define 'ventilation'

what is needed for cells to respire aerobically?

what is the muscular sheet of tissue which (together with the thorax) encloses the lungs in the ribs?

what joins each rib to the next?

what is a bronchial tree?

what is the function of the rings of cartilage in the trachea?

where does gas exchange with the blood take place?

how is the trachea kept clean?

what happens to our diaphragm when we breath in?

what happens when we breath out

how are alveoli adapted for gas exchange?

what causes a smoker's cough?

what is the cause of emphysema?

what is carboxyhaemoglobin?