RESP 2 Flashcards
Which are more distensible/compliant… systemic capillaries or pulmonary capillaries?
pulmonary
Which are shorter… pulmonary or systemic veins?
pulmonary veins
Why is blood in the left atrium slighly lower O2 conc than blood in the pulmonary capillaries?
some deoxygenated blood from the bronchial veins mixes with oxygenated blood in the pulmonary veins.
What is the blood pressure and MAP in the pulmonary circulation?
25/8
14 mmHg
What is the average pulmonary capillary pressure?
7 mmHg
Pulmonary blood volume accounts for ~ ____ of blood volume but is is highly variable.
9% (450ml)
What increases pulmonary blood volume?
- inspiration
- lying down
- disease states (heart failure)
What will opening more capillaries do to total resistance?
increase surface area and decrease resistance
An increase in blood flow leads to a ________ in pulmonary vascular resistance.
decrease
An increase in Flow (CO) to lungs will decrease pulmonary Resistance
through:
- Recruitment of pulmonary capillaries
- Distension of pulmonary capillaries
When PAO2 (Alveolar concentration of O2) drops 70% below normal, adjacent blood vessels…
constrict
What then would happen throughout the pulmonary circulation at a high altitude where PAO2 is reduced?
pulmonary hypertension
What happens in the systemic circulation when PaO2 levels drop?
vasodilation
If PAO2 is high adjacent vessels will…
dilate
Perfusion of a hypoventilated alveolus would result in blood with _______ PaO2 (if no vasoconstriction occurred)
decreased
What allows blood to be sent to better ventilated alveoli to maximize gas exchange?
Hypoxic pulmonary vasoconstriction (HPV)
In response to decreased PAO2, hypoxic pulmonary vasoconstriction (HPV) occurs to _______ blood flow to hypoventilated alveoli.
reduce
What are pulmonary vasodilators?
- High O2 in alveoli
- Dopamine
- Bradykinin
- Prostacyclin
- Nitric Oxide
- Histamine (H2)
- Acetylcholine
What are pulmonary vasoconstrictors?
- Low O2 in alveoli
- High CO2 in alveoli
- Norepinephrine
- Angiotensin II
- Endothelin
- Vasopressin
- Thromboxane A2
What vasodilator of pulmonary arteriole has opposite response in systemic versus pulmonary?
High O2 in alveoli is vasodilator
- vasoconstrict in systemic arterioles
What vasoconstrictor of pulmonary arteriole has opposite response in systemic versus pulmonary?
Low O2 and High CO2 in alveoli is vasoconstrictor
- vasodilates in systemic arterioles
What is PVR?
pulmonary vascular resistance (PVR)
- the total of Alveolar Vessels + Extra-alveolar Vessel Resistance
When the alveoli expand
during INSPIRATION…
1) Alveolar vessels are compressed/elongated and their resistance increases
2) Extra-alveolar vessels have decreased resistance
Resistance in the pulmonary circulation is lowest when lung volume is equal to ___
FRC
What is functional residual capacity (FRC)?
volume of air in the lungs after a normal (TV) expiration
What zone has the highest hydrostatic pressure and the highest blood floow per alveolus?
zone 3
In zone 1 which is lower Pa or PA?
Pa is lower (capillaries are compressed)
In zone 2 which is lower Pa or PA?
PA is lower (blood flow is intermittent)
In zone 3 which is higher Pa or PA?
very high Pa (due to gravity)
- continuous bloof low
What converts zone 2 to zone 3?
exercise
Normal Whole Lung V/Q is 0.8 which means there is more _________ flow than _________ flow.
more blood flow than air flow
In a normal individual, the _____ of the lung has a higher V/Q than the rest of the lung
apex
Fast, shallow breaths in upright position cause V/Q mismatch because…
air flows to upper lobes and blood to lower lobes
If ventilation is limited,
V/Q is…
O2 is…
CO2 is…
smooth muscles in the ____constrict
If perfusion is limited,
V/Q is…
O2 is…
CO2 is…
smooth muscles in the ____constrict
If _____ is negative, it is a filtration
pressure but if it is positive, it is an
absorption pressure.
Pif
What are the hydrostatic pressures?
- Capillary Pressure (Pc)
- Interstitial Fluid Pressure (Pif)
What are the osmotic pressures?
- Plasma Colloid Osmotic Pressure
(np) - Interstitial Fluid Colloid Osmotic
Pressure (nif)
What are the filtration pressures?
- Capillary Pressure (Pc) = 7 mmHg
- Interstitial Fluid Pressure (Pif) = -8 mmHg
- Interstitial Colloid Osmotic Pressure (nif) = 14 mm Hg
What are the absorption pressures?
- Plasma Colloid Osmotic Pressure (np) = 28 mmHg
The balance of pulmonary capillary and interstitial hydrostatic and colloid pressures can be disrupted resulting in __________
pulmonary edema
