Chapter 23 - Respiratory System Flashcards

Chapter 23 - Respiratory System Checklist

Introduction

• Definition of Respiration: The process of gas exchange, involving inhalation of oxygen and exhalation of carbon dioxide.

24.1 Introduction to the Respiratory System

• Functions of the Respiratory System:

  • Gas exchange (oxygen and carbon dioxide).

  • Regulation of blood pH.

  • Protection against pathogens and irritants.

  • Olfactory sensation (smell).

  • Vocalization and sound production.

• Organs of the Upper Respiratory Tract:

  • Nose.

  • Nasal cavities.

  • Paranasal sinuses.

  • Pharynx.

  • Larynx.

• Organs of the Lower Respiratory Tract:

  • Trachea.

  • Bronchi.

  • Bronchioles.

  • Alveoli.

• Conducting Zone vs. Respiratory Zone:

  • Conducting Zone: Includes all the respiratory passages that filter, humidify, and warm the air (nose, trachea, bronchi, bronchioles).

  • Respiratory Zone: The site of gas exchange (alveoli).

• Types of Epithelium in the Respiratory Tract:

  • Ciliated pseudostratified columnar epithelium: Lines the upper respiratory tract and removes debris through ciliary action.

  • Simple squamous epithelium: Lines the alveoli, facilitating gas exchange.

23.2 Upper Respiratory Tract

• Functions of Upper Respiratory Components:

  • Nose: Entryway for air; filters and humidifies air.

  • Nasal Conchae: Increase surface area for air filtration and warming.

  • Paranasal Sinuses: Lighten the skull, add resonance to voice, and provide a buffer against trauma.

  • Pharynx: Passage for air and food, contains tonsils for immune response.

  • Larynx: Voice box; routes air and food; protects the trachea against food aspiration.

• Air Conditioning Process: WARMS, HUMIDIFIES, and FILTERS air to prevent damage to the lungs.

• Vocal Cords/Folds:

  • True Vocal Cords: Produce sound by vibration; involved in phonation.

  • False Vocal Cords: No role in sound production; protect true vocal cords.

• Sound Production in the Larynx:

  • Sound is produced when air passes through the vocal folds, causing them to vibrate.

  • Range: Determined by the length and tension of the vocal cords (longer cords produce lower pitch).

  • Pitch: Controlled by the tension of vocal cords (tightening raises pitch).

  • Loudness: Determined by the force of air (greater force increases volume).

• Differences in Male vs. Female Voice:

  • Males typically have longer and thicker vocal cords, producing deeper voices.

• Articulation in Speech:

  • Involves structures such as the tongue, lips, hard palate, and soft palate.

  • These structures modify sounds produced by the larynx to form speech.

• Effects of Laryngitis: Inflammation affects vocal cords' ability to vibrate, resulting in hoarseness or loss of voice.

23.3 Lower Respiratory Tract

• Functions of Lower Respiratory Components:

  • Trachea: Conducts air to the bronchi; contains cartilage rings for support.

  • Bronchi: Branches from the trachea into the lungs, conducting air and filtering it.

  • Bronchioles: Small branches leading to alveoli, regulating airflow through constriction and dilation.

  • Alveoli: Sites of gas exchange; increase surface area for efficient diffusion.

• Histology of Bronchi and Bronchioles:

  • The decrease in the amount of cartilage and increase in smooth muscle in bronchioles allows for greater control over airflow.

• Types of Cells in Alveoli:

  • Type I Alveolar Cells: Simple squamous epithelium facilitating gas exchange.

  • Type II Alveolar Cells: Secrete surfactant to reduce surface tension.

  • Alveolar Macrophages: Immune cells that remove pathogens and particles.

• Respiratory Membrane Makeup: Consists of alveolar epithelium, capillary endothelium, and a fused basement membrane, allowing efficient gas diffusion due to its thinness.

Organs in the Respiratory Passageway

• Descending Order until Alveoli:

  • Nose -> Nasal Cavity -> Pharynx -> Larynx -> Trachea -> Bronchi -> Bronchioles -> Alveoli.

23.4 Lungs

• Tissue of the Lungs: Composed of elastic connective tissue, allowing for expansion and recoil during breathing.

• Pleurae: Double-layered membrane surrounding the lungs; consists of the parietal pleura (lines thoracic cavity) and visceral pleura (covers lungs).

• Inward and Outward Forces in Pulmonary Ventilation: The pleurae create negative pressure that keeps the lungs inflated.

• Intrapleural Pressure: The pressure within the pleural cavity, which is always negative relative to intrapulmonary pressure.

• Intrapulmonary Pressure: The pressure within the lungs that alternates with breathing; positive during expiration and negative during inspiration.

23.5 Respiration: Pulmonary Ventilation

• Definitions:

  • Inspiration: The process of inhaling air into the lungs.

  • Expiration: The process of exhaling air from the lungs.

  • Eupnea: Normal, unlabored breathing.

• Pressure in and around the Lungs:

  • Atmospheric pressure (Patm), Intrapulmonary pressure (Ppul), Intrapleural pressure (Pip).

• Process of Pulmonary Ventilation:

  • Involves the changes in air pressure resulting from volume changes in the thoracic cavity.

  • Sequential steps include:

  • Inhalation: Diaphragm contracts, thoracic volume increases, and Ppul decreases.

  • Exhalation: Diaphragm relaxes, thoracic volume decreases, and Ppul increases.

• Boyle’s Law: The relationship between pressure and volume of a gas at constant temperature: P imes V = k (Pressure multiplied by Volume is equal to a constant).

• Pressure Gradients: Refers to the difference in pressure that drives air movement into and out of the lungs.

• Muscles involved in Breathing:

  • Quiet Inspiration: Diaphragm and external intercostal muscles.

  • Forced Inspiration: Accessory muscles (sternocleidomastoid, scalenes).

  • Quiet Expiration: Passive process (relaxation of respiratory muscles).

  • Forced Expiration: Abdominal and internal intercostal muscles.

• Overall Changes in Forced Breathing: Increased force and volume of air moved during high-demand situations.

• Roles of Respiratory Muscles and Lung Elasticity: The diaphragm and intercostal muscles create volume changes, while the elastic properties of the lungs assist in passive expiration.

23.5c Nervous Control of Breathing

• Connection to respiratory muscles and their control via nervous stimuli.

• Physical Factors Influencing Pulmonary Ventilation:

  • Pressure Gradients: A higher pressure differential increases airflow.

  • Bronchoconstriction: Narrowing of airways, reducing airflow, influenced by parasympathetic stimulation.

  • Bronchodilation: Widening of airways, increasing airflow, stimulated by sympathetic fibers.

  • Factors causing variations include allergens, pollutants, or physical activity.

  • Surfactant Importance: Reduces alveolar surface tension; a lack leads to alveolar collapse and impaired gas exchange.

  • Compliance Definition: The ability of the lungs to stretch; influenced by elasticity and surface tension.

  • Resistance: Obstructed airflow due to diseases increases energy expenditure.

23.6 Respiration: Pulmonary and Tissue Gas Exchange

• Differentiation between Pulmonary and Tissue Gas Exchange:

  • Pulmonary Gas Exchange: Gaseous exchange in the alveoli and pulmonary capillaries.

  • Tissue Gas Exchange: Gaseous exchange in systemic capillaries and body tissues.

• Gas Laws:

  • Dalton’s Law of Partial Pressures: The total pressure of a gas mixture equals the sum of the partial pressures of each gas in the mixture.

  • Henry’s Law: The amount of gas dissolved in a liquid is proportional to the partial pressure of that gas above the liquid.

• Individual Gases in Air: Major components include nitrogen (78%), oxygen (21%), and carbon dioxide (0.04%).

• Composition Differences: Atmospheric air vs. alveolar air due to humidification and gas exchange (oxygen decreases, carbon dioxide increases in alveolar air).

• Partial Pressure Impacts:

  • In alveoli: P O₂ ~ 104 mmHg, P CO₂ ~ 40 mmHg.

  • Drives pulmonary gas exchange from alveoli to blood.

• Thickness of Respiratory Membrane: Affects gas diffusion rate; thicker membranes slow exchange.

• Surface Area Impact: Larger surface areas enhance gas exchange efficiency.

23.7 Gas Transport

• Carbon Dioxide Transport:

  • Primarily transported as bicarbonate ions (HCO₃⁻) after conversion within red blood cells.

  • Chemical Equation: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻.

• Oxygen Transport in Blood:

  • Hemoglobin (Hb) binds to oxygen; one hemoglobin can carry up to four oxygen molecules.

  • Oxyhemoglobin: Hemoglobin bound to oxygen; Deoxyhemoglobin: Hemoglobin without oxygen.

• Binding Sites on Hemoglobin: Oxygen, CO₂, and H⁺ ions bind to specific sites, altering hemoglobin's conformation and affinity for oxygen.

• Oxygen-Hemoglobin Saturation Curve:

  • Illustrates how hemoglobin's oxygen binding changes with different partial pressures of O2.

  • Factors influencing O2 release at tissues include:

  • Increased temperature.

  • Increased CO₂ concentration.

  • Increased H⁺ concentration (lower pH).

• Hemoglobin Saturation Changes: Saturation increases as P O₂ increases and decreases more gradually as P O₂ drops.

• Exercise Effects: Increased metabolism raises CO₂ and lowers pH, enhancing oxygen unloading from hemoglobin.

• High Altitude Effects: Lower atmospheric pressure decreases available oxygen, affecting gas exchange.

• Oxygen Reserve Importance: The reserve allows for sustained oxygen delivery during periods of increased demand.

23.8 Breathing Rate and Homeostasis

• Pulmonary Ventilation and Skeletal Muscles: Contraction of skeletal muscles, particularly the diaphragm, alters thoracic volume affecting air movement.

• Respiratory Centers:

  • Medullary Respiratory Center: Contains the dorsal and ventral respiratory groups; regulates rhythm and depth of breathing.

  • Pontine Respiratory Center: Modifies the rhythm of breathing and coordinates transitional phases.

• Receptors in Breathing Homeostasis: Chemoreceptors (central and peripheral) monitor P O₂, P CO₂, and pH levels in the blood.

• Nerves and Muscles: Innervate diaphragm and intercostal muscles via phrenic nerve and intercostal nerves.

• Respiratory Rhythm Generation: Primarily regulated by the medulla and pons, influenced by neural and chemical signals.

• Factors Affecting Respiratory Rate and Depth:

  • Blood P CO₂ is the strongest stimulus; high levels trigger increased breathing rate.

  • Hypoventilation: Decreased breathing rate leading to increased CO₂ (hypercapnia).

  • Hyperventilation: Increased breathing rate leading to decreased CO₂ (hypocapnia).

• Breathing Rate and Blood Composition Changes: CO₂ levels influence H⁺ concentration and blood pH; increased CO₂ leads to acidosis (lower pH).

• Effects of Low CO₂ Levels: Can cause cardiovascular instability and symptoms such as lightheadedness.

• Exercise Influence on Respiration: Exercise increases metabolic demand, leading to increased respiration rates to supply adequate oxygen.

• Partial Pressure Changes at Different Altitudes: Decrease in partial pressure of oxygen at higher altitudes impacts oxygen availability for gas exchange.

• Altitude Sickness Symptoms: Nausea, shortness of breath, fatigue, and headaches resulting from reduced oxygen levels at high altitudes.

Respiratory Diseases Overview

• Smoking: Damages respiratory tissues, impairs gas exchange, and leads to chronic conditions.

• Asthma: Characterized by bronchoconstriction and inflammation, leading to obstructed airflow.

• Emphysema: Progressive destruction of alveolar walls, reducing surface area for gas exchange.

• Pneumonia: Inflammation of the lungs, causing fluid accumulation and impaired gas exchange.

• Effects on Blood Gas Levels: Respiratory diseases lead to altered CO₂ and O₂ levels, affecting respiratory rates and overall homeostasis.