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Medicine Notes Respiratory System Notes

Respiratory Pump And Respiratory Cycle Notes

Updated Respiratory Pump And Respiratory Cycle Notes

Respiratory System Notes

Respiratory System

Approximately 49 pages

These notes are on the Respiratory System of the human body. helped me achieve a mark of 68% in my respiratory exam, which is the equivalent of a 2:1. The notes are based on a series of lectures on the subject. They are very clearly laid out and easy to follow. They cut out unnecessary information on the topic, making the notes very concise, and fast to get through. Anyone studying medicine, or any other subject requiring knowledge of the Respiratory system (e.g. physiology or anatomy), would ben...

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Lecture 5

Respiratory pump and respiratory cycle

  • Describe the functional anatomy of the respiratory pump including innervation of diaphragm & intercostals muscles

    • Respiratory pump

      • Mechanism that helps to pump blood back to the heart during inspiration

      • Intrathoracic pressure decreases during inspiration, causing the pressure in the atria of the heart to drop to around 2.1kPa

      • Aspirating blood towards the right atrium from the thoracic vein

    • Diaphragm

      • Sheet of internal skeletal muscle that extends across bottom of the rib cage

      • In inhalation, the diaphragm contracts, thus enlarging the thoracic cavity

      • Reduces intra-thoracic pressure, & creates suction that draws air into lungs

      • Innervation by phrenic nerve

    • Intercostal muscles

      • Groups of muscles that run between the ribs, & help form & move chest wall

      • External intercostal muscles, which aid in quiet and forced inhalation

      • Internal intercostal muscles, which aid in forced expiration

      • External & internal muscles are innervated by the intercostal nerves

  • List muscles of inspiration and expiration t rest, during exercise & during respiratory distress

    • Diaphragm

    • Intercostal muscles

      • External

        • Assist in deep inspiration by increasing the anterioposterior diameter of the chest

      • Internal

        • Assist in expiration by pulling the ribcage down

      • Innermost

        • Aid in forced expiration

    • Accessory muscles of respiration

      • Sternocleidomastoid; Scalene; Serratus anterior; Pectoralis major and minor; Upper trapezius; Latissimus dorsi; Erector spinae (thoracic); Iliocostalis lumborum; Quadratus lumborum; Serratus posterior superior and inferior; Levatores costarum; Transversus thoracis; Subclavius

  • Describe the intrapleural space

    • Space between two membranes in the lung (visceral and parietal)

    • Contains a thin layer of fluid

  • Explain why intrapleural pressure is negative

    • Intrapleural/Intrathoracic pressure at FRC= -5cmH2O (5cm water below atmosphere)

    • If FRC is atmospheric pressure, there is no gas flow

    • Lungs want to collapse and ribs want to expand, creating negative suction pressure

    • Breathing in is active, and breathing out is passive

  • Outline the measurement of intrapleural pressure

    • Directly by introducing a needle to pleural cavity

    • Indirect method: by introducing the oesophageal balloon into oesophagus

  • State typical values of intrapleural pressure at FRC & during inspiration for breathing at rest

    • At FRC= -5cmH2O

    • During inspiration the pressure is even more negative (8 cmH2O end of inspiration)

      • Lung volume increases, the elastic recoil of the lungs increases as well

  • Describe & explain changes that occur in intrapleural pressure, alveolar pressure, gas flow & lung volumes during respiratory cycle

    • Intrapleural pressure

      • Always negative

      • Reaches its lowest point at the end of inspiration

      • Collapsing force of the lung is the difference between intrapleural & intrapulmonary pressures

      • If intrapleural pressure is increased by that much the lung will collapse

    • Alveolar pressure

      • Lung expansion causes alveolar pressure to become negative & air enters

      • Inspiration stops when the entering air causes alveolar pressure to rise to atmospheric pressure

      • During expiration, the cycle is reversed, with decrease in lung size causing an increase in alveolar pressure

      • Air flows out of the lungs, alveolar pressure returns to atmospheric pressure

    • Gas flow

      • Inspiration=into the lungs; Expiration=out of the lungs

    • Lung volumes

  • Describe and explain the pathophysiology of simple pneumothorax & tension pneumothorax with particular emphasis upon intrapleural pressure and the effect on the CVS

    • Simple pneumothorax

      • Collection of air or gas in the pleural cavity between lung and the chest wall

      • Pleural space has (-) pressure, chest wall wants spring outward & lung's elastic recoil wants to collapse

      • If invaded by gas, lung collapses until equilibrium reached or rupture sealed

      • Decrease in vital capacity and partial pressure of oxygen

      • Pressure built up in cavity slows/stops return of blood to heart from veins

    • Tension pneumothorax

      • Progressive build-up of air within the pleural space, usually due to a lung laceration which allows air...

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