1. Mammals

2. Mammals
All mammals, in the class Mammalia, have 2 important features – hair and mammary glands.
In female mammals mammary glands produce milk to nourish their young.
All mammals also breathe air, have a 4 chambered heart, and are endotherms that generate body heat.

3. Form and Function in Mammals
Mammals are endotherms – their body can generate heat internally.
Mammals have a high metabolic rate. This helps makes body heat.
Mammals also have hair that keeps them warm. They also have a subcutaneous fat layer which is a layer of fat located under the skin. It help keeps the heat in.
Many mammals have sweat glands to help cool the body. When body temperature gets too high the mammal will start to sweat. The evaporation of sweat cools the body. Some mammals do not have sweat glands, like a wolf, so they pant.

4. Feeding
A mammal has to eat about 10x as much food as a reptile of the same size to maintain homeostasis.
Mammals have different types of teeth and jaws based on what they eat. Carnivores have different teeth than an herbivore.
Many herbivores have specialized digestive organs to break down plant materials, which is harder to digest than meat. Cows have a stomach chamber called the rumen. This is where food that was newly swallowed plant food is stored and processed. The rumen has bacteria that digest the cellulose of most plant tissues. After a period of time the animal will regurgitate the food from the rumen into its mouth. The partially digested food is chewed and swallowed again. This happens several times before the food moves to the intestines.

5. Respiration
All mammals use lungs to breathe. Lungs are controlled by 2 sets of muscles.
Mammals also have a diaphragm – this pulls the bottom of the chest cavity down, which increases the lungs volume. This pulls air into the lungs. When the diaphragm relaxes it pushes air out of the lungs.

6. Circulation
There are 2 complete loops with a four- chambered heart. The right side of the heart gets oxygen-poor blood from the body and pumps it to the lungs. After the blood gets oxygen in the lungs it returns to the left side of the heart. This blood is then pumped to the rest of the body.

7. Excretion
Mammals have highly developed kidneys. Kidneys help maintain homeostasis by filtering urea from the blood, as well as getting rid of extra water or keeping water when needed.

8. Response
Mammals have the most highly developed brains of any animals. There are 3 main parts: the cerebrum – makes complicated behaviors like thinking and learning possible, the cerebellum – controls muscles, and the medulla – regulates involuntary body function (heart rate and breathing).
Mammals have highly developed senses. Mammals have very good senses of smell and hearing.

9. Chemical Controls
The nervous system is not the only thing that controls body processes. They have endocrine glands that regulate body activities by releasing hormones. Hormones regulate many activities.

10. Fighting Disease
Mammals have immune system to protect the animals from disease. When animals get sick their immune system helps them get better.

11. Movement
Mammals have a backbone that flexes and helps them move side to side. There are many different types of limbs to allow different mammals to run, walk, climb, burrow, hop, pounce, swing, fly, leap, and swim.

12. Reproduction
Mammals reproduce by internal fertilization. All mammals feed on their mother’s milk.
Young mammals need to be taken care of after birth.