Circulatory System

Question 1

What is plasma composed of, and what is the percentage of water in it?

Answer 1

Plasma is made up of:
• 90% water
• 7% plasma proteins (e.g., antibodies, complement proteins, clotting proteins like Factor VIII)
• 3% dissolved substances (e.g., glucose, amino acids, vitamins, minerals, carbon dioxide, urea, hormones).

Question 2

What are the functions of plasma in the circulatory system?

Answer 2

1. Transporting dissolved substances: Plasma carries nutrients, hormones, carbon dioxide, and urea around the body.
2. Heat regulation: Plasma helps distribute heat generated by the liver to maintain body temperature.
3. Clotting: Plasma proteins are involved in forming blood clots with platelets to prevent excessive bleeding.

Question 3

Where are red blood cells produced, and what is their lifespan?

Answer 3

• Red blood cells are produced in the bone marrow.
• The lifespan of an RBC is approximately 4 months (120 days).

Question 4

What is the structure of red blood cells, and how does it aid their function?

Answer 4

• RBCs are biconcave in shape, which increases surface area for oxygen exchange and allows flexibility to move through narrow capillaries.
• They lack a nucleus and mitochondria, allowing more space for hemoglobin and preventing oxygen consumption by the cell itself.
• Contain hemoglobin, a protein that binds to oxygen in the lungs and carries it throughout the body.

Question 5

How are red blood cells broken down when damaged?

Answer 5

• Damaged RBCs are broken down in the liver or spleen.
• Hemoglobin’s iron is recycled to produce new RBCs, and the rest of the RBC is used to produce bile pigments (bilirubin and biliverdin).

Question 6

What is the function of hemoglobin in red blood cells?

Answer 6

Hemoglobin binds to oxygen in the lungs to form oxyhemoglobin, which is then transported to tissues. Hemoglobin also carries carbon dioxide from tissues back to the lungs.

Question 7

Where are white blood cells produced and stored, and what is their function?

Answer 7

• White blood cells are produced in the bone marrow and stored in the lymphatic system (lymph nodes and spleen).
• They are responsible for fighting infections as part of the immune system.

Question 8

What is the structure and function of lymphocytes?

Answer 8

• Lymphocytes have a large nucleus.
• They produce antibodies that target foreign substances (antigens), marking them for destruction by other white blood cells.
• There are two types: B cells (produce antibodies) and T cells (help in immune responses).

Question 9

What is the structure and function of monocytes?

Answer 9

• Monocytes have a kidney-shaped nucleus.
• They engage in phagocytosis, digesting foreign particles and pathogens.
• Monocytes mature into macrophages (large cells) which continue phagocytosis in tissues.

Question 10

What is the difference between an antibody and an antigen?

Answer 10

• Antibody: A protein produced by lymphocytes that binds to a specific antigen to mark it for destruction.
• Antigen: A substance that triggers the production of antibodies, typically a foreign molecule like bacteria or viruses.

Question 11

What are the two types of circulatory systems, and give examples?

Answer 11

1. Open Circulatory System: Blood leaves the vessels and flows freely in the body (e.g., insects).
2. Closed Circulatory System: Blood remains enclosed in blood vessels (e.g., humans).

Question 12

What are the advantages of a closed circulatory system?

Answer 12

1. Faster blood flow.
2. More efficient than an open system.
3. Blood can be maintained at high pressure, allowing better nutrient delivery.
4. The rate of blood flow can be controlled and directed to specific areas (e.g., increased flow to muscles during exercise).

Question 13

What is double circulation, and what are its advantages?

Answer 13

• Double circulation involves two separate circuits:
1. The systemic circuit pumps oxygenated blood to the body.
2. The pulmonary circuit pumps deoxygenated blood to the lungs.
• Advantages:
1. Separates oxygenated and deoxygenated blood.
2. Maintains high blood pressure for more efficient circulation.

Question 14

What is a portal system, and give an example?

Answer 14

A portal system is a blood pathway that begins and ends in capillaries.
• Example: The hepatic portal system, which connects capillaries in the villi of the ileum to the capillaries in the liver via the hepatic portal vein.

Question 15

Where is the heart located, and what is its function?

Answer 15

• Location: Between the lungs, slightly to the left side of the thorax, above the diaphragm.
• Function: The heart pumps blood throughout the body, supplying oxygen and nutrients to tissues and removing waste products.

Question 16

What is the structure of the heart?

Answer 16

• The heart has 4 chambers:
1. Atria (top chambers) receive blood.
2. Ventricles (bottom chambers) pump blood.
• Septum: A wall that divides the left and right sides of the heart.
• The heart is surrounded by a double membrane called the pericardium, filled with pericardial fluid to reduce friction during heartbeats.

Question 17

What are the main functions of the heart’s valves?

Answer 17

Valves ensure that blood flows in one direction through the heart, preventing backflow. They help control blood flow between the atria and ventricles and to the arteries.