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Regulation of acid/base by Lungs
- metabolism of CHO, fat, proteins --> CO2
- CO2 + H2O <--> H2CO3 <--> H+ + HCO3-
- H+ buffered by proteins (esp. Hgb and HCO3-) is transported to lungs --> CO2 --> exhaled
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Regulation of acid/base by Kidneys
- primary organs responsible for replenishing bicarb and keeping it at proper level to maintain acid/base
- renal damage and non-working renal tubules = ammonia not excreted to bind with H+ to produce ammonium (NH4+) --> remain acidotic
- if not excreting ammonium --> not getting rid of acid load due to not adding bicarb to the body
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Be able to identify urinary buffers
- 1) ammonia (NH3) = most important
- 2) phosphate (HPO4)
- ** react with H+ to produce new bicarb
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Disease processes that increase pCO2 levels and cause respiratory acidosis.
(p.6)
- 1) oversedation
- 2) obstructive lung diseases:
- a) COPD
- b) emphysema
- c) chronic bronchitis
- d) asthma
- e) cystic fibrosis
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Respiratory Acidosis
- caused by inadequate alveolar ventilation
- CO2 retention --> increased pCO2 --> decreased acid/base --> decreased pH
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Oversedation
- decreased respiratory rate --> retain CO2 --> acidosisOccurs even with normal lungs
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COPD
- airflow limitations or obstruction
- not fully reversible
- associated with abnormal inflammatory response (airway narrowing)
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Emphysema
- alveolar enlargement with destruction of elastic tissue in alveolar walls
- destroyed elastic tissue --> decreased recoil to exhale CO2 --> CO2 retention --> enlarge alveoli --> rupture
- causes:
- = hereditary deficiency of alpha-1-antitrypsin (elastase inhibitor)
- = smoking --> chemicals and particles --> macrophages and PMNs phagocytize --> release proteolytic granules (elastase) --> breaks down elastic tissue= free radicals from smoking --> inactivate/decrease levels of alpha-1-antitrypsin
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Chronic Bronchitis
- defined as persistent cough at least 3 consecutive months in at least 2 consecutive years
- irritants (smoke, air pollution) --> hypersecretion of mucus beginning in large airways
- hypersecretion of bronchial mucus glands --> hypertrophy of mucus glands --> metaplastic formation of mucin-secreting cells in surface epithelium of bronchi --> outflow obstruction with hypercapnia, hypoxemia, and cyanosis
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Asthma
- inflammation increases airway reactivity to stimuli --> episodic bronchoconstriction --> SOB, chest tightness, coughing, wheezing
- trouble getting air in then getting it out
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Status Asthmaticus
- associated with CO2 retention, respiratory acidosis, and severe hypoxia
- Medical Emergency
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Cystic Fibrosis
- inherited disorder occurring most frequently in white population
- defect in secretory process of all exocrine glands
- involves secretion of pancreatic enzymes, bile flow, and reproductive duct system
- most serious consequence is pulmonary disease
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