Respiratory system Physiology

Question 1

Explain the physical process that allows us to inhale and exhale

Answer 1

Pulmonary ventilation is the physical process that allows us to inhale and exhale. When we inhale, our chest moves up, an active process, and your muscles contract which reduces the pressure inside so that pressure in the lungs is less than pressure in the air, and air is then able to flow through the thoraric cavity. As we expire, which is usually a passive process, our muscles relax and the pressure in the lungs increases, which reduces the thoraric activity and air is forced out

Question 2

Understand how injury, illness and environmental factors affect breathing

Answer 2

In order for us to inspire our diaphragm contracts and moves lower in order to allow the chest cavity to enlarge, reducing the pressure inside the lungs. When the diaphragm relaxes and moves back up, the lungs increase in pressure and cheat walls push air out of the lungs. The intercostal muscles also allow us to breathe. The external intercostal muscles are responsible for forces and quiet inhalation. They raise the ribs and expand the chest cavity. The internal intercostal muscles are responsible for forces exhalation. During active expiration (forced), the muscles of the abdominal wall are extremely important as they drive abdominal pressure up when they contract, pushing up the diaphragm and this raising pressure.

Injury

• If we have a cervical injury for example, our diaphragm may only work partially or not at all. Therefore, our ability to breathe is impeded.
• If we have a thoracic and lumbar injury, our diaphragm works well however our intercostal muscles work but not well. In other instances, our intercostal muscles may work well but our abdominal muscles may be weak.

Illness
- Mucus can be stuck in the system

Environment
- Poor environments with pollution affect breathing

Question 3

State Boyle’s law and explain it

Answer 3

If temperature is constant:
Pressure1 x Volume1 = Pressure2 x Volume 2

• When you inhale, muscles increase the size of your thoracic cavity and expand your lungs. The volume is therefore increased, so pressure inside the lung decreases.
• When you exhale, the muscles decrease the size of your chest cavity, therefore the volume decreases and the pressure increases

Question 4

What is Fick’s law of diffusion

Answer 4

The volume of gas that diffuses is proportional to surface area available for diffusion, diffusion coefficient of gas, and the difference in the partial pressure of gases and inversely proportional to thickness of membrane

Vgas = A x D x (P1-P2)/ T

Allows us to know the relationship between the rate of diffusion that takes place in alveoli and the factors that affect it

Question 5

How does Fick’s law determine how much oxygen reaches arterial blood in healthy lungs and diseased lungs

Answer 5

Healthy lungs have a thin cross sectional area which allows gas to be diffused quickly according to Fick’s Law. Therefore, more oxygen reaches arterial blood. However, in diseases lungs there is less surface area for gas exchange. According to Fick’s law, this means that less gas will be diffused as surface area is proportional to volume, which result in difficulty in breakthing as a smaller amount of oxygen is able to go in and carbon dioixide is able to go out the lungs.
Fibrotic lung disease has a slow gas exchange due to the thickened alverolar membrane

Question 6

Define oxygen cascade

Answer 6

Oxygen cascade described the transfer of oxygen from air to mitochondria. In each step to PO2 changes. It demonstrates that oxygen delivery to tissues relies on the passive transfer of gas down partial pressure