Cardiac Anatomy & Physiology Quiz

Circulatory System Overview

• The heart is a hollow muscular organ that functions as a pump in the circulatory system.
• The circulatory system comprises the cardiovascular and lymphatic systems, which manage blood flow and lymph throughout the body.
• Key functions include transporting oxygen, nutrients, hormones, and gases to and from cells.

The Heart Structure

• Located centrally between the lungs, slightly to the left; roughly the size of a clenched fist.
• Functions continuously, never stopping its pumping action.
• Comprised of four chambers: two atria receive blood, and two ventricles pump blood.
• Surrounded by myocardial cells, enabling contraction and relaxation.

Cardiovascular System Components

• Contains approximately 4-6 liters of blood in a closed system, where blood remains within vessels at all times.
• Blood travels through arteries, arterioles, capillaries, and veins.
• Blood flow patterns include:
  • Pulmonary circuit: Blood flow between heart and lungs.
  • Systemic circuit: Blood flow to and from the rest of the body.
  • Coronary circuit: Blood flow to the heart itself.

Heart Functionality

• Heart valves facilitate unidirectional blood flow.
• The contraction process of the heart is termed systole, while relaxation is known as diastole.

Cardiac Cycle and Key Terms

• End Diastolic Volume (EDV): Blood volume in ventricles at end of filling (approximately 125 mls).
• End Systolic Volume (ESV): Blood volume remaining in ventricles at end of contraction (approximately 50 mls).
• Stroke volume (SV): Volume of blood pumped from ventricles per beat, averaging 70 mls in a healthy adult male.
• Formula for stroke volume: EDV - ESV = SV (e.g., 125 ml - 50 ml = 75 ml).

Cardiac Output (CO)

• Cardiac output refers to the blood ejected by the heart per minute, averaging 5-6 liters in a healthy adult at rest.
• Formula: CO = Heart Rate x Stroke Volume.
• Example calculation: CO = 70 bpm x 75 mls = 5,250 mls.

Conduction System of the Heart

• Two types of cardiac cells (myocytes):
  • Myocardial Cells: Contractile cells that respond to electrical impulses.
  • Specialized Cells: Form the conduction system that generates and transmits electrical impulses.
• Main impulse generation sites and rates:
  • SA Node: 60-100 impulses/min
  • AV Node: 40-60 impulses/min
  • Ventricles: < 40 impulses/min

Ejection Fraction

• Ejection fraction measures the percentage of blood pumped out of the heart with each contraction.
• Typically assessed via imaging techniques such as ECHO, cardiac catheterization, or MRI.
• Both cardiac output and ejection fraction are crucial indicators of heart efficiency in meeting the body's metabolic demands.

Balance of Blood Output

• The output from the right and left sides of the heart must be balanced.
• The ventricles do not completely empty, ensuring continual blood flow.
• Key values:
  • End Diastolic Volume: 125 mls
  • End Systolic Volume: 50 mls
  • Example SV Calculation: 125 mls - 50 mls = 75 mls.

Test your knowledge on the anatomy and physiology of the heart and the circulatory system. This quiz covers essential concepts about how the heart functions as a pump and its role in the cardiovascular system. Prepare to explore the intricate connections between the heart, blood, and nutrients.