By: Veronica Martinez and Paola Rios Health Class Spartans 2014

 The skin is the largest organ of your body.  It is part of the integumentary system, which includes all the external coverings of your body, like skin, nails, and hair.

 Skin covers your bones and muscles and protects them from the external environment.  It keeps your body from drying out in the sunlight and wind.  It also protects the cells and tissues under the skin.  Is the first line of defense against dirt, bacteria, and viruses that might enter your body.

The skin has special sensory receptors that detect texture. It also detects temperature and senses pain. The more sensory receptors in one area the more sensitive it is.

 Skin helps control body temperature.  Sweating is one way skin lowers your body temperature. As sweat evaporates, excess thermal energy leaves the body and skin cools.  Another way is by releasing thermal energy from blood vessels, which is why your face turns red while exercising.  This happens because blood vessels enlarge.

 When your skin is exposed to sunlight it can make vitamin D.  Your body needs vitamin D to help it absorb calcium and phosphorous and promote the growth of bones.  Vitamin D is usually added to milk and is found in some types of fish.

 Normal cellular processes produce waste products and the skin eliminates these wastes.  Water, salts, and other waste products are removed through the pores.  You might notice when you sweat.

 Instructions:  Touch the back of your hand with an ice cube in a plastic bag.  Now do the same to the back of your knee. Questions:  Which area was more sensitive to cold?  How do you think the skin senses temperature?  How does sensitivity to temperature protect the body?

 Instructions:  Put on one plastic bag in your hand.  Leave it on for about 5 min. Questions:  What happened inside the bag?  What might have caused this?

 Is the outmost layer of skin and the only one who comes in contact with the outside environment.  Is thin but tough. The epidermis on your eyelids in thinner than a sheet of paper.  The epidermis cells are constantly shed and replaced. Epidermis produces melanin. Melanin is a pigment that protects the body by absorbing some of the Sun’s damaging ultraviolet rays.

 The dermis is a thick layer of the skin that gives skin strength, nourishment, and flexibility.  It contains sweat glands, blood vessels, nerves, hair follicles, and muscles.  When the muscles in the dermis contract, you get goose bumps.

 The innermost layer of skin insulates the body, acts as protective padding, and stores energy.  It is sometimes called fatty layer.  It can be very thin or very thick, depending on its location on the body.

 A bruise is an injury where your blood vessels in the skin are broken, but the skin is not cut or opened.  The broken blood vessels release blood into the surrounding tissue, they change color as they heal.

 When you break one or more layers of skin, it is called a cut.  The blood you release will usually thicken and form a scab over the cut.  The scab prevents outside substances from entering the body.  Skin heals by producing new skin cells that repair the cut.  Some cuts are too large to heal, if that happens you may need to get stitches.

 Burns do not only occur by touching hot objects.  Burns can also be caused by touching extremely cold objects, chemicals, radiation, electricity, or friction.  There are degrees of burns.

BurnSymptoms First degree burn Damages top layer of skin Symptoms: Pain, redness, swelling Usually heals in 5-7 days without scarring

BurnSymptoms Second Degree Burn Damages top two layers of skin Symptoms: Pain, redness, swelling, blistering Usually heals in 2-6 weeks with some scarring

BurnSymptoms Third degree burn Damages all three layers of skin and sometimes the tissue below skin Symptoms: black or white charred skin, may be temporarily numb due to damaged nerves Heals over months with scarring; might require surgery

 One important thing you can do for your skin is protect it from sunlight.  By using sunscreen and protective clothing and avoid outside activities during the middle of the day you can protect your skin.  The rays of sunlight can cause permanent damage to the skin, including wrinkles, dry skin, and skin cancer.  You can keep your skin healthy by eating a balanced diet.  You can also apply lotion to your skin to keep it moist and use gentle soap to clean it.

 Homeostasis is an organism’s ability to maintain steady internal conditions when outside conditions change.  Skin also works with other body systems to maintain homeostasis.  Circulatory system: helps cool the body when it becomes overheated.  Nervous and muscular systems: help the body react to stimuli.

 Information and photos:  Science Book 