The Integumentary System Skin Hair and Nails Now

The Integumentary System

Skin, Hair and Nails Now using the microscopes. Examine your skin, hair and nails. In your spiral, diagram what you see.

Organs of the integumentary system The name is derived from the Latin integumentum, which means “a covering. ” l skin l hair l nails

Label and color the parts of the integumentary system finger nail

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