The Cardio-Respiratory System – Blood Vessels

Pulmonary circulation

Moves blood between the heart and the lungs, transporting deoxygenated blood to the lungs for oxygen absorption and carbon dioxide release.

Systemic circulation

Moves blood between the heart and the rest of the body, carrying oxygen and nutrients to cells and removing carbon dioxide and waste products.

Transportation

The primary role of blood vessels is to carry substances like oxygen, nutrients, hormones, carbon dioxide, and waste products throughout the body.

Communication

Blood vessels facilitate the delivery of blood containing essential substances to different body areas, allowing for communication.

Homeostasis

The role of blood vessels in maintaining equilibrium in the body, including temperature regulation and blood pressure control.

Arteries

Blood vessels that carry oxygenated blood away from the heart.

Arterioles

Smaller branches of arteries that lead to capillaries and help regulate blood pressure.

Capillaries

The smallest blood vessels where diffusion occurs.

Venules

Blood vessels that allow deoxygenated blood to move from capillaries to veins.

Veins

Blood vessels that return deoxygenated blood back to the heart, including the superior and inferior vena cava.

Diameter

The distance between the walls of a blood vessel.

Mean wall thickness

Measurement of how thick the walls of each type of blood vessel are.

Smooth muscle

Thick muscle layer in arteries that helps withstand high pressure from blood pumped out of the heart.

Thin walls

Characteristic of veins that allows them to accommodate low-pressure blood flow.

Diffusion

The movement of gases (O2, CO2) across capillary walls.

Transcytosis

The transport of larger lipid-insoluble molecules across endothelial cells via vesicles.

Bulk flow

The mass movement of fluid driven by pressure.

Continuous capillary

Type of capillary with tightly knitted endothelial cells, found in skin and muscle.

Fenestrated capillary

Capillary type with large pores, found in kidneys, intestines, and endocrine organs.

Discontinuous capillary

Capillary type found in the liver, bone marrow, and spleen. Endothelial lining starts to get less tight junctions and has more gaps and holes. There are large intercellular clefts, very leaky capillaries.

Lumen

The hollow passageway within a blood vessel where blood flows.

Tunica Intima

The innermost layer of blood vessels, consisting of endothelial cells and responsible for releasing nitric oxide.

Tunica Media

The middle layer of blood vessels containing smooth muscle, thicker in arteries than in veins.

Tunica Externa

The outer layer of blood vessels made primarily of collagen fibers, providing protection and reinforcement. Contained in both arteries and veins.

Cardiac output

The volume of blood the heart pumps per minute, increasing from 5 liters at rest to around 25 liters during intense exercise.

Blood flow redistribution

The ability of blood vessels to redirect blood from low-demand areas to high-demand areas during exercise.