Respiratory System – SPMD-2210 Lecture

75 question-and-answer flashcards covering definitions, structures, mechanisms, gas laws, respiratory volumes, control of breathing, and gas transport based on the November 8, 2024 Human Anatomy & Physiology lecture transcription.

What is respiration in human physiology?

The process of exchanging gases between the atmosphere and body cells so oxygen can be used to produce energy and carbon dioxide is removed.

Name the three major events that make up respiration.

External respiration (ventilation), internal respiration (gas transport & exchange with body cells), and cellular respiration (ATP production in mitochondria).

What occurs during external respiration?

Ventilation or breathing that allows gas exchange in the lungs.

What occurs during internal respiration?

Transport of gases in the blood and exchange of those gases with body cells.

What occurs during cellular respiration?

Mitochondria use oxygen to produce ATP and release carbon dioxide as a by-product.

List the organs of the upper respiratory tract.

Nose, nasal cavity, sinuses, pharynx, and larynx.

List the organs of the lower respiratory tract.

Trachea, bronchial tree, and lungs.

Which openings allow air to enter and leave the nasal cavity?

The nostrils (external nares).

What is the function of the nasal conchae?

They curl in from the lateral walls of the nasal cavity to increase surface area and help warm, moisten, and filter incoming air.

What type of epithelium lines the nasal mucous membrane?

Pseudostratified ciliated epithelium.

What is the role of goblet cells in the respiratory mucosa?

They produce mucus that traps dust and pathogens.

How do cilia within the respiratory tract help prevent infection?

They sweep mucus toward the pharynx where it is swallowed and destroyed in the stomach.

Name the four bones that contain paranasal sinuses.

Maxillary, frontal, ethmoid, and sphenoid bones.

Give two functions of the paranasal sinuses.

They reduce skull weight and act as resonance chambers for the voice.

How does cigarette smoking affect respiratory cilia?

Smoking slows and eventually paralyzes cilia, preventing removal of dirt and pathogens from the airways.

What causes "smoker’s cough"?

Loss of ciliary function leads to excess mucus that must be coughed up to clear the airway.

Name the three regions of the pharynx.

Nasopharynx, oropharynx, and laryngopharynx.

State two functions of the pharynx.

Serves as a passageway for food and air and aids in sound production.

Which laryngeal cartilage is commonly called the Adam’s apple?

The thyroid cartilage.

What is the function of the epiglottis?

It acts as a flap that closes the larynx during swallowing to keep food out of the airways.

Differentiate between true and false vocal cords.

False (vestibular) vocal cords do not produce sound and help close the airway; true vocal cords vibrate to create vocal sounds.

What is the glottis?

The opening between the true vocal cords.

Why does the trachea contain C-shaped rings of cartilage?

To prevent tracheal collapse while allowing the esophagus to expand posteriorly.

State the approximate diameter and length of the trachea.

About 2.5 cm in diameter and 12.5 cm in length.

At what structure does the trachea divide into primary bronchi?

The carina as it enters the thoracic cavity.

Give the complete sequence of airway branches from trachea to alveoli.

Main (primary) bronchi → lobar (secondary) bronchi → segmental (tertiary) bronchi → intralobular bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli.

Which airways are the first to engage in gas exchange?

Respiratory bronchioles.

Where in the respiratory system does actual gas exchange occur?

Across the walls of the alveoli and surrounding capillaries.

How many lobes are in each lung?

Right lung has 3 lobes; left lung has 2 lobes.

Define the hilum of the lung.

A medial region where the bronchus and large blood vessels enter the lung.

Name the two layers of the pleura.

Visceral pleura (on lung surface) and parietal pleura (lining thoracic cavity).

What is the pleural cavity?

The potential space between the visceral and parietal pleura filled with serous fluid.

Define breathing (ventilation).

Movement of air into and out of the bronchial tree and alveoli.

What constitutes one respiratory cycle?

One inspiration followed by one expiration.

What is normal atmospheric pressure at sea level?

760 mm Hg.

State Dalton’s Law.

The total pressure of a gas mixture equals the sum of the partial pressures each gas would exert independently.

State Boyle’s Law as it applies to breathing.

Pressure and volume are inversely proportional; as thoracic volume increases, intrapulmonary pressure decreases, drawing air in.

Which muscles are primarily responsible for normal resting inspiration?

The diaphragm and external intercostal muscles.

Name three muscles used during forced (deep) inspiration.

Pectoralis minor, sternocleidomastoid, and scalenes.

Why is normal resting expiration considered passive?

It relies on elastic recoil of lung tissues and surface tension, not on active muscle contraction.

Which muscles contract during forced expiration?

Internal intercostal muscles and abdominal wall muscles.

Define tidal volume (TV).

The volume of air moved in or out of the lungs during one respiratory cycle (about 500 mL).

Define inspiratory reserve volume (IRV).

The maximum volume of air that can be inhaled after a normal inspiration (about 3,000 mL).

Define expiratory reserve volume (ERV).

The maximum volume of air that can be exhaled after a normal expiration (about 1,100 mL).

Define residual volume (RV).

The volume of air that remains in the lungs after maximum expiration (about 1,200 mL).

Give the equation for vital capacity (VC).

VC = TV + IRV + ERV (approximately 4,600 mL).

What is anatomic dead space?

Air that remains in conducting airways and never reaches the alveoli (≈150 mL per breath).

Provide the formula for minute ventilation (MV).

MV = tidal volume (TV) × respiratory rate (RR).

Give two examples of nonrespiratory air movements.

Coughing and sneezing (others include laughing and crying).

Where are the main respiratory control areas located?

In the brainstem—the medulla oblongata and the pons.

What is the role of the ventral respiratory group?

It sets the basic rhythm of breathing.

What is the role of the dorsal respiratory group?

It modifies the activity of the ventral group, influencing inspiratory drive.

How do the pontine respiratory groups influence breathing?

They help set the rhythm by limiting the duration of inspiration.

Which two chemical factors most strongly influence breathing rate and depth?

Partial pressure of CO₂ (Pco₂) and hydrogen-ion concentration (H⁺).

How do central chemoreceptors respond to high Pco₂ or high H⁺?

They stimulate increased alveolar ventilation to expel more CO₂.

What effect does stretching lung tissue have on inspiration?

It inhibits inspiration to prevent over-inflation (Hering-Breuer reflex).

During exercise, why does shortness of breath usually reflect cardiovascular rather than pulmonary limitation?

The heart may not circulate enough blood to meet tissue demand, while lungs typically maintain arterial Po₂ and Pco₂ during steady activity.

List the three layers that make up the respiratory membrane.

Alveolar wall (simple squamous epithelium), fused basement membranes, and capillary wall (simple squamous epithelium).

What is the function of type I alveolar cells?

They form the thin simple squamous epithelium for gas exchange.

What is the function of type II alveolar cells?

They secrete pulmonary surfactant to reduce surface tension in alveoli.

Name four factors that increase diffusion across the respiratory membrane.

Greater surface area, shorter diffusion distance, higher gas solubility, and a steeper partial-pressure gradient.

Approximately what percentage of transported oxygen is bound to hemoglobin?

About 98-99 %.

What is oxyhemoglobin?

A compound formed when oxygen binds reversibly to the iron in hemoglobin.

List four factors that promote the release of O₂ from hemoglobin.

Low Po₂, high Pco₂, increased acidity (low pH), and increased temperature.

Roughly what percentage of oxygen remains bound to hemoglobin in venous blood?

About 75 % remains bound.

State the three forms in which carbon dioxide is transported and their approximate percentages.

As bicarbonate ions (~70 %), bound to hemoglobin as carbaminohemoglobin (~23 %), and dissolved in plasma (~7 %).

Write the reversible reaction that forms bicarbonate ion from CO₂ and water.

CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻.

What is carbaminohemoglobin?

A compound formed when CO₂ binds to amino groups of hemoglobin.

Why is carbon monoxide (CO) so dangerous to humans?

CO binds hemoglobin with about 210 × greater affinity than O₂, preventing oxygen transport and leading to hypoxia.

What is the typical partial pressure of oxygen (Po₂) in alveolar air?

Approximately 104 mm Hg.

What is the typical partial pressure of carbon dioxide (Pco₂) in blood entering alveolar capillaries?

About 45 mm Hg.

How does pulmonary surfactant aid inspiration?

It lowers surface tension inside alveoli, preventing their collapse and making inflation easier.

How does decreased surface area of the respiratory membrane affect diffusion?

It decreases the rate of gas diffusion, impairing gas exchange.

Define physiologic dead space.

The total volume of air that does not participate in gas exchange; under healthy conditions it equals anatomic dead space.

What is the normal value for both anatomic and physiologic dead space in a healthy adult?

Approximately 150 mL per breath.

What purpose do alveolar pores serve?

They permit air to pass between adjacent alveoli, providing alternate pathways for ventilation.