Melanin is a natural substance in the body that gives the iris of the eye, hair and skin its color. Skin cells called melanocytes produce melanin in the body. Melanin also acts as a kind of natural sunscreen to protect against harmful UV rays, however it cannot prevent sunburn all on its own.

Regular exercise is important for good health, so itching severely every time you work out isn't merely a nuisance, it can interfere with your ability to keep fit. Exercise-related itching isn't uncommon and particularly affects boys and men ages 10 to 30, note experts from the New Zealand Dermatological Society.

Heat bumps on the skin, also known as heat rash, usually develop from excessive exposure to heat or humidity. The condition may be as mild as a few small bumps but can also develop into painful blistering of the skin.

Dry, inflamed, itchy scalp is a common condition in children and adults. Red blotches on the scalp may indicate several different disorders, including dermatitis, psoriasis, ringworm, folliculitis, head lice or dandruff, according to MayoClinic.com and Skinsight.com.

Acne blemishes are characterized by the appearance of papules, pustules, nodules and cysts, which cause the skin to be severely irritated and red. This inflammation results in swelling, tenderness on the skin, and over time can affect self-esteem.

Melanin is what makes up your natural skin tone. Produced by cells called melanocytes, melanin also provides you with natural hair color. When melanin production slows, your hair and skin lighten, which sometimes forms a condition known as vitiligo.

Pinching your arm can cause blood vessels to break, leading to bruises. While it may appear red and swollen at first, your arm may turn a blue or purple color as the bruises start to appear. Most bruises heal on their own, but may cause discomfort in the process.

Dermatographia is a skin condition that produces bumps, or inflammation, on your skin after you scratch it. Dermatographia is not fully understood, but it appears to be some type of allergic response, the Mayo Clinic says. Often it's not a serious condition and doesn't require medical treatment.

Skin is a protective covering meant to guard the internal systems from infection. When skin develops a break, your body will take measures to isolate the break and fight bacteria by forming a film or crust. This is true regardless of what caused the break in the skin. A crusty bump can be the result of many conditions.

Doctors recommend exercise on most days of the week as an effective way to lose weight and ensure your overall well-being. Scalp itchiness that occurs during a workout can hinder your weight-loss efforts and is often linked to an allergic reaction.

There are many reasons for the development of bumps on the skin, which may range from a regular rash to something more serious such as cancer. If you notice bumps on the skin that resemble a volcano, it is important to seek medical advice as soon as possible for an accurate diagnosis of the problem.

Flesh-colored bumps are a common skin complaint. Depending on their location on the body, they can be unsightly, irritating or even painful, but most are harmless. Some of the more common types are moles, keratoses, keratoacanthomas and lipomas. The causes are as varied as the types and are often unknown.