Respiratory System

    Respiratory System
    What is the function of the goblet cells that make up part of the lining of the respiratory tree?
    Goblet cells secrete mucus. This traps small inhaled particles which are then moved out of the respiratory tree by the action of the ciliated cells (which also line the respiratory tree). Type II pneumocytes secrete surfactant, macrophages eat bacteria, etc.
    Author: rikazzz Comment
    Respiratory System
    A bronchiole differs from a bronchus in that it is:
    Bronchiole can constrict and dilate while bronchi cannot (they are held open by cartilage). Bronchioles are more distal than bronchi in the respiratory “tree”.
    Author: rikazzz Comment
    Respiratory System
    Given that the lung contains a residual air volume of ~1.2 L and has an expiratory reserve volume of ~1.2 L and the dead space is about 150 ml, while resting tidal volume is about 500 ml, approximately what percentage of the volume of air in the lung is turned over during one normal tidal inhalation at rest?
    Some people may remember the value (or by calculation). Lung volume at end of a tidal exhalation = RV + ERV = 1.2 L + 1.2 L = 2.4 L. The next inhalation brings in (TV – dead space) ml of fresh air, that is: (500–150) ml = 350 ml. 350 ml is 14.6% of 2400 ml (or 12.7% of 2750 ml if the 350 ml inhalation is added to the 2.4 L already present). Hence, choice B is the closest.
    Author: rikazzz Comment
    Respiratory System
    What term is applied to the exchange of dissolved gases between capillary blood and body tissues?
    Internal respiration refers to the movement of oxygen from the capillary blood into the tissues and carbon dioxide from the tissues into capillary blood. Choice B occurs between the alveoli and pulmonary capillaries and choice C occurs within the mitochondria.
    Author: rikazzz Comment
    Respiratory System
    In which form is the majority of CO2 transported in the blood?
    CO2 leaves the cell as dissolved gas. About 7% is transported in solution in plasma and 23% bound to haemoglobin (HbCO2) in RBC, while 70% reacts with water to form carbonic acid, which disassociates to form bicarbonate ions.
    Author: rikazzz Comment
    Respiratory System
    One statement below about the larynx is correct. Which one?
    The larynx is a cartilaginous tube that surrounds the glottis and consists of the thyroid and cricoid cartilages.
    Author: rikazzz Comment
    Respiratory System
    In red blood cells, carbonic anhydrase catalyses the formation of carbonic acid which then disassociates into bicarbonate ions and hydrogen ions. What happens next?
    Haemoglobin is a protein so can act as a buffer, thus removing the hydrogen ions from solution. The bicarbonate ions move out of the RBC into the plasma in exchange for chloride ions.
    Author: rikazzz Comment
    Respiratory System
    In what form is the majority of carbon dioxide that is generated by cellular respiration transported to the lungs?
    CO2 leaves cell as dissolved gas. About 7% is transported in solution in plasma, and 23% bound to haemoglobin (HbCO2) in RBC, while 70% reacts with water to form carbonic acid, which forms bicarbonate ions.
    Author: rikazzz Comment
    Respiratory System
    Chemoreceptors in the medulla oblongata are sensitive to:
    Peripheral chemical receptors send signals to respiratory centres of the brain located in medulla oblongata when blood carbon dioxide rises or blood oxygen concentration falls below 60 mmHg.
    Author: rikazzz Comment
    Respiratory System
    With regard to lung ventilation, what does “dead space” refer to?
    Dead space refers to air that is inhaled into the airways but does not reach the alveoli and hence is exhaled again without participating in gas exchange.
    Author: rikazzz Comment