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E&I respiration
Week 1 - external and internal respiration
Question | Answer |
---|---|
Why is external respiration carried out? | To meet the respiratory demands of cells |
What is internal respiration? | The absorption of oxygen and release of carbon dioxide from those cells |
What are the three steps involved in external respiration? | Pulmonary ventilation, gas diffusion and transport of oxygen and carbon dioxide |
Why does the parietal pleura follow the ribs when they move up and down? | When the ribs move upwards and outwards during inspiration the parietal fluid follows them. Due to the cohesion of water, the visceral pleura follows the parietal pleura and this stretches the alveoli along with the lungs, so the entire lung expands |
What is the intrapleural pressure? | A slight vacuum between the two pleura which usually measures -4mmHg and drops to -6mmHg during inspiration |
What makes air flow into the lungs? | Pressure gradient between the atmospheric pressure, intrapleural pressure, and intrapulmonary pressure |
What causes expiration? | Elastic recoil of the thoracic cage. This compresses the lungs and raises the intrapulmonary pressure to about +3mmHg so air flows down its pressure gradient out of the lungs |
What is Boyle's law? | The pressure of a given quantity of gas is inversely proportional to its volume (assuming a constant temperature) |
What is Charles' law? | the volume of a given quantity of gas is directly proportional to its absolute temperature (assuming a constant temperature) |
What is Dalton's law? | The total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases |
What is Henry's law? | At the air-water interface, the amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in the air (assuming a constant temperature) |
What are the 9 accessory respiratory muscles? | Internal intercostal, sternocleidomastoid, serratus anterior, pectoralis minor, scalene, transverse thoracis, transverse abdominis, external and internal oblique, rectus abdominis muscle |
Which muscles are used during inhalation? | -Contraction of diaphragm flattens floor of thoracic cavity, increasing its volume -Contraction of the external intercostal muscles raise the ribs -Contraction of the accessory muscles can assist the external intercostal muscles in elevating the ribs |
What muscles can be used during exhalation? | Internal intercostal and transversus thoracic muscles depress the ribs. The abdominal muscles can assist the intercostal muscles in exhalation by compressing the abdomen |
What muscle elevates the sternum? | Sternocleidomastoid muscle |
What do the scalenes do? | Fix or elevate the first or second ribs |
What muscle elevates ribs 3-5? | Pectoralis minor |
Which muscles depress ribs 1-11 and narrow the thoracic cavity? | Internal intercostal muscles |
What are the two different modes of breathing? | Quite breathing (eupnea) and Forced breathing |
Which muscles are involved during quiet breathing? | Diaphragm and external intercostal muscles |
What are the different types of quiet breathing? | Diaphragmatic (deep breathing) and Costal (shallow breathing) |
What happens during diaphragmatic breathing? | Contraction of the diaphragm provides necessary changes in thoracic volume. Air is drawn into the lungs as the diaphragm contracts, air is exhaled passively when the diaphragm relaxes |
What happens during costal or shallow breathing? | Thoracic volume changes because the rib cage alters its shape. Inhalation takes place when contractions of the external intercostal muscles raise the ribs and enlarge the thoracic cavity. Exhalation takes place passively when these muscles relax |
What is elastic rebound? | Expansion of the lungs stretches their elastic fibres and elevation of the ribcage stretches opposing skeletal muscles and elastic fibres in the connective tissues of the body wall. When the muscles of inhalation relax, the elastic components recoil |
What is forced breathing? (Hypernea) | Accessory organs assist with inhalation, and exhalation involves contraction of the internal intercostal muscles |
When do the abdominal muscles take part in exhalation? | At absolute maximum levels of forced breathing - they contract to durther reduce the volume of the thoracic cavity |
What are the oxygen needs of the body at rest? | 250 ml/min |
What is the carbon dioxide production of the body at rest? | 200 ml/min |
What connective tissue fibres are responsible for the elastic recoil of the lung? | Collagen and (particularly) elastin |
What is Ppl? What is Palv? What is Patm? | Ppl= pleural pressure Palv = alveolar pressure Patm = atmospheric pressure |
Is Ppl or Palv more negative? | Pleural pressure will be negative with respect to alveolar pressure |
What is functional residual capacity? | The lung volume at the point where respiratory muscles are relaxed |
Describe the pressures at functional residual capacity? | Palv= Patm so no air flow |
What pressure is necessary for inspiration? | Patm>Palv |
What pressure is necessary for expiration? | Palv>Patm |
What is airway resistance proportional to? | lenfth/radius^4 |
How can you calculate pulmonary ventilation? | tidal volume x respiration rate (Vt x f) |
What is the typical anatomical dead space value? | 0.15L |