Bio 50B Respiratory System Notes

Respiratory System Notes

Major Organs of the Respiratory System

  • Nose/Nasal Cavity

  • Pharynx

  • Larynx

  • Trachea

  • Bronchi

  • Lungs

Conducting Zone Structures

  • Nasal Cavity

  • Pharynx

  • Larynx

  • Trachea

  • Bronchi

  • Bronchioles

Respiratory Zone Structures

  • Respiratory bronchioles

  • Alveolar ducts

  • Alveolar sacs

  • Alveoli

Respiratory Epithelium in Conducting Airway

  • The respiratory epithelium is primarily composed of ciliated pseudostratified columnar epithelium with goblet cells that secrete mucus to trap dust and pathogens.

Pharynx Lining

  • The part of the pharynx lined by stratified squamous epithelium is the oropharynx.

Cartilages of the Larynx

  • The larynx is made up of 9 cartilages, including thyroid, cricoid, and arytenoid cartilages.

Location of Vocal Folds

  • The vocal folds are located within the larynx.

Largest Cartilage of the Larynx

  • The largest cartilage is the thyroid cartilage.

Ring-Shaped Cartilage Below the Thyroid

  • The ring-shaped cartilage just inferior to the thyroid cartilage is the cricoid cartilage.

Airway Between Larynx and Bronchial Tree

  • The airway that connects the larynx to the bronchial tree is the trachea.

Structure and Functions of the Trachea

  • The trachea is a flexible tube reinforced with C-shaped cartilage rings that maintain its shape, allowing air to pass and preventing collapse.

Order of Air Passage Through Airways

  1. Nasal cavity

  2. Pharynx

  3. Larynx

  4. Trachea

  5. Bronchi

  6. Bronchioles

  7. Alveoli

Sites of Gas Exchange

  • The actual sites of gas exchange are the alveoli.

Structure of the Respiratory Membrane

  • The respiratory membrane consists of:

    • Alveolar epithelium (simple squamous epithelium)

    • Capillary endothelium (also simple squamous)

    • Basement membrane interlinks both.

Structure and Functions of the Lungs

  • Lungs are paired organs with structures allowing for gas exchange, consisting of lobes, bronchi, and alveoli.

Body Systems Involved in Respiration

  • Respiratory system

  • Circulatory system

  • Nervous system

  • Musculoskeletal system (involved in breathing)

Four Parts of Respiration

  1. Pulmonary ventilation (breathing)

  2. External respiration (gas exchange in lungs)

  3. Internal respiration (gas exchange in tissues)

  4. Transport of gases by the blood

Atmospheric Pressure

  • Atmospheric pressure is the weight of the air above us, normal value is approximately 760 mm Hg.

Intrapulmonary and Intrapleural Pressure

  • Intrapulmonary pressure: pressure within the lungs.

  • Intrapleural pressure: pressure within the pleural cavity, usually negative to keep lungs inflated.

Atelectasis

  • Atelectasis is the collapse of part or all of a lung, reducing gas exchange.

Boyle's Law

  • Boyle's law states that at constant temperature, the volume of a gas varies inversely with its pressure: P<em>1V</em>1=P<em>2V</em>2P<em>1V</em>1 = P<em>2V</em>2.

Mechanisms of Inspiration and Expiration

  • Inspiration is active (muscle contraction to enlarge chest cavity).

  • Expiration is passive during quiet breathing (due to elastic recoil of lungs) or active during forced expiration.

Lung Volume Changes

  • If the volume of the lungs increases, the air pressure inside the lungs decreases.

Air Movement During Breathing

  • Air moves out of the lungs when the pressure inside the lungs is greater than atmospheric pressure.

Internal Respiration

  • Internal respiration is the exchange of gases between blood and tissues.

  • Carbon dioxide moves from tissues into the blood during this process.

Dalton's Law

  • Dalton's law states that in a mixture of gases, the total pressure is the sum of the partial pressures of individual gases.

External Respiration

  • External respiration involves gas exchange between the alveoli and blood in the pulmonary capillaries.

Types of Respiratory Volumes and Capacities

  • Tidal Volume (TV): volume of air inhaled/exhaled in a normal breath.

  • Inspiratory Reserve Volume (IRV): additional air that can be inhaled after a normal inhalation.

  • Expiratory Reserve Volume (ERV): additional air that can be exhaled after a normal exhalation.

  • Residual Volume (RV): air that remains in lungs after maximum exhalation.

Dead Space

  • Dead space refers to areas in the respiratory system where gas exchange does not occur, primarily in the conduction zone.

Factors Influencing External Respiration

  • Partial pressures of gases

  • Surface area for diffusion

  • Thickness of the respiratory membrane

  • Ventilation-perfusion ratio

Partial Pressure of O2 in Arterial Blood

  • The partial pressure of oxygen in arterial blood is approximately 80-100 mm Hg.

Partial Pressure of CO2 in Venous Blood

  • The partial pressure of carbon dioxide in venous blood is approximately 40 mm Hg.

Greatest Partial Pressure of CO2

  • The partial pressure of carbon dioxide is greatest in the tissues due to cellular respiration.

Oxyhemoglobin Formation

  • Oxyhemoglobin forms when oxygen binds to hemoglobin in red blood cells in the pulmonary capillaries.

Hemoglobin Saturation

  • Hemoglobin saturation refers to the percentage of hemoglobin molecules carrying oxygen.

  • At a PO2 of (100mmHg)(100 mm Hg) and normal temperature and pH, hemoglobin is about 98.5 percent saturated with oxygen.

Factors Influencing Hemoglobin Saturation

  • pH levels (Bohr effect)

  • Temperature

  • Partial pressures of oxygen and carbon dioxide

CO2 Transport in Blood

  • Carbon dioxide is transported in the blood in three forms:

    • Dissolved in plasma

    • As bicarbonate ions (HCO3−HCO_3^-)

    • Bound to hemoglobin (carbaminohemoglobin)

Bulk Transport of Carbon Dioxide

  • The bulk of carbon dioxide is carried in blood as bicarbonate ions.

Ventilation-Perfusion Coupling

  • Ventilation-perfusion coupling refers to the matching of air flow (ventilation) and blood flow (perfusion) in the lungs to optimize gas exchange.

Chemical Regulator of Respiration

  • The most important chemical regulator of respiration is carbon dioxide.

Emphysema

  • Emphysema is a chronic lung condition that involves damage to the air sacs (alveoli), causing breathlessness due to reduced surface area for gas exchange.

Respiratory Homeostatic Imbalances

  • Common respiratory imbalances include:

    • Asthma: involves airway constriction.

    • Tuberculosis: infectious disease affecting lungs.

    • Lung cancer: characterized by uncontrollable cell growth in the lungs.