Chapter Questions - Respiratory System
Air moving from the nose to the trachea passed by a number of structures. List as many of these as you can.
The respiratory system includes the nose, nasal cavity, and paranasal sinuses; the pharynx; the larynx
Which structure seals the larynx when we swallow?
During swallowing, the soft palate and its pendulous uvula (u vu-lah; “little grape”) move superiorly an action that closes off the nasopharynx and prevents food from entering the nasal cavity.
The epiglottis seals the larynx when we swallow
Which structural features of the trachea allow it to expand and contract, yet keep it from collapsing?
The incomplete, c-shaped cartilage rings of the trachea allow it to expand and contract and yet keep it from collapsing
What features of the alveoli and their respiratory membranes suit them to their function of exchanging gases by diffusion?
The many tiny alveoli together have a large surface area. This and the thinness of their respiratory membranes make them ideal for gas exchange
A 3 year old boy is brought to the ER after aspiring a peanut. Bronchoscopy confirms the suspicion that the peanut is lodged in a bronchus and then it is successfully extracted. Which main bronchus was the peanut most likely in? Why?
The peanut was most likely in the right main bronchus because it is wider and more vertical than the left.
The lungs are perfused by 2 different circulations. Name these circulations and indicate their roles in the lungs.
The two circulations of the lungs are the pulmonary circulation, which delivers deoxygenated blood to the lungs for oxygenation and returns oxygenated blood to the heart, and the bronchial circulation, which provides systemic (oxygenated) blood to the tissues
What is the driving force for pulmonary ventilation?
The driving force for pulmonary ventilation is a pressure gradient created by changes in the thoracic volume
What causes the intrapulmonary pressure to decrease during inspiration?
The intrapulmonary pressure decreases during aspiration because of the increase in thoracic cavity volume brought about by the muscles of inspiration
What causes the partial vacuum inside the pleural cavity? What happens to a lung if air enters the pleural cavity? What is the clinical name for this condition?
The partial vacuum inside the pleural cavity is caused by the opposing forces acting on the visceral and parietal pleurae. the visceral pleura are pulled inward by the lungs' natural tendency to recoil and the surface tension of the alveolar fluid. the parietal pleurae are pulled outward by the elasticity of the chest wall. If air enters the pleural cavity, the lung on that side will collapse. This condition is called pneumothorax
Resistance in the airways is typically low. Why?
Airway resistance is low because the diameters of most airways are relatively large, for smaller airways there are many in parallel, making their combined diameter large, and air has a low viscosity
Premature infants often lack adequate surfactant. How does this affect their ability to breathe?
A lack of surfactant increases surface tension in the alveoli and causes them to collapse between breaths
Explain why slow, deep breaths ventilate the alveoli more effectively than do rapid, shallow breaths
Slow, deep breaths ventilate the alveoli more effectively because a smaller fraction of the tidal volume of each breath is spent moving air into and out of the dead space
You are given a sealed container of water and air. The Pco2 and Po2 in the air are both 100mm Hg. What are the Pco2 and Po2 in the water? Which gas has more molecules dissolved in the water? Why?
In a sealed contain the air and water would be equilibrium. Therefore the partial pressure of CO2 and O2 (Pco2 and Po2) would be the same in the water as well as in the air: 100mm Hg each. More Co2 then O2 molecules will be dissolved in the water (even though they are at the same partial pressure) because CO2 is more soluable than O2 in water.
Po2 in the alveoli is about 56 mmHg lower than in inspired air. explain this difference
The difference in po2 between inspired air and alveolar air can be explained by the gas exchange occurring in the lungs, the humidification of inspired air, and the mixing of newly inspired air with gases already present in the alveoli
Suppose a patient is receiving oxygen by mask. Are the arterioles leading into the O2-enriched alveoli dilated or constricted? What is the advantage of this response?
The arterioles leading into the O2 enriched alveoli would be dialted. This responses allows amtching blood flow to availability of oxygen
Rapidly metabolizing tissues generate large amounts of CO2 and H+. How does this affect O2 unloading? What is the effect called?
Both co2 and h+ increase o2 unleading by binding to Hb. this is called the bohr's effect
List the three ways CO2 is transported in blood and state approximate percentages of each.
1. Dissolved in plasma (7–10%).
2. Chemically bound to hemoglobin (just over 20%).
3. As bicarbonate ion in plasma (about 70%).
What is the relationship between CO2 and pH in the blood? Explain.
As blood CO2 increases, blood ph decreases. This is because co2 combines with water to form bicarbic acid
Which brain stem respiratory area is thought to generate the respiratory rhythm?
The ventral respiratory group of the medulla (VRG) is thought to be the rhythm generating area.
Which chemical factor in blood normally provides the most powerful stimulus to breathe?
CO2 in blood normally provides the most powerful stimulus to breathe.
Central chemoreceptors are most important in this response
An injured soccer player arrives by ambulance in the emergency room. She is in obvious distress, breathing rapidly. Her blood Pco2 is 26 mg Hg and pH is 7.5. Is she suffering from hyperventilation or hyperpnea? Explain
The injured soccer players Pco2 is low. The low Pco2 reveals that this is hyperventilation and not hyperpnea.
What long-term adjustment does the body make when living at high altitudes?
Long term adjustments to altitude include an increase in erythropoiesis, resulting in a higher hemacrit; an increase in PBG which decreases Hb affinity for oxygen; and an increase in minute respiratory volume
What distinguishes the obstruction in asthma from that in chronic bronchitis?
The obstruction in asthma is reversible. An acute exacerbations are typically followed by symptom-free periods. In contrast, the obstruction in chronic bronchitis is generally not reversible
What is the underlying defect in cystic fibrosis?
The underlying defect in cystic fibrosis is an abnormality in a protein (CFTR protein) that acts as a membrane channel for chloride ions
List two reasons for the decline in vital capacity seen with age.
Vital Capacity declines with age because the thoracic wall becomes more rigid and the lungs lose their elasticity