Patm at sea level
760mmHG (atmospheric pressure - pressure exerted by the air surrounding the body. =1atm)
what does negative respiratory pressure mean? Ex -4
pressure is lower than atmospheric (Patm) (ex: 756mmHg)
what does positive respiratory pressure mean?
pressure is higher than atmospheric (Patm)
what does zero respiratory pressure mean?
pressure is equal to atmospheric (Patm)
Pressure in the alveoli is called
intrapumonary pressure (Ppul) (rises and falls with breathing)
pressure in pleural cavity (btw lungs and rib cage) is called
intrapleural pressure (Ppip) ( fluctuates with breathing. almost always 4mmHG less than Ppul)
True or false: Ppul is always negative to Ppip
false (Ppip is always negative to Ppul b/c Ppip is always 4 mmHg less than Ppul. This helps prevent lung collapse)
why is Ppip being 4mmHg less than Ppul beneficial?
prevents lung collapse
muscles that increase volume of lungs by 500mL (aid in inspiration)
diaphragm (expands thorax downwards) and external intercostal muscles (expands upward and out)
what is the normal tidal volume of air that enters lungs with each inhalation?
during inspiration, an increase in lung volume expands the alveoli. What does this do to the pulmonary pressure?
Decreases it to 1mmHg less than atmospheric (759mmHg)
describe process of inhalation
VRG of medulla sends neurons out through phrenic and intercostal nerves and stimulate the diaphragm and external intercostal muscles to contract which will expand the lungs which increases lung volume. Increase in lung volume expands the alveoli causing pulmonary pressure to decrease to 1mmHg less than atmospheric. This allows air to flow in.
quiet expiration relies on what?
elasticity of the lungs
what happens to the volume of the thoracic cavity as inspiration muscles relax
what happens to the alveoli when there is a decrease in lung volume during expiration?
during expiration, what happens to pulmonary pressure when lung volume decreases and alveoli are compressed?
rises to 1mmHg above atmospheric
describe sequence of events in quiet expiration
as inspiration muscles relax, volume in lungs decrease. Decrease in volume causes alveoli to compress. This increases pulmonary pressure to rise to 1mmHg above atmospheric (air flows areas of high --> low pressure. so air is exhaled)
what muscles are used in forced expiration?
obliques and transverse abdominal muscles
what are the two physical factors influencing pulmonary ventilation?
1. airway resistance (increased resistance= decrease air flow) 2. lung compliance (more compliant "stretchy" = easier to expand the lungs)
inadequate o2 delivery to tissues. hemoglobin sat <75% skin cyanotic
type of hypoxia in which poor o2 delivery from too few RBC or too little/abnormal hemoglobin
hypoxia from impaired circulation
type of anemia when cells are unable to use 02 even though adequate amounts are being delivered. Occurs from cyanide poisoning
hypoxia of inadequate 02 delivery to tissues from low partial pressure of oxygen in the blood
physical factors influencing pulmonary ventilation
1. airway resistance (less resistance is better for gas flow)
e. lung compliance (higher the lung compliance, the easier to expand the lungs)
what are 3 things that may increase airway resistance?
1.inhalation of irritants 2. asthma attack 3. parasympathetic nervous system stimulation
name something that decreases pulmonary resistance
epinephrine (dilates bronchioles. Released during SNS)
2 factors that increase lung compliance
1. distensibility of the lung tissue (amt of stretch or expand)
2. alveolar surface tension (tendency of lungs to stick. Typically low b/c of lung surfactant)
factors influencing external respiration (o2-> blood and co2 -> lungs)
1. partial pressure (larger the gradient, slower the diffusion. O2 gradient is bigger. Co2 capable of diffusing faster) 2. ventilation-perfusion coupling (Ventilation- amt of gas reaching alveoli. perfusion- amt of blood reaching alveoli should be equal.) 3. respiratory membrane (thinner membrane= more efficient gas exchange)
condition in which there is too much fluid in lungs. Causes membrane to thicken which decreases gas exchange efficiency.
primary rhythm generator for respiration. Contains neurons that fire to control inspiration and inhibit during expiration.
ventral respiratory group (VRG) (when neurons leave VRG, travel out to phrenic and intercostal nerves. stimulate contraction of diaphragm and ribcage.)
where is the VRG (ventral respiratory group) located?
normal respirations (eupnea)
site within the NS that transmits impulses to VRG of Medulla to modify and fine tune breathing rhythm
pontine respiratory centers
prolonged inspiration with pause at end followed by expiration. Often occurs when lesions are made to the superior region of the pontine respiratory center.
where are central chemoreceptors located (sense changing levels of Co2, O2, Ph
medulla (regulates PCO2. Stimulated when CSF ph drops from hypercapnea "Pco2 is too much". stimulates respiratory centers to increase rater and depth of bleeding)
where are the peripheral chemoreceptors located (sense changing levels of CO2, O2, Ph)
aortic arch and carotid arteries (Stimulated when P02 drops below 60 mmHg)
why does hyperventilation occur?
to remove co2 because too much and too acidic
2 ways 02 is transported in the blood
1. hemoglobin 2. dissolved in plasma
3 ways co2 is transported in the blood
1. hemoglobin 2. dissolved in plasma 3. as bicarbonate ion in plasma
what enzyme in the RBC can reversibly catalyze (speed up) conversions of co2 + h20 = carbonic acid?
leading cause of cancer death for men and women in north america
a hereditary disorder characterized by lung congestion and infection and malabsorption of nutrients by the pancreas. Abnormally sticky and viscous mucus that clogs up resp tract
infectious disease caused by a bacterium that is spread by coughing and inhaled air. Active and latent forms. Sx of active: fever, night sweats, weight loss, hacking cough, spitting up blood.