Physiological adaptation from foetus to neonate

Question 1

describe the in utero environment

Answer 1

• Foetus surrounded by amniotic fluid
• Warm cushioned quiet
• Fluid filled lungs
• Foetal circulation
• Relative hypoxia – oxygen and carbon dioxide exchange via placenta
• Nutrient acquisition and waste elimination via placenta

Question 2

what are the lungs like before brith

Answer 2

• Lungs are fluid filled – mediated by active chloride secretion
• Increasing secretion of surfactant with increasing gestation – starts at 24 weeks gestation, increased by glucocorticoids, cortisol and thyroid hormones
• The distending pressure of the fluid in the lung is important for lung exansopn and the development of the airways

Question 3

what does the foetus make breathing efforts

Answer 3

• Foetus makes breathing efforts primarily during sleep

Question 4

what happens to the foetus lungs at birth

Answer 4

• Physical pressure of labour squeezes some fluid out of the lung the rest goes into the lymphatic system
• Initial breath causes negative thoracic pressure – the hardest breath of your life, may cause small pneumothoraces from the initial breath
• Active absorption of alveolar fluid via sodium transport – stimulated by cortisol, catecholamines and thyroid hormone – switches from chloride to sodium absopriton
• Establishes a functional residual volume, onset of regular respriations

Question 5

what can the first breath produce

Answer 5

small pneumothraces from the initial breath

Question 6

what happens if you do not have surfactant

Answer 6

• get respiratory distress syndrome
• in order to treat them you have to give them surfactant and incubate them
• if you know they are gunna be born pre term then you give high doses of steroids to the mum as cortisol stimulate surfactant production

Question 7

describe the cardiovascular system of the foetus

Answer 7

• placenta leads to umbilical vein which leads to the ductus venous which pumps the blood into the IVC
• the IVC goes to the right atrium
• it can then go to the right ventricle, into the pulmonary artery pulomyar vein and into the left atrium
• or it can go to the right ventricle pulmonary artery and ductus arteries into the aorta
• or it can go into the the foramen oval to the left atrium then left ventricle then aorta then internal lilacs and umbilical artery

Question 8

where does most of the oxygenated blood supply go

Answer 8

supply the brain, and the coronary vessels from the heart

Question 9

the diameter of the ductus arterioles can equal that of the …

Answer 9

aorta

Question 10

what happens when the umbilical cord is clamped

Answer 10

• Umbilical cord is clamped
• And someone will cut it
• So the blood through the umbilical vessels are stop
• All that is left is the artery and body so the systemic vascular resistance rises
• The lungs have opened up the pulmonary blood flow has increased and pulmonary vascular resistance drops due to more oxygen, this reduces the blood pressure in the lungs
• RA pressure drops, LA pressure rises, reducing flow through foramen ovale
• Flow preferentially goes to RV and pulmonary artery
• Flow through ductus arteriosus changes

Question 11

what can the umbilical arteries and veins be used for

Answer 11

• the umbiclia arteries can be used for quick access therefore they can give richly concentrated infusions via candlers
• umbilical arterial catheter - gives access to do blood tests and so you can work out the babies blood pressure

Question 12

what happens in persistent pulmonary hypertension

Answer 12

• this is when the switch does not occur

- all the oxygenated blood is still pumping to the peripheral circulation

Question 13

what happens once the foetus is born to the cardiovascular system

Answer 13

• ductus arteriosus clsoes
• foramen ovale closes
• umbilical vein forms the round ligament of the liver
• the umbilical arteries either becomes the medial umbilical ligament or the branch of the anterior division of the internal iliac artery

Question 14

how does the ductus arterioles close

Answer 14

• Closure aided by increased oxygen and decreased prostaglandins (PGE2)
• Functionally closes within a few days
• Anatomically changes within a couple of weeks – forming ligamentum arteriosum

Question 15

how does foramen oval close

Answer 15

Fuses in the majority but significant minority have a PFO – this usually doesn’t cause any problems but this can cause stroke in young people,
• Umbilical vein forms the round ligament of the liver

Question 16

what happens to the umbilical artery after birth

Answer 16

• Partly obliterates and become the medial umbilical ligament
• Whereas A part remains open as a branch of the anterior division of the internal iliac artery.

Question 17

when to foetal cortisol levels increase

Answer 17

Foetal cortisol levels increase during the third trimester and at birth

Question 18

what does foetal cortisol levels do

Answer 18

• Stimulates surfactant production
• Activates thyroid hormone
• Matures hepatic glucose and gut digestive enzymes
• Increase in beta-adrenergic receptors

Question 19

when is there a surge of catecholamines

Answer 19

during delivery

Question 20

what do catecholamines do

Answer 20

• Raises blood pressure
• Supports energy metabolism
• Aids thermogenesis via brown fat - releasing energy as heat rather than ATP
- thyroid hormone surge has similar effects

Question 21

how do babies maintain heat

Answer 21

• chest contact

- thermaingoen in brown adipose tissue

Question 22

what is the main supply of food for the baby in utero and after birth

Answer 22

• glucose in utero

- after birth it is free fatty acids

Question 23

describe metabolic changes that the baby undergoes

Answer 23

• in babies nutritional supply from placenta stops at brith and blood glucose levels fall
• Reduction in insulin rise in glucagon and catecholamines
• Newborns tolerate lower blood sugar levels (normal low 2-2.6mmol/L)
• The use alternative energy soruces such as ketone bodies, free fatty acids
• Term neonates have laid down fat and glycogen reseveres

Question 24

what are babies more suspectible to in gestational diabetes

Answer 24

• more likely to get hypoglycaemia
• pancreas is using a lot of insulin in the womb to get rid of glucose but then there is a sugar drop and no sugar for the baby to use insulin in so they are more likely to get hypoglycaemia

Question 25

what is the rooting reflex

Answer 25

stroke their bottom lip or cheek they will think it is the breast and they will settle down

Question 26

when should babies pass meconium

Answer 26

within 48 hours - transition to milk stools within the first few days this is yellow and grey poo - If they don’t pass within 48 hours have ot thing about diseases such as blockages or cystic fibrosis

Question 27

what happens if the baby is stressed in utero

Answer 27

if the baby is stress.in utero they poo inside, this can go into the lungs and cause damage which reduces surfactant

Question 28

what happens to haematological changes during pregnancy

Answer 28

* Low oxygen levels in-utero. To overcome this: * Foetus and neonate have higher red blood cell levels (160-220 g/L) * Foetal haemoglobin has higher affinity for O2 * Hemopoiesis transitions from extra-medullary sites (liver) to bone marrow * Postnatally, HbF decreases by ~6 months * Clotting is variable – don’t really cross the placenta * Clotting factors don’t cross the placenta and neonates will have lower values than adults * Neonates are deficient in vitamin K so receive supplementation at birth – inejctoin or oral supplement – some are at risk of having haemorrhoid

Question 29

what is foetal haemoglobin made out of

Answer 29

Foetal haemoglobin – 2 alpha 2 gamma

Question 30

what is adult haemoglobin made out of

Answer 30

Adult haemoglobin – 2 alpha and 2 beta

Question 31

why is the baby anaemic at 2 months

Answer 31

baby seen anaemic at 2 months due to the switch in haemoglobin

Question 32

what causes neonatal jaundice

Answer 32

- The breakdown of foetal red cells results in high levels of bilirubin - Poor activity of hepatic glucuronyl transferase leads low levels of conjugation and excretion - Therefore, neonatal jaundice is common - Red cells start breaking down as soon as the baby is out and haemoglobin is breaking down and bilirubin is being formed - Goes to the liver to get conjgualted by glucuronyl transverase so it can be excreted but glucuronyl transferase is not up to the job so bilirubin is not conjgulated - Therefore jaundice develops

Question 33

what is the worry with jaucine

Answer 33

- Worry if the bilirubin goes very high, can start depositing itself in the brain and cause cerberoplasy –

Question 34

how do you treat jaundice

Answer 34

use blue phototerhapy lights to treat it, it swtiches the chemical formation of the bilirubin molecule so the kidneys can excrete it without conjugulation

Question 35

what time is urine produced from

Answer 35

- it is produced from around 16 weeks gestation

Question 36

where is urine produced form

Answer 36

- it is produced from the kidney

Question 37

what does the placenta do for the kidney

Answer 37

it maintains many of the kidneys functions such as - excretion - acid base balance

Question 38

what does nephrogensis completed by

Answer 38

approximately 34 weeks gestation

Question 39

what are babies full of in utero

Answer 39

- 80-90% water in utero

Question 40

why do babies have a natural weight loss when they are born

Answer 40

- because they loose some of there water that they had in Vitor

Question 41

what happens to babys and renal blood flow

Answer 41

- there is an increase in renal blood flow this further increases GFR which continues till mature until 1 month of age

Question 42

how does urine output in a newborn baby work

Answer 42

- Urine output is low on day 1, but all babies should pass urine within 24 hours – if they haven’t do they have an infection, are they dehydrated

Question 43

when does diuresis establish itself

Answer 43

- it establishes itself within the first few days with increase in urine output and loss of water

Question 44

can babys produce concentrated urine

Answer 44

– the baby is less able concentrate urine and excrete molecules – in healthy term baby don’t have to worry about this, issue in preterm babies and unwell term babies, if you give then tons of salt the kidney cannot regulate this

Question 45

does the baby have a immune system in utero

Answer 45

In-utero, the foetus is relatively immunosuppressed given its dependence on mother

Question 46

what does the immune system primarily rely on postnatally

Answer 46

- innate immune system - although has less capability to mount neutrophil response - maternally-derived IgG

Question 47

describe the other parts of the immune system of the baby

Answer 47

Cell-mediated immunity favours T-helper cell response, increasing vulnerability to certain infections Limited humoral response – low IgA, IgM levels Gains immune benefit from breastmilk IgA found in mucosal surfaces, complement, lactoferrin, lysozyme

Question 48

what are the disruption to normal transition

Answer 48

* Prematurity * Other disease states in baby, e.g. congenital abnormalities, infection, asphyxia * Non-labour deliveries, e.g. elective caesareans – baby hasn’t had a chance to do all hormone, it can go into respiratory distress * Complicated deliveries * Maternal health and medications (including anaesthesia) – baby can be anaesthetised when it comes outs