T2: Pulmonary System (1) Flashcards
The role of the respiratory system is to provide O2 to the _____.
tissues
Where does gas exchange take place?
the alveoli-capillary membrane
What are the 3 steps in the gas exchange process?
1) ventilation
2) respiration
3) transport of gases in the circulation
The process of moving air between atmosphere and lung alveoli and distributing air within the lungs to maintain appropriate concentrations of O2 and CO2 in the alveoli…
ventilation
The process by which alveolar air gases are moved across the alveolar-capillary membrane to the pulmonary capillary bed…
respiration
Movement of oxygen and carbon dioxide to and from the tissue cells…
transport of gases in the circulation
What are the 3 areas of ventilation?
Lung
Conducting airways
Gas exchange airways
Ventilation:
What is part of the lung?
Lobes
Mediastinum
Ventilation:
What is part of the conducting airways?
Upper airways
Trachea
Bronchial tree
Ventilation:
What is part of the gas exchange airways?
Bronchioles
Alveoli
What are the 2 types of alveoli?
Type I
Type II
What do Type I alveoli do?
gas exchange
They are squamous cells
What do Type II alveoli do?
secrete surfactant
Respiration:
What 5 things determine diffusion?
Remember: The gases are SHIPD to the tissues
1) Surface area
2) Hemoglobin
3) Integrity
4) Pressures
5) Diffusion co-efficient
Respiration:
“Surface area” refers to
SURFACE AREA available for gas exchange
Respiration:
“Integrity” refers to
INTEGRITY of alveolar-capillary membrane
Respiration:
“Hemoglobin” refers to
Amount of HEMOGLOBIN in the blood (anemia can interfere with this)
Respiration:
“Diffusion co-efficient” refers to
DIFFUSION CO-EFFICIENT of gas, amount of contact time
Respiration:
“Pressures” refers to
Driving PRESSURES
V stands for _____.
Q stands for _____.
V = ventilation Q = perfusion
1.0 ratio, _____ of each alveolus is accompanied by adequate _____.
ventilation
perfusion
Alveolar ventilation is ____ L/min.
4 L/min
remember, A in alveolus and 4 look similar
Pulmonary capillary perfusion is ____ L/min.
5 L/min
remember, turn the P in pulmonary upside down - it looks similar to 5
If there is 4 L ventilation and 5 L perfusion, how do I find the V/Q ratio? What does this mean?
V / Q = ratio
4 / 5 = 0.8
(Means there is 0.8 more perfusion than ventilation)
What is normal V/Q ratio?
0.8
What does a V/Q ratio of LESS THAN 0.8 indicate?
- decrease in VENTILATION in relation to perfusion
- similar to right to left shunt
- more deoxygenated blood is returning to the LEFT heart
What does a V/Q ratio of MORE THAN 0.8 indicate?
- decrease in PERFUSION in relation to ventilation
- pulmonary emboli, cardiogenic shock
Gas Transport:
Gases are dissolved in the _____.
plasma
PaO2 means ____.
SaO2 means ____.
(the “a” = arterial)
PaO2 = percentage of O2 dissolved in the plasma SaO2 = O2 saturation...percentage bound to Hgb molecules
What is the normal percentage of O2 dissolved in plasma?
~ 3%
What is the normal percentage of O2 bound to Hgb?
97%
What 6 factors shift the oxyhemoglobin dissociation curve to the LEFT?
(Remember: Left = LOW CO2)
1) increased pH
2) decreased PCO2
3) decreased temp
4) decreased 2,3-DPG
5) some congenital hemoglobinopathies
6) Carboxyhemoglobin
What can lead to a DECREASE in 2,3-DPG?
- hexokinase deficiency
- HYPOthyroidism
- bank blood
What are some congenital hemoglobinopathies that move the curve to the LEFT?
- Hgb Ranier
- Hgb Hiroshima
- Hgb San Francisco
What 5 factors shift the oxyhemoglobin dissociation curve to the RIGHT?
1) decreased pH
2) increased PCO2
3) increased temp
4) increased 2,3-DPG
5) some congenital hemoglobinopathies
What can lead to an INCREASE in 2,3-DPG?
- pyruvate kinase deficiency
- HYPERthyroidism
- anemia
- chronic hypoxemia
Does 2,3-DPG move with or opposite O2 levels?
Opposite:
High O2 = Low 2,3-DPG
Low O2 = High 2,3-DPG
What 2 things lead to chronic hypoxemia?
- high altitude
- congenital heart disease
What are some congenital hemoglobinopathies that move the curve to the RIGHT?
- Hgb Kansas
- Hgb Seattle
What is the oxyhemoglobin dissociation curve?
Describes the ability of Hgb to bind to oxygen at normal arterial O2 tension levels and release it at lower PO2 levels
The upper flat portion of the oxyhemoglobin dissociation curve indicates what?
Arterial association which protects the body by enabling Hgb to load O2, despite large decreases in PaO2
The lower steep portion of the oxyhemoglobin dissociation curve indicates what?
Venous dissociation portion. Protects the body by allowing the tissues to withdraw large amounts of O2
When I “shift to the right”…
Hgb has LESS affinity for O2
Right shift = remember the Rs:
- Reduced pH
- hypeRcapneia
- feveR
- incRease levels of 2,3-DPG
Shift to the right = acidosis or alkalosis
acidosis
When I “shift to the left”…
Hgb has MORE affinity for O2
Left shift = remember the Ls:
- alkaLosis
- Low CO2
- coLd
- Low levels of 2,3-DPG
- increased Level of CO poisoning
An organic phosphate found primarily in RBCs:
2,3-Diphosphoglycerate
What is the stimulus for 2,3-DPG production?
tissue hypoxia
