Cardiovascular System Anatomy: Blood Vessels and Heart Structure

Posted on Oct 2, 2025 in Biology

Blood Vessels: Structure and Labeling

Figure 1: Blood Vessel Anatomy

Instruction: Complete the labels of Figure 1 using the following terms: venules, capillaries, valves, arterioles, artery, vein.

Answer Key: A: Artery, B: Arterioles, C: Capillaries, D: Venules, E: Valves, F: Vein

Figure 2: Blood Vessel Cross-Section

Instruction: Complete the labels of Figure 2 using the following terms: vein, capillary, artery (you will need to use some terms more than once).

Answer Key: A: Artery, B: Vein, C: Capillary, D: Artery, E: Vein

Comparison of Blood Vessels

Based on the information provided about the blood vessels, complete Table 1 below:

Table 1: Comparison of the Three Types of Blood Vessels

B. Cardiac Muscle Tissue

Observe the slide of cardiac muscles. In the space provided, draw a representative section of the slide. Note the magnification. Label the nuclei, intercalated discs, and striations.

Figure 3: Microscopic View of Cardiac Muscle

Instruction: Complete the labels of Figure 3.

Answer Key: A: Cardiac Muscle Fiber, B: Intercalated Disc, C: Nucleus, D: Capillary

C. Layers of the Heart

Figure 4: Layers of the Heart Wall

Instruction: Complete the labels of Figure 4 using the following terms: endocardium, epicardium, myocardium, pericardium.

Answer Key: A: Epicardium, B: Myocardium, C: Endocardium, D: Pericardium

D. Internal Structures of the Heart

1. Determining the Right and Left Side of the Heart: The side of the heart is named based on the side of the person. Name the RIGHT & LEFT sides of the heart in the following diagram (Figure 5).

2. Identifying the Chambers of the Heart: The heart has two receiving chambers in the upper part, called atria (singular atrium), and two pumping chambers in the lower part, called ventricles.

   • Label the four chambers of the heart.
   • Color the chambers using two colors: one for the atria and one for the ventricles.
   • The tissue separating the right and the left side of the heart is the septum. Find the septum and label it.

Figure 6: Chambers of the Heart

3. Identifying the Blood Vessels that Bring Blood to the Heart:

   • The two main blood vessels on the right side of the heart that bring blood to the right atrium from the body are known as the superior and inferior vena cavae.
   • The blood from the lungs comes to the left atrium through the left and right pulmonary veins.

   Label these blood vessels and draw arrows to show the direction of blood flow in Figure 7.

4. Identifying the Blood Vessels that Take Blood Away from the Heart:

   • The two main blood vessels in the middle of the heart are the pulmonary trunk and the aorta.

   Label these blood vessels and draw arrows to show the direction of blood flow in Figure 8.

5. Identifying the Valves of the Heart:

   • The function of the valves is to prevent blood from flowing backward.
   • The valves between the atria and the ventricles are atrioventricular (AV) valves. The one on the right side is also called the tricuspid valve (has three cusps). The one on the left side is also called the bicuspid valve (has two cusps), or mitral valve.
   • The valve at the base of the pulmonary artery is called the pulmonary semilunar valve, and the one at the base of the aorta is called the aortic semilunar valve.

   Label these valves in Figure 9.

E. Blood Flow Through the Cardiovascular System

• Our body cells need oxygen and nutrients and produce wastes, including carbon dioxide. Therefore, the blood supplying our body cells is O₂ rich blood, and the blood transporting substances away from the cell is O₂ poor blood.
• The O₂ poor blood needs to get more oxygen and discard carbon dioxide. It does this in the lungs. Thus, the blood going into the lungs is O₂ poor, and the blood coming away from the lungs is O₂ rich.

Choose two contrasting colors for O₂ rich and O₂ poor blood. Color the arrows to show the nature of the blood (if it is O₂ rich or O₂ poor) in Figure 10.

1. Write the path of oxygen rich blood through the heart.
2. Write the path of oxygen poor blood through the heart.
3. Write the path of blood flow through the pulmonary circuit.
4. Write the path of blood flow through the systemic circuit.

In the following figure (Figure 11):

• Use contrasting colors to color the path of O₂ rich and O₂ poor blood.
• Circle the pulmonary and systemic circuits separately and label them.
• Draw arrows to indicate the direction of blood flow.

Use Figure 12 and trace the path of blood as indicated below:

1. From the heart to the head and back to the heart:
2. From the heart to the arms and back to the heart:
3. From the heart to the kidneys and back to the heart:
4. From the heart to the legs and back to the heart:

F. Test Your Knowledge

1. What are some of the differences between the left and right side of the heart?

   The left side pumps oxygenated blood to the body (systemic circuit), while the right side pumps deoxygenated blood to the lungs (pulmonary circuit).

2. What can be the problem if the heart valves malfunction?

   Malfunctioning valves can lead to inefficient blood flow, causing symptoms like shortness of breath and potentially leading to heart failure.

3. Which type of blood vessel (arteries or veins) has thicker walls? Why?

   Arteries have thicker walls than veins. Arteries carry blood under high pressure, and the thicker walls help withstand this pressure.

4. Which type of blood vessel has thinner walls?

   Veins have thinner walls because they carry blood back to the heart under lower pressure.

5. Complete the table by listing the blood vessel that carries blood to each part of the body and the vessel that carries blood away from those organs back to the heart.