PAX Physiology 1 — Questions and Answers
Question 1: The sinoatrial (SA) node is the heart's natural pacemaker. Where is it located?
- Left ventricle
- Right atrium (Correct answer)
- Left atrium
- Right ventricle
Correct answer: Right atrium
The SA node is located in the right atrium and generates the electrical impulses that initiate each heartbeat.
Question 2: Which blood vessels carry oxygenated blood away from the heart in systemic circulation?
- Veins
- Venules
- Arteries (Correct answer)
- Capillaries
Correct answer: Arteries
Arteries carry oxygenated blood away from the heart to body tissues in systemic circulation.
Question 3: During inhalation, what happens to the diaphragm?
- It relaxes and moves upward
- It contracts and moves downward (Correct answer)
- It remains stationary
- It moves laterally
Correct answer: It contracts and moves downward
During inhalation, the diaphragm contracts and flattens downward, increasing thoracic volume and drawing air into the lungs.
Question 4: Which molecule in red blood cells binds to oxygen for transport throughout the body?
- Myoglobin
- Albumin
- Fibrinogen
- Hemoglobin (Correct answer)
Correct answer: Hemoglobin
Hemoglobin is the iron-containing protein in red blood cells that binds oxygen in the lungs and releases it in body tissues.
Question 5: What is the normal resting heart rate range for a healthy adult?
- 40–60 beats per minute
- 60–100 beats per minute (Correct answer)
- 100–120 beats per minute
- 120–150 beats per minute
Correct answer: 60–100 beats per minute
A normal resting heart rate for adults is 60–100 beats per minute; below 60 is bradycardia and above 100 is tachycardia.
Question 6: Gas exchange in the lungs — oxygen entering the blood and carbon dioxide leaving — occurs in which structures?
- Bronchi
- Bronchioles
- Alveoli (Correct answer)
- Trachea
Correct answer: Alveoli
Alveoli are tiny air sacs where oxygen diffuses into the blood and carbon dioxide diffuses out, making them the primary site of gas exchange.
Question 7: What term describes the total volume of blood pumped by the heart per minute?
- Stroke volume
- Heart rate
- Cardiac output (Correct answer)
- Ejection fraction
Correct answer: Cardiac output
Cardiac output is the volume of blood the heart pumps per minute, calculated as heart rate multiplied by stroke volume.
PAX Physiology 1
The sinoatrial (SA) node is the heart's natural pacemaker.
Where is it located?