The Integumentary System Organs of the integumentary system

The Integumentary System

Organs of the integumentary system l skin l hair l nails

Integumentary System l Composed of skin, hair, sweat glands, and nails l The name is derived from the Latin integumentum, which means “a covering. ”

Skin l The largest organ in your body l Functions ¡Covers the body and prevents water loss ¡Protects the body from injury and infection ¡Regulates body temperature ¡Eliminates wastes (sweat) ¡Produces vitamin D ¡Gathers information about the environment ¡Stores fat for fuel and insulation

Prevents Water Loss l Skin prevents water from leaking out of your body

Prevents Infection l Skins acts as a barrier to bacteria and viruses

Maintains Homeostasis l Helps to keep the body temperature normal l Has blood vessels that tell the body when it is hot or cold ¡Hot – blood vessels get larger and sweating occurs ¡Cold – blood vessels constrict to keep blood in the body’s core

Eliminates Waste l Sweating eliminates dissolved waste from your body

Gathers Information l Skin contains nerves that can feel pain or pressure

Provide Vitamin D l With the help of sunlight, your skin produces vitamin D l Vitamin D is essential in calcium absorption from food

Layers of Skin l Skin consists of three main layers ¡epidermis ¡subcutaneous layer

Epidermis l Outermost layer l 30 -60 cells thick l No nerves or blood vessels l Top layer is dead l New cells formed at the bottom of this layer l Skin cells shed every 2 weeks l Where nails grow l Contains melanin

Epidermis l Where nails grow l Contains melanin l Every minute, 30, 000 - 40, 000 skin cells fall off l 95% of your skin cells make new cells l 5% make melanin l More sun exposure = more melanin (tan)

Dermis l Middle layer l Contains nerves and blood vessels l Contains sweat glands, oil glands and hair follicles l Contains collagen and elastin that allows skin to stretch

subcutaneous layer l Made mostly of fat l Keeps you warm l Absorbs shock l Attaches your skin to the underlying tissue

hair l Made of a strong, dead protein, called keratin l Grows out of a tiny tube called a follicle l Hair growth is caused by rapid mitosis in the follicle l Hair follicles are everywhere except ¡lips ¡palms ¡soles

hair l Over 100, 000 follicles on the scalp l Each follicle is attached to a gland that secretes sebum (oil) l Color is partially determined by melanin

nails l Modified hair that grows from your cuticle l Made of keratin l No nerve endings l Protects the end of fingers and toes l Takes 6 months to grow from cuticle to tip

nails l Fingernails grow faster than toenails l Nails grow faster on your dominant hand l Nails DO NOT grow after death

Body systems that work with the integumentary system; lrespiratory system to get oxygen and remove carbon dioxide lcirculatory system to deliver oxygen lexcretory system to eliminate waste