Page 51 - 84 human physiolofy part-1

The Integumentary System

hormones. If this growth runs out of control, cancer results. Almost all instances of breast cancer
originate in the lobules or ducts of the mammary
glands.

Types of breast cancer

• DCIS: Ductal Carcinoma in Situ
• LCIS: Lobular Carcinoma in Situ
• Invasive ductal carcinoma
• Invasive lobular carcinoma
• Inflammatory breast cancer
• Paget's disease

Other mammals

The number of complex and simple mammary
glands varies widely in different mammals. The
nipples and glands can occur anywhere along the two
milk lines, two roughly-parallel lines along the front of
the body. They are easy to visualize on dogs or cats,
where there are from 3 to 5 pairs of nipples following
the milk lines. In general most mammals develop
mammary glands in pairs along these lines, with a
number approximating the number of young typically
birthed at a time.
Early Signs of Breast Cancer
Male mammals typically have rudimentary
mammary glands and nipples, with a few exceptions: male mice don't have nipples, and male horses
lack nipples and mammary glands.

Mammary glands are true protein factories, and several companies have constructed transgenic
animals, mainly goats and cows, in order to produce proteins for pharmaceutical use. Complex
glycoproteins such as monoclonal antibodies or antithrombin cannot be produced by genetically
engineered bacteria, and the production in live mammals is much cheaper than the use of mammalian
cell cultures.

Homeostasis

As a whole, the integumentary system plays a big part in maintaining homeostasis. The
integumentary system is the outermost organ system of the body and many of its functions are related
to this location. The skin protects the body against pathogens and chemicals, minimizes loss or entry of
water, and blocks the harmful effects of sunlight. Sensory receptors in the skin provide information
about the external environment, helping the skin regulate body temperature in response to
environmental changes and helping the body react to pain and other tactile stimuli. The large surface
area of the skin makes it ideal for temperature regulation. The rate of heat loss can be regulated by the
amount of blood flowing through the the blood vessels in the dermis close to the surface of the skin.
When the body temperature rises, as for example during exercise, sympathetic tone is reduced and this

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