Podcast
Questions and Answers
What is the primary function of surfactant in the alveoli?
What is the primary function of surfactant in the alveoli?
Exhalation is an active process that requires energy.
Exhalation is an active process that requires energy.
False
Name two accessory muscles used during forced inhalation.
Name two accessory muscles used during forced inhalation.
Sternocleidomastoid and scalenes
The process of gas exchange that occurs between the intestinal fluid and the external environment is known as ______.
The process of gas exchange that occurs between the intestinal fluid and the external environment is known as ______.
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Match the type of respiratory resistance to its description:
Match the type of respiratory resistance to its description:
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Which of the following conditions can lead to reduced lung compliance?
Which of the following conditions can lead to reduced lung compliance?
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Airway resistance decreases as the airway size increases.
Airway resistance decreases as the airway size increases.
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What happens to the pressure in the lungs during exhalation?
What happens to the pressure in the lungs during exhalation?
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What is the primary function of Type 2 alveolar cells?
What is the primary function of Type 2 alveolar cells?
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The diaphragm increases lung volume during exhalation.
The diaphragm increases lung volume during exhalation.
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What is the exchange of gas from alveoli to blood called?
What is the exchange of gas from alveoli to blood called?
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Surfactant reduces ______ tension in the alveoli.
Surfactant reduces ______ tension in the alveoli.
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What causes air to move into the lungs?
What causes air to move into the lungs?
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Macrophages in the alveoli are responsible for gas exchange.
Macrophages in the alveoli are responsible for gas exchange.
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Match the following respiratory processes with their descriptions:
Match the following respiratory processes with their descriptions:
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What happens to alveolar pressure during quiet breathing?
What happens to alveolar pressure during quiet breathing?
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What is the primary difference between external and internal respiration?
What is the primary difference between external and internal respiration?
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Gas exchange occurs actively through the consumption of energy.
Gas exchange occurs actively through the consumption of energy.
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What is the partial pressure of oxygen (pO₂) in atmospheric air?
What is the partial pressure of oxygen (pO₂) in atmospheric air?
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Air is composed of ___________ oxygen, ___________ nitrogen, and ___________ carbon dioxide.
Air is composed of ___________ oxygen, ___________ nitrogen, and ___________ carbon dioxide.
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Which factor primarily drives the diffusion of gases during respiration?
Which factor primarily drives the diffusion of gases during respiration?
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Match the following types of chemoreceptors with their locations:
Match the following types of chemoreceptors with their locations:
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Expiration is primarily an active process that requires muscle contraction.
Expiration is primarily an active process that requires muscle contraction.
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What happens to the volume of the thorax during inspiration?
What happens to the volume of the thorax during inspiration?
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Study Notes
Respiratory System Overview
- The respiratory system's function is the uptake of O₂ and elimination of CO₂.
- It works in conjunction with the cardiovascular system to transport gases in the blood.
- Failure of either system can cause rapid cell death from O₂ starvation.
- Other functions include sound production, filtering of air, regulation of blood pH, and olfaction (sense of smell).
Session Overview
- Functions of the respiratory system
- Gross anatomy of lungs
- Classification of the respiratory system (nose, pharynx, larynx, bronchial tree)
- Respiratory membrane
- Events of respiration: Pulmonary Ventilation (pressure changes, quiet and labored breathing, factors affecting ventilation), Respiration (external and internal - gas exchange).
- Chemical regulation of breathing
Learning Outcomes
- Name the structures and describe the function of organs in the upper and lower respiratory system.
- List the component cells of the respiratory membrane and relate them to their function.
- Describe the difference between internal and external respiration.
Function
- The human respiratory system is designed to facilitate gas exchange.
- The function of the system involves the uptake of oxygen (O₂) and the expulsion of carbon dioxide (CO₂).
- This system is essential for maintaining homeostasis in the body and ensuring adequate cellular function.
- The respiratory system directly works with the circulatory system to transport the gases from the lungs to other body tissues.
Any Other Functions?
- Sound production
- Filtering of air
- Regulation of blood pH
- Olfaction (sense of smell)
Lungs
- Right lung has 3 lobes due to 2 fissures (oblique and horizontal).
- Left lung has 2 lobes due to an oblique fissure.
- The position of the heart affects the shape and size of the lungs.
- Blood vessels and airways enter the lungs at the hilum.
- Lungs are covered by pleura (double-layered serous membrane)
Pleural Cavity & Membranes
- The pleural cavity is lined by a double-layered serous membrane called the pleura.
- Visceral pleura covers the outer surface of the lungs.
- Parietal pleura covers the inner surface of the ribcage.
- This membrane produces a thin pleural fluid that helps the lungs glide smoothly during breathing.
- Conditions affecting the lungs include pleurisy (inflammation), pleural effusion (excess fluid), pneumothorax (air build-up), and hemothorax (blood build-up).
Double Blood Supply to the Lung
- Deoxygenated blood arrives through pulmonary arteries from the right ventricle.
- Bronchial arteries branch off the aorta to supply oxygenated blood to lung tissue.
- Alveolar capillaries are the primary source of angiotensin-converting enzyme (ACE) in the kidney.
Classification (Structural/Anatomical)
- Upper respiratory system: Nasal cavity, Pharynx
- Lower respiratory system: Larynx, Trachea, Bronchi, Lungs, Bronchioles, Alveoli
Classification (Functional)
- Conducting portion: Interconnecting tubes from the nose to the terminal bronchioles
- Respiratory portion: The site of gas exchange, specifically in the respiratory bronchioles and alveoli.
Nose - External Anatomy
- Bony framework (frontal, nasal, maxilla bones)
- Cartilaginous framework (lateral, nasal, septal, alar cartilages)
- Two openings called external nares (nostrils)
- Lined by mucous membrane
Nose - Internal Anatomy
- Nasal cavity
- Nasal meatuses
- Olfactory epithelium
Pre-sessional Task: Pharynx Worksheet
- Divisible into 3 sections: Nasopharynx, Oropharynx, Laryngopharynx.
- Functions as passageway for air and food/respiration and digestion.
- Connects nasal and oral cavities to the larynx and esophagus.
- Contains lymphoid tissues (adenoids and tonsils)
Larynx
- Allows unimpeded air passage to the lower respiratory portion.
- Composed of 9 pieces of cartilage.
- Epiglottis (leaf-shaped cartilage) covers the airway during swallowing.
- Thyroid cartilage (Adam's apple) - fused plates of hyaline cartilage, larger in males due to hormones.
- Cricoid cartilage is a ring of hyaline cartilage acting as a landmark for tracheotomy.
Trachea
- Hyaline cartilage rings (16-20) provide flexibility and open areas for esophagus.
- Contains trachealis muscle and elastic connective tissue to assist with coughing.
- Mucosa is pseudostratified columnar cells with cilia and goblet cells (produces mucus).
- Submucosa has loose connective tissue and seromucous glands.
Bronchi & Bronchioles
- Primary bronchi: Supply each lung.
- Secondary bronchi: Supply each lobe of the lungs (3 right, 2 left).
- Tertiary bronchi: Supply each bronchopulmonary segment.
- Bronchioles are further branching of the bronchi.
- Bronchial tree: Overall structure
Histology of Bronchial Tree
- Epithelium changes from ciliated pseudostratified columnar to non-ciliated simple cuboidal deeper into lungs.
- Incomplete rings are replaced by smooth muscle and connective tissue.
- Innervation by autonomic nerves (sympathetic, parasympathetic; bronchodilation and bronchoconstriction).
- Asthma attacks or allergic reactions constrict bronchial smooth muscle.
- Nebulizer therapy can relax smooth muscle and reduce mucus thickness.
Air Has Reached the Respiratory Portion
- Alveoli: The site of gas exchange.
- Alveolar ducts and sacs
- Respiratory membrane: Walls of alveoli & capillaries, for external respiration
Respiratory Membrane - Alveoli
- Vast surface area (70m²) from 300 million alveoli.
- Type 1 alveolar cells: Simple squamous cells for rapid gas exchange.
- Type 2 alveolar cells: Secrete surfactant that reduces surface tension to prevent alveolar collapse.
- Alveolar fluid: Balances surface tension with surfactant.
- Macrophages: Engulf and destroy debris.
Respiratory Membrane
- 0.5µm thick.
- Exchange of gas from alveoli to blood = external respiration.
- 4 layers: alveolar epithelial wall (Type I cells), alveolar epithelial basement membrane, capillary basement membrane, and endothelial cells of capillaries involved in the gas exchange during the breathing process
Main Function of Respiratory System
- Ventilation: physical movement of air into and out of the lungs via conducting airways.
- Respiration: transfer of gases across the respiratory membrane.
- Cellular respiration: Energy production from carbohydrates (glucose) using oxygen.
Events of Respiration (Pulmonary Ventilation)
- Moving air in and out of lungs.
- Governed by pressure changes (Changes in lung pressure relative to pressure in the air outside the body.) for inhalation and exhalation (breathing in and out).
Pressure Changes During Ventilation
- Volume changes create pressure gradients.
- If alveolar pressure = atmospheric pressure (760 mmHg), there is no air flow
Quiet Breathing
- Relies on diaphragm and external intercostal muscle movements.
- Exhalation is a passive process (elastic recoil, surfactant).
- Relaxing diaphragm increase pressure in lungs causing air to be pushed out of the lungs, via a process known as exhalation Important for understanding Normal Breathing Processes.
Forced/Labored Breathing
- Accessory muscles (e.g., sternocleidomastoid, scalene, internal/external intercostals and various abdominal muscles) aid in inhalation and assisted exhalation.
- Active process requiring use of various muscles involved during strenuous activities.
Factors Affecting Ventilation
- Surface tension of alveolar fluid
- Compliance of lungs
- Airway resistance
Alveolar Surface Tension
- Thin layer of fluid in alveoli causes inwardly directed force=surface tension
- H₂O molecules strongly attracted to each other
- Detergent-like surfactant produced by Type II alveolar cells, lowers surface tension to prevent alveoli from collapsing
- Important for normal breathing function.
Compliance of the Lungs
- Ease with which lungs and chest expand, reflecting flexibility and surface tension of lung tissue.
- High compliance: Expand easily
- Low compliance: Resist expansion
- Diseases like tuberculosis/pulmonary edema can reduce compliance.
Airway Resistance
- Resistance to airflow depends on airway size.
- Smaller airways: Increased resistance.
- Increase in chest size: Increase diameter, leading to decrease in resistance
- Relaxation of airway smooth muscle: Bronchodilation (expansion of air passageways).
Events of Respiration (External Respiration)
- Gas exchange between alveoli and blood.
Events of Respiration (Internal Respiration)
- Gas exchange between blood and systemic tissues/cells.
Gas Exchange: O₂ for CO₂
- Passive diffusion across the respiratory membrane.
- Dalton's Law: Each gas exerts its own pressure (partial pressure) and behaves independently.
- Total pressure: Sum of individual gas pressures.
- Gas exchange is driven by differences in partial pressures.
What is the Composition of Air?
- Air composition: 21% O₂, 79% N₂, 0.04% CO₂.
- Alveolar air composition: slightly different from air due to gas exchange.
- Expired air composition: slightly different from alveolar air due to anatomical dead space.
Chemical Regulation of Respiration
- Central chemoreceptors: Medulla neurons sensitive to changes in H+ or PCO2 in CSF.
- Peripheral chemoreceptors: Aortic arch and carotid artery neurons sensitive to changes in H+, PO2, or PCO2 in blood.
Negative Feedback Regulation of Respiration
- Inspiration active process.
- Diaphragm and external intercostal muscles contract increasing volume, lowering air pressure in lungs.
- Expiration.
- Passive process.
- relaxation of diaphragm and external intercostals Muscles decreases volume, increasing the air pressure in the lungs and pushes the air out of the lungs
What Else Affects Breathing?
- Pain
- Temperature
- Proprioceptors (receptors in muscles and joints)
- Limbic system (e.g., anticipation of activity)
- These factors, in addition to the chemical control mechanisms, regulate breathing patterns.
End
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Description
Test your knowledge on the functions and processes of the respiratory system with this quiz. Explore topics including surfactant functions, gas exchange, and lung mechanics. Perfect for students studying physiology or related fields.
