Lecture 11: Mammal Reproduction, Thermal Regulation

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Lecture 11 Mammal Reproduction, Thermal
Regulation Diversity of Organ Systems
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• Reproduction
• 3 kinds of birth
• oviparity, ovoviparity, viviparity
• Therians evolve new structure -placenta
• Thermoregulation
• How hot or cold is body?
• How variable is temperature?
• How is heat obtained?
• Diversity of Organ Systems
• Deep Diving- whales and seals
• Water conservation-kangaroo rats

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Reproduction -3 kinds
Monotremes oviparous (egg laying)
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Reproduction
 Placenta Chorioallantoic placenta
(placentals) longer gestation, fairly well
developed young Choriovitelline placenta
(marsupials) underdeveloped young
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Marsupials
crawl in pouch to finish development
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How hot or cold is body?
mammals relatively high body temperature (vs.
fish, reptiles)
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How variable is the temperature?
mammals-body temp with little fluctuation
(homeothermic) vs. fish, many reptiles variable
temp (pokilothermic)
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How is Heat Obtained? Ectotherms and Endotherms
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Ectotherms
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Endotherms
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Deep Diving
Fig. 49.21
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Deep diving
Respiratory and circulatory changes - lungs
collapse, alveoli empty - O2 stored in muscles
and blood vs. lungs - higher blood volume -
higher mysoglobin - bradycardia -redistribution
of blood to tissues
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Water Conservation
kangaroo rats live in desert and are able to
survive with little water by concentrating
urine can produce urine 12-15X more
concentrated than blood plasma (vs, humans only
4x)
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Mammalian Kidney
Excretory tubules nephrons approx 1
million/kidney Blood filtered through nephrons
nitrog. waste removed
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Mammalian Kidney-Nephron
Fig. 51.11
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Water Conservation
Countercurrent exchange multiplier (flow in
desc. limb vs. ascend. limb)
Fig. 51.12
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Mammalian Kidney