BIO 252 Module 3 Exam Study Guide: Anatomy and Physiology of the Cardiovascular System:100% Verified Questions & Answers

BIO 252 Module 3 Exam Study Guide: Anatomy and Physiology of the
Cardiovascular System
Section 1: Microscopic Anatomy & Excitation-Contraction
1. What is "auto rhythmicity" in cardiac muscle?
• A) The ability to contract only when stimulated by the brain.
• B) The ability to initiate its own electrical potential at a fixed rate.
• C) The process of repairing damaged muscle fibers via stem cells.
• D) The coordination of skeletal and smooth muscle during exercise.
Correct Answer: B
Rationale: Autorhythmicity allows the heart to beat independently of external
nervous or endocrine input.
2. Which cell type makes up 99% of the heart and is responsible for pumping?
• A) Myocardial conducting cells
• B) Myocardial contractile cells
• C) Purkinje cells
• D) Sinoatrial node cells
Correct Answer: B
Rationale: Contractile cells form the bulk of the heart and provide the force for
blood flow.
3. What is the primary metabolic pathway for cardiac muscle?
• A) Anaerobic glycolysis
• B) Lactic acid fermentation
• C) Aerobic metabolism
• D) Phosphagen system

,Correct Answer: C
Rationale: Cardiac muscle relies almost entirely on oxygen-using aerobic
metabolism.
4. What is the smallest functional unit of a muscle contraction?
• A) Myofibril
• B) Cardiomyocyte
• C) Sarcomere
• D) Z-line
Correct Answer: C
Rationale: The sarcomere, running from Z-line to Z-line, is the basic unit of
contraction.
5. During contraction, which of the following occurs to the Z-lines?
• A) They move further apart.
• B) They are pulled together.
• C) They disappear.
• D) They rotate 90 degrees.
Correct Answer: B
Rationale: As filaments slide, Z-lines move closer, shortening the muscle cell.
6. Which feature is unique to cardiomyocytes compared to skeletal muscle?
• A) Striated appearance
• B) Use of actin and myosin
• C) Intercalated discs
• D) Presence of sarcomeres
Correct Answer: C

,Rationale: Intercalated discs, containing desmosomes and gap junctions, are
unique to cardiac muscle.
7. Where are T-tubules located in cardiac muscle?
• A) In the A-band
• B) At the Z-lines
• C) In the nucleus
• D) Outside the sarcolemma
Correct Answer: B
Rationale: Cardiac T-tubules are found specifically at the Z-lines and are larger
than those in skeletal muscle.
8. Why does the heart rely on extracellular calcium (Ca2+) for contraction?
• A) It lacks a sarcoplasmic reticulum.
• B) T-tubules are too small.
• C) It has fewer SR calcium stores than skeletal muscle.
• D) Calcium cannot cross the sarcolemma.
Correct Answer: C
Rationale: Limited internal SR stores make the heart dependent on external
calcium inflow.
9. What is the function of desmosomes within intercalated discs?
• A) Allowing ion passage.
• B) Anchoring cells together to prevent pulling apart.
• C) Storing myoglobin.
• D) Initiating the action potential.
Correct Answer: B

, Rationale: Desmosomes provide structural stability during forceful contractions.
10. How do gap junctions assist heart function?
• A) They store lipids for energy.
• B) They anchor the heart to the pericardium.
• C) They allow ions to pass, enabling synchronized impulses.
• D) They block electrical signals from the atria.
Correct Answer: C
Rationale: Gap junctions allow the heart to function as a single unit, or syncytium.
11. What is the purpose of the long refractory period in cardiac muscle?
• A) To allow for faster heart rates.
• B) To prevent tetany (sustained contraction).
• C) To increase glucose uptake.
• D) To bypass the AV node.
Correct Answer: B
Rationale: A long refractory period ensures the heart relaxes and refills between
beats.
12. In the presence of calcium, which protein shifts to expose myosin-binding
sites?
• A) Actin
• B) Myosin
• C) Tropomyosin
• D) Troponin
Correct Answer: C Rationale: Calcium binds to troponin, which then shifts
tropomyosin off the binding sites.