2️⃣ The Circulatory System

Question 1

What are the key components of the circulatory system?

Answer 1

The heart, blood, and blood vessels.

Question 2

What are the primary functions of the circulatory system?

Answer 2

Transport of O₂, CO₂, nutrients, salts, hormones, immune cells; regulation of fluid balance, acid-base balance, body temperature; protection against infection and blood loss via clotting.

Question 3

Describe the structural layers of blood vessels.

Answer 3

Intima: endothelial layer + internal elastic lamina; Media: smooth muscle cells + extracellular matrix; Adventitia: connective tissue, nerves, and small vessels.

Question 4

Differentiate between arteries, capillaries, and veins.

Answer 4

Arteries: elastic, muscular, small arteries, arterioles—high pressure, resistance; Capillaries: ~7–8 μm, exchange O₂/nutrients, thin endothelium; Veins/venules: low pressure, thin walls, valves, site of inflammation.

Question 5

How do vessels receive their own blood supply?

Answer 5

Through fenestrations in the internal elastic lamina supplying inner SMCs and via the vasa vasorum supplying outer vessel layers.

Question 6

What roles does endothelium play in flow and coagulation?

Answer 6

Maintains laminar flow (anticoagulant/antithrombotic) and controls coagulation upon injury (procoagulant/prothrombotic).

Question 7

What are the cellular and plasma components of blood?

Answer 7

Plasma (55%: water, proteins, electrolytes, nutrients, waste), RBCs (45%), WBCs & platelets (1%).

Question 8

List major plasma proteins and their functions.

Answer 8

Albumin (osmotic pressure), globulins (immunity), fibrinogen (clotting).

Question 9

Explain the functions of RBCs, WBCs, and platelets.

Answer 9

RBCs carry O₂; WBCs (granulocytes, lymphocytes, monocytes) defend; platelets form clots and release growth factors.

Question 10

What is laminar flow?

Answer 10

A flow pattern where cellular elements remain central and slower-moving plasma forms an outer layer.