[PHYSIO] Respi (2024) Flashcards
- Which structure does not belong to the Upper airways?
- A) Pharynx
- B) Larynx
- C) Arytenoids
- D) Trachea
D) Trachea
Rationale: The upper airways include the nasal cavity, pharynx, and larynx. The trachea is part of the lower respiratory tract.
- Which structure is not included in the lower respiratory tract?
- A) Arytenoids
- B) Bronchioles
- C) Trachea
- D) Bronchi
A) Arytenoids
Rationale: The lower respiratory tract includes the trachea, bronchi, and bronchioles. The arytenoids are cartilages in the larynx, which is part of the upper airways.
- Which statement regarding the respiratory system is not true?
- A) Response to sympathetic stimulation is local
- B) Dopamine has no influence on the lungs
- C) Norepinephrine is an adrenergic neurotransmitter
- D) Response to the parasympathetic system is specific
A) Response to sympathetic stimulation is local
Rationale: Sympathetic stimulation generally has a more widespread effect rather than being local. Dopamine does influence the lungs, and norepinephrine is indeed an adrenergic neurotransmitter. The response to the parasympathetic system tends to be more specific.
- Substance P and this parasympathetic neurotransmitter excite motor neurons.
- A) Dynorphin
- B) Vasoactive Intestinal Peptide
- C) Dopamine
- D) Acetylcholine
D) Acetylcholine
Rationale: Acetylcholine is the main neurotransmitter used by the parasympathetic nervous system to excite motor neurons. Substance P also plays a role in this excitation.
- Which is not an effect of parasympathetic stimulation to the respiratory system?
- A) Blood vessel dilation
- B) Increased glandular secretion
- C) Airway constriction
- D) Blood vessel constriction
D) Blood vessel constriction
Rationale: Parasympathetic stimulation generally causes blood vessel dilation, increased glandular secretion, and airway constriction. Blood vessel constriction is not an effect of parasympathetic stimulation.
- Chronic smokers and jeepney drivers have an increase in these cells in response to chronic irritations.
- A) Goblet cells
- B) Submucosal glands
- C) Clara cells
- D) Type 1 alveolar cells
A) Goblet cells
Rationale: Chronic exposure to irritants leads to an increase in goblet cells, which produce mucus to trap and expel particulates.
- Which is not true?
- A) Amount of cartilage increases down the respiratory system
- B) Airway epithelium rests on spiral bands of smooth muscle
- C) Lung is innervated by ANS of the PNS
- D) CNS main control respiratory center
A) Amount of cartilage increases down the respiratory system
Rationale: The amount of cartilage actually decreases as you move down the respiratory system. The trachea and bronchi have significant cartilaginous support, while the bronchioles do not.
- Which statement is true?
- A) Fibroblasts are alveolar cells
- B) Collagen in the lung limits lung distensibility
- C) Elastin induces lung collapse
- D) Lymphoid structures in the alveolar spaces are organized
B. Collagen in the lung limits lung distensibility.
Explanation of Choices:
A. Fibroblasts are Alveolar Cells:
• Explanation: Fibroblasts are not alveolar cells. Alveolar cells primarily consist of two types: Type I pneumocytes (involved in gas exchange) and Type II pneumocytes (secrete surfactant). Fibroblasts are connective tissue cells that produce extracellular matrix components such as collagen and elastin, but they are not classified as alveolar cells.
B. Collagen in the Lung Limits Lung Distensibility:
• Explanation: This statement is true. Collagen fibers provide structural support and limit the extent to which the lung can expand. They help maintain the shape and integrity of the lung tissue but reduce its distensibility (ability to stretch).
C. Elastin Induces Lung Collapse:
• Explanation: Elastin fibers provide the lungs with elasticity, allowing them to return to their original shape after being stretched or expanded. While they contribute to the recoil of the lung, they do not induce lung collapse. Instead, they help the lung return to its resting state after inhalation.
D. Lymphoid Structures in the Alveolar Spaces are Organized:
• Explanation: Lymphoid structures, such as lymph nodes and lymphoid tissue, are typically organized in specific areas like the hilum of the lung, not within the alveolar spaces. The alveolar spaces are primarily involved in gas exchange and do not contain organized lymphoid structures.
Summary:
• Fibroblasts are Alveolar Cells (A): Incorrect, fibroblasts are connective tissue cells, not alveolar cells. • Collagen in the Lung Limits Lung Distensibility (B): Correct, collagen fibers provide structural support and limit the extent of lung expansion. • Elastin Induces Lung Collapse (C): Incorrect, elastin contributes to lung recoil but does not induce collapse. • Lymphoid Structures in the Alveolar Spaces are Organized (D): Incorrect, lymphoid structures are not typically organized within the alveolar spaces.
- What is not a physiological effect of Surfactants?
- A) Reduces the work of breathing by reducing surface tension
- B) Stabilizes alveoli those that tend to deflate at high surface tension
- C) Prevents collapse and sticking of alveoli
- D) Decreases surface tension
B. Stabilizes alveoli those that tend to deflate at high surface tension.
Explanation:
A. Reduces the Work of Breathing by Reducing Surface Tension:
• Explanation: True. Surfactant reduces the surface tension of the fluid lining the alveoli, decreasing the effort required to expand the lungs during inhalation.
B. Stabilizes Alveoli Those that Tend to Deflate at High Surface Tension:
• Explanation: Incorrect statement as given. Surfactant stabilizes alveoli that tend to collapse at low surface tension, not high surface tension. Smaller alveoli would collapse more easily without surfactant, which reduces surface tension more in smaller alveoli, helping to keep them open.
C. Prevents Collapse and Sticking of Alveoli:
• Explanation: True. Surfactant helps prevent the alveoli from collapsing and sticking together by reducing surface tension, particularly during exhalation when the alveolar volume is low.
D. Decreases Surface Tension:
• Explanation: True. This is the primary function of surfactant, to decrease the surface tension of the alveolar lining fluid, thereby preventing alveolar collapse and reducing the work of breathing.
Summary:
• Reduces the Work of Breathing by Reducing Surface Tension (A): True, surfactant decreases the effort needed to expand the lungs. • Stabilizes Alveoli Those that Tend to Deflate at High Surface Tension (B): Incorrect, the correct mechanism is stabilizing alveoli at low surface tension. • Prevents Collapse and Sticking of Alveoli (C): True, surfactant helps keep alveoli open and prevents them from sticking together. • Decreases Surface Tension (D): True, this is the fundamental action of surfactant.
- What alveolar epithelial cell, which is known as a brush cell and functions as chemoreceptors?
- A) Type 1
- B) Type 3
- C) Type 2
- D) Type 4
B) Type 3
Rationale: Type 3 alveolar cells, also known as brush cells, function as chemoreceptors in the lung.
- What type of pneumocyte is primarily responsible for gas exchange?
- A) Type 1
- B) Type 2
- C) Type 4
- D) Type 3
A) Type 1
Rationale: Type 1 pneumocytes are thin cells that cover the majority of the alveolar surface and are primarily responsible for gas exchange due to their extensive surface area and thin structure.
- What is the most common cause of hypoxemia?
- A) Pneumonia
- B) V/Q Mismatch
- C) Pulmonary embolism
- D) COPD
B. V/Q Mismatch.
Explanation:
A. Pneumonia:
• Explanation: Pneumonia can cause hypoxemia by filling alveoli with fluid or pus, which impairs gas exchange. However, it is not the most common cause of hypoxemia across all patient populations.
B. V/Q Mismatch:
• Explanation: Ventilation-perfusion (V/Q) mismatch is the most common cause of hypoxemia. It occurs when the air reaching the alveoli (ventilation) does not match the blood flow (perfusion) in the pulmonary capillaries. This imbalance can significantly impair gas exchange, leading to hypoxemia. • Mechanism: • High V/Q Ratio: Areas of the lung receive adequate ventilation but have reduced blood flow (e.g., pulmonary embolism). • Low V/Q Ratio: Areas of the lung have adequate blood flow but are poorly ventilated (e.g., chronic obstructive pulmonary disease, asthma, atelectasis).
C. Pulmonary Embolism:
• Explanation: Pulmonary embolism can cause hypoxemia by blocking blood flow to parts of the lung, creating areas of high V/Q ratio. While it can be a significant cause of hypoxemia in affected individuals, it is not the most common cause overall.
D. COPD:
• Explanation: Chronic obstructive pulmonary disease (COPD) can cause hypoxemia through mechanisms such as airway obstruction and destruction of alveolar-capillary units. However, the underlying cause in COPD often involves a combination of factors, including V/Q mismatch.
Discussion on V/Q Mismatch:
V/Q Mismatch:
• Definition: The mismatch between ventilation (V) and perfusion (Q) in the lungs. • Normal V/Q Ratio: The normal V/Q ratio is approximately 0.8, indicating a balance between air reaching the alveoli and blood flow in the pulmonary capillaries. • Types of V/Q Mismatch: • High V/Q Ratio: Adequate ventilation but poor perfusion. Commonly seen in conditions like pulmonary embolism. • Low V/Q Ratio: Poor ventilation but adequate perfusion. Commonly seen in conditions like asthma, chronic bronchitis, and pulmonary edema.
Mechanisms Leading to Hypoxemia:
1. Shunt: A situation where blood passes through the lungs without being oxygenated, such as in pneumonia or atelectasis. 2. Dead Space: Ventilated areas that are not perfused, seen in pulmonary embolism. 3. Diffusion Limitation: Conditions that impair the diffusion of oxygen across the alveolar membrane, such as interstitial lung disease.
Clinical Implications:
• Diagnosis: V/Q mismatch can be identified using imaging techniques like V/Q scan or through arterial blood gas analysis. • Management: Treatment depends on the underlying cause and may include oxygen therapy, medications to improve ventilation or perfusion, and addressing the specific condition causing the mismatch.
Summary:
• Pneumonia (A): Can cause hypoxemia but not the most common cause. • V/Q Mismatch (B): Most common cause of hypoxemia due to imbalance in ventilation and perfusion. • Pulmonary Embolism (C): Significant cause but not the most common overall. • COPD (D): Can cause hypoxemia, often through V/Q mismatch and other mechanisms.
- What causes the decrease in ventilation which V/Q ratio to decrease?
- A) Pulmonary embolism
- B) Pulmonary edema
- C) End-stage COPD
- D) Decrease cardiac output
B) Pulmonary edema
Rationale: Pulmonary edema leads to fluid accumulation in the alveoli, which impairs gas exchange and decreases ventilation, thereby decreasing the V/Q ratio.
Discussion on V/Q Mismatch:
V/Q Mismatch:
• Definition: The mismatch between ventilation (V) and perfusion (Q) in the lungs. • Normal V/Q Ratio: The normal V/Q ratio is approximately 0.8, indicating a balance between air reaching the alveoli and blood flow in the pulmonary capillaries. • Types of V/Q Mismatch: • High V/Q Ratio: Adequate ventilation but poor perfusion. Commonly seen in conditions like pulmonary embolism. • Low V/Q Ratio: Poor ventilation but adequate perfusion. Commonly seen in conditions like asthma, chronic bronchitis, and pulmonary edema.
Mechanisms Leading to Hypoxemia:
1. Shunt: A situation where blood passes through the lungs without being oxygenated, such as in pneumonia or atelectasis. 2. Dead Space: Ventilated areas that are not perfused, seen in pulmonary embolism. 3. Diffusion Limitation: Conditions that impair the diffusion of oxygen across the alveolar membrane, such as interstitial lung disease.
- What causes a decrease in perfusion resulting in an increase in the V/Q ratio?
- A) Bronchial Asthma
- B) COPD
- C) Increase in physiologic dead space
- D) Pulmonary edema
C) Increase in physiologic dead space
Rationale: An increase in physiologic dead space means that areas of the lung are ventilated but not perfused, leading to a higher V/Q ratio.
- A V/Q ratio of 0.8 means?
- A) V/Q ratio is increased
- B) V/Q ratio is decreased
- C) V/Q ratio is greatly decreased
- D) V/Q ratio is within limits
D) V/Q ratio is within limits
Rationale: A V/Q ratio of 0.8 is considered to be within normal physiological limits, indicating that ventilation and perfusion are adequately matched for effective gas exchange.
