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RDA > Lecture 13 - 2018/2017 > Flashcards

Lecture 13 - 2018/2017 Flashcards

1
Q

What is hCG?

A

Two chain hormone that shares an alpha chain with; TSH, LH, FSH. These hormones all have unique beta chains.

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2
Q

What produces beta-hCG?

A

Syncytiotrophoblast of the pre-implantation blastocyts and placenta.

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3
Q

When is beta-hCG detectable?

A

It is detectable in the maternal blood/urine within days of implantation.

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4
Q

What hormone is beta-hCG most like?

A

LH - beta-hCG is almost identical to this hormone. Beta-hCG has a longer half life. It transmits similar signals to LH.

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5
Q

What does hCG do in the first 6-8 weeks of pregnancy?

A

It binds to the LH/bhCG recptor and transmits a similar signal LH. It stimulates the production of estrogen and progesterone by the ovary and stops the regression of the corpus luteum (doubles in size) - as the CL continues to secrete progesterone and estrogen.

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6
Q

What does hCG do at 8-10 weeks of gestation?

A

The placenta takes over the ovary as the main source of progesterone.

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7
Q

What does progesterone do in the pregnancy?

A

Prevents menstruation and maintains the endometrium in a decidualised form.

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8
Q

What happens to the hCG of woman with multiple pregnancies?

A

They have increased levels - this is due to the increased amount of syncytiotrophoblasts.

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9
Q

Where are else are high levels of hCG found?

A

Trophoblastic tumours:

  1. Choriocarcinoma + hydatidiform mole.
  2. Testicular tumours.
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10
Q

How is hCG important in pregnancies with male fetuses?

A

hCG can help to stimulate testosterone synthesis by the leydig cells of the testis in the male fetus prior to the synthesis of LH by the fetal anterior pituitary.

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11
Q

What can hCG cause?

A

Hyperthyroidism - this is because hCG can bind to the TSH receptor or the LH receptor which is expressed in the thyroid.

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12
Q

What synthesises progesterone?

A

Syncytiotrophoblast of the placenta.

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13
Q

Can the trophoblasts synthesise progesterone from acetate?

A

No - they use LDL-cholesterol which is derived from maternal circulation, syncytiotrophoblast express various receptors to assist LDL uptake.

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14
Q

What happens to progesterone production if ovaries are removed?

A

Removal of the ovaries do not compromise human pregnancy after 6 weeks of gestation - suggests the placenta i producing adequate progesterone to maintain pregnancy.

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15
Q

What are the functions of progesterone for pregnancy?

A
  1. Maintains uterine quiescence - stops the uterine from contracting.
  2. Converts the uterine environment to one that is conducive for pregnancy.
  3. Induces the formation of the decidua - important for providing nutrients prior to tapping the maternal blood supply.
  4. Suppresses milk production.
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16
Q

Where are progesterone receptors expressed?

A

Both glands and stromal cells in the endometrium/decidua.

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17
Q

What does the production of estrogen require?

A
  1. Live fetus.
  2. Functioning adrenal glands.
  3. Intact feto-placental circulation.
  4. Functioning placenta.

(The placenta doesn’t express the enzyme 17-alpha-hydroxylase and can’t produce estrogen de novo).

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18
Q

How does the placenta make estrogen?

A

The placenta can aromatise testosterone, androstenedione and dehydroepianedrostene to estrone and estradiol.

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19
Q

How does the fetal-adrenal glands help to produce estrogen?

A

They produce androstenedione and dehydroepiandrostene. However they cannot convert it to estrogen.

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20
Q

What happens to the levels of estrogen in anencephalic pregnancies?

A

The fetal adrenal glands are atrophic, so they can’t produce andrpstenedione and dehydroepiandrostene. Therefore they have low levels of estrogen.

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21
Q

What changes occur in the mother during pregnancy?

A
  1. Cardiovascular system changes.
  2. Haematological system changes.
  3. Immune system changes.
  4. Genital system changes.
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22
Q

What are first pregnancies more prone to?

A

First pregnancies tend to be more prone to complications of adaptations than subsequent gestations e.g. pre-eclampsia.

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23
Q

What is pre-eclampsia?

A

Maternal hypertension and proteinuria.

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24
Q

When does pre-eclampsia mainly occur?

A

In mothers with first pregnancies with partner. If a women has sex with one male and has a baby with him she has a risk of pre-eclampsia. If she then has sex with another male her risk of pre-eclampsia is still the same as if it was the first pregnancy with the other male.

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25
Q

What triggers pre-eclampsia?

A

Something from the placenta.

26
Q

What can pre-eclampsia cause?

A

Exaggerated inflammatory response which leads to vascular dysfunction. Essential it is failure of the normal vascular adaptation to pregnancy. Which can cause loss of the normal maternal peripheral vascular resistance.

27
Q

What changes occur in the maternal cardiovascular system?

A
  1. Increase in cardiac output - very rapid at the beginning of pregnancy. It is caused by a 10% increase in SV and 10-15% increase in pulse rate.
  2. Reduced peripheral vascular resistance.
28
Q

What happens to peripheral resistance in pre-eclampsia?

A

In pregnant women with pre-eclampsia they have higher than normal peripheral resistance.

29
Q

When do these necessary changes to the CVS occur?

A

Prior to 9 weeks of gestation.

30
Q

What does estrogen act on in the CVS?

A

Blood vessels and can reduce vascular resistance mainly in reproductive tissues (this is to allow more blood to pass through). It can alter the ratio of type 1 and type 3 collagen in the vessel wall.

31
Q

When are high levels of estrogen reached?

A

9 weeks gestation - when fetal adrenals are made.

32
Q

What does progesterone act on in the CVS?

A

May induce vascular relaxation in the uteroplacental circulation but does not appear to have a systemic effect.

33
Q

When are high levels of progesterone reached?

A

10 weeks gestation.

34
Q

What does angiotensin II act on in the CVS?

A

It is a vasoconstrictor that acts on the blood vessels (arterioles) to contract and to cause an increase in BP - the uteroplacental unit produces large amounts of RAS. The effects of angiotensin II tend to be blunted in normal pregnancy.

35
Q

What does nitric oxide act on in the CVS?

A

Arterial wall relaxation and dilation.

36
Q

What produces nitric oxide?

A

Vascular endothelial cells by nitric oxide synthetase in response to the shear stress of blood flowing over the vessel surface.

37
Q

What haematological changes occur in pregnancy (maternal)?

A

Increased blood volume - plasma volume and blood volume both increase at different rates. As plasma volume increases the haematocrit declines - this is due to plasma volume increasing at a higher rate than cell mass.

38
Q

How much does plasma volume increase by during pregnancy?

A

1250 mLs by 30 weeks - remains stable post 30 weeks.

39
Q

What happens haematologically at 8-10 weeks gestation to the mother?

A

There are cyclic changes in blood/plasma volume during the menstrual cycle - 10% increase in plasma volume compared to non-pregnant. this is similar to that seen in the menstrual cycle.

40
Q

What happens to haematological changes during delivery?

A

There is substantial blood loss - 500mls for a single vaginal delivery and 1L for twins vaginal delivery and 1L for caesarean section.

Non-pregnant women respond to this via vasoconstriction and production of new RBC.

41
Q

How do pregnant women handle this blood loss?

A

In pregnant women the hypervolaemia modifies this response and the blood loss is no compensation for the loss - there is a continuing blood volume decline by diuresis and a slow loss of red cells with time postpartum.

42
Q

How does repeated exposure to sperm help with the immune system (mother’s)?

A

If a women has repeated exposure to the same sperm it appears to be beneficial at protecting against pre-eclampsia.

43
Q

Describe the fetus and it’s relation to the maternal immune system?

A

The fetus is genetically half paternal and half maternal - yet for 9 months the fetal tissue of the placenta and extraplacental membranes survive in intmate contact with the maternal immune system.

44
Q

Describe the relationship between sperm and the immune system?

A

Prior to pregnancy sperm must survive in the female geneital tract. Sperm are total foreign bodies to the mother, yet in most cases repeated acts of coitus do not stimulate the maternal immune system to react to sperm. The only immune response is to get rid of excess sperm.

45
Q

What has seminal plasma found to be in regards to the immune system?

A

The seminal plasma has been found to be immune suppressive - diminution of the maternal immune response to some organisms in pregnancy.

46
Q

What infections are pregnant women more susceptible to than non-pregnant women?

A
  1. Leprosy.

2. Listeriosis.

47
Q

What happens to the white cell count of pregnant women?

A

It increases due to the expansion of the neutrophil population - occurs in the luteal phase of the cycle and does not drop with pregnancy.

48
Q

When is the neutrophil count the highest?

A

30 weeks then rises again at the time of labour.

49
Q

What happens to lymphocyte count during pregnancy?

A

It doesn’t alter greatly but there is a belief to be a bias in the type of T Helper (CD4) cells and the cytokines they produce with a tilt in the balance towards Th2 cytokines - pregnancy towards Th2 responses (drive the immune system towards an antibody mediated response).

50
Q

What does the decidua contain in therms of the immune system?

A
  1. Almost no B cells - no antibody production.
  2. 10% of the leucocytes in the decidua are T cells.
  3. 70% of the leucocytes are specialiseduterine natural killer-like cells.
51
Q

How do NK cells act in a peripheral blood?

A

NK cells in peripheral blood can act by antibody-dependent cell mediated cytotoxicity. - there is a receptor CD16 which is required to effect ADCC (binds to antibodies).

52
Q

How do uterine NK cells act?

A

They lack receptor CD16 which allows other killer cells to kill antibodies.

53
Q

Define recurrent miscarriage?

A

3 or more miscarriages with the same partner.

54
Q

What is noticeable about those women who had recurrent miscarriages compared to those with normal pregnancies?

A

There was found to be a raise in decidual T cells in women who had recurrent miscarriages, compared to those who had normal pregnancies. It maybe due to the mother’s immune system not recognising the baby.

55
Q

What is the uterus like of a non-pregnant woman?

A
  1. Almost solid.
  2. Weighs 70g.
  3. Cavity = 10mls.
56
Q

What is the uterus like of a pregnant woman?

A
  1. Thin walled and muscular.
  2. 5L capacity (single birth) - can get up to 20L (twins).
  3. Weighs 1100g.
57
Q

What happens to blood flow to the skin during pregnancy?

A

Blood flow to the skin increases - flow to the hands is increased 6-7 fold (their hands are warm and clammy), flow to the feet has also increased.

58
Q

What changes occur during pregnancy in the skin?

A
  1. Increase in blood flow to the skin - warm and clammy hands.
  2. Pigmentation changes - particularly in area of nipplesz and areola.
  3. Linea nigra - dark line that runs in the midline of the belly during pregnancy.
59
Q

What can develop around the skin of the neck during pregnancy?

A

Chloasma.

60
Q

What are the pigmentation changes due to during pregnancy?

A

Increased secretion of melanocyte stimulating hormone (MSH) - it is markedly elevated from the second month of pregnancy.

61
Q

What hair changes can occur in pregnancy?

A

Hair loss stops during pregnancy - so hair appears thicker. But hair loss returns back to normal post-partum. Hence as to why mum thinks she has lost lots of hair after giving birth.

RDA (19 decks)

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