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Flashcards in Week 5- adaptions at birth Deck (37)
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1
Q

By which transport method do things move into/out of the placenta?

A

Diffusion

2
Q

What saturations does foetal oxygenated blood have?

A

80%.

3
Q

What immunoglobulin gives the baby passive immunity?

A

IgG

4
Q

What is the function of the placenta?

A
Fetal homeostasis
Gas exchange
Nutrient transport to the fetus 
Waste product transport from fetus
Acid base balance
Hormone production
Transport of IgG
5
Q

Which hormones does the placenta produce?

A

Insulin and insulin like growth factor
Glucocorticosteroids
Placental lactogen

6
Q

What is the function of insulin and insulin like growth factor in the fetus?

A

Essential for growth.

7
Q

What substance is responsible for growth of the placenta?

A

IgF 2.

8
Q

What is the function of glucocorticosteroids?

A

They are basically the opposite to insulin and insulin like growth factor where they restrict fetal growth, however allow the specialisation of tissues

9
Q

What is the function of placental lactogen in the fetus? Which types of pregnancy will this hormone be increased in?

A

Has anti-insulin effects.

Multiple pregnancies to keep the babies small so they can fit.

10
Q

What does the umbilical vein carry and where does it go in the fetus before birth?

A

Umbilical vein carries oxygenated blood from the placenta to the liver.

11
Q

Where is the ductus venosus and what does it bypass and why?

A

Ductus venosus is between the umbilical vein and the inferior vena cava. This means the oxygenated blood bipasses the liver.

12
Q

Describe the blood in the IVC after the ductus venosus?

A

Here you have mixing of oxygenated blood from the umbilical vein with deoxygenated blood from the limbs, so its a mix.

13
Q

Describe the flow of blood through the fetal heart?

A

Blood enters the right atrium and has two options:
Some of it goes into the right ventricle and is then pumped into the pulmonary artery.
Some of it goes through the foramen ovale and into the left atrium to be pumped into the left ventricle and out to the body.

14
Q

Describe the pulmonary arteries adaptations in the fetus?

A

The lungs aren’t being used so have a lot of resistance causing pressure in the pulmonary artery to be high. This means only a small amount of blood (7%) goes to the lungs. The rest of the blood goes through the ductus arterioles to the aorta to be pumped around the rest of the body.

15
Q

How does blood go back to the placenta?

A

The umbilical arteries.

16
Q

In the 3rd trimester, what adaptations does the fetus do in preparation for birth?

A

Surfactant production
Accumulation of glycogen- needs energy stores
Accumulation of brown fat- around scapulae and heart
Accumulates subcutaneous fat
Swallows amniotic fluid- to help its lungs develop.

17
Q

During labour, what physiological reactions does the fetus have?

A

Produces catecholamines and cortisol to increase its metabolic rate.
Stops synthesising lung fluid- reabsorbs sodium to reabsorb remaining fluid
In vaginal delivery- the lungs are squeezed.

18
Q

What does the baby do in the first few seconds of life?

A

Starts blue
Starts to breathe
Cries
Gradually goes pink (over about 5 mins)

19
Q

Describe how the foramen ovale closes after birth?

A

The pulmonary resistance drops and systemic vascular resistance rises. This means pressure in the left side of the heart is now higher than the right.
Also circulating prostaglandins drop and oxygen tension rises causing the duct to close.

20
Q

What does the ductus arteriosus become?

A

Ligamentum arteriosus

21
Q

What does the ductus venosus become?

A

Ligamentum teres.

22
Q

Which babies are at risk of cardiorespiratory abnormalities?

A

Preterm babies
Assisted delivery babies
Babies with infections
Babies who pass meconium during birth.

23
Q

What is persistent pulmonary hypertension of the newborn? What is the issue with this?

A

The two shunts- foramen ovale and ductus arteriosus persist.
There is no longer any oxygenated blood coming from the placenta so you get deoxygenated blood coming into the left ventricle and being pumped around the body.
Also there is very little blood going to the lungs so you can’t oxygenate it properly.

24
Q

How can you test for persistent pulmonary hypertension of the newborn?

A

Oxygen saturations in the arms will be 5-10% different to the legs because they are the first branches of the aorta.

25
Q

How do you manage persistent pulmonary hypertension of the newborn?

A

Ventilation
Oxygen
Nitric oxide
Sedation

If all else fails heart lung bypass

26
Q

What is transient tachyopneoa?

A

If the fluid in the lungs doesn’t drain properly. The switch from fluid excretion to sodium reabsorption hasn’t completed then fluid will persist in the lungs.

27
Q

What three things are important in the first few hours of babies life?

A

Thermoregulation- have to keep the baby warm
Glucose homeostasis- have to keep the babies blood sugar up
Nutrition- to grow.

28
Q

How do you keep the baby warm after birth?

A

Dry it- babies are wet when they come out
Skin- skin contact with mum
Dry warm towel so they can’t lose heat from convection and radiation.

29
Q

What four ways can babies lose heat?

A

Convection
Conduction- to objects
Radiation
Evaporation

30
Q

How do babies generate heat?

A

They are unable to shiver.
They do non-shivering thermogenesis- heat is produced by the breakdown of stored brown adipose tissue in response to catecholamines.
Peripheral vasoconstriction.

NOTE- these methods don’t work in the first few hours of life.

31
Q

Why are small for dates babies more at risk of hypothermia?

A

They haven’t got as much brown adipose tissue.
Little subcutaneous fat
Larger surface area to volume ratio

32
Q

Why is glucose homeostasis disrupted at birth?

A

The baby goes from having a constant infusion from the mum to not having any at all.
There is also a drop in insulin and an increase in glycogen.
Very little oral intake of breast milk.

33
Q

In what situations can babies become hypoglycaemic?

A

Small for dates- not a substantial stored energy supply
Mother had diabetes- goes from having so much blood sugar and accounting for this by producing so much insulin to having a lower blood sugar but with the same large insulin supply.
Increased energy demands- if the baby is hypothermic or unwell.

34
Q

How does suckling stimulate the mother to produce milk?

A

Sensory signals go from the nipple to the hypothalamus. This sends signals to the posterior pituitary causing release of oxytocin meaning milk is ejected. Also sends signals to the anterior pituitary causing release of prolactin meaning milk is produced.

35
Q

What causes the change in fetal haemoglobin to adult haemoglobin?

A

An increase in 2, 3 DPG

36
Q

What issues can arise with a change from fetal to adult haemoglobin?

A

Adult haemoglobin is produced a lot slower than fetal haemoglobin undergoes haemolysis- this can lead to temporary anaemia. This presents as physiological jaundice.

37
Q

What causes physiological jaundice?

A

Fetal haemoglobin breakdown
Conjugating pathways immature
Rise in circulating unconjugated bilirubin.