Out of them, the mantle is the thickest layer, while the crust is the thinnest layer. The Earth can be divided into four main layers: the solid crust on the outside, the mantle, the outer core and the inner core. Out of them, the mantle is the thickest layer, while the crust is the thinnest layer.

outer core

Outer core

Terms in this set (8)

• Stratum Corneum. made up of dead cells.
• Stratum Lucidum. Made up of dead cells.
• Stratum Granulosum. Made up of dead and alive cells.
• Stratum Spinosum. Made up of live cells.
• Stratum Basale. Made up of live cells, part of the epidermis.
• Papillary Layer.
• Reticular Layer.
• Hypodermis.

Each layer of skin regenerates in response to injury using a different process. The epidermis’ deepest layer, called the stratum basale, begins to regenerate with a proliferation of its cells, which move to fill up any empty space left by the injury.

If you’re average, your skin weighs about six pounds. It’s job is crucial: to protect you from infections and germs. Throughout your life, your skin will change constantly, for better or worse. In fact, your skin will regenerate itself approximately every 27 days.

Your skin gets its color from a pigment called melanin. Special cells in the skin make melanin. When these cells become damaged or unhealthy, it affects melanin production.

Your skin is crawling with hundreds of kinds of bacteria, NIH researchers find. There are up to 100 times more kinds of bacteria thriving in “vibrant communities” in healthy skin than previously known, report NIH researcher Elizabeth A.

Usually, all mammals have hair on the skin. It’s one of their biological characteristics. Some of the mammals are monkeys, lions, panda, platypus, cats. Some of the mammals even have very beautiful lustrous hair such as Siberian cats, Angora Rabbit.

Hair is actually a modified type of skin. Hair grows everywhere on the human body except the palms of the hands, soles of the feet, and lips. Hair grows more quickly in summer than winter, and more slowly at night than during the day.

The function of human hair depends on the part of the body from which it grows. Human hair performs several functions. It protects the skin from environmental influences. Scalp hair is also the only part of the human body that can be readily and consciously modified to change an individual’s external appearance.

Cards

The primary benefit of pubic hair is its ability to reduce friction during sexual intercourse. The skin in the area around the genitals is very sensitive. Pubic hair can naturally reduce friction associated with the movements during sexual intercourse and other activities wherein chafing may occur.

Naked molerats are naturally hairless. Other than that, there are many animals which were bred to have less hair. Afterall it’s all genetics. Sphynx cat, skinny pigs, hairless dogs, you name it.

Chinchilla. The softest vertebrate land animals in the world are chinchillas. They are small rodents found in the Andes mountain of South America. Their luxurious fur is the reason they have hunted centuries ago nearly to extinction.

Types of Body Coverings One of the main characteristics that is used to distinguish one class of animals from another is type of skin covering. Mammals have hair or fur, birds have feathers, reptiles have dry scales, amphibians have soft, moist skin, and fish have wet, slimy scales.

quill

Types of Feathers

• Flight feathers are found two places on birds: the wings and tail. Flight feathers are long, and on the wings, have one side of the vane wider than the other.
• Down feathers have little or no shaft. They are soft and fluffy.
• Bristle feathers are very stiff with only a few barbs found at the base.