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Lecture 31
Regulation of Respiration-Lung Diseases
Term | Definition |
---|---|
Medullary Control Centers | Dorsal respiratory group-DRG-rhythmic discharge leads to phrenic nerveleads to diaphram. Initiates normal breathing. ventral respiratory group-VRG-causes inc inspiration and expiration |
Pontine Control Centers | Modify medullary centers. pnemotaxic center-switches off inspiration. apneustic center-prolongs inspiration,normally inhibited. If PC is damaged, Hering Brewer reflex from lung stops inspiration |
Chemical Control of Respiration | Most powerful. Controller of rate. rasies blood CO2,raises brain CO2 raises H= and HCO3-. H+ in brain inc DRG rate. |
Peripheral Changes | In carotid bodies and aortic bodies. raises H+ or CO2 or dec O2 will raise rate of respiration. little effect in normal range. PO2<60mmHg raises rate,no help in CO poisoning. |
Sleep Apnea | Dec DRG activity or airway obstruction. In REM, pharyngeal muscles relax and tongue blocks trachea. Dec restful sleep |
SIDS | Sudden infant death syndrome-exact cause unknown. May be due to congenital DRG problem or cardiac arythmia. Baby sleeping on bach dec SIDS, mother smoking in pregnancy inc SIDS. Child abuse may have skewed SIDS stats. |
Pneumothorax | Rupturing of thorax-air enters intrapleural space. Pressure equalizes, lung collapses on rupture side. Dec flow in good side. danger of kinking of great veins if opening remains. Reclosed-normal breathing on good side,lung re-inflates. |
Asthma | Episodic or chronic wheezing,tightness in chest. Inc morbidity and mortality |
Airway Obstruction | Inc mucus production in response blocks airway. reduces air flow |
Inflammation | Response to allergies inc IgE. raises mast cell release of histamine and other cytokines. edema inc airflow |
Bronchoconstriction | some cytokines are bronchoconstrictors. Also cool air and exercises constriction dec airflow |
SRS-A | Slow reactive substance of anaphylaxis,leurktriens. powerful bronchoconstrictor during allergic attack. potentially fatal attack |
Epinephrine | beta 2 receptors bind epi. relax bronchioles, raises air flow. rescue from serious allergic attacks. steroids dec inflammation. side effects significant |
Emphysema | Cigarette smoke,coal,tar most common causes. |
Decreased alpha-Antitrypsin | lungs have digestive enzymes for defense. Alpha-antitrypsin protects lung tissue from digestion. inhibit alpha A T production and enzymes digest alveoli. dec # of alveoli and inc size of remaining alveoli. |
Surface Area | Progressive dec in surface area. may need pure O2 to fill Hb. Irreversible-right heart enlarges and fails |
Cystic Fibrosis | recessive gene-dec Cl- channel activity. loss of airway Na+ and water-mucus sticky and digestive enzymes inc. inc infection, lung destruction-fatal |