Mammals

1. Mammals Chapter 32.1 By: Rose, Ashley, Katelyn, and Tony

2. Characteristics • All mammals are characterized by two features; hair and mammary glands. • Mammary glands: gland in mammals that produces milk to nourish the young. • Other characteristics that help identify mammals are their lower jaw, consisting of a large, teeth-bearing bone connected by a joint directly to the skull. • Mammals all breath air, have four-chambered hearts, and are endotherms that generate their body heat internally.

3. Body Temperature Control • Mammals are endotherms, which means their bodies generate heat internally. • Mammals have a high metabolism that helps them generate body heat. • They also use subcutaneous fat. • Which is a layer of fat located beneath the skin, that helps conserve body heat. • They use sweat glands to cool the body when the body becomes too hot.

4. What do they eat? • A mammal eats nearly 10 times as much food as a reptile that’s the same size as it so that it can maintain homeostasis. • Homeostasis: the process by which organisms maintain a relatively stable internal environment. • Mammals can be classified as herbivores (eats plants), carnivores (eats meat), and omnivores (eats both plants and meats). • A mammal’s digestive tract is specialized to break down and absorb the type of food it eats. • Cows have a stomach chamber called a Rumen. This is where the newly swallowed plant food is stored and processed.

5. Respiration and Circulation • All mammals use lungs to breath, which are controlled by two sets of muscles. • When they breath they also use their diaphragm, which pulls the bottom of the chest cavity downward which increases its volume. • Their circulatory system is divided into two different loops with a four chambered heart. • The right side gets oxygen-poor blood and the left side releases oxygen-rich blood. • The two separate loops transports materials very well.

6. Picture Example of Heart :

7. Excretion • Mammals have highly developed kidneys that control the amount of body fluids that come in. • Kidneys help maintain homeostasis by filtering urea from the blood, as well as by excreting excess water or retaining needed water. • Because kidneys are so efficient at controlling the amount of water in the body, they enable mammals to live in many habitats.

8. Response • Mammals have highly developed brains which consist of 3 parts: the cerebrum, the cerebellum, and the medulla oblongata. • The cerebrum makes possible such complicated behaviors as thinking and learning. • The cerebrum contains a well-developed outer layer called the cerebral cortex, which is the center of thinking and other complex behaviors. • The cerebellum controls muscular coordination. • The medulla oblongata regulates involuntary body functions, or those that are not under conscious control, such as breathing and heart rate.

9. Movement • Mammals evolved many adaptations, such as the backbone, which flexes both vertically and side to side, to aid them in movement. • The shoulder and pelvic girdles are flexible and permit both front and hind limbs to move in a variety of ways. • Mammals also use variations in the limb bones and muscles to move about.

10. Reproduction • Mammals reproduce by internal fertilization. • Fertilization occurs when the male puts sperm inside the reproductive tract of the female. • Once the babies are born, the parents take care of them for a long time to help ensure that the young mammals will survive and reproduce. • The duration and intensity of parental care varies among different species.