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Bio 202 Exam > 11 - Mammals > Flashcards

11 - Mammals Flashcards

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Biology 101 flashcards
1
Q

Mammals and ancestral amniotes

A

most closely related group to ancestral amniotes1

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2
Q

Premammalian synapsids

A

present during mid-triassic

Bad thermoregulation so probably not true homeotherms (dimetrodon and cynognathus)

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3
Q

Evolutionary perspective mammals

A
  • first amniote lineage

- started 200 mya with therapsid subgroup

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4
Q

Therapsid subgroup

A
  • mammal-like teeth
  • hindlimbs directly beneath body
  • separation of thoracic and abdominal regions
  • near extinction 240 mya (dinos took over)
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5
Q

During dinosaurs

A
  • mammals survived nocturnally (bad colour vision)
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6
Q

Mammalian radiaton

A
  • 65 mya
  • mass extinctioin of dinos and other taxa
  • tertiary period “age of mammals”
  • mammals were able to be outside during the day
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7
Q

2 subclasses of mammals

A
  • prototheria

- theria

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8
Q

Subclass prototheria

A
  • cloaca, oviparous
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9
Q

Subclass prototheria infraclass

A

ornithodelphia (monotremes)

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10
Q

Subclass theria 2 infraclasses

A

Metatheria (marsupials)

Eutheria (placental mammals)

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11
Q

Monotremes

A
  • 6 species
  • found in australia/new zealand
  • eggs
  • ex: echidnas and platypus
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12
Q

Marsupials

A
  • around 250 species
  • viviparous but short gestation periods
  • born early but not developed so feed and develop in marsupium (pouch)
  • ex: koalas, kangaroos
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13
Q

Biogeography of mammals

A

Movement of continents explains the current distribution of mammals

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14
Q

Hair

A
  • guard hairs
  • insulating underhair
  • whiskers provide sense of touch
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15
Q

Glands

A
  • sebaceous (oil)
  • sudoriferous (sweat)
  • scent (pheromones)
  • mammary (nutrition for offspring)
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16
Q

Teeth

A
  • heterodonts (unlike homodont in reptiles where they’re uniformly conical)
  • specialized for different functions
  • deciduous (milk) teeth and permanent
  • single replacement of teeth is the diphyodont condition. reptiles are polyphydont
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17
Q

diphyodont

A

single replacement of teeth

18
Q

4 types of teeth

A
  • incisors
  • canines
  • premolars
  • molars
19
Q

humans teeth

A

2,1,2,3 on each side

incisors, canines, premolars, molars

20
Q

Diastema

A

missing teeth section separates the biting teeth at the front of the jaw, from the chewing teeth at the rear

21
Q

Skeleton

A
  • vertebral column

- appendicular skeleton

22
Q

Vertebral column 5 regions

A 
Cervical
thoracic
lumbar
sacral
caudal
23
Q

Appendicular skeleton

A
  • rotates under body

- appendages move in anteroposterior plane (makes them faster than reptiles)

24
Q

Digestive systems

A

Adapted for diverse feeding habits that reflect ecological specializations
Herbivores/ruminants: rumens, cecums and spiral loops (long digestive system)
Carnivores: much smaller, no storage/fermenting compartments

25
Q

Heart, circulation

A
  • complete separation of pulmonary and systemic circuits
  • similarities with bird hearts result from convergence within synapsid and archosaur lineages (adaptations to active lifestyles)
26
Q

Fetal circulation

A
  • nutrients/gases/wastes exchanged by diffusion across placenta
  • in fetus, blood shunted away from lungs until inflated at birth
27
Q

2 structures involved in shunting

A
  • foramen ovale (shunt between left and right atria)
  • Ductus arteriosus (most blood in pulmonary artery bypasses lungs)
    These close off after birth
28
Q

Respiration

A
  • respiratory passageways highly branched with large surface areas
  • thin membranes and high surface area
  • larynx, trachea, bonchi (1,2,3) bronchioles, alveoli
29
Q

Heat producing mechanisms

A
  • shivering thermogenesis

- nonshivering thermogenesis (metabolism of brown fat: hibernation)

30
Q

Heat conservation

A
  • insulating pelage and fat deposits (ex: hair, and blubber)
  • shunt blood from surface to core to keep it warm in water
  • heat conserving postures
  • countercurrent heat-exchange systems
31
Q

Cooling

A 
Radiation into air
Evaporative cooling (sweat glands/panting)
32
Q

Winter sleep

A
  • less active and metabolic rates drop somewhat
  • easily aroused/periodically wake
  • body temperature doesn’t change much
  • bears/raccoons
33
Q

Hibernation

A
  • metabolic rates drop substantially
  • hypothalamic thermostat reset
  • not easily aroused
  • insectivores, rodents, bats
34
Q

Conserving water; kidneys

A
  • very efficient kidneys
  • long loop of nephron (loop of henle)
  • concentrates urine and conserves water
  • countercurrent exchange system!
  • longer loop = better water usage
35
Q

More strategies for water conservation

A
  • Dry feces
  • Nocturnal habits
  • Water condensation in respiratory passages
  • Low protein diets
36
Q

2 reproductive cycles

A
  • estrus cycle

- menstrual cycle

37
Q

Estrus cycle

A
  • Female behaviourally and physiologically receptive to male
  • hormonal changes stimulate maturation of ova and ovulation
  • uterine lining proliferates
  • vaginal swelling and discharge
    Males show heightened interest in females
38
Q

Menstrual cycle

A
  • humans, apes, monkeys
  • periodic proliferation of uterine lining that correlates to maturation of ovum
  • Sloughing of lining occurs in absence of fertilization
39
Q

Delayed fertilization

A

Adaptation to winter dormancy in some bats.

suspended or slow growth of the embryo that can occur after implantation has occurred but prior to birth

40
Q

Embryonic diapause

A
  • Development arrested after fertilization

- development occurs when resources are most plentiful

41
Q

Modes of development

A
  • monotremes are oviparous

- all others are viviparous

42
Q

Viviparous

A

marsupials: nourished via uterine milk following short gestation period
Eutherian mammals: form placenta and have long gestation periods

Bio 202 Exam (12 decks)

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