Lecture 17 cont'd Flashcards
Breathe out
Which pulmonary disorder has destroyed elastic fibers and high lung compliance but low lung elastance.
What type of pulmonary disorder is it?
Emphysema
Obstructive pulmonary disorder
Which pulmonary disorder is characterized by the accumulation of fibrous connective tissue?
Pulmonary Fibrosis
Which pulmonary disorder has a feeling of shortness of breath and unpleasant or labored breathing?
What type of pulmonary disorder is it?
Asthma
Obstructive pulmonary disorder
What is Eupnea?
What is Dyspnea?
What is Apnea?
- Normal quiet breathing
- Difficulty breathing
- Cessation of breathing
What does HYPERVENTILATION cause? What does it lead to?
Causes low blood CO2 (hypocapnia) which leads to rise in blood pH and results in respiratory alkalosis
What does HYPOVENTILATION cause? What does it lead to?
Causes high blood CO2 (hypercapnia) which leads to drop in blood pH and results in respiratory acidosis
What is ventilation?
The bulk flow of air into and out of the lungs
What does dalton’s law state?
The total pressure of a gas mixture is the sum of partial pressures of each gas in mixture
What are some factors that decrease gas exchange in the lungs?
- Inadequate oxygen in the alveoli (decrease in alveolar P O2 means less O2 is available to enter blood
- Problems with diffusion of gases between alveoli and capillaries
- Impaired blood flow (aka PERFUSION) to the alveoli
What are two things that can lead to inadequate oxygen in the alveoli?
- Decreased oxygen intake due to increase in altitude
(think ppl climbing mount everest) - Hypoventilation
What are some pathological changes affecting diffusion of gases between alveoli and capillaries?
- Emphysema (decrease in amt of alveolar surface area)
- Fibrotic lung diseases (increase in amount of alveolar surface area)
- Pulmonary edema (increase in diffusion distance between alveoli and blood
O2 that enters pulmonary capillaries first dissolves in ______ and then enters ____ blood cells where it binds to ________
Plasma, Red, Hemoglobin
(slide 61) Where does loading and unloading of Hemoglobin (Hb) occur?
Loading in the lungs
Unloading in tissues
True or False: each Hb has 4 globin polypeptide chains and 4 heme groups that bind to O2
TRUE
High plasma O2 (P O2) favors _____ and low P O2 favors _____
Loading
Unloading
How are Hb levels in anemia? In polycythemia?
- Below normal levels
- Higher than normal levels
What is carboxyhemoglobin?
Why does this make carbon monoxide deadly?
- Heme combined with carbon monoxide
- Heme’s bond with carbon monoxide is 210x stronger than O2 bonds, so they will be more likely to bond with CO than O2
What is the percentage of oxyhemoglobin saturation of blood in systemic arteries?
What about venous blood?
97-98%
75%
What is the consequence of decreased affinity of hemoglobin?
More unloading of O2 to tissues
What is the Bohr Effect?
Affinity of hemoglobin for O2 decreases when pH decreases/ temperature or CO2 levels increase
What are 3 ways in whic CO2 is transported?
- 7% of CO2 is dissolved in plasma
- 23% is in RBC bound to Hb
- 70% is transported as bicarbonate ions in plasma
What is the chloride shift?
HCO3- diffuses out of RBC into plasma in exchange for CL-
GAS TRANSPORT IN BLOOD:
What are the first three steps?
- CO2 diffuses out of cells into systemic capillaries
- Only 7% of CO2 remains dissolved in plasma
- Nearly a fourth of CO2 enters RBCs and binds to hemoglobin, forming carbaminohemoglobin
GAS TRANSPORT IN BLOOD:
What is step 4 and what is the name of the enzyme that catalyzes this reaction?
- 70% of the CO2 load enters RBCs and is first converted to carbonic acid, then dissociates into bicarbonate and H+. Hemoglobin buffers H+
Carbonic anhydrase
GAS TRANSPORT IN BLOOD:
What are steps 5 and 6?
- HCO3- (bicarbonate) enters the plasma in exchange for Cl- (chloride shift)
- At the lungs, dissolved CO2 diffuses out of the plasma and enters alveoli
GAS TRANSPORT IN BLOOD:
What is step 7?
By the law of mass action, CO2 unbinds from hemoglobin and diffuses out of the RBC and then out of the plasma into the alveoli
GAS TRANSPORT IN BLOOD:
What is the final step?
The carbonic acid reaction reverses, pulling HCO3- back into the RBC and converting it back to CO2. The CO2 then diffuses out of the RBC and then out of the plasma into the alveoli.
Where is automatic breathing generated? Where specifically?
What is it influenced by?
In the brainstem, specifically the respiratory centers in the medulla oblongata and pons
Influenced by activity of chemoreceptors that monitor blood (P CO2, P O2, pH)
Where are central chemoreceptors found?
Where are peripheral chemoreceptors found?
- In medulla oblongata
- In aorta (aortic bodies) and carotid arteries (carotid bodies)
Which chemoreceptor is most crucial in ventilation and why?
P CO2 is most crucial because of its effects on blood pH (combines with H2O forming carbonic acid which dissociates quickly and results in increased levels of H+
