exam 4- respiratory and renal Flashcards
intrapulmonary or alveolar pressure
Pa (P sub a)
equals the atmospheric pressure at rest
altered by changes in the lung volume
with lung expansion, Pa falls below atmospheric pressure and air flows in
with lung compression, Pa rises above atmospheric pressure and air flows out
intrapleural pressure
Ppl (P sub pl)
sub-atmospheric at rest
determined by lungs and chest wall
always more negative than Pa
transpulmonary pressure
Pa-Ppl
pressure difference across lung
determines lung volume
atmospheric pressure
Patm
760 mmHg
what determines how compliant a lung is?
lung structure
surface tension
higher surface tension resists expansion
respiratory distress syndrome
premature babies type 2 alveoli do not develop (no surfactant) causes collapsed alveoli
fluid gets in lungs instead of air
elastic recoil
the ability for the lung to bounce back into shape after being inflated
just because it is very compliant does not mean it is necessarily good on elastic recoil
where does gas exchange happen in the lungs
respiratory zone
how do gases move between blood and air
diffusion due to concentration or partial pressure gradient
partial pressure of H2O in inspired air
variable (depends on humidity)
partial pressure of CO2 in inspired air
000.3 mmHg
partial pressure of O2 in inspired air
159 mmHg
partial pressure of N2 in inspired air
601 mmHg
total pressure of inspired air
760 mmHg
partial pressure of H2O in alveolar air
47 mmHg (humidification)
partial pressure of CO2 in alveolar air
40 mmHg (produced)
partial pressure of O2 in alveolar air
100 mmHg (used)
partial pressure of N2 in alveolar air
568 mmHg (makes room for water)
total pressure in alveolar air
760 mmHg
what determines the amount of each gas dissolved in liquid
temperature of the fluid
partial pressure of the gas
solubility of the gas
is O2 soluble in plasma
no
what do red blood cells have?
hemoglobin which increases oxygen concentration in blood (4 binding sites for oxygen on each hemoglobin)
what causes an O2 left shift (more binding affinity)
pH rise / H+ drop
pCO2 drop
temperature drop
2,3-DPG drop
what causes an O2 right shift (less binding affinity)
pH drop / H+ rise
pCO2 rise
temperature rise
2,3-DPG rise
What does CO2 transport in the blood consist of? (3 things)
HCO3 (70%)
dissolved CO2 (10%)
carbaminohemoglobin (20%) this is just CO2 in red blood cells
explain how CO2 is transported in the blood
H2O and CO2, through carbonic anhydrase (ca), get made into H2CO3, which turns into H+ and HCO3
what is the gradient of CO2
it moves from pulmonary blood into the alveolar air
eupnea
normal quiet breathing
hyperpnea
increased respiratory rate and/or volume in response to increased metabolism (ex:exercise)
hyperventilation
increased respiratory rate and/or volume without increased metabolism (ex: emotional hyperventilation, blowing up a balloon)
hypoventilation
decreased alveolar ventilation (ex: shallow breathing, asthma, restrictive lung disease)
tachypnea
rapid breathing, usually increased respiratory rate with decreased depth (ex: panting)
dyspnea
difficulty breathing (ex: various pathologies or hard exercise)
apnea
cessation of breathing (ex: voluntary breath-holding, depression of CNS control centers)
emphysema
destructive disease
decreased alveoli -> decreased surface area -> decreased gas exchange
decreased elastic recoil of lung
increased lung compliance
alveolar PO2 normal or low
plasma PO2 low
fibrotic lung disease
restrictive disease
thicker alveoli -> increases distance for diffusion -> slows gas exchange
loss of lung compliance
black lung (inhalation of particulate matter)
alveolar PO2 normal or low
plasma PO2 low
asthma
obstructive disease
increased airway resistance -> decreased ventilation
bronchioles restricted
alveoli PO2 low
plasma PO2 low
COPD
a mix of emphysema (destructive) and chronic bronchitis (obstructive)
treatment: stop smoking, avoid lung irritants, medicines, surgery
walls of alveoli are destroyed, bronchioles clogged with mucus
tidal volume
the amount of air going in and out of the lungs with each respiratory cycle (breathe in and out)
residual volume
the amount of volume in the lungs after you breathe all the way out
vital capacity
breathe all the way in and all the way out
total lung capacity
vital capacity plus residual volume
what does the forced vital capacity of someone with emphysema look like
due to collapsed airways, the FVC is smaller. the gas becomes trapped and cannot be exhaled
what do we use FEV1/FVC for
used to diagnose obstructive and restrictive lung diseases
it is the proportion of a person’s vital capacity that they can exhale in the first second of forced exhalation to the full FVC
restrictive disease FEV1/FVC
(ex: black lung)
ratio is similar to normal ratio, but there’s less volume
2.5/2.6 = .96 (restrictive)
4.0/4.5 = .89 (normal)
mild obstructive disease FEV1/FVC
(ex: asthma)
the resistance to air flow is higher, it’s gonna take this person longer to move the air and exhale
this reduces the ratio
severe obstructive disease FEV1/FVC
(ex: COPD)
harder to move the air, increases resistance and decreases FVC due to gas trapping (lowest ratio)
pulmonary edema
excess interstitial fluid increases the diffusion distance, taking longer for the diffusion to happen
congestive heart failure
alveolar PO2 normal
plasma PO2 low
pneumonia
infection of one or both of the lungs where the alveoli fill with pus and other liquid
COVID-19
can cause lasting lung damage (fibrosis)
fluid enters alveolus and disrupts normal gas exchange
alveoli can collapse due to fluid and loss of surfactant
obstructive sleep apnea
decreased PO2 of alveoli -> decreased arterial PO2 and increased arterial PCO2
three receptor types for reflexive automatic pathways
unmyelinated C fibers
rapidly adapting receptors
pulmonary stretch receptors
unmyelinated C fibers
respond to bradykinin (a peptide that promotes inflammation) and histamine (injury)
produces rapid/shallow breathing (pain)
rapidly adapting receptors
located in airway mucosa
respond to inhaled irritants (smoke causes coughing)
stimulates cough
pulmonary stretch receptors
aka hering-breuer reflex
sense lung volume, expansion reduces inspiration effort
important for normal breathing pattern in infants
prevents over expansion of the lung
Rf
respiratory frequency (breaths/min)
Vt
tidal volume (ml)
Vd
anatomical dead space
minute ventilation
Rf x Vt
alveolar ventilation
Rf x (Vt-Vd)
central hypoventilation syndrome
loss of automatic respiratory pathway
must be awake to voluntarily control breathing
this is rare, but it demonstrates that there are 2 pathways: voluntary and involuntary
conscious voluntary breathing path
cerebral cortex -> spinal cord (somatic motoneurons to skeletal respiratory muscles) -> chemoreceptors activated -> medulla oblongata
what do chemoreceptors do
monitor changes in arterial blood PCO2 and pH
central chemoreceptors
medulla, primarily sense PCO2 via pH of cerebral spinal fluid
peripheral chemorecptors
carotid and aortic bodies, primarily sensing for PCO2 (this dictates your 12 breaths/min) / H+, will sense PO2 if it drops significantly
path to chemoreceptors
CO2 starts in arteries, crossed blood brain barrier and gets diffused into cerebrospinal fluid. then CA turns it into HCO3 and H+, which is what activates the chemoreceptors in medulla oblongata
ventilation rates
normal ventilation PCO2=40
hypoventilation = increase in PCO2
hyperventilation = decreased arterial PCO2
what must arterial PO2 do before activation?
it must drop significantly (to about 60 mmHg) before activating peripheral chemoreceptors to increase ventilation back up to 100 mmHg
cardiac output at rest
5 L/min
cardiac output during exercise
25 L/min
percentages of cardiac output by organ during exercise
GI = 3-5%
heart = 4-5%
kidney = 2-4%
bone = 0.5-1%
brain = 3-4%
skin = variable
skeletal muscle = 80-85%
percentages of cardiac output by organ during rest
GI = 20-25%
heart = 4-5%
kidney = 20%
bone = 3-5%
brain = 15%
skin = 4-5%
skeletal muscle = 15-20%
what does ventilation do during exercise
it continues to increase so that everything else (blood gases) remain constant. however, once the ventilation gets beyond aerobic metabolism, then different systems have to jump in and create ATP and these systems tend to lower arterial pH, which sends a signal to activate chemoreceptors to cause hyperventilation
compliance
the ability for a lung to stretch
which gas has the biggest increase in alveolar partial pressure when compared to that found in warm humid atmospheric air?
carbon dioxide
lung compliance is likely to be decreased by
increased fibrosis
what occurs first in active expiration?
expiratory muscles contract
at rest, what is the normal PCO2 in the pulmonary artery of a healthy person?
46 mmHg
which value is about the same in both the pulmonary and the systemic circulations?
total blood flow per minute
which part of the brain is most important in determining the respiratory pattern for a person that is doing spirometric measurements like a forced vital capacity?
cerebral cortex
expiration of alveolar gas:
can follow contraction of the expiratory muscles
the volume of air inhaled between the FRC and a maximal inspiration is the:
inspiratory capacity
emphysema, a pulmonary blood clot, and lung cancer are all likely to:
decrease the surface area for gas exchange
hemoglobin in systemic arterial blood is usually described as:
fully saturated with oxygen
the oxygen-hemoglobin dissociation curve:
has a plateau portion that facilitates O2 loading in the lungs
the oxygen-hemoglobin dissociation curve is shifted rightward by increasing which property in the blood?
2,3-DPG
70% of CO2 in the blood is transported in what form?
HCO3-
when a patient secretes large amounts of mucus into the airways, you would expect the mucus to _________ the lumen of the conducting zone, __________ the resistance to airflow, and ________ the volume of dead space
narrow
increase
decrease
which aspect of blood chemistry elicits the greatest increase in activity of the peripheral chemoreceptors?
arterial PO2 less than 60 mmHg
when someone visits a region of high altitudes, what is the primary sensed variable that leads to an increase in one’s minute ventilation?
systemic arterial PO2
what causes the partial lung collapse in a person that has pneumonia?
transpulmonary pressure decreases
which cell type is most likely to be abnormal in a prematurely born baby?
type 2 alveolar
which brain region is most important in altering your breathing while watching a basketball game?
subcortical regions
gas exchange across your lungs may be reduced by:
congestive heart failure
pulmonary surfactant:
increases lung compliance
the pressure difference between the pressures in the atmosphere and in the alveoli is equal to:
pressure / flow
