Respiratory physiology Flashcards
Where is the medullary respiratory center located?
in the reticular formation
Minute ventilation=
tidal volume(liters/breath) x frequency (breaths/minute)
What happens to physiologic dead space during exercise?
it decreases
What is the Bohr effect?
in the peripheral tissue, increased H+ shifts the dissociation curve to the right unloading O2
Where are the central chemoreceptors for breathing and what stimuli increase breathing rate?
medulla; decreased pH (or increased CO2 which combines with water to make H+) of CSF
Under what conditions does 2,3-BPG accumulate? What is the effect of 2,3-BPG on hemoglobin A?
low oxygen conditions. this will cause a right shift in HbA. 2,3 BPG binds to the beta subunit of Hb and thus lowering the affinity of oxygen for Hemoglobin (to release this oxygen to other tissues)
What is the pressure of alveolar O2 and CO2
PO2=100mmHg; PCO2=40mmHg
What is V/Q at the base of the lung?
V/Q = 0.6 (wasted perfusion)
Where is the major site of airway resistance?
medium-sized bronchi
What is the composition of fetal Hb and how are its properties different from adult Hb?
composition: 2 alpha and 2 gamma chains; this causes a left-shift in the saturation curve resulting in increased affinity for O2 due to decreased affinity to 2,3-DPG
Ventilation of alveoli without perfusion is called ____.
dead space
In the pleural cavity, oncotic pressure favors the movement of fluid (into/out of) the pleural space.
out of
A failure of gas exchange manifests as (hypoxemia/hypercapnea) while a feailure of the respiratory pump manifests as (hypoxemia/hypercapnea).
hypoxemia; hypercapnea
Does hyperventilation result in respiratory alkalosis or acidosis?
respiratory alkalosis
Factors that shift oxygen dissociation curve to the left(8)`
CO2, low 2,3-BPG, hypothermia, alkalosis, HbF, methemoglobin, carbon monoxide, stored blood
What is the inspiratory reserve volume (IRV)?
air in excess of tidal volume that moves into lung on max inspiration
V/Q»1 is known as ___
dead space
Compare the amount of physiological and anatomical dead space in the healthy individual.
they are nearly equal. Lung diseases tend to increase the physiological dead space.
At the base of the lung, there is greater ventilation, perfusion, or both?
both are greater
CO2 transport: CO2 is transported form tissue to lungs in these 3 forms: ____
- bicarbonate
- bound to hemoglobin
- dissolved CO2
Vital capacity is everything except?
residual volume
What increases physiologic dead space? (4)
tumors, pneumonia, infection, fluid in lungs, anything that reduces surface area for gas exchange
What is the formula for inspiratory capacity(IC)?
IRV+TV
What is the ideal V/Q ratio?
V/Q= 1 (permits adequate oxgenation)
What is the formula for total lung capacity (TLC)?
IRV+TV+ERV+RV
At what point in the breathing cycle is alveolar pressure equal to zero?
at FRC, just before inspiration
In normal health, is O2 perfusion or diffusion limited?
perfusion - gas equilibrates along the length of the capillary
In the pleural cavity, hydrostatic pressure favors the movement of fluid (into/out of) the pleural space.
into
Does surfactant increase or decrease recoil? surface tension? compliance?
lowers lung recoil
lowers surface tension
increases compliance
In the oxygen-hemoglobin dissociation curve, what is a right shift?
this is a decreased affinity of hemoglobin for O2 and facilitates unloading of O2 to the tissue
V/Q= is known as a ____.
shunt
What is the formula for total lung capacity (TLC)
TLC=IRV+TV+ERV+RV
What is the normal V/Q ratio?
0.8
Central chemoreceptors (in brain) respond to ___ and ___ but do not directly respond to ____.
pH; pCO2; pO2
Lungs are elastic. The elastins and collagens in the interstitium causes lungs to ____ when expanded.
recoil
What is V/Q at the apex of the lung?
V/Q=3(wasted ventilation)
Factors that shift oxygen dissociation curve to the right. (4)
CO2, high 2,3-BPG, fever, acidosis
List the inspiratory muscles used during forced inspiration.
pectoris minor, SCM, scalenes
What is the functional reserve capacity (FRC)?
RV+ERV (volume in lungs after normal espiration)
CO2 transport: What is the Haidane effect?
oxygenation of hemoglobin promotes the dissociation of CO2 from hemoglobin
T/F: Pulmonary circulation is normally a low-resistance, low-compliance system
false- low-resistance, high-compliance
Normal pleural fluid is becarbonate (rich/poor) and protein (rich/poor)
bicarbonate-rich
protein-poor
What molecule causes off-loading of O2 from Hb in tissues?
2,3 -diphosphoglycerate
Distinguish tachypnea from hyperpnea from hyperventilation.
tachypnea=fast rate of breathing (>20/min) for whatever reason.
hyperpnea= increased ventilation that meets a metabolic need (fever, post-exercise etc)
hyperventilation= increased ventilation that exceeds metbolic need, often producing symptoms diziness, paesthesia, etc.)
Obstructive lung disease involved increased lung _____, restrictive lung disease involves decreased lung _____.
resistance; compliance
Where is surfactant produced?
type II alveolar cells
Define the ‘residual volume’ (RV)
air in lung at max expiration
What is a normal respiratory rate at rest?
12-14 breaths/min
What is the tidal volume(TV)?
air that moves into lung with each quiet inspiration (nl=500ml)
What is the formula for inspiratory capacity (IC)?
IC= IRV+TV
Thorax is elastic which cause chest to expand and oppose the recoil of lungs. What structure(s) contribute to this elasticity?
costal cartilages
What are physiologic adaptations in high altitude? (7)
alveolar P(O2) is decreased, arterial P(O2) is decreased (hypoxemia), hyperventilation, respiratory alkalosis, increased EPO, increased 2,3-DPG hypoxic pulmonary vasoconstriction
Respiratory acidosis-2 causes
HYPERventilation, aspirin ingestion (early)
What are the four mechanisms of hypoxemia?
hypoventilation, V/Q mismatch, shunt, low inspired pO2
Is hypo or hyperventilation the copensatory response to alkalosis?
hypoventialtion
Which of the following is diffusion limited CO2, N2O, or CO?
CO-gas does not equilibrate by the time the blood reaches the end of the capillary
How does resistance change with radius?
resistance=1/r4. As radius decreases, resistance increases.
When does a human embryo start to produce surfactant?
at seven months.
Oxygen-hemoglobin dissociation curve: A right shift is caused by an increase or decrease in each of the following factors; P50, metabolic needs, PCO2, temperature, H+, pH, altitude, and 2,3 -DPG
increase in all but pH
What is the relationship between compliance and elasticity?
inversely related
What limits gas exchange in pulmonary capillaries normally? HOw does this change during exercise?
perfusion normally. becomes diffusion limited during strenuous exercise.
What happens to the mean values of arterial P(O2) and P(CO2) during exercise?
they do not change
What is the formula for vital capacity (VC)?
TV+IRV+ERV
V/Q= 0 implies what serious problem?
airway obstruction (shunt)
The apices of the lungs receive better _____ while the bases of the lungs receive better _____.
ventilation; circulation
ACh _____ airway resistance, catecholamines ______ resistance.
increases (bronchoconstricution); decreases (bronchodialtion)
What does surfactant do? What is surfactant? What makes surfactant?
it decreases alveolar surface tension which increases compliance. It is made of dipalmitoyl phosphatidylcholine (lecithin) and it is produced by type II pneumocytes
CO2 transport: What percentage of CO2 is transported in the form of bicarbonate?
0.9
Oxygen-hemoglobin dissociation curve: Decreased affinity of hemoglobin for O2=shift_____.
right
Which binding site of Hb has the highest affinity for O2? Why is this important?
the fourth binding site–> it allows maximal loading of O2 in the lungs and unloading in the tissues
In asthma, FEV1 is _____ and FEVf1/FVC is _____.
reduced; reduced
In emphysema, FEV1 is ___ and FEV1/FVC is ____.
reduced; reduced
T/F: It is possible for a patient to hypoventilate and at the same time to be suffering from tachypnea
true
What is the intracellular enzyme that converts CO2 into H2CO3?
carbonic anhydrase
List the expiratory muscles used during forced expiration.
internal intercostals, obliques, rectus abdominus
H2CO3 is broken down into H+ and HCO3. What happens to the HCO3?
HCO3 is pumped out of the red blood cell in exchange for Cl-
Organisms such as TB that thrive in high O2 flourish in the apex or base of the lung?
apex
What is the main drive for ventilation?
H+ ions from dissociated H2CO3 which stimulate central chemoreceptors.
Cor pulmonale and subsequent RV failure are a consequence of pulmonary ____.
hypertension
What happens in restrictive lung disease to TLC, RV FRC, FEV1, FVC and FEV1/FVC?
reduction in TLC, FRC, and RV. A reduction in FEV1 and FVC with a normal or increased FEV1/FVC ratio suggests a restrictive pattern
What is the formula for vital capacity (VC)?
VC=TV+IRV+ERV
What is lung compliance? How is compliance altered in emphysema? In fibrosis?
it’s the change in volume with a change in pressure. Increased compliance means more air flows in with a given change in pressure. Decreased compliance means the opposite. Emphysema=very compliant; fibrosis=not compliant
What is the normal value of FEV1/FVC?
70%-80%
Where are the peripheral chemoreceptors for breathing and what stimuli increase breathing rate? (3)
carotid and aortic bodies; decreased P(O2) (if less than 60mmHg), decreased pH, increased P(CO2)
When is O2 diffusion limited? (3)
exercise, emphysema, fibrosis
What is the expiratory reserve volume (ERV)?
air that can still be breathed out after normal expiration
List the inspiratory muscles responsible for normal breathing.
diaphragm and external intercostals
Oxygen-hemoglobin dissociation curve; Fetal Hb curve is shifted toward the ____.
left (increased affinity for O2)
What is the action of 2,3 -DPG on hemoglobin?
binds to hemaglobin so that hemoglobin releases more 02
During exercise (increased cardiac output), the vessels in the apex of the lung___ so that V/Q approaches ___.
vasodilate such that V/Q approaches 1 (versus normal apex V/Q of 3)
What pathologic process has a deficiency of surfactant?
neonatal RDS (Respiratory distress syndrome)
How is CO2 carried in the blood? (3)
5% dissolved; 5% attached to Hb; 90% as bicarbonate
Name the five factors that cause a right shift?
high CO2, high acid/altitude, high DPG (2,3-DPG), exercise and increased temperature
What determines oxygen content? What determines PO2?
hemoglobin concentration determines content (1.34ml O2 combines with each gram of hemoglobin). Amount of oxygen dissolved in plasma determines PO2 (0.3ml O2 per 100ml plasma).
What are the peripheral chemoreceptors for breathing and what stimuli increase breathing rate?
carotid and aortic bodies; decreased P(O2) (if less than 60mmHg), decreased pH, increased P(CO2)
T/F: Pleural pressure is always lower than alveolar pressure under normal conditions.
true
What is an easy way to clinically differentiate between a shunt and a V/Q mismatch?
administer 100% O2. If patient has a shunt, pO2 won’t respond. If patient has V/Q mismatch, pO2 will increase.
In pulmonary fibrosis, FVC is _____.
reduced
Increased anion Gap-4 causes
renal failure, lactic acidosis, ketoacidosis, aspirin ingestions
