10) Circulatory System

Question 1

Q: What is the principal function of the circulatory system?

Answer 1

The principal function is the transport of oxygen and nutrients to tissues and the removal of carbon dioxide and metabolic waste. It also regulates temperature, distributes hormones, and supports immunity.

Question 2

What are the two main components of the circulatory system?

Answer 2

1. Cardiovascular system: Includes the heart, arteries, arterioles, capillaries, venules, and veins.
2. Lymph vascular system: Comprises lymphatic capillaries and larger lymphatic vessels that drain lymph into veins in the neck.

Question 3

Name the three layers of the heart.

Answer 3

1. Endocardium: Inner layer.
2. Myocardium: Middle layer.
3. Epicardium (Pericardium): Outer layer.

Question 4

What are the three layers of blood vessels?

Answer 4

1. Tunica intima: Inner layer.
2. Tunica media: Middle layer.
3. Tunica adventitia: Outer layer.

Question 5

What are the structural differences between arteries and veins?

Answer 5

Arteries have thicker walls with more smooth muscle and elastic fibers.

Veins have thinner walls, larger lumens, and valves to prevent backflow.

Question 6

What are the three types of arteries?

Answer 6

1. Elastic arteries: Largest, e.g., aorta and pulmonary artery.
2. Muscular arteries: Medium to small-sized, e.g., coronary arteries.
3. Arterioles: Smallest arteries.

Question 7

What is the role of Purkinje fibers?

Answer 7

Purkinje fibers coordinate ventricular contraction and are found in the bottom layer of the endocardium near the myocardium.

Question 8

Describe the composition of the myocardium.

Answer 8

The myocardium is the thickest layer of the heart and consists of cardiac muscle, connective tissue, blood vessels, and nerves.

Question 9

What is the primary function of the lymphatic system?

Answer 9

To collect excess tissue fluid (lymph) and return it to the venous system.

Question 10

What distinguishes small and medium veins structurally?

Answer 10

They have thin tunica media, a tunica intima that may form valves, and a well-developed tunica adventitia with longitudinal collagen and elastic fibers.

Question 11

What is the key feature of elastic arteries that helps maintain blood pressure?

Answer 11

Elastic arteries have a large amount of elastin, allowing them to expand and recoil to propel blood onward.

Question 12

How do venules differ from capillaries and small veins?

Answer 12

Venules have small lumens, thin walls with a single endothelial layer, and a few scattered smooth muscle cells, unlike capillaries, which lack muscle.

Question 13

What is the function of valves in veins?

Answer 13

Veins have valves to prevent backflow of blood.

Question 14

What is the difference between capillaries, veins, arteries, and venules?

Heart → Arteries → Arterioles → Capillaries → Venules → Veins → Heart

Answer 14

• Arteries carry oxygen-rich blood away from the heart to the tissues (except for the pulmonary artery, which carries oxygen-poor blood to the lungs).
• Arterioles control the flow of blood into the capillaries. They are the primary vessels responsible for regulating blood pressure by constricting or dilating
• Capillaries are the smallest blood vessels where the exchange of gases, nutrients, and waste products occurs between blood and tissues.
• Venules are small blood vessels that drain blood from capillary beds and transport it to larger veins.
• Veins carry oxygen-poor blood back to the heart (except for the pulmonary vein, which carries oxygen-rich blood from the lungs to the heart).

Question 15

What is the pericardial cavity and its role?

Answer 15

The pericardial cavity is the space between the two layers of the pericardium containing serous fluid, which facilitates the heart’s pumping action.