Bio 201 F09 True lect 18 (L20) v2r

Bio 201 F09 True lect 18 (L20) v2r - today’s factoid...

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Unformatted text preview: today’s factoid •  the only known species of amphibian that can tolerate salt water •  crab‐ea8ng frog Fejervarya cancrivora •  inhabits mangrove swamps in Southeast Asia –  brackish water (usually not as salty as ocean water) st mid term exam 2 •  Wed. Oct. 21st in class –  On material from 9/25 – 10/16 •  prac8ce ques8ons posted •  review sessions (see next slide) •  Be on 8me –  >10 min late will not be allowed into room •  Bring only your ID and pencils –  All other materials have to be leM on periphery of the room •  35 mul8ple choice ques8ons + 3 bonus factoid ques8ons •  lowest of the three mid terms is dropped, avg. of other 2 = 60% of your grade •  Only documented medical/family excuses accepted; we need to be NOTIFIED before end of the day on the day of the exam review sessions Features of mammals •  endothermic •  four‐chambered heart with single aor8c arch –  independently evolved from birds •  •  •  •  •  diaphragm hair mammary glands sweat glands secondary palate –  enables suckling Diaphragm •  Unique to mammals •  Band of muscle across bo\om of ribcage separa8ng chest from abdomen •  Crucial for breathing –  Contracts during inhala8on to expand thoracic cavity –  Relaxes to allow exhala8on The glands of mammals •  •  •  All appear to be evolved from a common ancestral gland formed from epithelial (ectoderm) cells Controlled by the nervous system and hormones Sweat glands: two kinds –  Apocrine ‐ secrete into hair follicles Sebaceous gland •  Armpit, groin, nipple areas Sweat gland Hair follicle •  Secrete a viscous substance beginning at PFF_Hyperhidrosis_Overview.asp puberty; may contain substances ac8ng as pheromones in humans –  Merocrine (also called “eccrine”) ‐ far more numerous and widespread on body (~3 million in adult human) ‐ secrete sweat Mammary glands and ceruminous glands (secrete ear wax) are evolu8onarily modified sweat glands Sebaceous glands –  Secrete sebum: waxy substance containing fat and cellular debris –  In rats and mice, these have been evolu8onarily modified into prepi8al glands which produce pheromones epidermis dermis •  •  •  90% of cells in epidermis are kera8nocytes –  Produce kera8n in skin –  Fish, rep8les, birds, also have kera8nocytes hair •  Melanocytes in epidermis produce melanin and export melanosomes to developing hair and skin –  Originate from neural crest in embryo –  Migrate into epidermis during development Skeletal features of mammals •  limbs ver8cally below body •  more sacral vertebrae •  reduced pectoral girdle •  no lumbar ribs Features of mammal skull •  reduc8on and fusion of some skull bones •  secondary palate (see previous slide) •  enlarged brain case with ver8cal walls •  greatly enlarged postorbital opening (single opening) •  differen8ated teeth •  lower jaw is a single bone (dentary) •  three middle ear bones (rep8les have one) A current view of mammal evolu8on Blue = name of an order Red = name of a superorder Monotremes (echidna, platypus) Marsupials tenrecs, golden moles, elephant shrews Xenarthra (anteaters, sloths, armadillos) Carnivora, Cetartiodactyla, Perissodactyla, Chiroptera, hedgehogs, shrews, moles, pangolins Rodents, lagomorphs, primates A current view of mammal evolu8on Monotremes (echidna, platypus) Marsupials THERIANS tenrecs, golden moles, elephant shrews PROTHERIANS Xenarthra (anteaters, sloths, armadillos) Carnivora, Cetartiodactyla, Perissodactyla, Chiroptera, hedgehogs, shrews, moles, pangolins Rodents, lagomorphs, primates EUTHERIANS Eutherian mammals •  Some8mes called “placental mammals” –  But this is not accurate, marsupials also have placentas •  Placenta: temporary 8ssue produced from fetal cells, used for respiratory and nutri8onal exchange with the mother –  Eutherians are born more developed than marsupials –  Eutherians do not have the pouches of marsupials Baby wombat Arctic wolf pup Convergence in placental and marsupial mammals Common ancestor: 100-150 mya drawing the main branches of the tree of life from memory please fill out an evalua8on of Prof. True ...
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