Respiratory System

Respiratory System Study Guide with Answers

Chapter 16: Respiratory System

Topic 1: Respiratory System Structure and Function (16.1-16.2)

Parts of the Respiratory System

Each part plays a role in breathing and gas exchange:

• Nose: Filters, moistens, and warms incoming air.

• Nasal Cavity: Lined with mucous membranes and cilia to trap dust and microbes.

• Epiglottis: A flap that prevents food from entering the trachea during swallowing.

• Pharynx (3 parts):

• Nasopharynx (upper part) - air passage.

• Oropharynx (middle part) - passage for food and air.

• Laryngopharynx (lower part) - directs food to the esophagus and air to the larynx.

• Larynx (Voice Box): Contains vocal cords and helps produce sound.

• Trachea (Windpipe): A tube that connects the larynx to the bronchi, reinforced with cartilage.

• Lungs: Main organs of respiration; contain alveoli where gas exchange occurs.

• Bronchi: Large airways branching from the trachea into each lung.

• Bronchioles: Smaller branches of the bronchi that lead to alveoli.

• Alveoli: Tiny air sacs where oxygen and carbon dioxide are exchanged with blood.

• Diaphragm: A muscle that contracts and relaxes to facilitate breathing.

• Capillaries: Small blood vessels surrounding alveoli for gas exchange.

Sinuses

Sinuses lighten the skull and help humidify and warm the air.

• Frontal Sinus: Located in the forehead.

• Maxillary Sinus: Found in the cheeks.

• Ethmoid Sinus: Located between the eyes.

• Sphenoid Sinus: Located behind the nasal cavity.

Tissues in the Respiratory System

• Trachea: Lined with pseudostratified ciliated columnar epithelium; contains goblet cells that produce mucus.

• Capillaries: Composed of simple squamous epithelium to allow rapid gas exchange.

• Alveoli: Lined with simple squamous epithelium for efficient oxygen and carbon dioxide exchange.

• Bronchi: Contain cartilage for support, lined with ciliated epithelium.

• Lungs: Made of alveolar tissue, elastic fibers, and capillaries for gas exchange.

Airflow Pathway

1. Nose/Mouth → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli (Gas exchange occurs) → Reverse path for exhalation.

Topic 2: Mechanism and Control of Breathing (16.3-16.4)

• Boyle’s Law and Airflow: Boyle’s Law states that pressure and volume are inversely related. When the thoracic cavity expands (inhalation), volume increases and pressure decreases, allowing air to flow in. When it contracts (exhalation), volume decreases and pressure increases, forcing air out.

• Thoracic Cavity Changes During Breathing:

• Inhalation: Diaphragm contracts and moves downward, intercostal muscles expand the rib cage, increasing lung volume.

• Exhalation: Diaphragm relaxes and moves upward, intercostal muscles contract, reducing lung volume.

• Lung Volumes and Capacities:

• Tidal Volume (TV): Air exchanged during a normal breath (~500 mL).

• Expiratory Reserve Volume (ERV): Extra air that can be exhaled after normal exhalation (~1200 mL).

• Vital Capacity (VC): Maximum air that can be exhaled after a deep breath (~4800 mL).

• Inspiratory Reserve Volume (IRV): Extra air inhaled after normal inhalation (~3100 mL).

• Residual Volume (RV): Air remaining in lungs after forced exhalation (~1200 mL).

• Respiratory Control Centers: Located in the medulla oblongata and pons, which regulate breathing rate and depth based on CO₂ and O₂ levels.

Topic 3: Gas Exchange (16.5)

• pO₂, pCO₂, and Gas Exchange:

• pO₂ (Partial pressure of oxygen): Higher in alveoli, so oxygen diffuses into the blood.

• pCO₂ (Partial pressure of carbon dioxide): Higher in blood, so CO₂ diffuses into the alveoli for exhalation.

• Transport Mechanisms in Gas Exchange:

• Oxygen Transport:

• 98% bound to hemoglobin in red blood cells (as oxyhemoglobin).

• 2% dissolved in plasma.

• Carbon Dioxide Transport:

• 70% transported as bicarbonate ions (HCO₃⁻).

• 20% bound to hemoglobin (as carbaminohemoglobin).

• 10% dissolved in plasma.

• Hemoglobin and Gas Transport:

• Oxyhemoglobin (HbO₂): Hemoglobin bound to oxygen in oxygen-rich conditions (lungs).

• Carbaminohemoglobin (HbCO₂): Hemoglobin bound to CO₂ in CO₂-rich conditions (tissues).

• Factors Affecting Hemoglobin’s Affinity for Oxygen:

• Higher pO₂ = Stronger O₂ binding (lungs).

• Higher pCO₂, temperature, or acidity = Weaker O₂ binding (tissues), promoting oxygen release.

• Bohr Effect (pH and Gas Exchange):

• Lower pH (more acidic, from CO₂ accumulation) causes hemoglobin to release oxygen more easily.

• Higher pH (less CO₂) strengthens O₂ binding to hemoglobin.

Topic 4: Diagrams

Be able to label the following:

1. Respiratory System Structures:

• Nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, diaphragm, lungs.

2. Respiratory Air Volumes and Capacities:

• Tidal Volume (TV), Expiratory Reserve Volume (ERV), Inspiratory Reserve Volume (IRV), Vital Capacity (VC), Residual Volume (RV).

Quick Summary:

• Air Pathway: Nose → Alveoli

• Boyle’s Law: More lung volume = lower pressure (air in); Less volume = higher pressure (air out).

• Lung Volumes: VC = IRV + TV + ERV; RV always remains.

• Gas Exchange: Oxygen in, CO₂ out; driven by partial pressures.

• Hemoglobin: Carries O₂ (as oxyhemoglobin) and CO₂ (as carbaminohemoglobin).

• Bohr Effect: Lower pH = more O₂ release; Higher pH = stronger O₂ binding.