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Gut, metabolism and hormones > Parturition and lactation - Reproduction 4 > Flashcards

Parturition and lactation - Reproduction 4 Flashcards

1
Q

Key learning objectives:
* Understand the key roles and source of
oestrogen and progesterone during pregnancy
* Describe the events responsible for both the
initiation and progression of labour
* Describe the process of lactation and its
control

A
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2
Q

See slide 3
Hypothalamus and Pituitary
What do they stand for?
PRH, PIH, CRH, ACTH

A

PRH= prolactin releasing;
PIH= prolactin Inhibiting;
CRH= corticotropin releasing (aka urocortin); ACTH= adrenocorticotropic

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3
Q

Oestrogen secreted into uterus causes?

A

Increased contractility of smooth muscle and increased responsiveness to oxytocin

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4
Q

Oestrogen secreted into anterior pituitary causes?

A

Prolactin secretion and growth and development of breast tissues

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5
Q

Oestrogen secretion in breasts causes?

A

Growth of duct tissue
Fat deposition
Suppression of lactation

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6
Q

Progesterone secretion into uterus?

A

Suppression of contractile activity (counteracts effects of oestrogens and oxytocin)
Maintenance of secretory-phase conditions

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7
Q

Progesterone secretion on breasts causes?

A

Growth of glandular tissue and suppression of lactation

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8
Q

hCG in male foetus causes?

A

production testosterone from Leydig cells= masculinization of the reprod. tract

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9
Q

MFP stands for?

A

Maternal-Placenta-Foetal-Unit

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10
Q

Problem with MPF?

A

Foetus cannot synthesise Progesterone (precursor for aldosterone and cortisol)
Placenta cannot synthesise Androgen (precursor for Oestrogens)

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11
Q

Solution to MFP?

A

– Placenta synthesises Progesterone for foetus (used by foetal adrenal glands → aldosterone, cortisol synthesis
– Mother and foetus synthesise Androgens for placenta

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12
Q

Placenta is an incomplete endocrine organ that needs help
SEE SLIDE 6 DIAGRAM
Can the foetus make oestrogen/progesterone?

A

No

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13
Q

Parturition requires?

A

– Dilation of cervical canal to accommodate passage of fetus from uterus
– Sufficiently strong contractions of uterine myometrium to expel fetus

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14
Q

Parturition means?

A

Childbirth

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15
Q

Mean pregnancy is how long and from when?

A

Mean pregnancy duration=38 weeks from ovulation/40 weeks from last menstruation

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16
Q

What is labor/delivery/birth?

A

Process whereby the foetus and its supporting placenta and membranes pass from the uterus to the outside world

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17
Q

Cervical dilation takes how long? up to?

A

24 hours

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18
Q

Delivery of the baby time period?

A

30-90 mins

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19
Q

Delivery of placenta - how long?
How much blood lost?
Uses what in the body?

A

15-30mins
350mL of blood lost
Smooth muscle cells and prostaglandins

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20
Q

Exact factors triggering increase in uterine contractility and initiating parturition not fully established

A
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21
Q

Factors that trigger increase in uterine contractility and initiating parturition could be?

A

From 2nd-3rd trimester - weak, spontaneous contractions (Braxton-Hicks) – uterine muscle fibres tighten and relax – not true labour. Toning uterine muscle? Blood flow to placenta?
Cervical softening?

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22
Q

What is prodromal labor?

A

– Days to weeks before true labour
– Consistent, uncomfortable contractions without/very little cervical dilation
– Cervix softening/ripening under influence of relaxin (placenta)
– Mucous plug expelled

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23
Q

Trigger for parturition what does the current theory suggest the signal is?

A

CRH: Corticotrophin-releasing hormone
Placenta: CRH released, acts on fetal pituitary
adrenocorticotropic hormone (ACTH)
– DHEA synthesis
– DHEA → Oestrogens
– Oestrogens enter maternal blood stream

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24
Q

Oestrogens level soaring towards onset of parturition is another trigger for parturition
1. What happens to connexions?
2. Oxytocin?
3. What happens with prostaglandins?

A
  1. Increases number of connexions - gap junctions between myometrial cells
  2. Increases oxytocin receptors in uterus;
  3. Increases prostaglandins produced by myometrium and foetal membranes
    * Prostaglandins increase uterine responsiveness to oxytocin
    * Cervical ripening – degrade local collagen fibres
25
Q

See slide 10
Oxytocin increases uterine contractions - how?

A

▪ Acts directly on smooth muscle
▪ Thought labor initiated when oxytocin responsiveness reaches critical threshold – in response to normal oxytocin circulating levels

26
Q

Inflammatory response is also a trigger or parturition?
1. What signals come from the foetus?
2. Immune cell invasion - what happens?
3. Inflammatory TFs play what role?
4. Increased proinflam cytokines and prostaglandins causes what to the uterus?

A
  1. Signals from fetus (surfactant lipoprotein
    secretion, placental CRH, cortisol, estrogen) and mother (uterine stretch with increased
    chemokine production, increased estrogen
    receptor signaling)
  2. Immune cell invasion of the fetal membranes, decidua, and myometrium – Proinflammatory cytokines (IL-1β, IL-8)
  3. Inflammatory TFs - NFB and AP-1 –
    Proinflammatory and CAP gene expression,
    decrease in PR activity
  4. Increased proinflam cytokines and
    prostaglandins: increased sensitivity of uterus to contraction inducing chemicals and help to
    soften the cervix.
27
Q

See slide 11 diagram

A
28
Q

What critical responsiveness is necessary for the progression of parturition?

A

Oxytocin

29
Q

Contractions begin at labor onset and what feedback cycle increases the force?

A

Positive-feedback cycle progressively increases
force

30
Q

Does oxytocin cause stronger/weaker contractions?

A

Stronger

31
Q

The pressure of foetus against cervix reflex causes what and what is this reflex called?

A

Pressure of fetus against cervix reflex increases oxytocin secretion – neuroendocrine
reflex

32
Q

How long does this positive-feedback cycle progressively increase until?

A

Until cervical dilation and delivery are complete

33
Q

Oestrogen has what effect with oxytocin?

A

Induces oxytocin receptors on uterus

34
Q

Oxytocin has a + feedback and comes from foetus and pituitary what does it stimulate the placenta to make and what does it stimulate with the uterus?

A

Oxytocin stimulates the uterus to contract and stimulates placenta to make prostaglandins

35
Q

Prostaglandins stimulated by oxytcin stimulates what?

A

More contractions of the uterus

36
Q

See slide 13
Stages of LABOR
1. 1st stage is called?
2. How long does it?

A
  1. Cervical dilation
  2. Lasts from several hours to 24 hours+
    in a first pregnancy
37
Q

2nd stage of labor is called?
Usually lasts?
When does it begin?

A
  1. Delivery od the baby
  2. Usually lasts 30 to 90 min
  3. Begins when cervical dilation is complete
38
Q
  1. 3rd stage of labor is called?
  2. What happens?
  3. How long?
A
  1. Delivery of the placenta
  2. Second series of uterine contractions separates placenta from uterine wall
  3. Shortest stage – usually completed within 15 - 30 min after baby is born
39
Q

Breast is mainly made of?

A

Primarily adipose tissue with basic duct system

40
Q

Duct system of breasts:
Secretory lobules empty into?
Ductless of 15-20 lobules combine into what?
This widens where?
Lactiferous duct carries the secretions where?

A

Secretory lobules empty into ductules
Ductules of 15 to 20 lobules combine into duct, Widens at the ampulla (reservoir).
Lactiferous duct carries the secretions to the outside.

41
Q

Alveoli are the fundamental?

A

Secretory units - secretory epithelial cells (alveolar cells, secrete milk) + myoepithelial cells (milk ejection).

42
Q

There are different pathways for secretion of the different milk components

A
43
Q

Much of breast development occurs when?

A

Much of breast development occurs during first months of pregnancy

44
Q

When are mammary glands capable of milk production?

A

Mid-pregnancy

45
Q

There is inhibition of lactation during pregnancy why?

A

Oestrogen and progesterone during last
half of pregnancy block effect of prolactin

46
Q

Prolactin and oxytocin roles in lactation?

A

Prolactin – Milk secretion
Oxytocin – Milk ejection

47
Q

What is gestation?

A

Time between conception and birth

48
Q

During gestation there is elevated placental oestrogen and progesterone which promotes the development of what?

A

Elevated placental oestrogen and progesterone promote development of ducts and alveoli in mammary glands - Prolactin

49
Q

What initiates lactation?

A

Decrease in placental steroids at child birth: parturition

50
Q

Lactation is sustained by?

A

Sucking as it triggers release of oxytocin and prolactin

51
Q

Oxytocin has what role with lactation?

A

Causes milk ejection by stimulating myoepithelium to squeeze secreted milk out
through ducts

52
Q

See diagram slide 17
Prolactin stimulates what in regards to lactation?

A

Stimulates synthesis of enzymes essential for milk production by alveolar epithelial cells
Stimulates secretion of more milk to replace milk ejected as baby nurses

53
Q

Note: If not breastfeeding, What happens to PRL levels?

A

They fall -> ↑ GnRH -> ↑ LH and resumption of ovulation ~ 4-8 weeks

54
Q

See slide 18

A
55
Q

Human milk is fully mature when?

A

4-6 weeks post martum

56
Q

Human milk how many kcal/dL
How much protein/dL
fat/dL
Lactose/dL
Leukocytes/dL

A

70kcal/dL
0.9g protein/dL (casein, lactalbumin)
4.5g fat/dL
7g lactose/dL
1-2*106 leukocytes/dL

57
Q

What is colostrum?

A

breast milk first 5 days post partum

58
Q

What is colostrum rich in?
Its a laxative to expel?
Prevents the build up of?

A

Rich in immunological content - IgA, IgG
Laxative to expel meconium
Prevents build up of bilirubin

59
Q

Colostrum how many kcal/dL
How much protein/dL
fat/dL
Lactose/dL
Leukocytes/dL

A

Colostrum – First 5 days post partum
54kcal/dL
2.7g protein/dL
2.9g fat/dL
5.7g lactose/dL
7-8*106 leukocytes/dL

Gut, metabolism and hormones (22 decks)

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