Chapter 32.1 Notes

Hannah Reagan3rd period

Mammals

Class Mammalia Have hair and mammary glands

(produce milk to nourish the young) Also, mammals breathe air, have

four-chambered hearts, and are endotherms that generate body heat internally

Evolution

Though you can’t see hair nor mammary glands in fossils, some fossilized mammal characteristics include: lower jaw connected by a joint directly to the skull, teeth that are replaced once in a lifetime, and discrete features of limbs and backbone

Mammals descend from reptiles First appeared during late Triassic

period; 220 million years ago

Body Temperature Control

High metabolic rate HairSubcutaneous fat: layer of fat

located beneath the skin Some have sweat glands and others often pant

Feeding As mammals evolved, the form and function of

their jaws and teeth became adapted to eat foods other than insects

Because of high metabolic rate, mammals have to eat 10 times more food as a reptile

Specialized teeth: 1. incisors

2. canines 3. molars 4. premolars

Carnivores have short intestine because digestive enzymes can quickly digest meat

Herbivores have long intestine because tough, fibrous plant tissue is hard to break down

Rumen: stomach chamber in which newly swallowed plant food is stored and processed

Respiration

Circulation

All mammals use lungs Diaphragm: powerful muscle that pulls the

bottom of the chest cavity downward, which further increases volume when breathing in

2 separate loops with a four chambered heart

Right ventricle and atrium pump oxygen poor blood from body to lungs. Left ventricle and atrium pump oxygen rich blood from lungs to the rest of the body.

Excretion

The kidneys of mammals help maintain homeostasis by filtering urea from the blood, as well as by excreting excess water or retaining needed water.

Kidneys also help retain sugars, salts, etc.

Kidneys allow mammals to live in different habitats just by being able to stabilize the amount of water in the body efficiently

Response

Highly developed brains: main parts include cerebrum-thinking and learning, cerebellum-muscular coordination, and medulla oblongata-involuntary body functions

The cerebrum outer layer is the cerebral cortex: center of thinking and other complex behaviors

Many have well developed sense of smell, sight, and hearing

Other super cool fun stuff

Endocrine glands regulate body activities by releasing chemicals called hormones that affect other organs and tissues

Immune systems help stop pathogens from infecting the mammal (includes skin barrier, and specialized cells that recognize and destroy pathogens)

Movement

Backbone Shoulder and pelvic girdles Diversity in limb bones of climbers,

runners, diggers, flyers, and swimmers. Pictures of limbs on page 826!

Reproduction

Internal fertilization All newborn mammals feed on their

mother’s milk Strong parental care and interaction

1. What is the cerebral cortex?

A. Covering of the olfactory bulbB. Outer layer of the cerebrumC. Helps in excretionD. Another name for the medulla oblon

gata

2. What defines a mammal?

A. Four chambered heartB. Breathe airC. Generate their body heat internallyD. All of the above

3. When and about how long ago did the first mammal appear?

A. Triassic Period; 220 million years ago

B. Jurassic Period; 206 million years ago

C. Permian Period; 260 million years ago

D. Carboniferous Period; 330 million years ago

4.What system is the kidney a part of?

A. NervousB. DigestiveC. ExcretoryD. Circulatory

5. How do mammals reproduce?

A. Asexual reproductionB. External fertilizationC. Internal fertilizationD. They don’t reproduce

CORRECT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

WRONG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!