Human Anatomy and Physiology - Alveoli Function
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Questions and Answers

What is the primary function of the pores of Kohn in the alveoli?

  • To allow movement of immune cells between alveoli (correct)
  • To maintain the structure of alveoli
  • To secrete mucus for trapping microorganisms
  • To facilitate gas exchange between blood and alveoli

    • Which gas diffuses from the alveoli into the blood during gas exchange?

  • Nitrogen
  • Water vapor
  • Carbon monoxide
  • Oxygen (correct)

    • What is the primary role of type I alveolar epithelial cells in the lungs?

  • Secretion of pulmonary surfactant
  • Production of alveolar macrophages
  • Maintenance of the gas-blood barrier and gas exchange (correct)
  • Defense against pathogens

    • What percentage of the total alveolar surface do type I alveolar epithelial cells comprise?

    <p>90%</p> Signup and view all the answers

    What is the thickness of the alveolar-capillary membrane?

    <p>0.5 micron</p> Signup and view all the answers

    What happens to the Pco2 levels in capillary blood after gas exchange?

    <p>They fall</p> Signup and view all the answers

    At which anatomical level is the carina positioned?

    <p>At the level of the aortic arch</p> Signup and view all the answers

    What is the main function of type II alveolar epithelial cells?

    <p>Secretion of pulmonary surfactant</p> Signup and view all the answers

    Where does the pulmonary artery receive blood from?

    <p>Right side of the heart</p> Signup and view all the answers

    What prevents the trachea from collapsing during bronchoconstriction?

    <p>Cartilaginous rings</p> Signup and view all the answers

    What happens to the lungs when there is a severe loss of pulmonary surfactant?

    <p>Alveolar instability and collapse</p> Signup and view all the answers

    How are alveolar macrophages formed?

    <p>From blood monocytes that migrate into the alveoli</p> Signup and view all the answers

    Which arteries supply the tissues in the left side of the thorax?

    <p>Bronchial arteries</p> Signup and view all the answers

    Which bronchus is wider and angles more directly toward the lung?

    <p>Right bronchus</p> Signup and view all the answers

    What component primarily makes up pulmonary surfactant?

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

    What type of blood does the left atrium normally contain?

    <p>Oxygenated blood</p> Signup and view all the answers

    What generation of the bronchial tree includes the main stem bronchi?

    <p>First generation</p> Signup and view all the answers

    What is the main cause of diffusion stopping in the alveolar-capillary membrane?

    <p>Equalization of pressures on both sides</p> Signup and view all the answers

    What effect does pulmonary disease have on surfactant synthesis?

    <p>Reduces synthesis and storage of surfactant</p> Signup and view all the answers

    Which of these bronchioles have a diameter of less than 1 mm?

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

    Which cell type is most susceptible to injury in the pulmonary system?

    <p>Type I alveolar epithelial cells</p> Signup and view all the answers

    In which part of the respiratory system does gas exchange primarily occur?

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

    Which generation of bronchi do the segmental bronchi belong to?

    <p>Third generation</p> Signup and view all the answers

    How many alveoli are approximately contained in each terminal respiratory unit?

    <p>2000</p> Signup and view all the answers

    What is the primary factor that determines the direction of diffusion of gases in the lungs?

    <p>The driving pressure difference between the alveoli and pulmonary capillaries</p> Signup and view all the answers

    How does supplemental oxygen affect the driving pressure of oxygen?

    <p>It raises the driving pressure of oxygen</p> Signup and view all the answers

    What is true regarding the diffusion coefficient of gases?

    <p>Carbon dioxide diffuses 20 times more rapidly than oxygen due to its higher diffusion coefficient</p> Signup and view all the answers

    Which condition would decrease the rate of gas diffusion across the alveolar-capillary membrane?

    <p>Thicker alveolar-capillary membrane</p> Signup and view all the answers

    At high altitudes, what impact does gravity have on the diffusion of oxygen?

    <p>It diminishes the driving pressure for oxygen</p> Signup and view all the answers

    Which of the following best describes gas transport within the body?

    <p>Gas transport is facilitated by the blood and occurs via diffusion at the cellular level</p> Signup and view all the answers

    What happens to carbon dioxide in the lungs during diffusion?

    <p>It moves from pulmonary capillaries into the alveoli</p> Signup and view all the answers

    How do conditions like pulmonary edema affect diffusion?

    <p>They increase the thickness of the alveolar-capillary membrane</p> Signup and view all the answers

    What is one of the primary functions of the lymphatic system in the lungs?

    <p>Producing antibodies</p> Signup and view all the answers

    What is the primary reason the lungs have a rich supply of lymphatic tissue?

    <p>To manage exposure to external environments</p> Signup and view all the answers

    Which pressure is typically less than atmospheric pressure in a normal lung?

    <p>Intrapleural pressure</p> Signup and view all the answers

    What is the term used for the movement of air into the lungs?

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

    What typically measures pressure at sea level?

    <p>760 mmHg</p> Signup and view all the answers

    What occurs during external respiration?

    <p>Diffusion of oxygen and carbon dioxide between air and blood</p> Signup and view all the answers

    Which pressure is affected by the size of the thorax?

    <p>Intrapulmonary pressure</p> Signup and view all the answers

    What type of particles does the lymphatic system in the lungs help to remove?

    <p>Foreign particles and cell debris</p> Signup and view all the answers

    Which factor does NOT contribute to an increased work of breathing?

    <p>Enhanced pulmonary surfactant production</p> Signup and view all the answers

    What is the primary function of pulmonary surfactant?

    <p>To reduce surface tension in the alveoli</p> Signup and view all the answers

    Which muscle is NOT typically involved in accessory breathing?

    <p>Latissimus dorsi</p> Signup and view all the answers

    What is the approximate tidal volume (VT) during normal breathing?

    <p>500 to 600 mL</p> Signup and view all the answers

    Which pulmonary capacity represents the maximal amount of air that can be inhaled?

    <p>Total lung capacity (TLC)</p> Signup and view all the answers

    Which gas exchange is referred to as internal respiration?

    <p>Diffusion of gases in and out of cells</p> Signup and view all the answers

    What is the residual volume (RV) typically in the lungs after a forced expiration?

    <p>1000 to 1200 mL</p> Signup and view all the answers

    Which volume is included in the calculation of inspiratory capacity (IC)?

    <p>Tidal volume and inspiratory reserve volume</p> Signup and view all the answers

    Which structure separates the thoracic and abdominal cavities?

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

    How many lung segments are located in the right lung?

    <p>10</p> Signup and view all the answers

    What type of pleura adheres directly to the lungs?

    <p>Visceral pleura</p> Signup and view all the answers

    Which area contains the heart, great vessels, and esophagus?

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

    What is the normal range of intrapleural pressure during inhalation?

    <p>4 to -10 cm H2O</p> Signup and view all the answers

    Which muscles are responsible for decreasing the size of the chest during exhalation?

    <p>Muscles of exhalation</p> Signup and view all the answers

    During deep inhalation, what intrapleural pressure can be generated?

    <p>12 to -18 cm H2O</p> Signup and view all the answers

    What is the primary muscle responsible for the majority of the work of breathing during normal, quiet breathing?

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

    Which nerve is primarily responsible for controlling the diaphragm's actions during breathing?

    <p>Phrenic nerve</p> Signup and view all the answers

    What occurs during exhalation in a healthy lung?

    <p>It is a passive event.</p> Signup and view all the answers

    Which muscles are considered accessory muscles of ventilation during exercise?

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

    What is one of the main purposes of the conducting airways?

    <p>To filter out pathogens</p> Signup and view all the answers

    During inhalation, how does the diaphragm affect the abdomen?

    <p>It flattens and pushes down.</p> Signup and view all the answers

    Which group of muscles is primarily active during normal inhalation?

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

    What happens to the activity of the accessory muscles during exercise?

    <p>They enhance chest expansion.</p> Signup and view all the answers

    What is the composition of the upper airway structures?

    <p>All structures above the glottis</p> Signup and view all the answers

    What happens during inhalation when intrapulmonary pressure falls?

    <p>Air enters the lungs and inhalation occurs.</p> Signup and view all the answers

    Which factors primarily determine the work of breathing?

    <p>Elastic and resistive properties of the lungs.</p> Signup and view all the answers

    What happens during expiration when intrapulmonary pressure rises?

    <p>Air exits the lungs and exhalation occurs.</p> Signup and view all the answers

    Which pulmonary disease is associated with decreased lung compliance?

    <p>Atelectasis.</p> Signup and view all the answers

    Which condition is likely to increase airway resistance?

    <p>Asthma.</p> Signup and view all the answers

    At what level is the carina typically positioned?

    <p>Fifth thoracic vertebra</p> Signup and view all the answers

    What is the function of the C-shaped cartilaginous rings in the trachea?

    <p>They prevent tracheal collapse</p> Signup and view all the answers

    Which bronchus is narrower and angles toward the left lung?

    <p>Left bronchus</p> Signup and view all the answers

    What is the most common site of aspiration for foreign objects in the lungs?

    <p>Right main stem bronchus</p> Signup and view all the answers

    What do the fourth to ninth generations of the bronchi consist of?

    <p>Small bronchi</p> Signup and view all the answers

    What is the diameter of bronchioles?

    <p>Less than 1 mm</p> Signup and view all the answers

    What marks the transition zone of the lungs for gas exchange?

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

    How many alveolar ducts does each respiratory bronchiole give rise to?

    <p>10 to 16</p> Signup and view all the answers

    How many segmental bronchi are included in the bronchial tree?

    <p>18</p> Signup and view all the answers

    What is the primary characteristic of the walls of bronchioles?

    <p>They have no connective tissue or cartilage</p> Signup and view all the answers

    What process helps keep the alveoli clean and sterile?

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

    What is the primary role of the pulmonary artery?

    <p>To transport deoxygenated blood to the lungs</p> Signup and view all the answers

    During gas exchange, why does oxygen diffuse from the alveoli into the blood?

    <p>Higher concentration of oxygen in the alveoli</p> Signup and view all the answers

    How does the capillary blood Pco2 level change after gas exchange?

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

    What is the thickness of the alveolar-capillary membrane critical for diffusion?

    <p>0.5 micron</p> Signup and view all the answers

    What is a typical characteristic of blood entering the pulmonary capillaries?

    <p>High Pco2 and low Po2</p> Signup and view all the answers

    Where does blood go after gas exchange in the alveoli?

    <p>To the left side of the heart</p> Signup and view all the answers

    What role does physiological shunting play in the pulmonary circulation?

    <p>It mixes oxygenated and deoxygenated blood</p> Signup and view all the answers

    Which of these structures branches off from the aorta to perfuse the left side of the thorax?

    <p>Bronchial arteries</p> Signup and view all the answers

    How does the diffusion of gases across the alveolar-capillary membrane occur?

    <p>Based on concentration gradients</p> Signup and view all the answers

    Study Notes

    Pulmonary Anatomy and Physiology

    • The pulmonary system comprises the thorax, conducting airways, respiratory airways, and pulmonary blood and lymph supply.
    • The primary functions of the pulmonary system are ventilation and respiration.
    • Ventilation is the movement of air in and out of the lungs, involving oxygen uptake and carbon dioxide release.
    • Respiration is the process of gas exchange, where oxygen is taken into the bloodstream and carbon dioxide is expelled.
    • A strong understanding of anatomy and physiology is critical for patient care in cases of pulmonary dysfunction.

    Thorax

    • The thorax houses the major organs of respiration and is a cone-shaped structure with a rigid frame.
    • The framework features 12 thoracic vertebrae, ribs, and the sternum.
    • Ribs are attached to the vertebrae posteriorly and, in the anterior portion, their attachment varies. The first seven pairs are directly linked to the sternum while the 8th, 9th, and 10th attach to the ribs above by cartilage. The 11th and 12th, also referred to as floating ribs, lack anterior attachment.
    • The second rib attaches to the sternum at the angle of Louis, a notable ridge beneath the suprasternal notch.
    • The thorax's components form a ventilatory pump, the mechanism for breathing.

    Lungs

    • Lungs are cone-shaped organs, with an apex (superior portion) and a base (inferior portion).
    • The apex of each lung extends a few centimeters above the clavicle.
    • The right lung, larger and heavier than the left, is divided into three lobes (upper, middle, and lower).
    • The left lung is divided into two lobes (upper and lower).
    • Fissures divide the lobes. Lobes are further separated into segments (a total of 18). Each has its own bronchus branching. Ten segments are found in the right lung, and eight in the left.

    Mediastinum

    • The mediastinum sits between the lungs, encompassing the heart, great vessels, lymphatics, and esophagus.

    Pleura

    • The pleura is a thin membrane that lines the outside of the lungs and the inside of the chest wall.
    • The visceral pleura attaches to the lungs, extending to the hilar bronchi and major fissures.
    • The parietal pleura lines the inner chest wall and mediastinum.
    • An airtight space exists between these pleural membranes, containing a lubricating fluid.
    • The pleural membranes glide over each other without friction during breathing.

    Intrapleural Pressure

    • Intrapleural pressure is the pressure within the pleural space. It's less than intrapulmonary and atmospheric pressure.
    • Under normal conditions, it ranges from 4 to -10 cm H₂O during inhalation and exhalation.
    • Deep inhalation can create intrapleural pressure of 12 to -18 cm H₂O.

    Muscles of Ventilation

    • The central nervous system governs the muscles of ventilation through nerve impulses that cause their contraction and relaxation.
    • Muscles that expand the chest are called inhalatory muscles, and those that reduce chest size are called exhalatory muscles.
    • The diaphragm is the principal inspiratory muscle; during quiet breathing, it contributes to about 80% of the work involved. This dome-shaped fibromuscular structure separates the thoracic and abdominal cavities.
    • Accessory muscles such as the sternocleidomastoid, scalene, and pectoral muscles aid in breathing, particularly during exercise.
    • Exhalation in healthy individuals is usually passive and requires minimal energy.

    Conducting Airways

    • The conducting airways (upper and lower) warm and moisten inhaled air.
    • They also function as a protective barrier against foreign particles entering the gas exchange areas.
    • The upper airways comprise structures above the glottis (nose, mouth, pharynx).
    • The lower airways are below the glottis (larynx, trachea, bronchi).

    Larynx

    • The larynx, or voice box, consists of nine cartilages, six of which are paired and three are unpaired.
    • The unpaired cartilages—thyroid (Adam's apple), cricoid, and epiglottis—are crucial.
    • The epiglottis is a leaf-shaped cartilage that prevents food from entering the trachea during swallowing.
    • The vocal cords regulate the airflow and are responsible for voice production.

    Trachea

    • The trachea is the windpipe, roughly 11 cm long and 2.5 cm in diameter.
    • It's a hollow tube, supported by C-shaped cartilaginous rings, and connects the larynx to the bronchi branching at the carina.
    • The trachea divides into two main bronchi.

    Bronchial Tree

    • The bronchial tree has sequentially branching structures within the lungs.
    • Bronchi split into progressively smaller structures such as lobar, segmental, and subsegmental bronchi.
    • Finally, they divide into bronchioles, then to alveolar ducts and alveoli.
    • The right main bronchus is wider and angles more directly downward compared to the left, placing the right lung as more vulnerable to aspirated foreign bodies.
    • The characteristics of increasing branching and decreasing tube diameter throughout the bronchial tree are key to understanding respiratory physiology.

    Respiratory Airway

    • The respiratory bronchioles connect conducting airways to gas exchange units (alveoli).

    Alveoli

    • Alveoli are the primary site of gas exchange in the lungs. Hundreds of millions of clustered alveoli give enormous surface area for gas diffusion.
    • Alveolar walls contain specialized cells (type I and type II alveolar epithelial cells and alveolar macrophages). Each terminal respiratory unit contains approximately 100 alveolar ducts and 2000 alveoli.
    • Type I cells form the majority of the alveolar wall and are pivotal to forming the gas-blood barrier.

    Alveolar-Capillary Membrane

    • The alveolar-capillary membrane is a very thin structure separating the alveoli from the capillaries, enabling efficient gas exchange. Its thinness facilitates the rapid transfer of both oxygen and carbon dioxide across its membrane.
    • Factors like thickness of the membrane and the surface area affect the rate of diffusion.

    Pulmonary Circulation

    • The pulmonary circulatory system begins at the pulmonary artery and ends at the pulmonary veins.
    • Venous blood from the right heart enters the pulmonary artery, which branches into smaller vessels leading to the alveolar capillaries surrounding the alveoli.
    • After gas exchange, oxygenated blood returns to the left heart via the pulmonary veins.

    Work of Breathing

    • The work of breathing is the amount of effort required to overcome the lung's elastic and resistive properties aided by the muscles of inhalation and exhalation to achieve the necessary mechanical actions.
    • Lung recoil, chest wall compliance, and surface tension are key elastic determinants of the work of breathing.
    • Airway resistance and the presence of pathologies are key in influencing the work of breathing.
    • During normal quiet breathing, the work required is relatively low (less than 1% to 2%). However, the work load increases during heavier work or presence of pathologies.

    Pulmonary Volumes and Capacities

    • Measures of the volume of air that can be exchanged throughout varying respiratory actions and stages.
    • Key measurements such as tidal volume (amount of air exchanged during a normal breath), inspiratory reserve volume (maximal inspiration after a normal breath), expiratory reserve volume (maximal expiration after a normal breath), and residual volume (air remaining after a maximal expiration) dictate the lungs' capacity for breathing.

    Respiration

    • Respiration encompasses external respiration (gas exchange in the lungs) and internal respiration (gas exchange at the tissue level).
    • Diffusion is the primary mechanism of gas transport, moving gases across the thin alveolar-capillary membrane down a pressure gradient.
    • Factors influencing the diffusion rate include the membrane's thickness and surface area, and the diffusion coefficient of each gas.

    Gas Transport

    • Gas transport refers to the movement of oxygen and carbon dioxide between the lungs and tissues.
    • The blood stream moves these gases throughout the body.
    • At the tissue level, oxygen and carbon dioxide diffuse across membranes and move into and out of cells as needed.

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    Dive into the fascinating world of human anatomy with this quiz focusing on the alveoli and their functions. Explore questions related to gas exchange, epithelial cells, and the structure of the respiratory system. Perfect for students studying human physiology or preparing for exams.

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