which part of the heart generates the qrs complex on an ecg

ATI TEAS 7

TEAS 7 science practice

1. Which part of the heart is responsible for generating the QRS complex on an ECG?

A. Sinoatrial node (SA node)
B. Atrioventricular node (AV node)
C. Bundle of His
D. Ventricular muscle cells

Correct answer: D

Rationale: The QRS complex on an ECG represents ventricular depolarization. This electrical activity is generated by the ventricular muscle cells. While the SA node generates the P wave, the AV node delays the impulse, and the Bundle of His and Purkinje fibers assist in rapidly conducting the impulse through the ventricles, it is the ventricular muscle cells that specifically create the QRS complex. Therefore, choice D, Ventricular muscle cells, is the correct answer. Choices A, B, and C are incorrect as they are primarily involved in initiating and coordinating the electrical impulses in the heart but do not directly generate the QRS complex on an ECG.

2. Which of the following is an example of a salt?

A. Sodium hydroxide (NaOH)
B. Hydrochloric acid (HCl)
C. Sodium chloride (NaCl)
D. Sulfuric acid (H₂SO₄)

Correct answer: C

Rationale: Sodium chloride (NaCl) is an example of a salt. Salts are ionic compounds formed by the reaction of an acid with a base. In this case, sodium chloride is formed by the reaction of sodium hydroxide (a base) with hydrochloric acid (an acid). Sodium hydroxide (NaOH), hydrochloric acid (HCl), and sulfuric acid (H₂SO₄) are not salts because they are not formed by the neutralization reaction of an acid and a base, which is a characteristic of salts.

3. Write 290% as a fraction.

A. 29/10
B. 58/20
C. 145/50
D. 290/100

Correct answer: D

Rationale: To convert a percentage to a fraction, you write the percentage as the numerator of the fraction over 100. Therefore, 290% is equivalent to 290/100, which simplifies to 29/10. Choices A, B, and C are incorrect because they do not represent 290% as a fraction by placing the percentage value over 100.

4. In which of the following battles were there more Confederate casualties than Union casualties?

A. Cold Harbor
B. Chancellorsville
C. Atlanta
D. Shiloh

Correct answer: D

Rationale: Shiloh had more Confederate casualties than Union casualties. In the Battle of Shiloh, fought in April 1862, the Confederates suffered around 10,700 casualties, while the Union forces had approximately 13,000 casualties. Therefore, Shiloh is the correct answer. Choice A, Cold Harbor, is incorrect because in that battle, the Confederate casualties were fewer than the Union casualties. Choices B and C, Chancellorsville and Atlanta respectively, also had more Union casualties than Confederate casualties, making them incorrect answers.