Question

need to know a,b,c,d

A. explain the mechanics of the process of ventiliation: inhalation/exhalation.

B. how does a fetus breath

C. why cant a fetus use its lungs?

D. what happens to a fetus as it is pushed through the birth canal, as far as the respiratory system is concerned?

Answer 1

A. Ventilation is mechanism of air moving in & out of the lung.

Inhalation - taking the air into the lungs

Exhalation - making air out of the lungs

This involves the airway from the nasal cavity upto the lungs. It divides into upper respiratory tract & lower respiratory tract.

URT - Includes from nose ,nasal cavity , pharynx & larynx.

LRT - includes from the traghea, brochchii & upto the alveoli.

Respiration :

The respiration is the series of sequences which started because of the pressure changes. The three pressure changes involved are

Atmospheric pressure

Intraalveolar pressure

Intrapleural pressure

Intraalveolar pressure is equal to the atmospheric pressure because they are connected through the airway. If inhalation starts, the lungs expands which causes negative in alveolar pressure ( volume increases pressure drops). So air flows into the lungs from the outside. It means air flows from higher to lower concentration area.

Once the oxygen taken, exhalation starts. The thoracic cage backs to normal in size so the pressure becomes positive ( volume reduces pressure increases). Increased alveolar pressute causes the airflow from the lungs into the atmosphere.

Gaseous exchange:

  The air inspired from the atmosphere taken into airway. It fills the lungs. In the lung tissue ( alveoli) , the gaseous exchange takes place. The Oxygen in the air is taken & Co2 is dropped here. So the pulmonary artery ( deoxygenated blood) leaves the Co2 at the level of capillaries & the O2 carried and the oxygenated blood formed in the pulmonary veins. This is called the process of Gaseous exchange.

This is what happens everytime we takes air in & out.

B. The required oxygen for fetus is provided by Placenta. So no breathing is there in fetus.

The main purpose of the breathing is to deliver the oxygen to all the cells in the body.

Oxygen is the basic energy source which needed for each & every cell in the body. The only way we getting oxygen is from the breathing. In the junction of alveoli & the cappilaries of pulmonary vrssels, the oxygen is extracted.

So once the lungs got the oxygen is carried out through the blood to all cells.

Transportation of oxygen:

The red blood cells has a part called Hemoglobin and it carries the oxygen in the blood. It has a binding site for the oxygen.

But incase of fetus it differs. Inside the womb, the fetus lungs are developed ( developed at the end of third trimester only) but not activated.

Here the role of lungs is actually done by the Placenta. It provides the blood supply & all nutritions to the fetus and also it gives the oxygen then carried away the Co2.

C. Lung is the breathing organ. The fetus is with the amniotic fluid inside the woman. It cannot breathe inside it. Moreover, as the fetus already getting the oxygen from the mother (through the umblical cord) there is no necessary for using the lungs.

D. Usually the fetus lungs are filled with fluid. They are like collapsed inside as there is no air. Once the baby came out & cuts the placenta will stops the oxygen supply.

Here the brain awakes, understand the situation sends signals. It triggers the lungs to start work. The lungs started expands, fluids drained out. The baby inhaled for the first time.

Its a inborn reflex, automatically the baby starts to adopt the environment.

This happens in few seconds after the delivery. The first breathing & lung expansion is the reason for the cry.