Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
52 Cards in this Set
- Front
- Back
What is Surfactant, chemically?
|
Lecithin = dipalmitoyl phosphatidylcholine
|
|
4 other important Lung Products?
|
Prostaglandins
Histamine ACE Kallikrein |
|
Fxn of Histamine in lungs?
|
--> bronchoconstriction
|
|
Fxn of ACE?
|
Ang I ---> Ang II
Inactivates Bradykinin |
|
Fxn of Kallikrein?
|
Activates Bradykinin
|
|
What is Physiological Dead Space?
|
Anatomical dead space of conducting airways
+ Functional Dead Space of alveoli = Volume of inspired air that doesn't take part in gas exchange |
|
What is the largest contributor of Functional Dead Space?
|
Apex of healthy lung
|
|
Typical makeup of Hemoglobin?
|
2 alpha subunits
2 beta subunits |
|
2 forms of hemoglobin?
|
Taut (T) w/ low O2 affinity
Relaxed (R) w/ high affinity |
|
Difference between fetal Hb and adult?
|
Fetal = 2 alphas and 2 gamma subunits
Lower affinity for 2,3-BPG--->thus higher affinity for O2 (pulls it out of mom's blood) |
|
5 things that favor the T over R form? so?
|
Inc Cl
Inc H Inc CO2 Inc 2,3 BPG Inc Temperature shifts the dissociation curve to the right---> inc O2 unloading |
|
How is the majority of CO2 transported?
|
In the blood
As Bicarbonate if not bound to Hb |
|
How can CO2 bind to Hb?
|
Binds to AA's in globin chain at N terminus, but not to heme
|
|
How does CO2 binding affect Hb?
|
Favors T form, promoting O2 unloading
|
|
2 modified forms of Hb?
|
Methemoglobin
Carboxyhemoglobin |
|
What is Methemoglobin?
|
Oxidized form of Hb (Fe3+ instead of 2+)
Doesn't bind O2 as well, but doesn love CN- |
|
So how can you treat Cyanide poisoning?
|
Use nitrites to oxidize Hb--->metHb
This binds CN, allowing cytochrome oxidase to fxn Then give Thiosulfate to bind this cyanide, forming thiocyanate, which is renally excreted |
|
What is CarboxyHb? significance?
|
Hb bound to CO instead of O2
causes dec O2 binding capacity w/ left shift of dissociation curve-->dec O2 unloading |
|
CO vs O2 affinity for Hb?
|
CO has a 200X's greater affinity than O2 does
|
|
Factors affecting oxygen dissociation curve? significance?
|
P50
Metabolic Needs PCO2 Temperature H+ pH 2,3-DPG An inc in any of the factors (besides pH) shifts the curve to the right A dec in any of the factors (except pH) shifts it left |
|
What happens to Pulmonary Circulation if PAO2 decreases?
|
Hypoxic Vasoconstriction occurs to shift blood to well-ventilated regions of lung
|
|
Two types of Pulmonary Capillary circulation limitations?
|
Perfusion Limited
Diffusion Limited |
|
What is Perfusion Limited?
|
Normal
Seen w/ O2, CO2, N2O Gas equilibrates early along length of capillary only way to change diffusion is to change perfusion (i.e. change blood flow) |
|
What is Diffusion Limited?
|
Seen with O2 in emphysema, fibrosis
Also seen w/ CO Gas doesn't equilibrate by time blood reaches the end of the capillary |
|
Normal Pulmonary Artery Pressure?
|
10-14 mmHg
|
|
Pulmonary HTN is?
|
Pressure > 25 mmHg or > 35 mmHg during exercise
|
|
Results of pulmonary HTN?
|
Athersclerosis
Medial Hypertrophy Intimal Fibrosis of pulm. arteries |
|
Cause of Primary Pulm. HTN?
|
Due to inactivating mutation in BMPR2 gene (usually fxns to inhibit vascular smooth muscle prolif)
|
|
Px for Primary Pulm. HTN?
|
POOR
|
|
Causes of Secondary Pulm. HTN?
|
COPD
Mitral Stenosis Recurrent Thromboemboli Autoimmune Disease (systemic sclerosis) Left-to-Right Shunt Sleep Apnea Living at High Altitude |
|
Clinical Course of Pulm HTN?
|
Severe Resp. Distress-->Cyanosis and RVH--->Death from decompensated cor pulmonale
|
|
What is Pulm. Vascular Resistance = ?
|
PVR = (pressure in pulm art - pressure in LA) / CO
|
|
What is O2 content = ?
|
(O2 binding capacity X % saturation) + dissolved O2
|
|
How much O2 can 1 g of Hb normally bind?
|
1.34 mL of O2
|
|
Normal O2 binding capacity?
|
20.1 mL O2/dL
|
|
Oxygen delivery to tissues = ?
|
CO * Oxygen content of blood
|
|
What is the Alveolar Gas Equation?
|
PAo2 = PIo2 - (PAco2/R)
PAO2 = alveolar PO2 PIO2 = PO2 in inspired air PACO2 = alveolar PCO2 R = resp quotient = CO2 produced/O2 consumed |
|
What is the A-a gradient? what does it normally = ?
|
PAO2 - PaO2 = 10-15 mmHg
|
|
Difference between Hypoxemia, Hypoxia, and ischemia?
|
Hypoxemia = dec PaO2
Hypoxia = dec delivery of O2 to tissue Ischemia = Loss of blood flow |
|
Causes of Hypoxemia?
|
High altitude (normal A-a)
Hypoventilation (normal A-a) V/Q mismatch (inc A-a) Diffusion Limitation (inc A-a) Right-to-Left Shunt (inc A-a) |
|
Causes of Hypoxia?
|
Dec CO
Hypoxemia Anemia CN poisoning CO poisoning |
|
Causes of Ischemia?
|
Impeded arterial flow
Reduced venous drainage |
|
What is V/Q normally = ?
|
1
i.e. they're match-->adequate gas exchange |
|
Lung Zones and their V/Q's?
|
Apex of Lung: V/Q = 3 (wasted ventilation)
Base of Lung: V/Q = 0.6 (wasted perfusion) |
|
Ventilation and Perfusion at the base of the lungs are...
|
both Greater than at the apex
|
|
What's going on if V/Q--> 0?
|
Airway Obstruction, so no V
|
|
What's going on if V/Q --> infinity?
|
Blood Flow Obstruction, so no Q
i.e. physiological dead space |
|
How is CO2 transported to Lungs?
|
Bicarb (90%)
Bound to Hb as carbaminoHb (5%) Dissolved CO2 (5%) |
|
What is the Haldane Effect?
|
In the lungs, Oxygenation of Hb---> dissociation of H+ from Hb--->shifts equilibrium toward CO2 formation and thus CO2 is released from RBC's
|
|
What is the Bohr Effect?
|
In peripheral tissue, inc H+ from tissue metabolism shifts the curve to the right, unloading O2
|
|
Progression of Responses to high altitude?
|
Acute inc in ventilation
Chronic inc in ventilation Inc EPO--->inc Hct and Hb Inc 2,3-DPG (binds to Hb, so Hb will release more O2) Cellular Changes (inc mito's) Inc renal excretion of bicarbonate to compensate for resp. alkalosis Chronic hypoxic pulmonary vasoconstriction ---> RVH |
|
Response to Exercise?
|
Inc CO2 production
Inc O2 consumption Inc Ventilation rate to meet O2 demand V/Q ratio from apex to base become more uniform Inc Pulm blood flow from inc CO Dec pH secondary to lactic acidosis No change in PaO2 or PaCO2, but inc in venous CO2 content |