Explain The PHYSIOLOGY and ANATOMY of BREATHING and Exchange of Gases in human beings
Answers
Anatomy and physiology
The lungs are situated within the ribcage enclosed by two pleural membranes (Fig 1). At the base of the thorax, separating it from the abdominal cavity, lies the diaphragm. This is the main muscle of inspiration, and is innervated by the phrenic nerve.
fig 1 the respiratory system
The lungs are made up of large and small airways – the trachea being the largest and first of 23 generations of airways. The airways in each generation arise from the previous one by a system of irregular dichotomous branches (Davies and Moore, 2010). The smaller airways (respiratory bronchioles) contain alveoli in their walls. Alveoli are the site of gas exchange and their presence increases as the airways become smaller. This allows for the total surface area of the lung to increase exponentially allowing maximum opportunity for gas exchange.
Central and peripheral chemo receptors sensitive to hypoxia (low O2 levels) and hypercapnia (increased CO2) control the drive to breathe (Davies and Moore, 2010).