PHILS simulation 21
decreases
ion channels and enzymes are both proteins. if cooling decreases the rate of enzymatic activity, what does cooling do to the rate that channels open and close? cooling __________ (increases / doe snot change / decreases) the rate that channels open and close, and slows pacemaker activity and the heart rate.
directly via gap junctions
the pacemaker cells in the SA node produce action potentials in atrial fibers: (via the AV node/ directly via gap junctions/ through nerves/ none of the above)
acetylcholine; slow
the parasympathetic nervous system secretes _____________ (acetylcholine/norepinephrine) onto the SA node to _______ (increase/slow) heart rate.
SA node
the rhythmic contractions of the healthy human heart are initiated by action potentials produced by cells in the: (SA node/ AV node/ brain / ANS)
norepinephrine; increase
the sympathetic nervous system secretes _____________ (acetylcholine/norepinephrine) onto the SA node to _______ (increase/slow) heart rate.
increases; increases
what is the effect of adrenaline on the amplitude of each contraction and the cardiac output? the contraction amplitude ________ (decreases / increases / does not change) and the cardiac output _________ (decreases / increases / does not change)
decreases
what is the effect of cooling on enzymatic action? cooling (increases / decreases/ does not change) enzymatic action
decreases
what is the effect of cooling on heart rate? cooling (increases / decreases/ does not change) heart rate.
SA node
where is the pacemaker for the normal healthy heart? (AV bundle / AV node / SA node / Purkinje fibers)
further from; slower
ACh opens K+ channels in the membrane of the pacemaker cells. in this way, ACh hyperpolarizes the membrane, which moves it ______ (closer to / further from) threshold so that action potentials (and heart contractions) take place at a ________ (faster / slower) rate
increases
adrenaline (decreases / increases / does not change) blood pressure
increases
adrenaline (decreases / increases / does not change) heart rate
decreases
acetylcholine (decreases / increases / does not change) blood pressure
decreases
acetylcholine (decreases / increases / does not change) heart rate.
via the AV node
pacemaker cells in the SA node produce action potentials in ventricle fibers: (through nerves/ via the AV node/ directly via gap junctions/ none of the above)
