38 Questions
What is the consequence of having high ventilation but low perfusion in the lung?
Increased dead space
Which of the following describes a reason for nonuniform ventilation of the alveoli?
Different metabolic demands in different lung regions
What is the purpose of the shunt equation in understanding pulmonary physiology?
To quantify the amount of blood bypassing the lungs
How does physiologic dead space affect gas exchange in the lungs?
It decreases alveolar ventilation
Which statement accurately summarizes regional differences in ventilation and perfusion?
V/Q ratios vary across different lung regions
How do V/Q ratios relate to gravity in the lungs?
V/Q ratios are highest at the lung's apex due to gravity
What influences mixed venous blood to bring CO2 into the lungs and take up alveolar O2?
Both neural and humoral/chemical regulation
Which of the following is a pulmonary vasoconstrictor that increases pulmonary vascular resistance (PVR)?
Histamine
What effect does sympathetic innervation have on pulmonary vascular resistance (PVR)?
Increases PVR
Which chemical is known to produce vasodilation in the pulmonary vasculature?
Acetylcholine
What intrinsic autoregulation mechanism produces vasoconstriction in the pulmonary vasculature?
Hypoxic pulmonary vasoconstriction
How does parasympathetic innervation affect the pulmonary vasculature?
Causes vasodilation
What is the impact on the V/Q ratio when the airway is occluded, preventing ventilation?
V/Q = 0
What does a shunt in the context of gas exchange refer to?
Allows blood to reach the arterial system without passing through ventilated lung regions
How does a pulmonary embolus affect the V/Q ratio?
V/Q increases
What happens if there is matched ventilation and perfusion at the alveolar-capillary unit?
Optimal gas exchange
What is the impact of an intrapulmonary shunt on alveoli?
Alveoli are underventilated or overperfused
How are small shunts typically identified?
By measuring partial pressures during 100% inspired oxygen
What can cause nonuniform ventilation of the alveoli?
Bronchoconstriction
What is one cause of nonuniform ventilation due to obstruction according to the text?
Decreased lumen
How can one assess the distribution of inspired gas in the lungs?
Lung scans after IV administration of dissolved Xe
What may lead to nonuniform compliance in different lung regions?
Regional variations in surfactant production
What is the physiological shunt equal to?
Physiological dead space
What does a pathological right-to-left intracardiac shunt involve?
An abnormal passage between the right and left sides of the heart
What is the equation to calculate venous admixture in the context of shunting?
Shunt equation
Supplemental oxygen will not improve which type of shunt?
Absolute intrapulmonary shunt
Intrapulmonary shunts are associated with which of the following?
Collapsed alveoli
What does increased arterial-alveolar CO2 difference indicate?
An increase in physiological dead space
What is the primary cause of a normal (A-a) DO2?
Ventilation-perfusion mismatch
Which regions of the lung have high VA/Q ratios?
"Apical regions"
Absolute intrapulmonary shunts are also known as 'true shunts' and can be improved with supplemental oxygen.
False
Physiological shunt corresponds to anatomic dead space in the lungs.
False
Anatomic shunts include venous blood from bronchial, thebesian, and pleural veins entering the left ventricle without passing through pulmonary capillaries.
True
Absolute intrapulmonary shunts are associated with well-ventilated alveoli.
False
What is the key feature of an anatomic shunt?
Blood from pleural veins entering the left ventricle without passing through pulmonary capillaries
How do absolute intrapulmonary shunts differ from shunt-like states?
Absolute shunts cannot be improved with supplemental oxygen, while shunt-like states can
What does the shunt equation conceptually divide all alveolar-capillary units into?
Well-ventilated and poorly ventilated units
Which is a pathologic characteristic of the pulmonary vasculature that may contribute to nonuniform ventilation of the alveoli?
Compression by tumors causing regional compliance issues
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
