physiology for scope Flashcards

1
Q

what are the placental hormones in pregnancy?

A

oestrogens
progesterone
human placental lactogen (hpl)
Human Chorionic gonadotrophin (hCG)

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2
Q

what are the maternal hormones of pregnancy?

A

oxytocin
prolactin
relaxin

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3
Q

what are the functions of oestrogen? what effects can it cause on the body?

A
  • increase in protein synthesis to stimulate tissue growth
  • stimulates uterine growth by increasing uterine blood flow
  • causes development of mammary ducts in breasts
  • increases water in extracellular matrix (causing softening of connective tissues)

body effects?
pelvic discomfort due to stretching of pelvic joints and ligaments
odema

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4
Q

Progesterone is produced by the _______ _______ in the first __ - __ weeks of pregnancy

A

corpus luteum
6-8 weeks

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5
Q

actions of progesterone in pregnancy are;

A
  • stimulates secretion of glycogen from endometrial glands
  • decreases excitability of myometrial cells (inhibiting uterus from contracting)
  • relaxes smooth muscle in GI tract, urinary tract & of blood vessels
  • suppresses maternal responses to fetal antigens
  • promotes lobular and alveolar growth in breasts
  • inhibits prolactin
  • increases sensitivity of respiratory system to CO2
  • increases body temp
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6
Q

function of human Gonadotropin hormone (hCG)?

A

maintain the corpus luteum (which secretes oestrogens and progesterone) until the placenta takes over. hCG levels peak around 7-11 weeks

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7
Q

human placental lactogen (hPL) what does it do?

A
  • peaks around third trimester
  • promotes fetal growth
  • inhibits prolactin
  • supports mammary growth
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8
Q

why is human Placental Lactogen described as an “insulin antagonist”

A

It gives the mother an alternative source of energy so that the fetus can preserve its glucose and amino acid stores. it causes a rise in free fatty acids as the energy source and limits cell glucose uptake (usually achieved with insulin) thus the blood glucose level may be higher to travel to the fetus for cell growth.

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9
Q

role of oxytocin in pregnancy?

A

(produced in hypothalamus and released from AP gland)

acts on myometrium (muscle layer of the uterus) during labour

oxytocin receptors increase throughout pregnancy. causing braxton hicks contractions more frequently in the latter stages of pregnancy

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10
Q

relaxin?

A

secreted by corpus luteum - breaks down collagen fibres by increasing water abundance in connective tissue which softens it (pelvic ligaments, areola, cervix).

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11
Q

what are the haematological changes in pregnancy?

A

an increase in blood volume causing haemodilution

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12
Q

explain why haemodilution occurs in pregnancy and what changes can this create for the woman?

A

in pregnancy, blood volume is increased by 30-40% to provide more oxygen and nourishment to the fetus.
The majority of this volume increase comes from an increase in plasma making the blood less concentrated in its other constituents such as red blood cells and plasma proteins.
This leads to lower viscosity of the blood which reduces peripheral resistance and lessens the cardiac workload. It also lowers osmotic pressure and can cause odema.
Haemodilution causes a lower concentration in ferritin making pregnancy a risk factor for iron deficiency anaemia.

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13
Q

what are the coagulation changes that occur in pregnancy?

A

In pregnancy the blood becomes hyper-coagulable due to an increase in fibrinogen and clotting factors however there is a decrease in platelets due to haemodilution.

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14
Q

What cardiac changes occur in pregnancy?

A
  • Stroke volume increases due to plasma increase
  • heart rate increases by about 10-15bpm
  • cardiac output increases due to above by about 40-50%
  • peripheral resistance reduces due to relaxed blood vessels (progesterone causing)
    (this and the the increase in utero-placental circulation accommodates the increase in blood volume)
  • blood pressure remains stable or may drop slightly due to the decrease in peripheral resistance
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15
Q

why does pregnancy predispose women to an increased risk of developing urinary tract infections?

A

Due to the increase in blood volume, the kidneys have more fluid to filter and produce more urine. This means the kidneys have to filter the blood at a higher rate - increasing the Glomerular filtration rate (GFR). Because of this, it can cause the filter to become leaky, allowing protein and glucose molecules to be secreted into the urine. Protein and glucose in the urinary tract facilitate the growth of bacteria. Additionally due to the effects of progesterone in pregnancy relaxing the smooth muscle of the urinary tract can cause dilation of the renal pelvis causing urinary stasis.
Both of these factors (urinary stasis and protein and glucose in the urinary tract) increases the risk of developing a UTI.

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16
Q

what effect does a supine position have when heavily pregnant?

A

The enlarged uterus presses on the inferior vena cava - venous pressure is lower than arterial pressure meaning the force from the enlarged uterus obstructs venous return, decreasing stroke volume and reducing the amount of oxygen to the rest of the body including the uterus, placenta and fetus. this can cause fetal hypoxia and fetal distress.

17
Q

what are the stages of labour?

A

latent phase - frequent mild regular or irregular contractions, can last hours to days
1st stage - active labour defined as 6cm -10cm dilation and characterised by long strong frequent regular painful contractions
2nd stage - full dilation of the cervix to the birth of the baby
3rd stage - from birth of baby to birth of the placenta
4th stage - the first 1-2 hours after delivery - skin to skin, uterus involution, after pains.

18
Q

what are the signs of placental separation?

A

separation bleed
lengthening of the cord
maternal response to contractions
vulval bulging

19
Q

what physiological changes happen to the respiratory system? And how does it affect maternal blood gases in pregnancy?

A

As the uterus grows through pregnancy, it places pressure on the diaphragm which presses on the lungs ad increases intrapulmonary pressure, however, the ribs widen to accomodate for this which then increases the volume of the thoracic cavity.

Progesterone affects the respiratory centre in the brain to cause an increase in respiration to make a 50% increase in air flow per minute.

the increase in oxygen intake causes an increase in carbon dioxide output increasing the carbon dioxide in the blood (an acid). However the kidneys then secrete bicarbonate (base) to balance it. Thus the pH balance is maintained if not, slightly alkaline. This moderate alkalosis can increase gas diffusion across the placenta to the fetus.

20
Q

what happens to the level of haemoglobin in pregnancy

A

due to haemodilution, the concentration of Hb decreases in pregnancy, reaching its lowest in the second trimester and increasing again in the 3rd.

21
Q

what defines the completion of he 3rd stage of labour.

A

The completed delivery of the placenta

22
Q

What are the 2 most commonly administered uterotonics?
what are the doses and what is the route?

A

for third stage management or treating PPH, the 2 most commonly given uterotonics are:
- Oxytocin either given 1ml IM 10iu/ml, or 0.5ml IV 10iu/ml.
- syntometrine (oxytocin 5iu / ergometrine maleate 0.5mg) given IM 1ml

23
Q

which hormone regulates the blood glucose levels to increase glucose to the fetus?

A

human Placental Lactogen (hPL)

24
Q

what are the effects of haemodilution on the body?

A

decrease in osmotic pressure - causing odema
decrease in concentration of Hb and iron increasing risk of IDA
decrease in blood viscosity causing reduced peripheral resistance and thus less cardiac work

25
Q

when does haemostasis (hypercoagulation) peak?

A

2 weeks before delivery

26
Q

what mechanisms help to control blood loss after birth?

A
  • oxytocin
  • living ligatures
  • hypercoagulation