Respiratory System 1

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Respiratory System 1
2011-05-24 00:18:03

NPB101- Exam3
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    • author "colorpencil1"
    • tags "NPB101 "
    • description "Midterm 3"
    • fileName "NPB 101.txt"
    • Respiration
    • the process of obaining O2 from the environment and eliminating CO2 from the body.
  2. What are the 4 steps of breathing?
    • Breathing- physical exchange of gas btwn the environment and the alveoli.
    • Alveolar gas exchange- exchange of O2 and CO2 btwn gas in the alveoli and blood in the pulmonary capillaries.
    • Gas transport- the transport of O2 and CO2 by the blood from the lungs to the tissues of the body.
    • Blood gas exchange- the exchange of O2 and CO2 btwn the blood and the tissues.
  3. What are the steps of External Respiration?
    • Ventilation or gas exchange btwn the atmosphere and air sacs (alveoli) in the lungs.
    • Exchange of O2 and CO2 btwn air in the alveoli and the blood.
    • Transport of O2 and CO2 btwn the lungs and the tissues.
    • Exchange of O2 and CO2 btwn the blood and the tissues.
  4. What is Internal (Cellular) Respiration?
    • Intracellular metabolic processes that take place w/in mitochondria.
    • Where the following reaction takes place:
    • Food + O2 -> CO2 + H2O + ATP
  5. What is External Respiration?
    Exchange of O and CO btwn the environment and the cells of the body.
  6. The Anatomy of the Respiratory System.
    (the system responsible for the first two stages of external respiration)
    • nasal passages- nose
    • pharynx- common passageway for the lungs and the stomach.
    • larynx- voice box located at the entrance to the trachea.
    • trachea- tube through which air is conducted to the lungs.
    • brochi- division of the trachea into 2 main branches.
  7. What are Alveoli?
    (Anatomy from Bronchi)
    • small, thin-walled sacs where gas exhcange takes place.
    • -tiny, air-filled chambers (~300um in diameter) w/in the lungs that serve as the site for the exchange of O2 and CO2 w/the blood.
    • Attached to brachioles: small branches of the respiratory airway.
  8. Microscopic Anatomy of an Alveolus
    • Type I cell: form the walls of the alveoli.
    • Type II cells: secrete a pulmonary surfactant that acts to reduce the surface tension of the water inside the alveoli.
    • Each alveolus is in very close proximity to pulmonary capillaries.
  9. The Lungs are...
    • a pair of organs consisting of the lower portion of the respiratory airways, the pulmonary circulation, and connective tissue.
    • Pleural Sacs- a pair of thin, fluid-filled, membranes that enclose the lungs. the space btwn the pair of membranes is referred to as the pleural cavity.
  10. Respiratory Mechanics
    a gradient in pressure btwn the alveoli and the atmosphere provides the force to move air into and out of the lungs.
  11. Pressures important in ventilation...
    • Atmospheric pressure- pressure exerted by the weight of the gas in the atmosphere on objects on Earth's surface (760 mm Hg at sea level)
    • Intra-alveolar pressure- the pressure w/in the alveoli (760 mm Hg when equilibrated with atmospheric pressure)
    • Intrapleural pressure- pressure w/in the pleural sac (the pressure exerted outside the lungs w/in the thoracic cavity 4mm Hg less than atmospheric pressure - 756 mm Hg)
    • Intra-pleural fluid cohesion- the force acting to attract two surfaces when they are separated by a layer of fluid.
    • Transmural pressure gradients
  12. Transmural pressure gradients are...
    • differences in pressure btwn the intra-pleural space and the intra-alveolar and atmospheric spaces.
    • helps ensure that the lungs maintain close proximity to the thoracic wall.
  13. Pneumothorax is...
    • An extremely dangerous condition that occurs when air is allowed to enter the plural cavity (either by a puncture wound in chest, or a hole in lung).
    • -As a result, the transmural pressure gradient is lost and the lungs and thorax separate and assume their own inherent dimensions (lungs collapse and thoracic wall expands).
  14. Boyle's law
    • At any constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas.
    • Restated:
    • decreased gas volume -> increased pressure exerted by gas
    • increased gas volume -> decreased pressure exerted by gas
  15. Changes in lung volume and intra-alveolar pressure during inspiration and expiration.
    • Before inspiration- system is equilibrated; no net movement of air.
    • During inspiration- size of teh lungs increases as they are stretched to fill the expanded thorax.
    • as the lungs increase in volume, intra-alveolar pressure decreases creating a pressure gradient that favors the flow of air into the alveoli.
    • During expiration- as the lungs recoil to their pre-inpiratory size, intra-alveolar pressure increases, establishing a pressure gradient that favors the flow of air out of the alveoli into the atmosphere.
  16. Intra-alveolar & intrapleural pressures during respiration...
    • Throughout the respiratory cycle, intra-pleural pressure is always less than intra-alveolar pressure. Thus, a transmural pressure gradient always exists that serves to stretch the lungs to fill the available thoracic space.
    • When intra-alveolar pressure is less than atmospheric pressure, air enters the lungs. When intra-alveolar pressure is greater than atmospheric pressure, air exits the lungs.
  17. Respiratory Muscles
    • Accessory muscles of inspiration- contract only during forceful inspiration.
    • Major muscles of inspiration- contract every inspiration; relaxation causes passive expiration.
    • Muscles of active expiration- contract only during active expiration.
  18. Inspiration...
    • Diaphragm- contracts increasing the vertical dimensions of the thoracic cavity.
    • External intercostal muscles- contract elevating the rib cage and increasing the thoracic cavity form side-to-side and front-to-back.
    • (a) Elevation of ribs causes sternum to move upward and outward, which increases front-to-back dimension of thoracic cavity.
    • (b) Lowering of diaphragm on contraction increases vertical dimension of thoracic cavity.
    • (c) Contraction of external intercostal muscles causes elevation of ribs, which increases side-to-side dimension of thoracic cavity.
  19. Expiration...
    • Passive expiration- the ribs, sternum, and diaphragm return to resting position upon relaxation of the inspiratory muscles.
    • Active expiration- contraction of abdominal muscles causes the diaphragm to be pushed upward, further reducing the vertical dimension of thoracic cavity.
    • Also, contraction of internal intercostal muscles flattens the ribs and sternum further reducing the size of the thoracic cavity.
    • (a) Contraction of internal intercostal muscles flattens ribs and sternum, further reducing side-to-side and front-to-back dimensions of thoracic cavity.
    • (b) Return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size.
    • (c) Contraction of abdominal muscles causes diaphragm to be pushed upward, further reducing vertical dimension of thoracic cavity.
  20. Airway resistance...
    • influences airflow
    • F= ΔP/R
    • where...
    • F= airflow rate
    • ΔP= difference btwn atmospheric and intra-alveolar pressure.
    • R= resistance of the airways, determined by their radius.
  21. Bronchoconstriction
    • A decrease in the radius of bronchioles.
    • resistance due to a in radius
    • caused by:
    • contraction of airway smooth muscle
    • - parasympathetic nervous stimulation
    • - CO2 concentrations
    • -allergies
    • physical factors such as mucous, edema, airway collapse
  22. Bronchodilation
    • An increase in bronchiolar radius.
    • resistance due to radius
    • caused by:
    • relaxation of airway smooth muscle
    • - sympathetic nervous stimulation
    • - hormonal control: epinephrine
    • - CO2 concentrations
  23. Chronic Obstructive Pulmonary Disease (COPD) is...
    What are the the 3?
    • a group of lung diseases characterized by increased airway resistance resulting from narrowing of the lumen of the lower airways. (pathalogical increase in airway resistance)
    • 1) Chronic Bronchitis: long-term inflammatory responses to irritants, pathogens or allergens lead to thickening and edema of the airway walls and overproduction of thick mucus.
    • 2) Asthma: long-term inflammatory responses to irritants, pathogens or allergens lead to thickening and edema of the airway walls, overproduction of thick mucous, and hyper-resonsiveness of airway smooth muscle.
    • 3) Emphysema: macrophage enzynes released in response to irritants cause collapse of airways and breakdown of alveolar walls. Many alveoli can burst and then enlarge.
  24. Elastic recoil is the...
    • force that restores the lungs to their preinspiratory volume after the inspiratory muscles relax at the end of inspiration.
    • Due to:
    • elastic properties of pulmonary tissue- elastin fibers are arranged in a meshwork that provides the tissue with a high degree of elasticity.
    • alveolar surface tension- force due to the attraction of water molecules to each other; opposes expansion of the alveoli.
    • Alveolar surface tension is reduced by a pulmonary surfactant (mixture of lipids and proteins) synthesized by type II alveolar cells.
  25. Surfactant...
    plays a major role in preventing the collapse of small alveoli.
  26. Law of LaPlace