Question

1) what would be the net effect of blocking ryanodine receptor channels in cardiac contractile cells?
   a)asystole
    b) positive inotropic effect
   c) negative inotropic effect
    d) positive chronotropic effect
     e) negative chontropic effect
2) A drug that partially blocked voltage gated k+ channels in myocardial contractile cells would likely have what effect?
   a) aysytole
    b) positive inotropic effect
    c)negative inotropic effect
     d)positive chronotropic effect
     e) negative chronotropic effect
3)The I_f channels in the ______ have the slowest leakage of Na+ and k+.
a)AV node
b)bundle branches
c)SA node
d) AV bundle
e)intermodal pathways
4)A drug that specifically blocked spontaneous electrical activity (but not conductivity)in the AV node would most likely:
   a)have little effect on heart rate
b)result in an increase in heart rate
c)desynchronize ventricular contraction from atrial contraction
   d)result in decrease in heart rate
e)rapidly cause death because the ventricles would fail to contract
5)Which of the following systolic and diastolic pressures would increase flow rate the most?
   a) 120/80
   b)160/120
   c)140/90
    d)200/170
    e)all would effect equally

Answer 1

1. Negative ionotropic effect ie reduce contraction by reduce Ca 2+ ion release from sarcoplamic reticulum.

2. Negative ionotropic effect by k+ blocker . Drug bind k+ channel and reduce Na + k+ pump function .

3.SA node has special funny channels so they beat at faster speed upto 150 / min.

4. Desynchronise between atria and ventricle ventricle beats start it's own signal

If AV electric activity is blocked

5. C 140/90 .

Pulse pressure is 50 mmhg ... higher than other .

So flow rate is depend on Area of cross section x velocity of liquid.

More pressure more velocity.