Respiratory Physiology Quiz

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Questions and Answers

What primarily causes inhalation to occur?

Active engagement of accessory muscles

Expansion of the pleurae

Contraction of the diaphragm (correct)

Increased pressure in the thorax

Which muscles contribute to exhalation during normal quiet breathing?

External intercostals

Elastic recoil of chest wall and lungs (correct)

Diaphragm

Accessory muscles

What percentage of air entering the lungs during normal quiet breathing is contributed by the external intercostals?

50%

10%

25% (correct)

75%

What is the primary function of the pleural fluid?

To reduce friction and produce surface tension Signup and view all the answers

How does surface tension of alveolar fluid influence the lungs?

Prevents collapse of alveoli at exhalation Signup and view all the answers

Which statement accurately describes the lobes of the lungs?

The right lung has three lobes, while the left lung has two due to the cardiac notch. Signup and view all the answers

Which factor affects the rate of airflow during pulmonary ventilation?

Lung compliance Signup and view all the answers

What characterizes Type II alveolar cells?

They secrete alveolar fluid and contain microvilli. Signup and view all the answers

During forceful exhalation, which muscle contractions contribute actively to the process?

Accessory muscles and abdominal muscles Signup and view all the answers

What is the anatomical significance of the cardiac notch?

It makes the left lung approximately 10% smaller than the right lung. Signup and view all the answers

What results from increased airway resistance?

Decreased airflow Signup and view all the answers

What is the correct sequence of branching starting from terminal bronchioles?

Terminal bronchioles → respiratory bronchioles → alveolar ducts Signup and view all the answers

What happens to intrapulmonic pressure as lung volume increases during inhalation?

It decreases Signup and view all the answers

What is the partial pressure of carbon dioxide (PCO2) in the inhaled air?

0.3 mmHg Signup and view all the answers

Which gas is estimated to be 24 times more soluble than oxygen in blood?

Carbon dioxide Signup and view all the answers

During external respiration, when does oxygen diffusion stop?

When the PO2 of pulmonary capillary blood equals that of alveolar air Signup and view all the answers

What is the total pressure of gases in inhaled air?

760 mmHg Signup and view all the answers

Why does nitrogen dissolve in blood to a lesser extent compared to carbon dioxide?

Nitrogen is less soluble in blood Signup and view all the answers

What is the primary function of the conducting zone in the respiratory system?

Conducts air to the lungs Signup and view all the answers

Which part of the respiratory system is directly responsible for gas exchange?

Alveoli Signup and view all the answers

What structures are included in the upper respiratory system?

Nose and pharynx Signup and view all the answers

What is the purpose of the nasal conchae within the nasal cavity?

To filter and warm the air Signup and view all the answers

Which muscle action is primarily assisted by the pharynx during swallowing?

Contraction of skeletal muscles Signup and view all the answers

What structure closes off the glottis during swallowing?

Epiglottis Signup and view all the answers

What anatomical regions comprise the pharynx?

Nasopharynx, oropharynx, and laryngopharynx Signup and view all the answers

What is a hallmark feature of the cricoid cartilage?

Indicates a possible site for tracheotomy Signup and view all the answers

What is the primary function of the ventricular folds in the larynx?

To hold breath against pressure in the thoracic cavity Signup and view all the answers

How do the vocal folds create sound?

By vibrating when air flows between them Signup and view all the answers

What impact do androgens have on the vocal folds?

They make folds thicker and longer, affecting pitch Signup and view all the answers

What is the primary structural change in the bronchi as they branch out?

Incomplete cartilage rings become plates and disappear Signup and view all the answers

Where is the most sensitive area for triggering the cough reflex located?

At the carina of the trachea Signup and view all the answers

Which layer of the trachea is primarily responsible for its structural integrity?

Hyaline cartilage Signup and view all the answers

What role does the sympathetic autonomic nervous system (ANS) play in the bronchi?

It promotes relaxation and dilation Signup and view all the answers

What is the relationship between bronchial structure and the autonomic nervous system?

The parasympathetic system causes constriction while the sympathetic leads to dilation Signup and view all the answers

What is the formula for calculating minute ventilation (MV)?

MV = breaths/min x tidal volume Signup and view all the answers

What percentage of tidal volume typically reaches the respiratory zone in healthy adults?

70% Signup and view all the answers

Which of the following best defines vital capacity?

Tidal volume plus inspiratory and expiratory reserve volumes Signup and view all the answers

What does Dalton’s Law state about gases in a mixture?

Each gas contributes to total pressure based on its partial pressure. Signup and view all the answers

What is the function of anatomical (respiratory) dead space?

Conducts air but does not participate in gas exchange Signup and view all the answers

In respiratory physiology, what is the significance of the alveolar ventilation rate?

It indicates the volume of air actually reaching the respiratory zone per minute. Signup and view all the answers

Which volume of air is considered to be residual volume?

Air remaining in the lungs after a forceful exhalation Signup and view all the answers

What typically occurs to the rate of gas diffusion when the difference in partial pressures increases?

The rate of diffusion increases. Signup and view all the answers

Study Notes

Chapter 23: The Respiratory System

This chapter covers the anatomy and physiology of the respiratory system.
The structural components are categorized into upper and lower respiratory systems.
Upper respiratory system parts include the nose, pharynx, and associated structures.
Lower respiratory system parts include the larynx, trachea, bronchi, and lungs.
The functional components are categorized as conducting zone and respiratory zone.
Conducting zone components include the structures that transport air to the lungs (nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles).
Respiratory zone components are structures involved in gas exchange (respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli).

Nose

External nose - visible exterior portion of the nose.
Internal nose - large cavity beyond the nasal vestibule.
Internal nares (choanae) - Internal openings of the nasal cavity.
Ducts from paranasal sinuses and nasolacrimal ducts open into the nasal cavity.
Nasal cavity is divided by the nasal septum.
Nasal conchae subdivide the cavity into meatuses, increasing surface area and preventing dehydration.
Olfactory receptors are in the olfactory epithelium.

Pharynx

Starts at internal nares and extends to the cricoid cartilage of the larynx.
Skeletal muscle contraction during swallowing aids in deglutition.
Functions as a passageway for air and food.
It's a resonating chamber.
Tonsils are housed in the pharynx.
3 anatomical regions: nasopharynx, oropharynx, and laryngopharynx.

Larynx

Short passageway connecting the laryngopharynx to the trachea.
Composed of 9 pieces of cartilage.
Thyroid cartilage (Adam's apple).
Cricoid cartilage is essential for tracheotomy.
Epiglottis closes off the glottis during swallowing.
Glottis includes vocal folds (true vocal cords) and rima glottidis (space).
Cilia in the upper respiratory tract move mucus and particles downward toward the pharynx.
Cilia in the lower respiratory tract move mucus upward.

Structures of Voice Production

Mucous membranes (false vocal cords).
Function in holding breath against pressure in the thoracic cavity.
Vocal folds (true vocal cords).
Muscle contraction stretches vocal folds into the airway to create sound vibrations.
Androgens (male hormones) make folds thicker and longer, leading to lower pitch.

Trachea

Extends from the larynx to the superior border of T5.
Divides into the right and left primary bronchi.
4 layers: mucosa, submucosa, hyaline cartilage, adventitia.
16-20 C-shaped rings of hyaline cartilage.
Open part of the rings faces the esophagus.

Bronchi

Right and left primary bronchi lead to the right lung.
Carina is an internal ridge that triggers the cough reflex.
Branches of bronchi form a bronchial tree.
Structural changes occur with branching (Incomplete cartilage rings, plates, muscles).
Sympathetic nervous system dilates; parasympathetic constricts bronchioles.

Lungs

Separated by the heart and other mediastinum structures.
Each lung has a double-layered pleural membrane.
Parietal pleura lines the thoracic cavity wall.
Visceral pleura covers the lungs themselves.
Pleural fluid reduces the friction between layers.
Cardiac notch - heart makes the left lung slightly smaller than the right lung.

Alveoli

Cup-shaped outpouching, 2 or more alveoli sharing a common opening.
2 types of alveolar epithelial cells:
Type I alveolar cells form a nearly continuous lining, facilitating gas exchange (major).
Type II alveolar cells secrete alveolar fluid (surfactant), reducing the tendency of alveoli to collapse.

Respiratory Membrane

Alveolar wall (Type I and Type II alveolar cells).
Epithelial basement membrane.
Capillary basement membrane.
Capillary endothelium.
Thin structure facilitating gas diffusion.
Lungs receive blood from pulmonary arteries (deoxygenated) and bronchial arteries (oxygenated).

Pulmonary Ventilation

Respiration steps include pulmonary ventilation, external respiration, and internal respiration.
Pulmonary ventilation is inhalation and exhalation, moving air between the atmosphere and alveoli.
External respiration exchanges gases between alveoli and blood.
Internal respiration exchanges gases between systemic capillaries and tissue cells.

Inhalation

Pressure inside the alveoli must become lower than atmospheric pressure.
Achieved by increasing the size of the lungs (Boyle's law).
Diaphragm and external intercostals contract to increase lung volume and decrease pressure.

Exhalation

Pressure in the lungs is higher than atmospheric pressure.
Normally a passive process, muscles relax.
Elastic recoil of the chest wall and lungs, and surface tension of alveolar fluid is responsible for decreasing volume and increasing pressure.

Airflow

Air pressure difference drives airflow.
Factors affecting airflow include surface tension of alveolar fluid, lung compliance, and airway resistance.

Lung Volumes and Capacities

Minute ventilation (MV) - total volume of air inhaled and exhaled each minute (about 6 liters/minute in a healthy adult).
Tidal volume - volume of air moved in and out of the lungs during a single breath (about 500ml).

Exchange of Oxygen and Carbon Dioxide

Gases exert pressure in a mixture of gases as if no other gases are present (Dalton's Law).
Partial pressure of a gas is the pressure that gas exerts individually.
Total pressure is the sum of all partial pressures.
Gases diffuse down their pressure gradients.

Henry's Law

Quantity of gas dissolved in a liquid is proportional to the partial pressure of the gas and its solubility.

External Respiration

Oxygen diffuses from alveolar air (high partial pressure) into blood in pulmonary capillaries (low partial pressure).
Carbon dioxide diffuses from blood in pulmonary capillaries (high partial pressure) to alveolar air (low partial pressure).

Internal Respiration

Oxygen diffuses from systemic capillary blood into tissue cells (low partial pressure).
Carbon dioxide diffuses from tissue cells to systemic capillaries (high partial pressure).

Transport of Oxygen

Oxygen is mostly bound to hemoglobin (98.5%) inside red blood cells.
Hemoglobin's heme portion contains 4 iron atoms, each binding one oxygen molecule.
Oxyhemoglobin can release oxygen to cells.

Transport of Carbon Dioxide

CO2 is transported dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.
A majority of CO2 is transported as bicarbonate ions (about 70%).
Enzyme carbonic anhydrase forms carbonic acid (H2CO3), which dissociates into H+ and HCO3-.
The chloride shift moves chloride ions in and out of red blood cells to maintain ionic balance.

Relationship between Hemoglobin and Oxygen

Fully saturated hemoglobin combines to oxyhemoglobin.
Percent saturation represents the average oxygen saturation of hemoglobin.
Oxygen-hemoglobin dissociation curve shows the relationship between oxygen partial pressure and hemoglobin saturation.

Other Factors Affecting Hemoglobin Affinity for Oxygen

Factors affecting hemoglobin's affinity for oxygen include acidity (Bohr effect), partial pressure of carbon dioxide (Bohr effect), and temperature.

Bohr Effect

As acidity (pH) decreases, hemoglobin's affinity for oxygen decreases.
Increasing acidity (lower pH) enhances oxygen unloading from hemoglobin.
Increased PCO2 also shifts the oxyhemoglobin dissociation curve to the right and enhances oxygen unloading.

Temperature Changes Affecting Hemoglobin Oxygen Affinity

Higher temperatures decrease hemoglobin's affinity for oxygen, and unloading also promotes at higher temperatures.
During hypothermia (low temperature), hemoglobin's affinity for oxygen is increased, hindering oxygen unloading.
2,3-bisphosphoglycerate (BPG) formed by red blood cells during glycolysis helps unload oxygen by binding to hemoglobin.

Fetal and Maternal Hemoglobin

Fetal hemoglobin has a higher oxygen affinity than adult hemoglobin, facilitating the transfer of oxygen from maternal to fetal blood.

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Test your knowledge on the mechanics of breathing and lung anatomy with this quiz. Explore topics such as inhalation, exhalation, and the functions of various respiratory components. Ideal for students of physiology or anyone interested in respiratory health.