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19 Cards in this Set
- Front
- Back
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Name some characteristics of asthma.
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-chronic eosinophilic a/w inflammation.
-increased a/w responsiveness -variable level of reversible a/w obstruction. |
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Subepithelial tissue is normally acellular.
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True
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What happens to the subepithelial tissue in asthma?
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Very cellular and disrupted.Eosinophils release toxins which destroy epithelium.
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What causes rapid narrowing of a/w?
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SM constriction.
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How is SM arranged around a/w?
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Helically
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What happens as we move down a/w?
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SM completely encircles smaller a/w.
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There is a single band of SM in trachea.
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True
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Describe SM distribution in smaller intraparenchymal bronchi.
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Irregular with cartilage plates which disappear in later generations.
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Explain the concept of parenchymal tethering/tidal stretch.
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-Generally a/w surrounded by tissue pulling on it.
--->During inspiration,alveoli fill & alv. walls become taut.Hard for a/w to narrow. --->Durinf exp.,walls of alveoli relaxed.Muscles contract more readily as less load on it.(why asthmatics have problems on exp.) |
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Name 2 mechanisms which increase free Ca2+ intracRly.
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1.Voltage operated Ca2+ channels in vascular SM.
2.Phospholipase C/ IP3 release from intracR stores. |
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Give 2 examples of mechanisms decreasing free Ca2+ intracellularly.
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1. Plasma Ca2+ ATPase---> extrusion across plasma mb out.
2.Sarcoplasmic reticulum Ca2+ ATPase with uptake into internal stores. |
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Functional antagonism occurs in a/w SM.
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True.Balance between contraction and relaxation via mediators acting on receptors on a/w SM.
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Name some mediators responsible for a/w SM contraction.
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ACh,histamine,LTC4,LTD4.
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Give examples of mediators causing a/w SM relaxation.
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PGE2,CIRCULATING adrenaline,PGI2.
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How fast and how much shortening occur doesnt depend on load on a/w SM.
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False.Load is critical.Unloaded muscle shortens faster.
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WHat happens to load during expiration?
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Load decreased,causing increase in a/w resistance and increased likelihood of a/w collapse.
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Velocity of contraction is a determinant of a/w resistance during EXPIRATION.
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True.
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Name some manoeuvres that increase tidal volume and stretch(which opposes shortening)
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Cough(bronchodilator effect lost in asthma),sigh,yawn + bronchodilator effect of breathing deep in/out.
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What does prostaglandin do to a/w in asthmatics?
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PG dilate blood vessels and causes fluid to leak in walls of a/w-------> a/w SWELLING---->smaller lumen. + secretion of mucus not cleared by cilia.
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