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22 Cards in this Set
- Front
- Back
What are the functions of the placenta? |
Protection from mother's immune system, nutrition, gas exchange, excretion, hormone secretion |
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What is need for communication between foetus and mother? |
Keeps pro/oe high to prevent ovulation presence of foetus signalled to maternal pituitary-ovarian axis |
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How does the placenta develop? |
1-3: zygote down fallopian tube to uterus
3-6: blastocyst in uterine fluid 7: blastocyte in endometrium 7: placenta forms |
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Does the maternal and foetus blood mix? |
No
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How are molecules transported to placenta? |
Hydrophilic - higher in mother
Lipophilic - equilibrate readily, faster transfer |
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How is O2 transported? |
Diffusion Different O2-Hb dissociation curve |
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How is CO2 transported? |
Bohr effect Improved by ability of deoxyhb to form carbamino compounds and its ability to take up H+ |
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How is water transported? |
Osmotic balance |
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How is Na transported? |
membrane limited passive diffusion - maternal venous plasma slightly lower Na+ than foetal some active transport- Na/K ATPase esp. on foetal surface of placental membrane Na+/H+ exchange and Na+/aa co-transport in maternal placental membrane |
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How is glucose transported? |
Facilitated diffusion Na+ independent Always conc grad - risks to diabetic foetal growth |
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How are Ig transported? |
From maternal to foetal blood Receptor mediated endocytosis on maternal side,exocytosis on foetal side IgG - passive immunity |
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What is parturition?
What are events leading to it? |
Giving birth
1. Increased uterine contraction, cervical dilation 2. Complete dilation 3. Delivery of placenta - Ferguson reflex of oxytocin upon pressure, pos fb |
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What are the changes associated with parturition? |
Softening & dilation of cervix, increased uterine contractions Cervix - collagen breakdown, increased water content, Regulated by Prostaglandins, leukotrienes, oestrogen, relaxin |
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What factors stimulate uterine contractions? |
increase in electrical activity PgE2, PgF2a, oestrogen Oxytocin |
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What triggers parturition? |
Corticotropin-releasing factor (CRF) secretion by cytotrophoblast & fetal membranes placental CRF stimulated by glucocorticoids |
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What are the sources of pro and oe? |
Cholesterol |
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What is galactopoiesis? |
maintenance or enhancement of established lactation - later |
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What is lactogenesis? |
lactation function, initiated near the time of parturition, during breastfeeding |
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What is mammary gland development controlled by? |
Changing hormones Early preg - hypertrophy of ductal-lobular-alveolar system takes place |
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What is the composition? |
Contains colostrum in 1st week. Less fat and lactose than mature milk - more protein, minerals, fat-sol vitamins & IgGs |
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Why does breastfeeding have a contraceptive effect? |
prolactin inhibits: - GnRH - action of GnRH on pituitaryaction of gonadotrophins on ovaries - Prevents ovulation occurring |
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What is Priapism? |
persistent and painful erection of the penis. |