Respiratory Physio Flashcards
What is the P50 of Hgb?
Partial pressure of O2 at which hemoglobin is 50% saturated.
What state is hemoglobin in when the P50 is high?
Taut
What state is hemoglobin in when the P50 is low?
Relaxed
When Hgb is in the relaxed state, what kind of affinity for oxygen does it have and how does the curve shift?
What about when it is in the taut state and how does the curve shift?
High affinity
Left shift
Low affinity
Right shift
At what location does hemoglobin have a high affinity for oxygen? Low affinity for oxygen?
Lungs
Tissues
What are some conditions when you would see a right shift of the P50 hgb curve? Are you on or offloading oxygen at that time?
Left shift?
Decreased CO2, [H+], 2B/DPG, low temps. Onloading O2.
Increased CO2, [H+], 2-B/DPG, high temperature. Offloading O2.
What is the Bohr effect?
Increased CO2 in blood causes O2 to be displaced from hemoglobin. Occurs in tissues and describes release of oxygen.
What is the Haldane effect?
Binding of O2 with hemoglobin causes CO2 to be displaced from hemoglobin. Occurs in Lungs and describes the release of CO2.
Where is most oxygen found in the body?
98% bound to hemoglobin (1-2%) dissolved in plasma.
What are the 3 major forms of carbon dioxide in the body?
- Dissolved in plasma (7%)
- In RBCs (70%)
- Bound to hemoglobin (23%)
How does carbon dioxide and water cause a chloride shift in the red blood cell?
CO2 + H2O makes carbonic acid under the influence of carbonic anhydrase. Carbonic acid dissociates into H+ and HCO3- (bicarb).
The H+ combines with carbamino compounds and the leftover bicarb diffuses out of the cell while Cl- diffuses in causing a chloride shift.
Where is carbonic anhydrase catalyzing important reactions in the body?
- In the RBC to combine CO2 and water
- In parietal cells leading to acid secretions
- In pancreatic cells to allow for bicarb secretion
- In the renal tubules where the intercalated cells of the collecting duct are involved in acid/base balance.
Where is CO2 the more important regulator of regulation of respiration, centrally or peripherally?
Centrally because CO2 can cross BBB where H+ cannot.
What is the name of the cell that is found in the chemoreceptors that is sensitive to O2 changes? How does that cell result in respiratory stimulation of CN ____?
Glomus cell
Decreased O2 leads to potassium eflux and Ca influx leading to cell depolarization and dopamine release which results in respiratory stimulation of CN 9 (glossopharyngeal).
Where is the respiratory center located?
Pons and medulla
What group is responsible for inspiration?
What group is mostly inactive during normal respiration but is involved in expiration during exercise.
What center controls, rate, depth, and acts as an inspiratory off switch.
Dorsal Respiratory Group in medulla
Ventral Respiratory Group in medulla
Pneumotaxic center in the pons.
What are some non-respiratory functions of the lungs
- Coagulation - rich in thromboplastin and heparin
- Defense - mucus, cilia, surfactant, defensins, alveolar macrophages, proteases. Humoral immunity (IgA upper airway, IgG lower).
- Removes 30% of NE, removes ANP, removes leukotrienes and prostaglandins, inactivates seratonin and bradykinin
How does ANP work?
Atrial naturitic peptide opposes RAAS system. When the atrium are very dilated it shuts down Raas to prevent too much volume.
What breed is likely to get ciliary dyskenesia?
Old English Sheepdogs
What is the difference between type 1 and type 2 alveolar epithelial cells and what are two other names for them? Are they ciliated?
Clara cells, pneumocytes
Type 1 - 95% of cells lining alveoli. Have tight junctions and are responsible for gas exchange. Highest oxygen exposure in body so prone to oxygen toxicity and do not divide so need to be replaced.
Type 2 - Stem cell for type 1. No gas exchange. Stores surfactant and responsible for defense. Resistant to O2 toxicity. Found at alveolar junctions and are more rounded.
Non ciliated
What muscles play biggest role in inspiration (little role at rest)? What about expiration?
Inspiratory (negative pressure), expiratory (positive pressure)
What is the interpleural pressure when there is a pneumothorax?
0
What determines lung compliance?
What conditions would decrease or increase compliance?
Elastin/collagen ratio and surfactant (SA).
Decrease:
- increased lung volume
- surfactant deficiency
- pulmonary edema
- lung/alveolar collapse
- fibrosis
- smooth muscle airway constriction (asthma)
Increase:
- Age (change in elastin ratio)
- emphysema (decreases SA)
- increased body size
What shift does emphesyma show on a volume vs distending pressure graph?
Left
