Question

1. Trace the flow of air from the nasal/oral cavity to the alveoli of the lungs. 2. Describe the respiratory membrane. 3. How are ciliated cells and mucus important in the respiratory system?

Answer 1

1. Air enters the nostrils then it air goes through where It is moistened by mucus, warmed up to body temperature and dust is filtered out of the air, by hairs and trapped by mucus. At the same time air can also go in your mouth but it doesn’t warm, filters the air, or clean the dust and dirt. The the air passes to the nasopharynx, to the oral pharynx. Next, it passes the glottis, to the trachea, or windpipe. Rings of cartilage support this breathing tube which leads to the right and left bronchi. These branch into each lung and further branch into smaller and smaller tubes. These are known as bronchioles. At the end of each bronchiole, is a cluster of air sacs or alveoli. Gas exchange occurs in the thin-walled alveoli which provide a huge surface area for the diffusion of oxygen from the alveoli into capillaries, so oxygen can be transported by the bloodstream to all the body's cells. Carbon dioxide diffuses from the capillaries surrounding the alveoli, into the alveoli, so it can be excreted when exhalation occurs.

Nostrils → Nasal Cavity → Pharynx → Larynx → Trachea → Main Bronchus à Lobar Bronchiole → Segmental Bronchus → Bronchiole → Terminal Bronchiole → Respiratory Bronchiole → Alveolar Duct → Atrium → Alveolus External nares, internal nares, nasopharynx, pharynx, larynx, trachea, bronchus, primary bronchiole, secondary bronchiole, tertiarty bronchiole, alveolar duct,

2. The respiratory membrane allows gases to be exchanged between the pulmonary capillaries, or blood vessels, and the respiratory units of the lungs, which consist of bronchioles, alveolar ducts, atria and alveoli, This exchange transports oxygen from the alveoli into red blood cells and carbon dioxide from blood cells into the alveoli. An exchange of gases supplies oxygen to the cells and removes carbon dioxide, a waste product that is exhaled by the lungs. The respiratory membrane can be thickened by fluid in the lungs, which forces gases to diffuse through the fluid and the membrane.

      Pulmonary diseases that result in fibrosis or scarring of the lungs can also cause the membrane to become thicker. The surface area of the lung is decreased by the removal of a lung or by emphysema, causing the alveoli to coalesce, thus destroying alveolar walls. The loss of alveolar walls decreases the surface area of the respiratory membrane, which impedes the exchange of gases and hinders the ability of the lungs to expel air.The respiratory membrane is coated with mucus, a clear, slippery substance that protects tissues from dust, bacteria and viruses.

3

Tiny hairs called cilia trap large pieces of debris and waft them out of the airways; the reflexes of sneezing and coughing help to expel particles from the respiratory system and the production of mucus keeps the tissues moist and helps to trap small particles of foreign matter.

Mucus production in the airways is normal. Without it, airways become dry and malfunction. But sometimes the mucus is produced in excess and changes in nature. This results in the urge to cough and expectorate this mucus as sputum. Sputum expectoration is not normal and there is always an underlying pathological cause.