Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be

talking to you about neonatal physiology. And if you want to follow along with written notes on this topic,

you can follow along at Zero to Finals.com slash neonatal physiology or in the neonatology section of the zero to finals pediatrics book.

So let's get straight into it.

We're going to talk about surfactant and some of the cardiorespiratory changes at birth

to discuss some of the key features you need to know about for the neonatal physiology that will come up in your exams and

clinical practice. Firstly, we need to discuss surfactant. Surface tension is the attraction of

molecules in a liquid to each other, and this pulls them closer together and minimizes the

surface area of the liquid.

This is why in zero gravity, water floats around in a ball rather than diffusing into a mist.

Alveoli are the small sacks in the lung

where gas collects and diffuses into the blood during inhalation.

The alveolite aligned with fluid and the molecules of this fluid

pull together due to surface tension, in turn pulling the walls of the alveoli towards each

other and attempting to collapse the space in the alveoli.

Sepactin is a fluid produced by type 2 alveola cells, and it contains proteins and fats,

and it sits on top of the water in the lungs.

It has a hydrophilic side that faces the water, and a hydrophobic side that faces the air in the alveoli.

The surfactin reduces the surface tension of the fluid in the lungs,

essentially providing a barrier that reduces the water molecule's tendency to pull towards each other.

The result is that the surfactant keeps the alveoli inflated and maximizes the surface area of the alveoli.

This reduces the force needed to expand the alveoli,

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