physiology for scope

Question 1

what are the placental hormones in pregnancy?

Answer 1

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

Question 2

what are the maternal hormones of pregnancy?

Answer 2

oxytocin
prolactin
relaxin

Question 3

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

Answer 3

• 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

Question 4

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

Answer 4

corpus luteum
6-8 weeks

Question 5

actions of progesterone in pregnancy are;

Answer 5

• 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

Question 6

function of human Gonadotropin hormone (hCG)?

Answer 6

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

Question 7

human placental lactogen (hPL) what does it do?

Answer 7

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

Question 8

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

Answer 8

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.

Question 9

role of oxytocin in pregnancy?

Answer 9

(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

Question 10

relaxin?

Answer 10

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

Question 11

what are the haematological changes in pregnancy?

Answer 11

an increase in blood volume causing haemodilution

Question 12

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

Answer 12

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.

Question 13

what are the coagulation changes that occur in pregnancy?

Answer 13

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.

Question 14

What cardiac changes occur in pregnancy?

Answer 14

• 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

Question 15

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

Answer 15

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.

Question 16

what effect does a supine position have when heavily pregnant?

Answer 16

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.

Question 17

what are the stages of labour?

Answer 17

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.

Question 18

what are the signs of placental separation?

Answer 18

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

Question 19

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

Answer 19

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.

Question 20

what happens to the level of haemoglobin in pregnancy

Answer 20

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

Question 21

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

Answer 21

The completed delivery of the placenta

Question 22

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

Answer 22

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

Question 23

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

Answer 23

human Placental Lactogen (hPL)

Question 24

what are the effects of haemodilution on the body?

Answer 24

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

Question 25

when does haemostasis (hypercoagulation) peak?

Answer 25

2 weeks before delivery

Question 26

what mechanisms help to control blood loss after birth?

Answer 26

• oxytocin
• living ligatures
• hypercoagulation