Unit 3: Pulmonary Physiology Pt 3 Flashcards
What is the average concentration of O2 in alveoli?
What is the average CO2 conc?
O2 conc. = 104 mmHg
CO2 conc. = 40 mmHg
About how many alveoli does the respiratory unit consists of?
300 million
What is the respiratory membrane made up of?
2 layers:
- alveolar epithelium
- capillary endothelium
Under resting conditions, what is the diffusion capacity of the respiratory membrane of oxygen?
230 ml/min
21 ml/min/mmHg x 11 mmHg
What happens to the concentration of oxygen and carbon dioxide as one expires a normal tidal volume of 500 ml?
- O2 falls
- CO2 rises
What is the following ml of expired air from:
First 100 ml
last 250 ml
Middle 150 ml
First 100 ml –> from dead space
Last 250 ml –> from alveolar air
Middle 150 ml –> is a mix of above (dead space + alveolar air)
Normally alveolar ventilation is matched to pulmonary capillary perfusion at a rate of _____ of air to ____ of blodd.
4 L/min of air
to
5 L/min of blood
What is the normal Ventilation-Perfusion ratio (V/P ratio)?*
4/5 = .8
4 L/min of air over 5 L/min of blood
What is usually occurring if the Ventilation/Perfusion ratio decreases?**
usually due to problem with decreased ventilation (not enough ventilation for the amount of pulmonary blood flow-perfusion)
will increase physiological shunted blood
What is usually occurring if the Ventilation/Perfusion ratio increases?**
usually due to a problem with decreased perfusion of lungs (not enough pulmonary blood flow-perfusion, for the amount of ventilation)
results in increased physiological dead space
What is the maximum oxygen that can be absorbed from the lung and delivered to the tissue/minute called?
VO2 Maximum
What is used to get the best measure of cardiovascular fitness?
VO2 maximum (= max O2 that can be absorbed from lung and delivered to tissue/min)
T/F. Pulmonary ventilation is what limits our VO2 maximum.
False– CO limits it; NOT pulmonary ventilation
What is the equation for VO2 maximum?
= COmax x A-V O2max
For the following, what is the average VO2 maximum during exercise:
- Cardiac Patient
- Sedentary Person
- Endurance athlete
- Cardiac Patient–> 1.5 L/min
- Sedentary Person–> 3.0 L/min
- Endurance athlete–> 6.0 L/min
During exercise, VO2max improves as ____ increases as ___ stays constant.
as SVmax increase as HRmax stays constant
improve SV with exercise
What percentage of transported oxygen is dissolved? Bound?
3% dissolved
97% bound to hemoglobin (mainly)
About ____ ml/dl of oxygen is carried from the lungs to the tissues. About ___ ml/dl of CO2 is carried from tissues to the lungs.
5 ml/dl
4 ml/dl
What percentage of transported CO2 is dissolved? Bound? or as Bicarbinate ion?
7% dissolved
23% bound to hemoglobin
70% bicarbinate ion
What is the blood pH of oxygenated arterial blood? What about deoxygenated venous blood?
arterial blood –> 7.41
venous blood –> 7.37 (slightly more acidic, but gets buffered by blood buffers)
During exercise, what can venous blood’s pH change to?
from the normal 7.37 –> may drop to 6.9
What is the respiratory exchange ratio?
ratio of CO2 output to O2 uptake
R = 4/5 = .8
(recall: V/P-ratio = .8 too, but these are not the same thing, just got lucky)
What happens oxygen in the cells? What is it converted to?
80% converted to CO2
20% converted to metabolic water
For the Oxygen-Hemoglobin Dissociation curves, a shift to the left will promote______, and a shift to the right will promote ______.
shift to the left–> promotes association
shift to the right –> promotes dissociation
As P-O2 decreases, will hemoglobin do?
will release more oxygen
What is the arterial P-O2 and saturation of Hemoglobin and O2? What is the venous P-O2 and saturation of Hemoglobin and O2?
Arterial P-O2 = 95 mmHg –> 97% saturation
Venous P-O2 = 40 mmHg –> 70% saturation
What type of shaped curve does the Oxygen-Hemoglobin Dissociation Curve have? What is the steep portion below?
a sigmoid shaped curve
steep portion below a PO2 of 40 mmHg
What will a slight decrease in P-O2 below the point of 40 mmHg, do about the saturation of Hemoglobin and oxygen?
slight decrease in P-O2 will create a LARGE release in O2 from Hemoglobin
Where in the body will a “shift to the left” of the oxygen-hemoglobin dissociation curve occur?
Where will a “shift to the right” occur in the body?
shift to to the left–> occurs in lungs
shift to the right–> occurs in tissues/muscle (want to release O2 from hemoglobin)
What three things will shift the oxyen-hemoglobin dissociation curve to the right?
- increase temp
- increase CO2 (Bohr effect) decrease pH
- increase 2,3 diphosphoglycerate (2,3 DPG)–> RBC’s produce and it allows O2 to be released easier from hemoglobin
What determines the metabolic use of O2 by cells when intracellular PO2 is greater than or equal to 1 mmHg?
the concentration of ADP
What determines the metabolic use of O2 by cells under normal operating conditions?
the rate of energy expenditure w/in the cells
in other words the rate at which ADP is formed from ATP
What enzyme in RBCs catalyzes the reaction of water and CO2?
carbonic anhydrase
As HCO3- (bicarbonate) leaves RBC’s, what is it replaced by? What is this called?
CL- (most abundant anion in ECM)
Chloride Shift
Where would be expect to see a higher Chloride Shift, in venous or arterial blood?**
in venous* blood (b/c producing more CO2 and therefore buffering it by making HCO3- being release by RBCs?)
70% of CO2 is carried in form of bicarbonate, what is the “equation” for this?
CO2 + H2O H2CO3 H+ + HCO3-
What does carbonic acid dissociate into?
H+ and HCO3-
T/F. Oxygen has a 250x greater affinity for hemoglobin over Carbon Monoxide.
False– CO has a 250x greater affinity for hemoglobin over oxygen
What complete with oxygen for binding sites on Hemoglobin?
carbon monoxide (and it has a 250x greater affinity for hemoglobin)
What percent of Carbon monoxide can be lethal?
.1% (partial pressure of .6 mmHg)
T/F. Carbon monoxide is produced by the body in small quantities.
True
What are the functions of producing physiologic Carbon monoxide?
- signaling molecule in NS
- vasodilator
- important role in immune, respiratory, GI, kidney, and liver systems
What is the goal of neural control of ventilation regulation?
to keep arterial levels of O2 and CO2 constant
What sets the basic drive of ventilation?**
Dorsal Respiratory group
Where is the Dorsal Respiratory Group located?
nucleus tractus soliatrius in medulla
What are the 7 ways of Neural Control of Ventilation?
- Dorsal Respiratory Group
- Pneumotaxic center
- Ventral respiratory group of neurons
- Apneustic center
- Herring-Breuer Inflation Reflex
- Irritant receptors
- J receptors
What does the Dorsal Respiratory Group receive input from?
- peripheral chemoreceptors
- baroreceptors
- receptors in lungs
T/F. The Dorsal Respiratory group is rhythmically self excitatory.
True
Does the Dorsal Respiratory Group excite muscles of inspiration or expiration?
muscles of inspiration
- -turns on when we inhale
- -turns off when we exhale
What inhibits the duration of inspiration by turning off the Dorsal Respiratory Group ramp signal after start of inspiration?
Pneumotaxic center
What can stimulate both inspiratory and expiratory respiratory muscles during increased ventilatory drive?
Ventral Respiratory Group of neurons (like in coughing or exercise)
What functions to prevent inhibition of the Dorsal Respiratory Group under some circumstances?
Apneustic center
What will the Pneumotaxic center due to ventilation?
will shorten inspiration and breathes become more rapid and shallow
What will the Apneustic center do to ventilation?
breathes will become deeper and slower
Which center tends to dominate the other, the Pneumotaxic center or Apneustic center?
Pneumotaxic center dominates the Apneustic center
so breathes become for rapid and shallower
What are the stretch receptors that are located in the walls of airways that are stimulated when stretched at tidal volumes greater than 1500 ml and will therefore inhibit the Dorsal respiratory group?
Herring-Breur Inflation reflex
back up to Pneumotaxic center
What are the receptors that are among the airway epithelium that are stimulated sneezing, coughing, and possible airway constriction?
Irritant receptors
What are stimulated when pulmonary caps are engorged or there is pulmonary edema and they are in alveoli next to pulmonary caps? What feeling does the ind experience?
J receptors
create a feeling of dyspnea
What type of chemoreceptor is responsible for the majority, 70-80%, of the ventilatory response to an elevation in arterial CO2?
Central Chemoreceptors
Where are the Central Chemoreceptors located?
in the brain stem
What type of chemoreceptors are unresponsive to falls in oxygen, and the hypoxia depresses neuronal activity?**
Central Chemoreceptors
How are Central Chemoreceptors sensitive to Hydrogen ions when they can’t cross the BBB? How come the stimulation of ventilation is faster?
b/c CO2 can cross BBB–> and once inside cell it reacts with H2O to liberate H+
so rises in CO2 in CSF will have an effect on stimulating ventilation faster due to lack of buffers compared to plasma
Where are Peripheral Chemoreceptors located/called?
aortic and carotid bodies
What type of receptors are responsible for less of the ventilatory response, 20-30%, of a rise in arterial CO2?
Peripheral Chemoreceptors
central chemoreceptors are responsible for 70-80%
What type of chemoreceptors are responsive to hypoxia?**
Peripheral Chemoreceptors
T/F. Peripheral Chemoreceptors are responsive to slight falls in O2, but not slight rises in CO2.
False– they are responsive to slight rises in CO2, but NOT similar falls in O2
What is the term for a the rise in CO2 in the blood?
Hypercapnia
What are pathophysiologic consequences of hyperventilation?
- SV and CO decreased
- Coronary blood flow decreased
- repolarization of heart impaired
- oxyhemoglobin affinity increased
- cerebra blood flow decreased
- skeletal ms spasm and tetany
- serum potassium decreased
What effect will brain edema have on ventilation?
depression of inactivation of respiratory centers
What is the most prevalent cause of respiratory depression?**
Narcotics and anesthesia
Ex: sodium pentobarbital, morphine, oxycotton
What are three things that help to stimulate ventilation during exercise?
1, increased corticospinal traffic, collaterally stimulate respiratory centers in brain stem
- reflex neural signals from active muscle spindle and joint proprioceptors
- fluctuations in O2 and CO2 levels in active muscle stimulating local chemoreceptors
What is the extra O2 that is consumed post exercise to replenish O2 stores and remove lactic acid called?
O2 debt
How much stored O2 does the body contain that can be used for aerobic metabolism?
about 2 L
.5 L in lungs
.25 L in body fluids
1 L combined w/ hemoglobin
.3 L in muscle myoglobin
During heavy exercise, how fast is the stored O2 used? What can O2 debt reach?
within 2 minutes
can reach 11.5 L
After exercise what will remain high until O2 debt is “repaid”?
ventilation and O2 uptake
What are the two components of replenishing the O2 Debt created during exercise?
- Alactacid Oxygen Debt (3.5 L)–> first couple minutes post exercise
- Lactic Acid oxygen Debt (8.0 L)–> over 40 minutes post exercise
What two things in first couple minutes post exercise is the Alactacid Oxygen Debt doing to make up for the O2 debt?
- reconditioning of phosphagen system (1.5 L)
2. Replenishing oxygen stores (2 L)
What is the Lactic Acid oxygen debt doing over 40 minutes post exercise to make up for the O2 debt?
removal of lactic acid –> lactic acid causes extreme fatigue
