Gaseous Exchange

What happens during Inhalation?

Intercostal muscles contract, diaphragm contracts and flattens, volume of thorax increases, pressure inside thorax decreases.

What happens during Exhalation?

Intercostal muscles relaxes, diaphragm relaxes and becomes dome shaped, volume of thorax decreases, pressure inside thorax increases.

Give adaptations for alveoli that makes it great for gas exchange

• There are many rounded alveolar sacs which give a very large surface area to volume ratio.

• Alveoli (and the capillaries around them) have thin, single layers of cells to minimize diffusion distance.

• A good blood supply ensures a constant supply of blood high in carbon dioxide and low in oxygen, again to maintain concentration gradients for diffusion.

• It has a moist lining which means the gases will dissolve before diffusing.

Give me comparison between smoking and electronic smoking (vaping)

nicotine:

• narrows blood vessels and increases heart rate, leading to increased blood pressure

• causes high blood pressure that leads to blood clots forming in the arteries, potentially resulting in heart attack or stroke

tar:

• is a carcinogen linked to increased chances of cancerous cells developing in the lungs

• contributes to COPD, which occurs when chronic bronchitis and emphysema occur together

carbon monoxide:

• binds irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen

• puts more strain on the breathing system, as breathing frequency and depth need to increase to supply the same amount of oxygen

• means that the circulatory system needs to pump blood faster, raising blood pressure and increasing the risk of coronary heart disease and stroke