Respiratory System Components and Functions
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Respiratory System Components and Functions

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Questions and Answers

What happens to intrapulmonary pressure during inspiration?

  • It remains constant
  • It fluctuates randomly
  • It drops below atmospheric pressure (correct)
  • It increases above atmospheric pressure

    • Which muscle is considered the prime mover during breathing?

  • Sternocleidomastoid
  • Intercostal muscles
  • Scalene muscles
  • Diaphragm (correct)

    • What role do the expiratory neurons play during quiet breathing?

  • They are active during inspiration
  • They control muscle contraction
  • They increase intrapulmonary volume
  • They trigger relaxed expiration (correct)

    • Which respiratory centers are found in the brainstem?

    <p>Ventral, dorsal, and pontine respiratory groups</p> Signup and view all the answers

    What occurs during expiration when the diaphragm and intercostal muscles relax?

    <p>Thoracic cavity volume decreases</p> Signup and view all the answers

    What is the main function of central chemoreceptors in the brainstem?

    <p>To respond to changes in pH of cerebrospinal fluid</p> Signup and view all the answers

    Which of the following factors stimulates bronchodilation?

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

    How do irritant receptors in the airway respond?

    <p>By causing bronchoconstriction</p> Signup and view all the answers

    What characterizes tidal volume in quiet breathing?

    <p>It measures air inhaled and exhaled per cycle</p> Signup and view all the answers

    What is the main result of bronchoconstriction?

    <p>Reduction of air passage diameter</p> Signup and view all the answers

    The pontine respiratory group primarily modifies the rhythm of which group?

    <p>Ventral respiratory group</p> Signup and view all the answers

    What primarily reflects the CO2 levels in the blood for central chemoreceptors?

    <p>pH of cerebrospinal fluid</p> Signup and view all the answers

    What does anatomical dead space refer to?

    <p>Air that fills the conducting pathway without gas exchange</p> Signup and view all the answers

    What is the primary function of the respiratory zone?

    <p>To facilitate gas exchange</p> Signup and view all the answers

    Which structure is NOT part of the conducting zone of the respiratory system?

    <p>Alveolar ducts</p> Signup and view all the answers

    Which of the following best describes the function of the diaphragm?

    <p>It helps in the ventilation process</p> Signup and view all the answers

    What process describes the exchange of gases between the lungs and blood?

    <p>External respiration</p> Signup and view all the answers

    What role does the nasal cavity play in respiration?

    <p>Filtering and warming inspired air</p> Signup and view all the answers

    What characterizes the structure of the trachea?

    <p>It is a flexible tube supported by C-shaped cartilage rings</p> Signup and view all the answers

    Which region of the pharynx is located above the soft palate?

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

    How many orders of branching do air passages undergo in the lungs?

    <p>23</p> Signup and view all the answers

    The primary type of cell responsible for gas exchange in the alveoli is:

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

    What is the function of surfactant in the alveoli?

    <p>To reduce surface tension for easier lung expansion</p> Signup and view all the answers

    What distinguishes quiet respiration from forced respiration?

    <p>Forced respiration includes deep or rapid breathing</p> Signup and view all the answers

    Which of the following characteristics is NOT true about bronchioles?

    <p>They contain mucus-producing cells</p> Signup and view all the answers

    What marks the end of the trachea?

    <p>The carina</p> Signup and view all the answers

    Study Notes

    Respiratory System Components

    • The respiratory system is comprised of the respiratory zone and the conducting zone.
    • The respiratory zone is where gas exchange takes place and consists of the bronchioles, alveolar ducts, and alveoli.
    • The conducting zone provides a pathway for air to reach the gas exchange sites and includes the nose, nasal cavity, pharynx, trachea, and other respiratory structures.
    • The diaphragm and other muscles, known as respiratory muscles, facilitate ventilation.

    Respiratory System Pathway

    • The path an inspiration takes is as follows, in order: mouth and nose, pharynx, larynx, trachea, bronchi and bronchioles, alveolar ducts, and alveoli
    • Mouth and nose, pharynx, and larynx are all part of the upper respiratory system.

    Major Functions of the Respiratory System

    • The respiratory system's main role is to deliver oxygen to the body and remove carbon dioxide.
    • Respiration involves four distinct processes:
      • Pulmonary ventilation: moving air into and out of the lungs.
      • External respiration: gas exchange between the lungs and the blood.
      • Transport: oxygen and carbon dioxide movement between the lungs and tissues.
      • Internal respiration: gas exchange between systemic blood vessels and tissues.

    Function of the Nose

    • The nose serves multiple roles:
      • It acts as an airway for breathing.
      • It humidifies and warms the air that is inhaled.
      • It filters and cleanses the incoming air.
      • It functions as a resonating chamber for speech.
      • It houses the olfactory receptors for smell.

    Nasal Cavity

    • The nasal cavity humidifies incoming air due to its high water content.
    • It warms the air through a dense network of capillaries.
    • The ciliated mucous cells within the nasal cavity remove contaminated mucus.

    Pharynx

    • The pharynx is a funnel-shaped muscular tube connecting the nasal cavity and mouth to the larynx and esophagus.
    • It extends from the base of the skull to the sixth cervical vertebra.
    • The pharynx consists of three sections:
      • Nasopharynx
      • Oropharynx
      • Laryngopharynx

    Larynx (Voice Box)

    • The larynx attaches to the hyoid bone and connects to the laryngopharynx above and the trachea below.
    • It serves three purposes:
      • Maintain an open airway.
      • Route air and food to their proper channels.
      • Produce speech.

    Trachea

    • The trachea is a flexible, mobile tube that extends from the larynx to the mediastinum.
    • It comprises three layers:
      • Mucosa: made up of goblet cells and ciliated epithelium.
      • Submucosa: connective tissue beneath the mucosa.
      • Adventitia: the outer layer composed of C-shaped hyaline cartilage rings.

    Conducting Zone: Bronchi

    • The carina, the last tracheal cartilage, marks the transition from the trachea to the right and left bronchi.
    • By the time air reaches the bronchi, it is warm, cleansed of impurities, and saturated with moisture.
    • The bronchi branch into secondary bronchi, each supplying a lobe of the lungs.
    • Within the lungs, air passages undergo 23 branching orders.

    Conducting Zone: Bronchial Tree

    • The bronchi's tissue walls are similar to the trachea's.
    • Structural changes occur as the conducting tubes become smaller:
      • Cartilage support alters.
      • Epithelium types transform.
      • Smooth muscle increases.
    • Bronchioles:
      • Composed of cuboidal epithelium.
      • Have a full circular layer of smooth muscle.
      • Lack cartilage support and mucus-producing cells.

    Respiratory Zone

    • The respiratory zone begins with terminal bronchioles leading into respiratory bronchioles, characterized by the presence of alveoli.
    • Respiratory bronchioles connect to alveolar ducts, which then lead to alveolar sacs, clusters of alveoli.
    • There are roughly 300 million alveoli:
      • Occupying the majority of the lung's volume.
      • Providing a vast surface area for gas exchange.

    Respiratory Membrane

    • The air-blood barrier, crucial for gas exchange, is composed of:
      • Alveolar and capillary walls.
      • Their combined basal laminas.
    • Alveolar Walls:
      • Are a single layer of type I epithelial cells.
      • Allow gas exchange through simple diffusion.
      • Secrete angiotensin-converting enzyme (ACE).
    • Type II cells secrete surfactant.

    Alveoli

    • Alveoli are surrounded by delicate elastic fibers.
    • They have open pores connecting adjacent alveoli, equalizing air pressure throughout the lungs.
    • Macrophages reside in alveoli, keeping their surfaces sterile.

    Pulmonary Ventilation

    • The respiratory cycle consists of one complete breath, including inspiration and expiration.
    • Quiet respiration is relaxed, unconscious, and automatic breathing.
    • Forced respiration involves deep or rapid breathing, like during exercise, singing, or blowing up a balloon.

    Inspiration

    • The diaphragm and external intercostal muscles (inspiratory muscles) contract, causing the rib cage to rise.
    • The lungs stretch, increasing intrapulmonary volume.
    • Intrapulmonary pressure drops below atmospheric pressure (-1 mm Hg).
    • Air flows into the lungs down the pressure gradient until intrapulmonary pressure equals atmospheric pressure.

    Expiration

    • The inspiratory muscles relax, the rib cage descends due to gravity, and thoracic cavity volume decreases.
    • The elastic lungs recoil passively, decreasing intrapulmonary volume.
    • Intrapulmonary pressure rises above atmospheric pressure (+1 mm Hg).
    • Gases flow out of the lungs down the pressure gradient until intrapulmonary pressure reaches 0.

    Respiratory Muscles

    • Principal Muscles:
      • Diaphragm: the primary muscle for breathing.
      • Intercostal muscles: both external and internal.
    • Accessory Muscles:
      • Sternocleidomastoids.
      • Scalenes.
      • Pectoralis.
      • Serratus anterior of the chest.

    Brainstem Respiratory Centers

    • Unconscious, automatic breathing is controlled by three pairs of respiratory centers in the medulla oblongata and pons:
      • VRG: ventral respiratory group.
      • DRG: dorsal respiratory group.
      • Pontine respiratory group.

    VRG

    • The VRG is the primary rhythm generator for breathing.
    • It contains two neuron groups:
      • Inspiratory neurons (I): fire for approximately 2 seconds at a time during quiet breathing.
      • Expiratory neurons (E): relaxed during quiet breathing, leading to expirations lasting about 3 seconds.

    DRG

    • The DRG acts as an integration center, receiving input from various sources.
    • It is influenced by:
      • Pontine respiratory group.
      • Central chemoreceptors in the medulla.
      • Chemoreceptors in major arteries.

    Pontine Respiratory Group

    • Located on each side of the pons.
    • Modifies the VRG's breathing rhythm.
    • Receives input from higher brain centers, including the hypothalamus, limbic system, and cortex.
    • Sends output to both the VRG and DRG, influencing breathing depth and rate (shorter and shallower or longer and deeper).

    Central and Peripheral Input

    • Central Receptors:
      • Central chemoreceptors in the brainstem: neurons sensitive to CSF pH changes. They respond to changes in blood CO2 levels since CSF pH reflects blood CO2 content.
    • Peripheral Receptors:
      • Located in carotid (via glossopharyngeal nerve) and aortic bodies (via vagus nerve) of large arteries: respond to oxygen and carbon dioxide content in the blood, primarily to pH.
      • Stretch receptors: found in the smooth muscle of bronchi and bronchioles (via vagus nerve).
      • Irritant receptors: nerve endings in epithelial cells or airway (via vagus): respond to irritants like smoke, dust, and pollen.

    Voluntary Control of Breathing

    • Allows for conscious control of breathing for actions like singing, speaking, and breath-holding.
    • Originates in the motor cortex.
    • Neurons send impulses to integrating centers in the spinal cord.

    Bronchodilation

    • Increase in the diameter of bronchus or bronchioles.
    • Stimulated by epinephrine and sympathetic nerves (norepinephrine).
    • Leads to increased airflow.

    Bronchoconstriction

    • Decrease in the diameter of bronchus or bronchiole.
    • Stimulated by histamine, parasympathetic nerves (acetylcholine), cold air, and chemical irritants.
    • Reduces airflow.

    Other Respiratory Terms

    • Anatomical dead space: air filling the conducting pathways that does not exchange gases with blood (approximately 150 mL or 1 mL per pound of body weight).
    • Tidal volume: air inhaled and exhaled per breathing cycle (500 mL during quiet breathing).
    • Residual volume: air remaining after maximum expiration.

    Homeostatic Imbalances

    • Chronic Obstructive Pulmonary Diseases:
      • Chronic bronchitis.
      • Emphysema.
    • Asthma.
    • Tuberculosis.
    • Lung cancer.

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    Description

    Explore the essential components and functions of the respiratory system through this quiz. Understand the pathways air takes in the body and the roles of various respiratory structures. Assess your knowledge on gas exchange and respiratory processes.

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