Control of Respiratory Function Part I

Questions and Answers

What is the primary function of the conducting airways?

To transport air into and out of the lungs (correct)

To regulate lung volumes and capacities

To facilitate gas exchange

To absorb oxygen directly from the air

What does the mucociliary blanket primarily do?

It secretes large amounts of carbon dioxide

It helps in gas diffusion across the alveoli

It filters and traps dust, bacteria, and foreign bodies (correct)

It enhances lung elasticity

Which structure is NOT part of the conducting airways?

Nasal passages

Bronchi

Larynx

Alveoli (correct)

What effect does smoking have on ciliated cells in the conducting airways?

It paralyzes their motility Signup and view all the answers

Which of the following is a function of the conducting airways?

Warming and humidifying incoming air Signup and view all the answers

What is the primary function of the larynx during swallowing?

Preventing food from entering the trachea Signup and view all the answers

What primarily supports the walls of the trachea?

C-shaped rings of hyaline cartilage Signup and view all the answers

Which function is NOT performed by the lungs?

Producing digestive enzymes Signup and view all the answers

What composition primarily makes up the walls of bronchioles?

Smooth muscle and elastic fibers Signup and view all the answers

How does an increase in respiratory rate during a fever affect the lungs?

Increases withdrawal of moisture from mucosal surfaces Signup and view all the answers

What is the primary function of Type I cells in the alveoli?

Facilitate gas exchange Signup and view all the answers

How does surfactant prevent alveolar collapse?

By disrupting the forces creating surface tension Signup and view all the answers

Which of the following best describes the role of surfactant in the alveoli?

It stabilizes alveoli and helps distribute ventilation Signup and view all the answers

What would happen to alveoli without surfactant?

They would collapse due to high surface tension Signup and view all the answers

What effect does surfactant have on pulmonary edema?

It prevents excess water from entering the alveoli Signup and view all the answers

What is the primary reason carbon dioxide diffuses more rapidly than oxygen in the respiratory membrane?

CO2 is more soluble in the respiratory membrane Signup and view all the answers

What is a consequence of dead air space in the lungs?

Reduced efficiency of gas exchange Signup and view all the answers

Which statement is correct regarding shunt in pulmonary circulation?

It causes blood to bypass areas of the lung that are ventilated Signup and view all the answers

What is the typical normal value for the partial pressure of oxygen (PO2) in arterial blood?

80 mmHg or above Signup and view all the answers

How is most oxygen transported in the blood?

In combination with hemoglobin Signup and view all the answers

What is the primary function of pulmonary circulation?

To provide blood flow to the gas exchange portion of the lungs Signup and view all the answers

What determines lung compliance?

Elastin and collagen fibers, water content, and surface tension Signup and view all the answers

Which lung volume represents the amount of air that can be exhaled beyond normal tidal volume?

Expiratory reserve volume (ERV) Signup and view all the answers

What occurs during alveolar ventilation?

Air moves within the lungs for gas exchange Signup and view all the answers

What phenomenon leads to pulmonary hypertension in chronic lung disease?

Generalized hypoxia resulting in vasoconstriction Signup and view all the answers

Which of the following lung capacities includes the tidal volume?

Vital Capacity (VC) Signup and view all the answers

How does hypoxia affect blood vessels in the lungs?

It produces marked vasoconstriction Signup and view all the answers

What is NOT a part of pulmonary gas exchange?

Respiration Signup and view all the answers

What factor can decrease the efficiency of gas diffusion in the lungs?

Pulmonary edema increasing membrane thickness Signup and view all the answers

Which volume indicates the air remaining in the lungs after forced expiration?

Residual volume (RV) Signup and view all the answers

Study Notes

Anatomy & Physiology of the Respiratory System

The respiratory system includes air passages and lungs, divided into conducting airways and respiratory tissues.
Conducting airways consist of the nasal cavity, mouth, pharynx, larynx, trachea, bronchi, and bronchioles.

Conducting Airways Function

Air is warmed, filtered, and humidified within conducting airways.
Lined by epithelial cells including mucus-secreting cells and ciliated cells.
Mucociliary blanket traps dust and bacteria; cilia help clear lower airways.

Larynx Functions

Promotes speech through glottis control.
Protects lungs during swallowing by covering the larynx with the epiglottis.

Trachea and Bronchioles

Supported by C-shaped hyaline cartilage to prevent collapse during negative thoracic pressure.
Bronchioles lack cartilage, composed mainly of smooth muscle and elastic fibers.

Lung Functions

Gas exchange, angiotensin conversion, heparin production, and inactivation of vasoactive substances.

Alveolar Structures

Composed of Type I (for gas exchange) and Type II cells (produce surfactant).
Surfactant decreases surface tension, prevents alveolar collapse, stabilizes ventilation, and reduces pulmonary edema risk.

Ventilation Mechanics

Gas pressure inversely relates to volume; air moves from high to low pressure.
During inspiration, chest cavity increases in size, allowing air entry into lungs.

Lung Compliance

Refers to the ease of lung inflation, influenced by elastin, collagen, water content, and surface tension.
Diseases like pulmonary fibrosis result in reduced compliance.

Lung Volumes

Tidal Volume (TV): 500 ml of air exchanged during normal breathing.
Inspiratory Reserve Volume (IRV): additional 3100 ml possible inhalation.
Expiratory Reserve Volume (ERV): 1200 ml of additional exhalation.
Residual Volume (RV): 1200 ml remains post-exhalation.

Lung Capacities

Vital Capacity (VC) = IRV + TV + ERV.
Inspiratory Capacity (IC) = IRV + TV.
Functional Residual Capacity (FRC) = RV + ERV.
Total Lung Capacity: sum of all lung volumes.

Gas Exchange Processes

Gas exchange consists of ventilation, perfusion, and diffusion.
Effective gas exchange relies on matching alveolar ventilation with perfused pulmonary capillaries.

Ventilation Types

Pulmonary Ventilation: total air exchange between atmosphere and lung.
Alveolar Ventilation: specific to gas exchange regions of the lungs.

Perfusion Importance

Blood flow through pulmonary capillaries is crucial for gas exchange and filtration of toxins.
Blood flow distribution is influenced by gravity and body position.

Hypoxia Effects

Hypoxia causes vasoconstriction when alveolar oxygen levels drop below 60 mmHg.
Regional hypoxia diverts blood flow from obstructed areas, while generalized hypoxia can lead to pulmonary hypertension.

Diffusion Influencing Factors

Surface area for diffusion, membrane thickness, differences in gas partial pressure, and gas characteristics (e.g., CO2 diffuses rapidly due to greater solubility) affect diffusion efficacy.

Ventilation-Perfusion Matching

Efficiency in gas exchange requires proper matching of ventilation to perfusion.
Dead air space occurs when alveoli are ventilated but not perfused, and shunts happen when unventilated areas receive blood.

Oxygen and Carbon Dioxide Transport

Gases are transported as dissolved gases or bound to hemoglobin.
Normal arterial values: PO2 above 80 mmHg and PCO2 between 35 to 45 mmHg.
Increased alveolar gas partial pressure generally correlates with arterial pressure.

Oxygen Transport Forms

Primarily (98-99%) transported in chemical combination with hemoglobin.

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Description

This quiz covers the anatomy and physiology of the respiratory system, including the functions of the lungs, lung volumes and capacities, as well as the exchange and transport of gases. It is essential for understanding the respiratory system's structure and function in clinical practice.