Endo-Repro L29 Flashcards Preview

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Flashcards in Endo-Repro L29 Deck (41):
1

1st stage


Onset of regular uterine activity associated with effacement and dilation of the cervix, and descent of the presenting part. The latent phase of labour is from the onset of contractions until the cervix is fully effaced and the active phase is when the fully effaced cervix dilates.
→7-14 hours

2

2nd stage

Full dilation of the cervix to delivery time of the baby. Subdivided into the propulsive phase (when the head descends to the pelvic floor) and the expulsive phase (when the mother experiences a desire to push until the baby is delivered)
→1-3 hours

3

3rd stage

After delivery of the baby until the delivery of the Cervical ripening factors controlling:

placenta
→30 min, Contractions, tonic

4

Duration of pregnancy →

38-40 weeks

5

Duration of Labour →

→ 8-16 hours (reg. contractions every 5 mins)

6

Cervical ripening factors controlling:

1. Prostaglandins
2. Oestradiol
3. Progesterone and antiprogesterone
4. Relaxin
5. Inflammatory mediators
6. Nitric Oxide
7. Apoptosis

7

Hormonal control of Labour →

1. Progesterone
2. Oestrogens
3. Oxytocin
4. Prostaglandins
5. Fetal adrenal glands

8

Initiation of Labour →

Unknown → oxytocin
• Prostaglandins
• Growth Factors
• Cytokines
• Endothelins
• Gap junction formation
• Placental corticotrophin – releasing hormone
• Nitric Oxide withdrawal

9

Role of fetus in Labour →

1. Fetal adrenal glands, fetal cortisol.
2. Increase in the ratio of oestradiol to progesterone stimulates.

10

Progesterone

Is an anti-inflammatory agent, labour is inflammatory process. It inhibitis human myometrial contractions and decreases gap junction formation.

11

Exogenous progesterone

Does not postpone the onset of parturition at term.

12

Anti-progesterone

Activate many of the pathways involved in the onset of labour and induce uterine contractility and cervical ripening.

13

Suggests role in maintenance of pregnancy

1. Hyperpolarises myometrial cells inhibits contractions
2. Reduces oxytocin sensitivity
3. Stabilises decidua and membranes (stops PG formation)
4. Decreases gap junction formation.

14

Role in late pregnancy in initiation of labour

• Uncoupling of action (local metabolism of progesterone, progesterone inactivation by specific binding protein, by endogenous anti-progesterone, or by a change in number or affinity of progesterone receptors)
• Decline in progesterone sensitivity
• No fall in concentration

15

CRH is

A peptide hormone, hpothalalmic releasing factor, secreted by placental trophoblasts.

16

Maternal plasma CRH during pregnancy

Rise

17

Elevated CRH levels associated with

Preterm labour

18

CRH present are present in

Myometrium and fetal membranes

19

CRH is secreted by

Placenta trophoblasts

20

Three weeks before the onset of spontaneous labour

1. Rise in plasma CRH concentrations
2. Abrupt fall in CRH-BP (blocks bio-availability of CRH) concentrations in the maternal circulation and amniotic fluid.

21

CRH action

• Stimulates the release of prostaglandins from human amnion and deciduas
• Potentiate the action of oxytocin (stimulating myometrial contractions)
• Potentiate the actions of prostaglandins
• Induces synthesis of prostaglandins and glucocorticoids

22

Induced synthesis of prostaglandins and glucocorticoids stimulates

Placental CRH secretion → positive feedback loop

23

Oestrogen and progesterone

• Synergises to stimulate uterine growth
• Oestrogens oppose the progesterone block on uterine contractions

24

Actions

Increase uterine contractions
• Increase actinomyosin and glycogen in myometrium
• Depolarises myometrial cells
• Increase gap junctions
• Increase oxytocin sensitivity (receptors)
• Destabilise decidua and membranes (prostaglandin formation)

25

Oxytocin and Labour Released from

The magnocellular neurosecretory neurones projecting directly to the posterior pituitary

26

Oxytocin and Labour Function

Potent stimulated of myometrium (if estrogen primed)

27

Oxytocin and Labour Stimulation

Dilation of cervix by fetal head

28

Oxytocin and Labour Levels

Rise in 1st and 2nd stage
Reduce in 3rd

29

Prostaglandins
Description

Local tissue hormones – rapidly destroyed in the circulation.

30

Prostaglandins Function

Powerful contractors of smooth muscle

31

Prostaglandins Control of PG synthesis

Via phospholipase from lysosomes

32

What liberates phospholipase

Increase in oestrogen: progesterone ratio and mechanical damage liberate phospholipase.

33

Levels in pregnancy of PGs

Rise in early labour
Can promote labour at any stage

34

PGs Mainly produced in

Endometrium but can be also in myometrium

35

Control of PG synthesis during labour

Oestrogen (increased) and progesterone (reduced) and mechanical disruption leads to conversion of phospholipids to arachadonic acid and then converted to PGE and PGF
→ Phosphoslipase and PG synthetase

36

Artificial induction of labour →

1. Prostaglandins → ripen cervix
2. Artificial rupture of membranes → Increases PG and puts head onto cervix
3. Syntocinon → womb contraction

37

Main stimulation of breast tissue →

• Oestrogen (duct system) and progesterone (secretory system).
• Prolactin and GH and hPL from placenta contribute.

38

Initiation of secretion inhibition of mammary gland

Oestrogens
Progesterone

39

Stimulator of secretion from mammary glands

Prolactin (and hPL)

40

Maintenance of secretion from mammary gland

Prolactin released during sucking
• Sucking stimulus inhibits release of dopamine from hypothalamus
• Lactotrophs are free of dopamine inhibition and release prolactin
• Complete emptying of mammary gland

41

Control of milk removal:

Proper attachment
Active milk-ejection reflex
Suckling causes oestrogen release during suckling, acts on myoepithelial cells

Can be conditioned e.g. sound of baby

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