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19 Cards in this Set

  • Front
  • Back
Name some characteristics of asthma.
-chronic eosinophilic a/w inflammation.
-increased a/w responsiveness
-variable level of reversible a/w obstruction.
Subepithelial tissue is normally acellular.
True
What happens to the subepithelial tissue in asthma?
Very cellular and disrupted.Eosinophils release toxins which destroy epithelium.
What causes rapid narrowing of a/w?
SM constriction.
How is SM arranged around a/w?
Helically
What happens as we move down a/w?
SM completely encircles smaller a/w.
There is a single band of SM in trachea.
True
Describe SM distribution in smaller intraparenchymal bronchi.
Irregular with cartilage plates which disappear in later generations.
Explain the concept of parenchymal tethering/tidal stretch.
-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.)
Name 2 mechanisms which increase free Ca2+ intracRly.
1.Voltage operated Ca2+ channels in vascular SM.
2.Phospholipase C/ IP3 release from intracR stores.
Give 2 examples of mechanisms decreasing free Ca2+ intracellularly.
1. Plasma Ca2+ ATPase---> extrusion across plasma mb out.
2.Sarcoplasmic reticulum Ca2+ ATPase with uptake into internal stores.
Functional antagonism occurs in a/w SM.
True.Balance between contraction and relaxation via mediators acting on receptors on a/w SM.
Name some mediators responsible for a/w SM contraction.
ACh,histamine,LTC4,LTD4.
Give examples of mediators causing a/w SM relaxation.
PGE2,CIRCULATING adrenaline,PGI2.
How fast and how much shortening occur doesnt depend on load on a/w SM.
False.Load is critical.Unloaded muscle shortens faster.
WHat happens to load during expiration?
Load decreased,causing increase in a/w resistance and increased likelihood of a/w collapse.
Velocity of contraction is a determinant of a/w resistance during EXPIRATION.
True.
Name some manoeuvres that increase tidal volume and stretch(which opposes shortening)
Cough(bronchodilator effect lost in asthma),sigh,yawn + bronchodilator effect of breathing deep in/out.
What does prostaglandin do to a/w in asthmatics?
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.