respiratory pt. 2 Flashcards
tidal volume =
500 ml
what makes up inspiratory capacity (IC)?
inspiratory reserve volume (IRV) + tidal volume (TV)
what makes up functional residual capacity (FRC)?
expiratory reserve volume (ERV) + residual volume (RV)
what makes up vital capacity?
inspiratory capacity (IC) + functional residual capacity (FRC)
what is obstructive pulmonary disease?
increased airway resistance ex: bronchitis
what is restrictive disease?
reduced TLC due to disease or exposure to environmental agents
ex: fibrosis
pulmonary function tests can measure _______ of gas movement
rate
pulmonary function tests
- forced vital capacity (FVC)
- forced expiratory volume (FEV)
what is forced vital capacity?
the amount of gas forcibly expelled after taking a deep breath
what is forced expiratory volume?
the amount of gas expelled during a specific time interval of FVC
what is alveolar ventilation rate?
flow of gases into and out of alveoli during a particular time
what is the better indicator of effective ventilation?
AVR
what does AVR consider?
the amount of dead space, TV, and rate of breathing
what is AVR affected by?
TV and frequency
what is dalton’s law of partial pressure?
total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas
nitrogen makes up ______ of air
78.6 %
oxygen makes up ______ of air
20.9%
alveoli contain more CO2 and water vapor than atmospheric air because of:
- gas exchanges in lungs
- humidification of air by conducting passages
- mixing of alveolar gas with each breath
exchange is influenced by:
- partial pressure gradients and gas solubilities
- thickness and surface area of the respiratory membrane
- ventilation-perfusion couple
what is ventilation-perfusion coupling?
matching of alveolar ventilation with pulmonary blood perfusion
arterial blood has ______ oxygen
high
venous blood has _______ oxygen
low
partial pressure gradient for CO2 is . . .
less steep
respiratory membrane are very . . .
thin
what is perfusion?
blood flow reaching alveoli
what is ventilation?
amount of gas reaching alveoli
why must ventilation and perfusion rates match?
optimal, efficient gas exchange
P-O2 controls perfusion by . . .
changing arteriolar diameter
P-CO2 controls ventilation by . . .
changing bronchiolar diameter
when alveolar O2 is high then arterioles . . .
dilate
when alveolar O2 is low then arterioles . . .
constrict
why is tissue P-O2 always lower than in arterial blood P-O2?
so oxygen moves from blood to tissues
why is tissue P-CO2 always higher than arterial blood P-CO2 ?
so CO2 moves from tissues into blood
molecular O2 is carried in blood in two ways:
dissolved in plasma
loosely bound to each Fe of hemoglobin in RBCs
each hemoglobin is composed of . . .
4 polypeptide chains
what is oxyhemoglobin?
hemoglobin-O2 combination
what is reduced hemoglobin (deoxyhemoglobin)?
hemoglobin that has released O2
loading and unloading of O2 is facilitated by what?
a change in shape of Hb
fully saturated:
all four heme groups carry O2
partially saturated:
when only one to three hemes carry O2
why is rate of loading and unloading of O2 regulated?
to ensure adeqaute oxygen delivery to cells
factors that influence hemoglobin saturation:
P-O2
other factors influencing hemoglobin saturation:
temperature
blood pH
P-CO2
concentration of BPG
what happens when there is a decrease in hemoglobin saturation?
shifts the curve to the left which is a decrease in oxygen unloading from blood
what is the bohr affect?
declining blood pH and increasing P-CO2 cause hemoglobin - O2 bond to weaken
hemoglobin dissociation curve (left & right)?
left = decrease
right = increase
OXYhemoglobin dissociation curve (left & right)?
left = increase
right = decrease
O2 carrying capacity of blood is ____________ upon the hemoglobin concentration
dependent
what is lower than normal O2 carrying capacity?
anemia
what is higher than normal O2 carrying capacity?
polycythemia
CO2 is transported to blood in three forms:
- dissolved in plasma
- chemically bound to hemoglobin
- as bicarbonate ion in the plasma
increased CO2 _________ blood pH
decreased CO2 _________ blood pH
decreased
increased
haldane effect
amount of CO2 transported is affected by PO2
the lower the PO2 and hemoglobin O2 saturation then . . .
the more CO2 can be carried in blood
changes in ____________ and _______ affect blood pH
what is hypoxia?
inadequate O2 delivery to tissues
anemic hypoxia:
too few RBCs or abnormal or too little Hb
ischemic hypoxia:
impaired or blocked blood circulation
histotoxic hypoxia:
cells unable to use O2 as in metabolic poisons
hypoxemic hypoxia:
abnormal ventilation; pulmonary disease, low levels of oxygen in air
respiratory rhythms are regulated by:
- higher brain centers (medullary and pons respiratory centers)
sets eupnea:
normal respiratory rate and rhythm
clustered neurons in two areas of medulla are most important:
ventral respiratory group
dorsal respiratory group
lesions in the pontine respiratory centers lead to . . .
apneustic breathing
respiratory centers are affected by:
- chemical factors
- influence of higher brain centers
- pulmonary irritant reflexes
- inflation reflex
what is the most potent and closely controlled factor influencing breathing rate and depth?
influence of PCO2
what is hypercapnia?
blood PCO2 levels rise
if blood PCO2 levels decrease respiration becomes . . .
slow and shallow
apnea
breathing cessation that may occur when PCO2 levels drop abnormally low
hyperventilation:
increased depth and rate of breathing that exceeds bodys need to remove CO2
what is hypocapnia?
decreased blood CO2 levels
what sense arterial O2 levels?
peripheral chemoreceptors in aortic and carotid bodies
Changes in arterial pH resulting from CO2 retention or metabolic factors act indirectly through
peripheral chemoreceptors
Normally, blood PO2 affects breathing only indirectly by
influencing peripheral chemoreceptor sensitivity to changes in PCO2
Hypothalamic controls
act through limbic system to modify rate and depth of respiration
Cortical controls
direct signals from cerebral motor cortex that bypass medullary controls
Pulmonary irritant reflexes
Receptors in bronchioles respond to irritants such as dust, accumulated mucus, or noxious fumes
Inflation reflex
Hering-Breuer reflex (inflation reflex)
