Most of the internal organs are in the abdominal area.
During development, the coelom develops.
The coelom in humans and other mammals is divided into two parts.
The heart and lungs are in the chest.
The main parts of the digestive system, including the accessory organs, are located in the abdomen.
The female reproductive organs and some of the male reproductive organs can be found in the bladder.
There are two organ systems that protect the body.
List the body parts found in humans.
Explain the function of the two main regions of skin.
The average human has 21 square feet of skin and accounts for 15% of their body weight.
Scales are protective outgrowths of the skin of most fishes.
The skin of Amphibians is usually covered with mucus.
Scales are found on the legs and feet of birds, but only birds have feathers, which grow from specialized follicles in the skin.
All mammals have hair on their skin at some point in their life.
Skin protects the body from disease and trauma.
It's important to regulate body temperature.
The skin of small aquatic or semiaquatic animals is exchange, but it prevents water loss and thus was probably an important evolutionary adaptation to life on land.
Birds have unique appendages that function in insulation, waterproof and flight.
Skin has a variety of sensory structures that monitor touch, pressure, temperature, and pain.
After exposure to UV light, skin cells make precursor molecule that are converted to vitamin D.
The epidermis and the dermis are the main regions.
The skin has two regions, the epidermis and the dermis.
The hypodermis lies below the skin.
Human skin can be described as thin or thick.
Thin skin covers most of the body and is associated with hair, oil, and sweat.
The palms of the hands and soles of the feet are places where thick skin appears.
Thick skin has no hair or sweat.
Stem cells from the skin become flattened and hardened as they push to the surface.
1.5 million cells are shed from the human body every day.
A thick layer of dead, keratinized cells, arranged in spiral and concentric patterns, forms fingerprints, which are thought to increase friction and aid in gripping objects.
The surface of the skin protects it.
There is a hair follicle in the cross section.
The cells at the border are being pushed to the surface and eventually shed.
The cells in the skin's surface produce melanin.
It's concentrated in moles and freckles.
Light-skinned people who are exposed to sunlight produce more melanocytes, which are distributed to cells on the surface of the skin.
Although we think of a tan as a sign of health, it actually means that the body is trying to protect itself from the harmful rays of the sun.
Good health seems to require some UV radiation.
Some pros and cons of sun exposure are examined in the Biological Systems feature.
The epidermal layer is vulnerable to a number of diseases.
Human skin can be more traumatizing than animals with scales or fur.
It is prone to a variety of infections.
The organisms that cause ringworm and athlete's foot are called dermatophytes, and they grow on keratinized tissue.
Warts, caused by the human papillomaviruses, are small areas of epidermal proliferation that are generally harmless.
Life on Earth is powered by the sun.
Most organisms would die out if the sun weren't there.
The sun's energy can be harmful.
UV radiation has a higher energy than visible light and is shorter in wavelength.
Only UVA and UVB reach the Earth's surface, so only the three types of UV radiation can be grouped.
The UV index is used to determine how powerful the solar rays are.
Maps show the daily risk levels in the U.S.
Skin cells can be damaged by both UVA and UVB rays.
The tanning process increases the number of cells at the surface of the skin to prevent further damage by the UV rays.
Too much exposure to the sun's harmful rays can cause skin cancer.
The redness and pain of a sunburn is caused by UVB.
UVA rays do not cause sunburn, but they penetrate deeper into the skin, causing premature aging of the skin, and some types of skin cancer.
In the United States, skin cancer is the most common type of cancer, accounting for more than half of all cancer diagnoses.
In adolescents and young adults, melanoma is the most deadly form.
If the cancer cells have already spread throughout the body, less than 20% of patients can expect to live this long.
Any moles that turn into tumors are removed.
Chemo and other treatments are available if the cancer has spread.
In March 2007, the USDA approved a vaccine to treat melanoma in dogs, which was the first time a vaccine has been approved as a treatment for any cancer in animals or humans.
The vaccine is being tested for use in humans.
The FDA approved a drug called Yervoy in March of 2011, after it was shown to extend the lives of patients with advanced, late-stage melanoma.
According to the Skin Cancer Foundation, exposure to the sun's UV radiation can cause skin cancer.
Wear protective clothing, hats, and sunglasses when the UV rays are the most intense.
UVB rays are blocked better by sunscreens.
People may have a false sense of security because many sunscreens don't provide as much protection against UVA.
Look for sunscreens that contain zinc oxide, titanium dioxide, avobenzone, or mexoryl SX.
The tanning salon uses lamps that emit more powerful UVA rays than the sun emits.
Most medical experts recommend avoiding indoor tanning salons because of the potential damage to deeper layers of skin.
When UVB rays interact with a form of cholesterol found in the skin, vitamins D and D2 are produced in the body.
It's important for the body to have sunshine vitamins, like this one, to keep bones strong, boost the immune system, and reduce blood pressure.
It can be difficult to get sufficient amounts of vitamins D and E through diet alone.
After exposure to a few minutes of midday sun, a fair-skinned person will be able to synthesise a lot of vitamins D and E. During the winter months, anyone living north of Atlanta probably doesn't get enough UV rays to get enough vitamins D and D2 through the diet.
Melanoma is rarely fatal if it is caught early.
There is a lot of debate about the level of intake of vitamins D and E.
Basal cell carcinomas are the most common type of skin cancer.
In sun-exposed areas, scythes arise from the epidermis.
Malignant melanomas are caused by proliferation of cells.
Changes in size, shape, or color of a mole can be warning signs.
The dermis is a dense area beneath the skin.
The dermis is made of elastic fibers.
The skin is protected from being torn by the elasticity of the collagen fibers.
Stretching of the dermis can cause stretch marks.
The elastic fibers stretch to allow movement of underlying muscles and joints.
The skin has blood vessels that nourish it.
Sensory endings in the skin respond to external stimuli.
Touch, pressure, pain, and temperature can be felt.
Our ability to use our fingers for delicate tasks is boosted by the fact that the fingertips contain the most touch receptors.
The hypodermis is not a part of the skin.
It is made of loose tissue and fat.
Subcutaneous adipose tissue helps insulate the body from both heat gain from the outside and heat loss from the inside.
There is excessive development of the fat layer.
Even though some parts of hair and glands are found in the dermis, they are not of epidermal origin.
The fingers and toes are covered with nails.
The nail root contains cells from the base of the nail.
The nail root is hidden by a fold of skin.
The cells of a nail grow over the nail bed.
The appearance of nails can tell a lot about a person's health.
In clubbing of the nails, the nails turn down.
A deficiency of oxygen in the blood is associated with this condition.
Contraction of the arrector pili muscles causes the hairs to stand on end.
Epidermal cells form the root of hair.
As the cells are pushed farther from the root, they die.
The hair is made of dead, hardened cells and the root is at the base of a follicle.
A person has an average of 100,000 hair follicles.
Straight hair has a round shaft, while wavy hair has an oval one.
The hair color is determined by the color of the skin.
Dark hair and blond hair have the same amount of melanin.
The red hair is caused by the presence of pheomelanin.
A hair on the head grows about 1 millimeter a day.
Drug substances are incorporated into hair shafts where they can be detected by laboratory tests.
There is a certain amount of hair loss.
Most people lose about 100 hairs from their hair every day, but sometimes it is more dramatic.
There are many causes of sudden hair loss.
The color of the skin is caused by oxidation.
During adolescence, when hormonal changes lead to increased oil production, there is an inflammation of the sebaceous glands.
There is a tubule in the skin that can either open into a hair follicle or onto the surface of the skin.
Sweat glands all over the body help regulate body temperature.
Sweat glands become active when body temperature goes up.
Sweat absorbs body heat.
Sweat glands are no longer active once the body temperature drops.
The groin and axillary regions have different types of sweat glands.