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What part of the lung has larger Va/Q ratio?
Top of the lung
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During exercise, increased blood flow and ventilation optimize what?
Va/Q ratios in all parts of the lungs
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Pulmonary venous blood is diluated by what as it hits the left side of the heart?
- Bronchial venous blood
- Drop from 104 to 95mmHg
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What percentage of Hemoglobin is bound to Oxygen?
97%
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Normal blood has how many grams of Hgb?
15g in 100 ml of blood
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What is the Bohr effect?
Hgb affinity for oxygen is decreased when blood CO2 and acid [H+] increases
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What are 3 ways CO2 is transported in the blood?
- Dissolved in blood
- Directly attached to Hgb
- "exists" as bicarbonate and H+
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What is the Haldane Effect?
O2 binding to Hgb decreases Hgb affinity for CO2
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What is the normal amount of O2 delivered to blood from tissues?
5ml per 100ml of blood
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What is the normal amount of CO2 delivered from tissues to the blood?
4ml per 100 ml of blood
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How much more of an affinity does CO have on Hgb than O2?
250X more
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When CO is bound to hemoglobin, PO2 levels of blood remain near ______ levels
normal
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What else does DO bind to?
myoglobin and cytochrome oxidase (aerobi respiration enzyme)
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What are symptoms of CO poisoning?
- Headaches
- dizziness
- nausea
- fatigue
- disorientation
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What is the Respiratory Control Center?
Set of nuclei in the medulla and ons that control ventilation
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What does the dorsal respiratory group control?
Controls inspiration
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What does the ventral respiratory group control?
Controls expiration
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What does the pneumotaxic center control?
controls rate of breathing
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What does the apneustic center control?
control depth of breathing
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What do the dorsal group neurons receive peripheral input from?
- Vagus and glossopharyngeal nerves
- peripheral chemoreceptors
- baroreceptors (aorta, carotid arteries)
- lung receptors (chemo and mechano receptors)
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How does the dorsal group control breathing?
Discharges begin weakly, with steady increases in a "ramping" manner
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Where is the pneumotaxic center located?
parabrachialis of the pons
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What affects peripheral chemoreceptors (carotid, aortic bodies)?
Blood oxygen concentrations
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What do chemoreceptors signal to increase ventilation?
- Carotid bodies send signals via CN9
- Aortic bodies send signals via CN10
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What is the chemosensitve area?
- Area in the medulla, anterior to VRG and DRG
- Stimulated by increased levels of CO2 and H+
- Results in increased ventilation
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What does stimulation of chemosensitive area result in?
Increased signaling to the other portions of the respiratory center
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What is the ventilation reflex?
- Prevents over-inflation of the lung
- Smooth muscle stretch receptors stimulate the reflex
- CN X sends inhibitory signals to inspiratory center to "stop" inspiration
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What are some factors that can affect respiration?
- Voluntary control of respiration
- Irritants in the airways
- Brain edema
- Anesthesia
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How can brain edema affect breathing?
Increased cerebral pressures can depress or inactivate the respiratory center
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What is Hypoxemia?
- Low blood O2 levels created by:
- -Hypoventilaion
- -Ventilation-perfusion mismatching
- -Shunting of deoxygenated blood past the lungs
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What is Hypoxia?
- Low levels of tissue O2
- Availability of O2 to cells is decreased
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What is Hypercapnia?
- Excess CO2 in the blood
- Usually a result of hypoventilation and/or circulatory deficiency (in the lungs)
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What is Cyanosis?
- Blueness of the skin due to excessive amounts of deoxygenated Hgb in the blood (hypoxemia, hypoxia)
- Cyanosis is dependent on the presence of deoxygenated Hgb to create the bludish color
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What are some examples of Cyanosis?
- Anemia (low Hgb in the blood) does NOT create cyanosis
- Polycythemia (excess Hgb) readily creates cyanosis due to high levels of Hgb
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What is Dyspnea?
- "Air hunger"
- Mental anguish associated with the inability to ventilate enough to satisfy O2 demands
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What are three factors associated with developing dyspnea?
- Abnormal respiratory gases in body fluids (mainly hypercapnia, less influenced by hypoxia)
- Amount of work performed by respiratory muscles
- State of mind (neurogenic, emotional dyspnea)
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