Physiological adaptation from foetus to neonate Flashcards
define neonate
newborn
before baby is born what is happening in its lungs?
its type II alveolar cells (pneumocytes) are secreting surfactant (lowers surface tension at the air–liquid interface thus preventing alveolar collapse at end-expiration). ALSO glucocorticoids + thyroid hormones will stimulate the surfactant production {if we think a mother is gonna birth premature u give her a steroid injection to speed up the maturation of type II alveolar cells so boosts baby to produce more surfactant}
*in the foetus the lungs are fluid filled; this is mediated by active chloride secretion into alveoli (sodium and water follows chloride)
what is the role of ENaC cells in fully grown human vs in baby
Epithelial sodium channels (ENaC) are responsible for sodium reabsorption by the epithelia lining the distal part of the kidney tubule
whereas in bby; active absorption of alveolar fluid is also done via sodium transport in ENaCs! this process is stimulated by cortisol, catecholamines + thyroid hormones
bby initial breath causes[] thoracic pressure (intrapleural)
bby initial breath causes NEGATIVE thoracic pressure (intrapleural)
- hardest breath of ur life
- -may cause small pneumothoraces
babies born prematurely can develop breathing problems, why is this?
pulmonary surfactant is made by type II pneumocytes in alveoli; this process starts around week 24 and surfactant levels are not significant until week 33
surfactant is a lipoprotein consisting of phospholipids, surfactant proteins ABCD.
surfactant lowers the surface tension of air-liquid surface of alveoli + prevents alveolar collapse; it reduces surface tension by:
*increasing pulmonary compliance
*preventing atelecstasis (collapse of lungs)
What’s the difference between atelectasis and pneumothorax?
Atelectasis is a condition where alveoli in your lung or a part of your lung deflates, causing a partial or complete collapsed lung.
Pneumothorax is a condition where air leaks into the space around your lung (intrapleural space); It occurs when air accumulates between the parietal and visceral pleura inside the chest. The air accumulation can apply pressure on the lung and make it collapse.
explain the cardiovascular changes in fetal circulation.
what is ductus arteriosus
ductus arteriosus is a blood vessel that connects the pulmonary artery (main vessel supplying the blood to the lungs) to the aorta (main vessel supplying the blood to the body)= THIS CLOSES AT BIRTH
the closure is aided by increased o2 + decreased prostaglandins (PGE2)
explain some of the structures in the foetus that will change; ‘transitional circulation’
ductus arteriosus {vessel between pulmonary artery + aorta} must close; the closure is aided by increased o2 + decreased prostaglandins (PGE2 works on EP4 receptor cAMP + PKA produces hyaluronic acid; n.b. crosslinking goes on in aorta not ductus arteriosus)
*foramen ovale {a muscular aperture between left and right atrium that allows blood to cross the atria and bypass pulmonary circulation during fetal development} closes soon after birth
- umbilical vein forms round ligament of the liver
*n.b. round ligament of the liver/ aka ligamentum teres/aka ligamentum teres hepatis is a ligament that forms part of the free edge of the falciform ligament of the liver. It connects the liver to the umbilicus. It is the remnant of the left umbilical vein.
*umbilical artery; part obliterates to become medial umbilical ligament + a part remains open as a branch of anterior division of internal iliac artery
during delivery, there is a surge of catecholamines. What is there function
during delivery the surge of catecholamines:
* raises blood pressure
* supports energy metabolism
* aids thermogenesis via brown fat- releasing energy as heat rather than ATP
n.b. the thyroid hormone surge has similar effects to above^
fetal cortisol levels increase during the third trimester and at birth; what affects does this cortisol have
- stimulates surfactant production by type II pneumocytes in alveoli
*activates thyroid hormone (helps mature hepatic glucose + gut digestive enzymes)
*increases beta-adrenergic receptors (this increases production of noradrenaline + adrenaline; will increase heart rate and contractility)
neonate should not lose more than [] of birth weight
neonates shld not lose more than 10% of birth weight (a lil weight loss norm as their blood glucose levels are low so they will be breaking down fat + glycogen reserves to raise these resulting in a lil weight loss)
neonates are injected with which vitamin
vitamin K injection on first day of life as neonates are deficient in it and need it to produce clotting factors (as clotting factors dont cross placenta)
why is neonatal jaundice of baby common?
breakdown of fetal RBCs results in high levels of bilirubin; poor activity of hepatic glucuronyl transferase leads to low levels of conjugation + excretion
they put these babies in blue light to deal w this ; nothing to worry abt its just unconjugated bilirubin that baby can’t break down as its liver + the enzyme hepatic glucuronyl transferase not active enough yet
Postnatally, the innate immune system is starting to develop, the bby has maternally derived IgG, but what immune benefits does the baby gain from breastmilk?
baby gains immune benefit from breastmilk: IgA, complement, lactoferrin, lysozyme
