BI0005 - Lecture 19 - The newborn Child

• In foetus some organs not fully functional

• Changes required at birth

• To give fully functional organs

• Foetal Lungs
• • Collapsed or partially filled
• • Produce surfactant (6 months)
•    - Dependent upon mother for oxygen supply and carbon dioxide removal

• At Birth
• • Oxygen supply ceases
• • Carbon dioxide accumulates
• • Respiratory centre in the brain stimulated
•    - Baby draws first breath
•    - Unusually deep
•    - Inflates lungs
•    - Surfactant prevents collapse of alveoli
• • High respiration rate (45/min)
• • Decreases to 12/min

• Foetal circulation adapted for lack of lung function

• Receiving blood from mother

• • Hence 3 shunts to by-pass blood
•    – 1 in heart
•    – 1 ensures some blood from mother by
•    - passes liver and goes straight to heart
•    – 1 prevents too much blood going to collapsed lungs

• • Sole responsibility for maintaining fluid balance & waste disposal
•    – Takes few years to fully mature

• • Not as effective at concentrating urine
•    – Babies dehydrate more easily

• Limited secretion of enzymes and hormones by foetus

• • Takes a few days to properly establish after birth
•    – Use fat and glycogen stores

• • 1st milk feeds gives:
•    – Rapid increase in gut size
•    – Stimulation of digestive juices and motility

• Adjust from warm, moist, constant environment of mother’s uterus to cooler outside world

• Heat lost by variety of routes

• • Large surface area relative to volume
•    – Makes heat loss easy

• Needs Brown adipose tissue
• • Extra brown fat – 200g high proportion of body mass
• • Generates heat
• • Well vascularised so heat taken to rest of body