1. 18B- Class Mammalia

2. Class Mammalia
The class mammalia is one of the smallest vertebrate classes, but it encompasses animals of great variety that inhabit virtually every habitat imaginable.

3. Common Characteristics
Air breathing
Endothermic
4 chambered heart
Specialized teeth
Produce milk for young
Hair
3 middle ear bones

6. Reproduction Monotremes: egg-laying mammals
Have a single perforation or hole for the digestive, excretory and reproductive systems (like cloaca).
They are the only egg-laying mammals. They lay and incubate eggs like a bird, but when hatched, the young nurse on milk that empties onto the skin.
Duck-billed platypus—one of the few known venomous mammals. Males hind legs have sharp spurs that can inject poison.
2 species of echidnas or spiny anteaters. They have a small pouch where the egg hatches and nurses

7. Reproduction Marsupials: pouched mammals
Kangaroos, koalas, wallaby, wombat, sugar glider, Tasmanian devil…
No placenta, no shelled egg
Babies are very altricial (Red Kangaroo, largest living marsupial, 33 day gestation, 7 months in pouch)
Young nourished by a small yolk sac; when depleted the immature offspring crawls out of the uterus and onto the mother’s fur, instinctually moves towards the mother’s marsupium (pouch) where it is sustained by the mother’s milk while it completes its development.

8. Reproduction Placentals
Most mammals have young that develop internally; nurtured by a placenta—the interface between mother and the developing offspring through which gases, nutrients, and wastes are exchanged. Blood supplies do not mix.
Umbilical cord- blood vessels and surrounding membranes that connect the placenta and the embryo
Uterus- muscular chamber where the young develops
Estrus- period where ovum (egg) is ready to be fertilized. Female releases chemical odors to attract males
Internal fertilization- fertilization is a uniting of the male gamete (sperm) and the female gamete (egg). This produces a zygote.
Zygote begins to divide and is implanted into the uterine wall
Placenta forms which is composed of a portion of the uterine wall and tissues of the embryo
Gestation = period of pregnancy, the embryo develops

9. Reproduction
Mammary glands- produce milk rich in nutrients and antibodies

10. Hair
All mammals have hair which is a collection of nonliving cells filled with filaments of the protein keratin
Produced by hair follicles
Two types
Underhair- soft, insulating fur layer next to the animal’s skin
Guard hair- coarser, longer, found over the underhair, gives animal color
Functions
Insulating ability
Camouflage
Sensory (whiskers are innervated, enlarged hairs)
Repelling attackers (porcupine)

11. Limbs
Very diverse
Forelimbs of the bat have elongated webbed fingers used as wings
Moles have short stout limbs with wide paws and large claws that they use as a shovel
Whale has forelimbs fused into swimming paddles
Primates have opposable thumbs for climbing and grasping items
Ungulates have hooves to protect phalanges
Lions have needle-sharp retractable claws used for tearing into prey

13. Digestion
Most mammals have a variety of specialized teeth arranged in jaws
Types of teeth usually match a particular diet
Incisors- flat, thin teeth in the front of the mouth, used in gnawing or biting
Canines- rounded, pointed teeth toward the front of the mouth, used for tearing
Molars- thick, squat teeth in the back of the mouth, used for grinding and chewing

14. Digestion Carnivores have enlarged canine teeth
Gnawing animals, like rats and beavers, have large incisors and no canines
Herbivores have sharp incisors and flat molars to cut and grind foliage
Omnivores have well-formed teeth of each kind

16. Digestion
Digestive organs vary in mammals with different diets; however, no vertebrate can digest cellulose without help

17. Complex Carbohydrates
Cellulose- plants, structural
Starch- plants, storage
Chitin- arthropods, fungi, structural
Glycogen- animals, storage

18. Starch OH O
CH2OH
CH2

19. Chitin

20. Glycogen

21. Digestion
Rumen- (cows, camels, giraffes, deer are ruminants) a special section of the multi-chambered stomach of certain mammals. Bacteria maintained within the rumen produce enzymes that digest cellulose.
Cud— partially digested food that ruminants regurgitate and re-chew for improved digestion. Mixes enzymes with food
Ruminants and other herbivores have long digestive tracts which allows for more digestion and absorption

23. Order Artiodactyls
Suborder Suiformes
Family Suidae - swine (pigs, hogs)
Family Tayassuidae - peccaries (javelina)
Family Hippopotamidae - hippopotamus, pygmy hippopotamus
Suborder Tylopoda
Family Camelidae - camels, llamas, alpacas
Suborder Ruminantia (ruminants - having a 3- or 4-part stomach)
Family Tragulidae - chevrotains (mouse deer)
Family Giraffidae - giraffe, okapi
Family Cervidae - deer, including musk deer, moose, muntjacs, brockets, roe deer, pudu, caribou, elk, etc.
Family Antilocapridae - pronghorn
Family Bovidae - antelope, cattle, goats, sheep

24. Digestion
Cecum—a pouch-like extension between the large intestine and the small intestine containing bacteria for digestion of cellulose for some mammals that don’t chew their cud. (horses, elephants, manatees)

25. Digestion
Carnivores (seals, wolves) eat primarily protein which is easier to digest; therefore, they have a shorter digestive tract & don’t require specialized stomach or digestive bacteria. Unsegmented stomach similar to humans.

26. Respiration and Circulation
Oblong spongy lungs in upper chest cavity
Lungs separated from abdominal organs by muscular diaphragm- air is drawn into lungs by the contraction of the dome-shaped diaphragm
Larynx- voice box, cartilaginous organ containing vocal cords which vibrate to produce sound.
4 chambered heart
Contraction flattens the diaphragm
Diaphragm is up when it relaxes
Elastin proteins around the alveoli are like rubberbands, drives the exhaling process, elastic potential energy

27. Diaphragm contracts and flattens Intercostal muscles contract
Ideal Gas Law
PV=nRT
P is pressure
V is volume
N is the number of moles
R is the universal gas constant
T is temperature (K)
Atmospheric pressure = 760 mmHg
Inhaling
Diaphragm contracts and flattens
Intercostal muscles contract
Volume of lungs goes up
Pressure goes down. At this point pressure in lungs is less than atmospheric pressure, so air moves in to equalize the pressure
Exhaling
Diaphragm relaxes into arched orientation
Stretchy protein called elastin which surrounds alveoli recoils
Volume of lungs goes down
Pressure goes up. At this point pressure in lungs is more than atmospheric pressure, so air moves out
Atmospheric pressure 760mmHg
Volume and pressure
Train car
Barrel

28. Nervous System Olfac Cerebrum- controls voluntary muscle activity
Optic Lobes
Cerebellum- coordinates muscle activity and some involuntary activities
Medulla Oblongata

29. Nervous System Nervous system contains: Brain Spinal cord
Cranial nerves (branch from the brain)
Spinal nerves (branch from the spinal cord)
Sensory organs( eyes, ears, taste buds)
Divisions of the Five major lobes of the brain, from anterior to posterior:
Olfactory lobes ~ receive impulses from the smell receptors of the nostrils
Cerebrum ~ controls voluntary muscle activity
Optic lobes ~ Receives impulses from the eyes
Cerebellum ~ coordinates muscle activity and some involuntary activities
Medulla oblongata ~ transports impulses to and from the spinal cord, including some reflexes.
Nervous System

30. Nervous System
Mammalian brains are relatively very large. 2X as large as bird of the same size. 10X as large as a reptile of the same size.
Cerebrum = brain
Cerebral cortex is the outermost layered structure of the brain important for receiving and processing information. It has many more layers in mammals (6 layers) than other vertebrates (neocortex or isocortex).
Telencephalon = cerebrum or brain