Mammals

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Mammary glands: feature for which mammals are named-produce milk to nourish the young. Having hair, ability to nourish their young with milk, all breathe air, have four chambered hearts, and are endotherms. The first true mammals appeared during the late Triassic period, about 220 million years ago. Mammals are descended from ancient reptiles.

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* Form and Function in Mammals
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* Body Temperature Control
* High metabolic rate, helps generate body heat. External body hair that helps them keep warm. * Subcutaneous fat: layer of fat located beneath the skin, helps conserve body heat. * Sweat glands that help coo the body.

* The ability of mammals to regulate their body heat from within is an example of homeostasis. *
* Feeding
* As mammals evolved, the form and function of their jaws and teeth became adapted to eat foods other than insects. * Canines, Incisors, Molars, Premolars.
* The more efficiently an animal can obtain and process its food, the more energy it can obtain. * Carnivores have relatively short intestine, herbivores have relatively long intestine. * Cows and their relatives have a stomach chamber called the rumen, in which food is stored and processed. It contains symbiotic bacteria that digest the cellulose of most plant tissues. *

* Respiration
* Lungs to breathe, has a diaphragm
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* Circulation
* Two completely separate loops, with a four chambered heart. The two separate circuits efficiently transport materials throughout the body.

Excretion
Highly developed kidneys that help control the composition of body fluids. Kidneys extract nitrogenous wastes from the blood in the form of urea, urea other wastes and water combine to form urine. The kidneys of mammals help maintain homeostasis by filtering urea from the blood, as well as by excreting excess water or retaining needed water.

Response
Brain consists of three main parts: the...
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