Question

multiple choice question
the muscular pump that keeps blood flowing through blood vessels is the ______.

muscularis externa

heart

biceps brachii

lung

Explanation:

To solve this, we analyze each option:

• "muscularis externa" is a layer of muscle in organs like the digestive tract, not a pump for blood.
• "heart" is a muscular organ that contracts to pump blood through blood vessels, matching the description.
• "biceps brachii" is an arm muscle, not involved in blood circulation.
• "lung" is for gas exchange, not pumping blood.

Answer:

B. heart