Respiratory System: Inspiration and Expiration

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Questions and Answers

What is the shape of the diaphragm?

  • Convex
  • Concave
  • Cylindrical
  • Dome-shaped (correct)

What happens to the ribs when the diaphragm contracts?

  • They move downward and rotate toward the vertical plane
  • They move upward and rotate toward the horizontal plane
  • They remain still and do not move
  • They move downward and rotate toward the horizontal plane (correct)

What is expiration?

  • An active event due to muscle contraction
  • A process that occurs during asthma
  • A process that occurs during exercise
  • A passive event due to elastic recoil of the lungs (correct)

Why do the internal intercostal muscles and the anterior abdominal muscles contract during expiration?

<p>To accelerate expiration (A)</p> Signup and view all the answers

How are the lungs attached to the chest wall?

<p>They are indirectly attached to the chest wall through a thin layer of liquid (C)</p> Signup and view all the answers

What type of coupling exists between the lungs and the chest wall?

<p>Liquid coupling (C)</p> Signup and view all the answers

What is the shape of the thoracic cage?

<p>Conical (C)</p> Signup and view all the answers

How many apertures (openings) does the thoracic cage have?

<p>Two (A)</p> Signup and view all the answers

What happens to the diaphragm during inspiration?

<p>It contracts and moves downward (C)</p> Signup and view all the answers

What is the name of the movement of the ribs during normal inspiration?

<p>Pump handle movement (A)</p> Signup and view all the answers

Which muscle is the most important inspiratory muscle?

<p>Diaphragm (B)</p> Signup and view all the answers

What is the name of the joint that bounds the inferior opening of the thoracic cage anteriorly?

<p>Xiphisternal joint (A)</p> Signup and view all the answers

Which muscle increases the antero-posterior diameter of the thoracic cavity during forced inspiration?

<p>Pectoralis major (B)</p> Signup and view all the answers

Which of the following muscles acts as a rib depressor during forced expiration?

<p>Internal intercostal (D)</p> Signup and view all the answers

Which nerve supplies the intercostal muscles?

<p>Intercostal nerves (B)</p> Signup and view all the answers

Where do the intercostal vessels and nerve lie in relation to the internal intercostal muscle?

<p>Behind the internal intercostal muscle (A)</p> Signup and view all the answers

Which of the following muscles helps in compression of abdominal viscera to aid in ascent of the diaphragm during forced expiration?

<p>Rectus abdominis (B)</p> Signup and view all the answers

What is the origin of the sternal part of the diaphragm?

<p>Xiphoid process of sternum (B)</p> Signup and view all the answers

Which muscle is responsible for elevating the 1st and 2nd ribs during inspiration?

<p>Scalene muscles (B)</p> Signup and view all the answers

What is the nerve supply of the diaphragm?

<p>Phrenic nerve (C3, 4, 5) (A)</p> Signup and view all the answers

What is the action of the diaphragm during contraction?

<p>Increase vertical diameter of thoracic cavity (A)</p> Signup and view all the answers

What is the insertion of the diaphragm?

<p>Central tendon (C)</p> Signup and view all the answers

What is the direction of the fibers of the external intercostal muscle?

<p>Downward, forward, and medially (C)</p> Signup and view all the answers

What is the maximal volume of air inhaled after a normal expiration?

<p>3.6 L (D)</p> Signup and view all the answers

What is the volume of gas that remains in the lung at the end of a passive expiration?

<p>2-2.5 L (B)</p> Signup and view all the answers

What is the volume of gas that remains in the lung after maximal expiration?

<p>1-1.2 L (D)</p> Signup and view all the answers

What is the maximal lung volume that can be achieved voluntarily?

<p>5-6 L (A)</p> Signup and view all the answers

What is the volume of air moved between TLC and RV?

<p>4-5 L (B)</p> Signup and view all the answers

What is the technique used to measure Functional Residual Capacity (FRC) and Residual Volume (RV)?

<p>Helium Spirometry (A)</p> Signup and view all the answers

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Study Notes

Muscles of Respiration

  • Pectoralis major: involved in forced inspiration, origins from sternum and costal cartilages, inserts into humerus, and increases antero-posterior diameter of thoracic cavity when arm is fixed
  • Scalenus posterior: involved in forced inspiration, origins from cervical vertebrae, and inserts into 1st and 2nd ribs
  • Rib depressors: involved in forced expiration, includes internal intercostal, innermost intercostal, subcostals, and transversus thoracis muscles
  • Anterior abdominal wall muscles: involved in forced expiration, includes external oblique, internal oblique, transversus abdominis, and rectus abdominis muscles

Inspiration and Expiration

  • Inspiration: active process involving contraction of diaphragm and rib elevators, increases vertical and antero-posterior diameter of thoracic cavity
  • Expiration: passive process due to elastic recoil of lungs, but can be active during forced expiration involving contraction of internal intercostal and anterior abdominal muscles

Diaphragm

  • Structure: dome-shaped, separates thoracic and abdominal cavities, and is the most important muscle of inspiration
  • Action: contraction moves downward and rotates ribs, increasing vertical diameter of thoracic cavity
  • Origin: costal (lower 6 ribs and costal cartilages), sternal (xiphoid process), and vertebral (upper 3 lumbar vertebrae)
  • Insertion: central tendon
  • Nerve supply: phrenic nerve (C3,4,5)

Thoracic Cage

  • Structure: conical in shape, formed by sternum and costal cartilages anteriorly, ribs and intercostal spaces laterally, and thoracic vertebrae posteriorly
  • Apertures: superior (thoracic outlet) and inferior (closed by diaphragm)

Respiratory Movements

  • Diaphragm movement: inspiration (contraction and descent), expiration (relaxation and ascent)
  • Rib movement: pump handle (elevation of ribs, increasing antero-posterior diameter of thoracic cavity) and bucket handle (elevation of ribs, increasing lateral diameter of thoracic cavity)

Lung Volumes and Pulmonary Function Tests

  • Total Lung Capacity (TLC): 5-6 L, maximum lung volume achieved voluntarily
  • Vital Capacity (VC): 4-5 L, volume of air moved between TLC and RV
  • Functional Residual Capacity (FRC): 2-2.5 L or 40% of TLC, volume of gas remaining in lung at end of passive expiration
  • Residual Volume (RV): 1-1.2 L, volume of gas remaining in lung after maximal expiration
  • Inspiratory Capacity (IC): 3.6 L, maximum volume of air inhaled after normal expiration
  • Total Minute Volume: 6 L/min at rest, increases to 100-200 L/min during exercise

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