Talk:BGDA Practical 12 - Birth: Difference between revisions
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! Hormones | |||
! Roles | |||
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| Progesterone | |||
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* maintains pregnancy - initially synthesized by corpus luteum, then levels maintained by placenta | |||
* hyperpolarizes myometrial cells (-65 mV), reduces excitability and conductivity | |||
* Level in plasma may fall just before parturition, definitely decreases following delivery of placenta | |||
|- | |||
| Estrogens | |||
| | |||
* Group of steroidal hormones, peak when parturition begins | |||
* induce increased synthesis of actomyosin and ATP in myometrial cells | |||
* alter membrane potential (-50 Mv) enhances excitation/conduction | |||
* act to directly increase myometrial contraction | |||
* indirectly by increasing oxytocin from pituitary gland | |||
* Estriol - synthesized by fetus and placenta | |||
|- | |||
| Oxytocin | |||
| | |||
* Peptide hormone (8aa) from maternal posterior pituitary, initiation and maintenance of labour (synthetic form labour induction) | |||
* myometrium sensitivity to oxytocin (increased by estrogen, decreased by progesterone) | |||
* stimulus for release - mechanical stimulation of uterus, cervix and vagina (ethanol inhibits release) | |||
|- | |||
| Prostaglandins | |||
| | |||
* hydroxy fatty acids - sythesized by placenta, amniotic fliud contains mainly PGF2 alpha, causes myometrial contraction (also in maternal plasma) | |||
* prostaglandin F2 alpha (PGF2 alpha) and [[P#prostaglandin E2|prostaglandin E2]] (PGE2) - used to induce labour (intravenous, oral, intravaginal, intraamniotic) | |||
* Aspirin inhibitor of PG synthesis - leads to increased duration of pregnancy | |||
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=== External Environment === | |||
* mainly shown in other species parturition occurs in peaceful undisturbed surroundings, stress may have an inhibitory effect on oxytocin release | |||
* Most human births occur at night (peak at 3am) diurnal rhythm influence |
Revision as of 11:49, 2 June 2013
Practical Audio
BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4.
listen Part 6 | download (2.13 Mb MP3 18:36) |
Hormones | Roles |
---|---|
Progesterone |
|
Estrogens |
|
Oxytocin |
|
Prostaglandins |
|
External Environment
- mainly shown in other species parturition occurs in peaceful undisturbed surroundings, stress may have an inhibitory effect on oxytocin release
- Most human births occur at night (peak at 3am) diurnal rhythm influence