Guided reading 7

What is the major function of the lungs?

Ventilate the alveoli, diffuse gases into and out of the blood, and perfuse the lungs so the organs and tissues receive oxygen-rich

What are the main functions of the upper airway?

Warm, humidify, and filter inspired air

- Protect lower airways by trapping particles and preventing aspiration via the epiglottis

- Nose, mouth, pharynx, epiglottis, larynx, and trachea

What are the three major roles of the conducting airways?

1. Passageway for air to move between the environment and alveoli.

2. Filter, warm, and humidify inspired air.

3. Distribute air evenly to gas-exchange areas.

Explain the 'trachea as a cylindric tube.

A cylindric tube supported by U-shaped cartilages that keep it open while allowing the esophagus to expand during swallowing

What is the purpose of the trachea?

It conducts air from the larynx to the bronchi

Describe how the trachea branches out into the lungs.

It bifurcates at the Carina into the right and left mainstem bronchi

What are the anatomical differences between the right and the left bronchi?

- Right main bronchus: shorter, wider, and straighter → more prone to aspiration

- Left main bronchus: longer and more angled

Why is it so important to anatomically locate the Carina?

Located at the Angle of Louis

- It is extremely sensitive

- Stimulation during suctioning causes vigorous coughing

What is the role of the mucociliary clearance system?

Traps and moves mucus with debris and microorganisms up toward the pharynx to be swallowed or coughed out

How does the role in inflammation and the release of biochemical mediators impact intrinsic protection of the lungs?

Inflammation releases biochemical mediators that can cause broncho constriction and airway edema, impacting airway defense and contributing to diseases like asthma

- Biochemical Mediators: histamine or leukotrienes

How do the bronchioles react with infection, irritation, and irritants?

It reacts with inflammation, swelling, and mucus production and narrowed airways

What manifestations would a patient present with, when bronchioles 'become full of mucous, pus, or respond to an allergen/ antigen/ foreign environmental substance like cigarette smoke?

- Wheezing

- Dyspnea

- Cough

- Mucus/Pus Production

- Chest tightness

Are ciliated bronchioles found below the level of the respiratory bronchioles?

They are NOT found below the respiratory bronchioles

What immune defense does the lungs 'use' when a bacterium, virus, antigen, fungus 'reaches' the alveolar?

Alveolar Macrophages

- It phagocytize bacteria, viruses, fungi, and debris

Discuss the respiratory unit of the lungs

It includes respiratory bronchioles, alveolar ducts, and alveoli

Where does gas exchange occur?

Occurs across the alveolar-capillary membrane

Compare/ contrast type I and type Il alveoli cells

Type I alveolar cells: Provide Structure

Type II alveolar cells: Secrete surfactant, reducing surface tension to prevent alveolar collapse

Compare: Epithelial cells that line the alveoli, form part of the alveolar-capillary membrane, and essential for proper lung function and gas exchange

Pulmonary Circulation

Responsible for moving blood between the heart and the lungs to allow for gas exchange

Compare and contrast the function of the pulmonary artery and the pulmonary veins

- Pulmonary artery: carries deoxygenated blood from the right ventricle to the lungs

- Pulmonary vein: carries oxygenated blood from the lungs back to the left atrium

- Compare: Both are part of the pulmonary circulation, essential for gas exchange and maintaining oxygen and CO₂ balance, and connect directly with the lungs and heart

How do pleural effusions occur?

Accumulation of fluid in the pleural space, often due to inflammation, infection, or increased capillary permeability

Anatomical membranes of the chest wall and the

pleura?

- Visceral Pleura: covers the lungs

- Parietal Pleura: lines the chest wall

- The Pleural Space: which contains lubricating fluid for smooth expansion

What patients are most at risk for developing pleural effusions?

Patients with pneumonia, heart failure, infection, or malignancy

ventilation

Moving air in and out of the airway (lungs)

- Mechanical Process

Respiration

Gas exchange (O₂ and CO₂) during cellular metabolism

- Use of oxygen to make energy aerobically

Perfusion

Movement of oxygenated blood through pulmonary circulation to tissues

- Supplies oxygen to blood and organs through blood vessels

Central Chemoreceptors

Responds to changes in pH and CO₂ levels in the cerebrospinal fluid

- Located near the respiratory center in the medulla

Peripheral Chemoreceptors

Respond primarily to low oxygen (PaO₂), but also pH and CO₂

- Stimulate ventilation when arterial O₂ drops (hypoxemia)

- Located in the aortic arch and carotid bodies

Compare function and role of the central chemoreceptors and the peripheral chemoreceptors

- Monitor blood gases (CO₂, O₂, and pH) to regulate breathing

- Send signals to the respiratory center in the brainstem to adjust ventilation

- Help maintain homeostasis by keeping oxygen, carbon dioxide, and pH within normal ranges

Mechanics of respirations: Mechanics of breathing

1. Muscles of inspiration and expiration

2. Elastic properties of the lungs and chest wall

3. Airway resistance

Mechanics of respirations: Inspiration and Expiration

Inspiration: The diaphragm contracts and flattens which increases thoracic volume and creates negative pressure allowing air to flow in

- The external intercostals elevate the ribs, expanding the chest cavity

- Accessory muscles used when effort is increased (sternocleidomastoid and scalene muscles)

- Expiration: Normally passive — due to elastic recoil of the lungs

What is meant by the phrase, 'increased work of breathing'?

It means more muscular effort (and oxygen/energy use) is required to ventilate the lungs.

- Occurs when Lung compliance is decreased, Chest wall compliance is decreased, and Airways are obstructed

What are the major museles of inspiration and what are the accessory muscles of inspiration?

Major: Diaphragm and External Intercostals

Accessory muscles of inspiration: Sternocleidomastoid and Scalene Muscles