Open Question
After Randy was diagnosed with stomach cancer, nearly all of his stomach had to be removed. Postoperative treatment included regular injections of vitamin B12. Why was this vitamin prescribed, and why were injections specified?
18. The Heart
Electrical Conduction System of the Heart
Back18. The Heart
Electrical Conduction System of the Heart
- Open QuestionHow does the heart's ability to contract differ from that of other muscles of the body?
- Open QuestionIdentify the structures in the following diagram of a sectional view of the heart. a. ___b. ___c. ___d. ___e. ___f. ___g. ___h. ___i. ___j. ___k. ___l. ___m. ___
- Open QuestionThe serous membrane covering the outer surface of the heart is the (a) parietal layer of the serous pericardium,(b) endocardium, (c) myocardium, (d) visceral layer of the serous pericardium.
- Open QuestionThe simple squamous epithelium covering the heart valves is the (a) epicardium, (b) endocardium, (c) myocardium, (d) endothelium.
- Open QuestionDescribe the three distinct layers that make up the heart wall.
- Open Question
Cardiac muscle cells are joined by structures called:
a. T-tubules.
b. tight junctions.
c. sarcoplasmic reticulum.
d. intercalated discs.
- Open QuestionThe portion of the intrinsic conduction system located in the superior interventricular septum is thea. AV node,b. SA node,c. AV bundle,d. subendocardial conducting network.
- Open QuestionMultiple ChoiceMore than one choice may apply.Using the figure, identify the most external part of the pericardium. a. b. c. d. e.
- Open QuestionDraw a diagram of the heart showing the three layers composing its wall and its four chambers. Label each. Show where the AV and semilunar valves are, and name them. Show and label all blood vessels entering and leaving the heart chambers.
- Open QuestionName three different factors that increase heart rate.
- Open Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
e. The heart plays a role in the regulation of blood pressure and secretes the hormone atrial natriuretic peptide.
- Open Question
The ______is the primary pacemaker of the heart.
a. atrioventricular node
b. sinoatrial node
c. Purkinje fiber system
d. atrioventricular bundle
- Open Question
The AV node delay:
a. allows the atria and ventricles to depolarize and contract as a unit.
b. allows the two ventricles to depolarize and contract separately.
c. allows the atria and ventricles to depolarize and contract separately.
d. speeds up the impulse transmission from the atria to the ventricles.
- Open Question
A newer drug, Ivabradine, lowers the heart rate by blocking the nonselective HCN cation channels. Why would this action decrease the heart rate? Would this drug have an effect on pacemaker cells, contractile cells, or both? Explain.