PHYSIO-LEC-LE-3-Feed-2022 (1) Flashcards
- The greatest blood volume
A. Arteries
B. Arterioles
C. Capillaries
D. Veins
D. Veins
- Capillaries are ideal for the exchange of substances because they have:
✔ Large cross sectional area
- Slow response action potential is present in one of these:
A. Atrial myocytes
B. Bundle of his
C. Purkinje fibers
D. SA node
D. SA node
- Conduction is more likely to be_____ due to its slow response action potential that causes response due to _____ of action potential (question unclear).
✔ Slow Amplitude
- Phase 0 of cardiac action potential is due to:
A. Ca++ influx
B. Ca++ efflux
C. K+ efflux
D. Na+ influx
A. Ca++ influx
- During phase 4 of an action potential, this occurs.
✔ Sodium enters cell through 3 sodium 1 Calcium antiporter
- Depolarization of slow response action potential is due to
✔ Lets Calcium influx through Calcium channels
- Effect of acetylcholine to myocardial
A. Decrease in Ca channels
B. Decrease in K channels
C. Increase in Ca conductance
D. Increase in Na Funny channels
A. Decrease in Ca channels
- Importance of effective refractory period
✔ Prevents cardiac muscle to produce new AP
- Conduction velocity increases when there is
✔ Increase the rate of depolarization
- Effect of more negative action potential in conduction velocity is
✔ Increase conduction due to larger amplitude of an action potential
- Ionic currents involve slow response depolarization occurs outward
✔ Calcium influx and potassium efflux, potassium currents depolarizes cell
- Heart rate decreases when there is
✔ Increase negativity in the pressure potential
- Heart rate decreases when there is
✔ Increase negativity in the pressure potential
- Mechanism for overdrive suppression is:
A. Activation of cell’s intrinsic automaticity
B. Depolarization of cardiac cell with Na+ influx
C. Hyperpolarization of cell with Na+ efflux
D. Suppression of NaKATPase
C. Hyperpolarization of cell with Na+ efflux
- Importance of conduction delay in AV node is:
✔ Allow sufficient ventricular filling.
- Significance of long refractory period of Purkinje fibers is to:
A. Prevent premature contraction of atria
B. Prevent premature contraction of ventricle
C. Promote premature contraction of atria
D. Promote premature contraction of ventricle
B. Prevent premature contraction of ventricle
- This phenomenon is responsible for the initiation of impulses through the SA node as the pacemaker
A. Absolute Refractory Period
B. Overdrive Suppression
C. Post-repolarization refractories
D. Depolarization of diastole
B. Overdrive Suppression
- The major factor responsible for contractile stage of myocardium is:
A. Free intracellular Ca++
B. K+ gradient across membrane
C. Na+ gradient across membrane
D. Sarcoplasmic Ca++ concentration
A. Free intracellular Ca++
- What occurs during myocardial contraction?
✔ Entry of calcium through calcium channels
- Cardiac glycosides increase cardiac contractile force through
✔ Increase in intracellular sodium decrease in calcium (…)
- Catecholamines have one of these effects on excitation-contraction coupling
✔ Inhibit binding of calcium by troponin C
- Increased Preload
A. Decrease BP
B. Decrease Myocardial Contraction Force
C. Increase Afterload
D. Increase Stroke Volume
D. Increase Stroke Volume
- Frank-Starling mechanism is responsible for one of this:
✔ Increased stroke volume when ventricular diastolic volume is increased