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Biology
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2. 32-1 Introduction to the Mammals
Photo Credit: ©Zefa (RM)/M. Botzek/Masterfile
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Mammals Chapter 32 p821
What are the characteristics of a mammal?
Hair
mammary glands (in female)
breath air
4 chambered hearts
endotherms
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4. Form and Function in Mammals p822
Body Temperature Control – like birds, mammals are endotherms; their bodies can generate heat internally.
endotherms have a higher metabolic rate than ectotherms (most other chordates)
external body hair helps keep mammals warm.
subcutaneous fat, which is a layer of fat located beneath the skin also helps to conserve body heat.
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5. Form and Function in Mammals
Sweat glands help to keep an animal cool.
Mammals, like wolves, that lack sweat glands, pant to rid themselves of excess heat.
The ability of mammals to regulate their body heat from w/in is an example of homeostasis.
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6. Form and Function in Mammals
Draw a diagram that depicts the internal feedback mechanism of sweating.
List 4 possible ways that a mammal regulates its body temperature. 1. 2. 3. 4.
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Feeding p822
B/c of its high metabolic rate a mammal must eat nearly 10X as much food as a reptile of the same size to maintain homeostasis.
mammals can be herbivores, carnivores, omnivores; most whales are filter feeders.
The form and function of a mammals jay and teeth enables it to eat foods other than insects.
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Feeding
Mammals have specialized teeth – incisors, canines, molars and premolars.
Mammals teeth enable food to be processed efficiently.
Mammals have a digestive tract to break down and absorb the food it eats.
B/c digestive enzymes readily break down meat carnivores have a shorter intestine than do herbivores or omnivores.
Incisors
Molars and premolars
canines
Wolf
Horse
Herbivore
Carnivore
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Feeding
Herbivores usually have a specialized digestive organ, called the rumen to break down plant matter.
Newly swallowed plant food is stored and processed in the rumen. The rumen contains symbiotic bacteria that digest the cellulose of most plant tissues. The processed food in the rumen gets regurgitated from the rumen into the mouth. The partially digested food is chewed and swallowed again. After several cycles of regurgitation, the food moves to the stomach and through to the intestines.
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Feeding
What is the function of the rumen?
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Respiration p824
Use lungs to breath.
The lungs are controlled by two sets of muscles:
Intercostal muscles (found btw each rib)
Diaphragm (found below the rib cage)
The contraction of the intercostal muscles expands the rib cage, increasing the volume of the chest cavity.
The contraction of the diaphragm pulls the chest cavity downward which further increases its volume.
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Respiration
When the muscles relax, the rib cage lowers and the volume of the chest cavity decreases.
Organs of respiration include:
Nostrils
Pharynx
Trachea
bronchus
bronchioles
alveoli – alveoli is where gas
exchange occurs.
What are the characteristics of a respiratory surface?
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Circulation
p824
2 separate loops with a 4 chambered heart.
The right side of the heart receives oxygen poor blood from all over the body and pumps it to the lungs.
After picking up oxygen in the lungs, the oxygen rich blood is returned to the left side of the heart, then pumped through blood vessels to the rest of the body.
refer to diagram on page 824
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14. Form and Function in Mammals
Mammalian heart
Left atrium
Right atrium
Left ventricle
Right ventricle
Complete division
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Excretion
p824
Excretory organs:
Kidney
ureter
urinary bladder
urethra
The kidneys help maintain homeostasis by filtering urea from the blood, as well as by excreting excess water or retaining water as needed.
The kidneys also can retain salts, sugars and other cmpds the body should not be losing.
The presence of kidneys is what enables some animals to live habitats with minimal water.
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16. Form and Function in Mammals
Response p825
The brain consists of three parts:
Cerebrum
Cerebellum
Medulla oblongata
What is the function of each part?
Mammals have large brains in proportion to their body size. Most of the brain is taken up by an enlarged cerebrum, which contains a well-developed cerebral cortex.
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17. Form and Function in Mammals
Response p825
A mammals cerebrum contains a well-developed outer layer called the cerebral cortex, which is the centre of thinking and other complex behaviours.
Mammals rely on highly developed senses to detect and respond to stimuli from their external environment. The degree of development is animal specific. For example, dogs have a highly developed olfactory organ; dogs, bats and dolphins can detect sounds at much higher frequencies that we can.
Not all mammals have color vision. Color vision is most useful to animals that are active during the day.
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18. Response: Chemical Controls
Along with the nervous system, the endocrine system is involved in controlling body responses.
Endocrine glands produce and release chemicals called hormones which enter the blood stream and carried to the hormones target organ.
Ex. Calcitonin, Parathyroid hormone – regulate calcium levels
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19. Response: Chemical Controls
Calcitonin is produced by the thyroid gland and acts on the digestive system and on bones.
Parathyroid hormone is produced by the parathyroid gland and acts on bone and the digestive tract.
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Rat anatomy
What structures are involved in:
-digestion?
-circulation?
-respiration?
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32-1
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32-1
One characteristic commonly used to determine whether fossils are mammals is
subcutaneous fat.
mammary glands.
a jaw joint that allows movement from side to side.
hair or fur.
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32-1
How many chambers do mammalian hearts have? 2 3 4 6
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32-1
Mammals are called endotherms because they
produce milk to nourish their young.
have well-developed sense organs.
have powerful jaws and specialized teeth.
generate their body heat internally.
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32-1
The first true mammals appeared in the fossil record
soon after the extinction of the dinosaurs.
about the same time as the first reptiles.
during the Triassic when dinosaurs were the dominant land animals.
long after the extinction of the dinosaurs.
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26. END OF SECTION