Respiratory System Anatomy
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Questions and Answers

What is the primary function of the conducting zone in the respiratory system?

  • To produce surfactant to reduce surface tension in the alveoli
  • To remove debris and pathogens from the air, and warm and humidify it (correct)
  • To regulate breathing rate and depth
  • To facilitate gas exchange between the lungs and bloodstream

    • What is the main characteristic of the alveoli that makes them ideal for gas exchange?

  • Their large size and thick walls
  • Their ability to produce surfactant
  • Their small size and thin walls, surrounded by capillaries (correct)
  • Their connection to the diaphragm

    • What is the term for the volume of air that does not participate in gas exchange in the respiratory system?

  • Respiratory zone
  • Alveolar volume
  • Dead space (correct)
  • Conducting zone

    • What is the primary function of Type 2 alveolar cells?

    <p>To produce surfactant to reduce surface tension</p> Signup and view all the answers

    Which of the following structures is NOT part of the conducting zone?

    <p>Alveoli</p> Signup and view all the answers

    What is the term for the smallest branches of the bronchial tree?

    <p>Terminal bronchioles</p> Signup and view all the answers

    What is the relationship between pressure and volume in the lungs?

    <p>Inversely proportional</p> Signup and view all the answers

    What is the primary mechanism that allows air to move in and out of the lungs?

    <p>Pressure difference between the lungs and atmosphere</p> Signup and view all the answers

    What happens to the pressure in the lungs during inhalation?

    <p>Decreases</p> Signup and view all the answers

    Which muscles are responsible for changing the volume of the lungs during quiet breathing?

    <p>Diaphragm and external intercostal muscles</p> Signup and view all the answers

    What is the typical volume of air breathed in and out with each breath at rest?

    <p>500ml</p> Signup and view all the answers

    What is the maximum volume of air that can be exhaled past a normal tidal breath?

    <p>1200ml</p> Signup and view all the answers

    What is the purpose of residual volume in the lungs?

    <p>To prevent lung collapse</p> Signup and view all the answers

    What is the total lung capacity a measure of?

    <p>The volume of air in the lungs upon maximum effort of inspiration</p> Signup and view all the answers

    What is the primary function of spirometry?

    <p>To measure the amount of air moving in and out of the lungs</p> Signup and view all the answers

    What is the vital capacity a measure of?

    <p>The maximum amount of air that can be moved in and out of the lungs</p> Signup and view all the answers

    Where does gas exchange occur in the respiratory system?

    <p>In the alveoli and tissues</p> Signup and view all the answers

    What is the driving force behind gas exchange?

    <p>The differences in partial pressure of gases</p> Signup and view all the answers

    What happens to oxygen in the alveoli?

    <p>It is added to the blood and transported to the tissues</p> Signup and view all the answers

    What is the relationship between the partial pressure of oxygen in the alveoli and in the blood?

    <p>pO2 alveoli &gt; pO2 blood</p> Signup and view all the answers

    What is the purpose of Dalton's law?

    <p>To explain the concept of partial pressure in a gas mixture</p> Signup and view all the answers

    In which direction does carbon dioxide move in the tissues?

    <p>From the tissues into the blood</p> Signup and view all the answers

    What percentage of oxygen is carried around as dissolved O2 in plasma?

    <p>1.5-2%</p> Signup and view all the answers

    What is the primary factor that affects the binding of oxygen to haemoglobin?

    <p>Local pO2</p> Signup and view all the answers

    What is the approximate percentage of oxygen that is released by haemoglobin to the tissues?

    <p>25%</p> Signup and view all the answers

    What is the percentage of carbon dioxide that is transported in the form of bicarbonate ions?

    <p>70%</p> Signup and view all the answers

    What is the primary function of the dorsal respiratory group (DRG) in the medulla?

    <p>Maintaining normal quiet breathing rhythm</p> Signup and view all the answers

    What is the primary function of the pontine respiratory group (PRG) in the pons?

    <p>Modifying the activity of the dorsal respiratory group</p> Signup and view all the answers

    What is the most important input for controlling breathing?

    <p>Chemoreceptors</p> Signup and view all the answers

    What is the approximate number of breaths an average person takes per day?

    <p>20,000</p> Signup and view all the answers

    What is the term for the relationship between pO2 and the binding of oxygen to haemoglobin?

    <p>O2/Hb dissociation curve</p> Signup and view all the answers

    What is the percentage of oxygen that is bound to haemoglobin in the lungs?

    <p>95-99%</p> Signup and view all the answers

    Study Notes

    Anatomy of the Respiratory System

    • Nasal/oral cavity, pharynx, larynx, trachea, bronchi and branches (bronchioles), and alveoli are the major structures that make up the respiratory system.

    Functional Zones of the Respiratory System

    • The respiratory system is divided into two functional zones: conducting and respiratory zones.
    • Conducting zone: consists of structures that air travels through to reach the respiratory zone (no gas exchange occurs here); includes nasal cavity, pharynx, larynx, trachea, and bronchial tree.
    • Respiratory zone: where gas exchange takes place; includes terminal bronchioles, alveolar ducts, alveolar sacs, and alveoli.

    Alveoli

    • Alveoli are small (~200 μm) sacs connected via alveolar pores, surrounded by capillaries, with thin walls and large surface area, ideal for gas exchange.
    • Two types of alveolar cells: Type 1 (~97%) for gas exchange and Type 2 for secreting surfactant.

    Pressure and Volume in the Lungs

    • Boyle's Law: pressure is inversely related to volume; as volume increases, pressure decreases, and as volume decreases, pressure increases.

    Inspiration and Expiration (Pulmonary Ventilation)

    • Air moves from high to low pressure; during inhalation, lung pressure is less than atmospheric pressure, and during exhalation, lung pressure is greater than atmospheric pressure.
    • Respiratory muscles (diaphragm and external intercostal muscles) contract to increase lung volume during inhalation (active process) and relax to decrease lung volume during exhalation (passive process).

    Respiratory Volumes and Capacities

    • Respiratory volumes:
      • Tidal volume: volume of air breathed in/out with each breath (average: 500ml)
      • Inspiratory reserve volume: maximum volume of air inhaled above a normal tidal breath (typically: 3000ml)
      • Expiratory reserve volume: maximum volume of air exhaled past a normal tidal breath (typically: 1200ml)
      • Residual volume: volume left in lungs after emptying as much as possible (typically: 1500ml)
    • Respiratory capacities:
      • Vital capacity: maximum amount of air that can be moved in and out of the lungs
      • Total lung capacity: volume of air in the lungs upon maximum effort of inspiration

    Mechanisms of Gas Exchange

    • Gas exchange occurs in two spots: lungs (alveoli, external respiration) and tissues (internal respiration)
    • In the lungs, gas is exchanged between the blood and outside air
    • Oxygen enters the blood and carbon dioxide is removed from the blood
    • pO2 alveoli > pO2 blood = O2 moves from alveoli into blood
    • pCO2 alveoli < pCO2 blood = CO2 moves from blood into alveoli
    • Gas exchange occurs through simple diffusion down gradients created by differences in gas partial pressure
    • Dalton's law: total pressure of a mix of gases is made up of the partial pressure exerted by each gas

    Oxygen Transport in the Blood

    • Only a small portion (~1.5-2%) of O2 is carried as dissolved O2 in plasma
    • Most O2 is carried in red blood cells bound to haemoglobin (Hb)
    • Oxygen transport process:
      • Initially dissolves in plasma
      • Diffuses into RBC
      • Reversibly binds to Hb
      • Moves through blood as HbO2
      • Once at tissues, dissociates from Hb
      • Diffuses out of RBC and into tissues

    Structure and Function of Haemoglobin

    • Made up of 4 subunits, each with a haem group containing iron
    • O2 binds to the specific haem group
    • Each molecule can bind up to 4 O2 molecules
    • Binding of Hb + O2 affected by local pO2
    • O2/Hb dissociation curve: describes the relationship between pO2 and the binding of O2/Hb
    • Curve is flat at the top, steep at the bottom

    Carbon Dioxide Transport in the Blood

    • CO2 is more soluble than O2, but still needs alternate transport methods
    • Three ways CO2 is transported:
      • Bound to Hb (~20%)
      • In the form of bicarbonate ions (~70%)
      • Dissolved in plasma (~10%)

    Regulation of Breathing by Respiratory Centres

    • Respiratory centres in the medulla and pons control breathing
    • Medulla: contains dorsal respiratory group (DRG) and ventral respiratory group (VRG)
    • DRG: maintains normal quiet breathing rhythm
    • VRG: innervates accessory respiratory muscles, active during forced breathing
    • Pons: contains pontine respiratory group (PRG), modifies the activity of DRG based on input from various receptors/brain regions

    Chemoreceptors and Breathing Regulation

    • Chemoreceptors: respond to changes in pH/pCO2 in CSF (central) and changes in PCO2, pH and pO2 in the blood (peripheral)
    • Chemoreceptors are the most important input for controlling breathing
    • pCO2 is the primary determinant of breathing rate
    • pCO2 changes directly link to pH changes, which is bad for the body
    • pO2 changes are less sensitive, and RBCs/Hb can efficiently bind/deliver O2 even when pO2 levels drop

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    Description

    This quiz covers the major structures of the respiratory system, including the nasal/oral cavity, pharynx, larynx, trachea, bronchi, and alveoli, as well as the difference between the conducting and respiratory zones.

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