Ch 18 Flashcards
areas of the brain that regulate breathing
medulla and pons
oxygen and Co move into and out of the blood at
pulmonary and systemic capillaries
oxygen exchange occurs at
alveolar-capillary interface
oxygen is transported via
hemoglobin
oxygen is exchanged with cells for
carbon dioxide
CO2 is exchanged from
capillaries to alveoli
fisk’s law of diffusion states
diffusion rate = (SA x conc gradient x permeability) / membrane thickness
which factor is most important to diffusion rate
concentration gradient
moving from a gas to a liquid is directly proportional to which factors
pressure gradient
solubility
temperature
is O2 or CO2 more soluble
CO2 is much more soluble`
partial pressures of O2 in circulation
alveoli - 100 mm Hg
oxygenated tissue - 100 mm Hg
peripheral tissue - <40 mm Hg
de-oxygenated tissue - 40 mm Hg
partial pressures of CO2 in circulation
alveoli - 40 mm Hg
oxygenated tissue - 40 mm Hg
peripheral tissue - >46 mm Hg
oxygenated tissue - 46 mm Hg
types of hypoxia
hypoxic - low O2
anemic - low O2 bound to Hb
Ischemic - reduced blood flow
Histotoxic - failure to use O2 bc poison
hypercapnia
too much Co2
cause system to panic
emphysema effect on alveolar ventilation
destruction of alveoli means less SA for gas exchange
Gibrotic lung dieseas effect on alveolar ventilation
thickening of alveolar membrane slows gas exchange
loss of lung compliance may decrease alveolar ventilation
pulmonary edema
fluid in interstitial space increases diffusion distance
CO2 levels may not be altered
asthma
increased airway resistance decreases alveolar ventilation
oxygen diffuses across ______ to enter the plasma
alveolar epithelial cells and capillary endothelial cells
gas transport in the blood begins with
O2 leaving alveoli for blood bc of low partial pressure in blood
once in the blood, 98% of O2 _____ while the other 2% _____
binds to hemoglobin;
dissolves in plasma
hemoglobin and O2 dissolved in plasma both
transport to cells and exit the blood
physical factors that alter Hb affinity for O
pH, temperature, P(CO2), 2,3-DGP
an increase in pH ____ HbO binding
increases; more basic
an increase in temperature ____ HbO binding
decreases
an increase in P(CO2) ____ HbO binding
decreases;
CO2 competes for binding sites
an increase in 2,3-DPG ____ HbO binding
decreases;
a normal amount is needed so that O will stay bound long enough to be delivered
percentages of CO2 in transport
dissolved: 7%
converted to bicarbonate ion: 70%
bound to Hb: 23%
before being converted to bicarbonate, CO2 becomes
carbonic acid
bicarbonate has the ability to
dissolve in plasma and act as a buffer
stimuli for reflex control of ventilation
emotions, CO2, O2`=
integrating centers for stimuli
emotions - higher brain centers + limbic
all - MO and pons
sensory receptors for stimuli
Co2 - medullary chemoreceptors
CO2 and O2 - carotid and aortic chemoreceptors
respiratory neurons in the medulla control _____ while neurons in the pons modulate ______
inspiration and expiration;
ventilation
peripheral chemoreceptors properties
-located in carotid and aortic arteries
-specialized glomus cells
-sense changes in PO2, pH and PCo2 central chemoreceptors
