat, and a small amount of waste and salts. Sebaceous glands are oil glands that usually open onto hair follicles. They produce sebum, which is an oil that keeps the skin and hair soft and pliable. It also acts as a barrier against bacteria and fungi to help prevent infections.

Lesson 1– Hair and Nails Hair helps protect the body Root Shaft Nails protect the fingers and toes from injury Hair and Nails Hair and nails are two other parts of the integumentary system. Hair helps protect the body and is present on all surfaces except the palms of the hands and the soles of the feet. Each hair has two parts, a root and a shaft The root grows beneath the skin surface in a tube called a follicle. The shaft protrudes from the skin and is visible. Nails protect the fingers and toes from injury. They are made of dead epithelial cells packed closely together in a dense surface. They are formed in the nail bed. As long as the nail bed is not damaged, a nail will always grow, even if one has been lost.