Blood and the Circulatory System

Flashcards for key vocabulary relating to the circulatory system.

Plasma

Yellow liquid component of blood that transports RBCs, WBCs, carbon dioxide, platelets, hormones, and heat. It is mostly water and acts as a solvent.

Red Blood Cells (RBCs)

Cells that transport oxygen around the body. They are produced in red bone marrow, lack a nucleus, and are broken down by the liver. They are biconcave to maximize surface area and contain haemoglobin to carry oxygen.

White Blood Cells (WBCs)

Cells that fight infection. They are produced in bone marrow, have no definite shape, and include lymphocytes (produce antibodies) and monocytes/macrophages (engulf and destroy pathogens).

Platelets

Cell fragments that clot blood to reduce blood loss and prevent entry of microorganisms. They are produced in the bone marrow.

Arteries

Blood vessels that carry blood away from the heart. They have no valves, a narrow lumen, and thick walls.

Veins

Blood vessels that carry blood towards the heart. They have wide lumen, thin walls and contain valves to prevent backflow of blood.

Capillaries

Thin-walled blood vessels that connect veins to arteries and allow nutrients to diffuse through.

The Heart

An organ located in the thoracic cavity, composed of cardiac muscle, and surrounded by the pericardium. It has four chambers: left atrium, left ventricle, right atrium, and right ventricle.

Valves

Structures within the heart that prevent backflow of blood. These include the tricuspid valve, bicuspid valve, and semi-lunar valves. Their closing produces the lub-dub sounds.

Vena Cava

Major blood vessel that carries deoxygenated blood to the right atrium.

Pulmonary Artery

Major blood vessel that carries deoxygenated blood to the lungs.

Pulmonary Vein

Major blood vessel that carries oxygen-rich blood from the lungs to the left atrium.

Aorta

Major blood vessel that carries oxygenated blood to the rest of the body.

Pulmonary Circuit

One of the two circulatory circuits, involving blood flow between the heart and the lungs (heart - lungs - heart).

Systemic Circuit

One of the two circulatory circuits, involving blood flow between the heart and the rest of the body (heart - rest of body - heart).

Coronary Artery

Blood vessel that supplies oxygenated blood to the heart muscle. Blockage of this artery can lead to heart attacks.

Hepatic Portal System

A blood pathway that begins and ends in capillaries. The hepatic portal vein connects the small intestine to the liver, allowing nutrients to move directly to the liver.

Pacemaker (SA node)

Located in the right wall of the atria, it generates impulses and causes the atria to contract, controlling the rate of the heartbeat.

AV Node

Located between the right atrium and right ventricle, it generates impulses and causes the ventricles to contract.

Diastole

Phase of the cardiac cycle where the heart is relaxed and not contracting.

Systole

Phase of the cardiac cycle where the heart is contracting.

Pulse

The expansion of an artery, often taken at the wrist or side of the neck.

Blood Pressure

The force that blood exerts against the wall of a blood vessel.