MFWB_A - Mammals Birth and Lactation

embryonic diapause

roe deer, bears, seals, embryo remains frozen until environmental conditions improve

human babies

large, semi-altricial, adipose rich with unusually large head and broad shoulders

eutheria birth

usually born heard first - breathing, fully aquatic animals born tail first - swimming

relaxin

remodel ligamentous capsule of pelvis to allow pelvic bones to be more flexible for birth

fontanelles

foetal skull gets compressed during birth, remoulded after birth

lung development

gradually develop larger surface area to aid respiration

lung development stages

embryonic, pseudoglandular, canalicular, saccular, alveolar

SP-A and D

lectins that provide newborn with innate immunity

SP-B and C

hydrophobic membrane proteins, limit surface tension and needed for lung function

foetal circulation

reliant on placenta for oxygenated blood via umbilical vein, ductus venous to heart, enters right atrium via inferior vena cava, foramen ovale to left atrium, ductus arteriosus connects aorta with pulmonary artery, to head and body and back to placenta

end of gestation steps

cervical ripening mediated by inflammatory-like process, cervical softening and dilation, increased myometrial contractility, rupture of chorioamniotic membranes and placenta from uterus

how to counter problems when delivering

internal rotation, delivery by extension of head after dilation, head rotation upon delivery

evolution of milk

all mammals produce, males also have functional mammary glands under hormonal control, initial function is unknown - immune protection or nutrition

milk diversity across animal kingdom

some birds produce crop milk - contains prolactin, some fish feed their young with skin secretions, some amphibians feed the young dead skin, tsetse feed their intrauterine larvae with milk

preparing for lactation

hormonal changes, oestrogen and progesterone drop at birth, removes block to prolactin-induced milk secretion, likely to provide lactobacilli to foetus, milk release by suckling, more production, somatosensory pathways release oxytocin and prolactin o

oxytocin in lactation

promotes milk release

prolactin in lactation

promotes milk production

mammalian milk functions

nutrition, maternal-infant bonding, microbial flora, immunity

milk contents

sugars (human - mainly lactose) - energy, lipids - energy and help membrane construction, minerals, vitamins, proteins

marsupials milk phases

several distinct milk phases to optimise milk for external gestation, tailored to ecology

eutherian milk changes

large differences in milk composition and can be temporal lactation changes - giant panda milk takes 30 days to mature, seals have short lactation period - 20 days