The Circulatory System Structures and Their Functions

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The Circulatory System Structures and Their Functions

Blood

Connects all of the organ systems of the body by transporting materials throughout. It is considered a connective tissue and has four main parts: plasma, red blood cells, white blood cells, and platelets.

Platelets

Makes up 1-2% and blood. Function is to help blood clot and prevent bleeding.

White Blood Cells

Make up 1-2% of blood. Function is to protect the body against disease and invaders.

Red Blood Cells

Makes up 45-50% of blood. Function is to carry oxygen to cells and deliver carbon dioxide to lungs.

Plasma

Makes up 50-55% of blood. Main contents include water, glucose, hormones, enzymes, proteins, minerals, and various waste products

Capillaries

Veins

Vessels carrying blood toward the heart

Arteries

Vessels carrying blood away from the heart

Lungs

Carbon dioxide travels from the blood to the air within the lungs and oxygen travels from the air into the blood. This oxygenates the blood.

The Heart

Myogenic Muscles

Muscle fibres of the heart that contract without being stimulated to do so by an external nerve cell. This causes the heart to beat.

Sinoatrial node (SA Node)

A group of cells located in the wall of the right atrium that generate electrical signals to control the rhythm of the heart

Atrioventricular Node (AV Node)

Receives electrical impulses from the SA Node and directs them to the walls of the ventricles down the Purkinje fibres.

Superior Vena Cava

Delivers deoxygenated blood from the upper body into the heart. It is a vein.

Pulmonary Arteries

Carry deoxygenated blood from the heart to the lungs.

Inferior Vena Cava

Delivers deoxygenated blood from the lower body into the heart. It is a vein

Arteries To Head and Arms: the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery

These arteries carry blood upwards towards the head and arms.

Aorta

Carries oxygenated blood away from the heart, to the rest of the body. It is the largest artery in the body.

Function: Directs the blood to flow through the proper circuit. Deoxygenated blood flows through the pulmonary circuit and oxygen-rich blood flows through the systemic circuit.

Chordae Tendineae

Tough, string-like cords that attach to the special papillary muscles in the ventricles. They keep the tricuspid and mitral valves in place when the ventricles contract, and are needed to provide extra support due to the pressure caused by the pumping of the ventricles.

Valves: the semilunar (pulmonary) valve, atrioventricular (tricuspid) valve, atrioventricular (mitral) valve, and the semilunar (aortic) valve

Their function is to make sure that blood flows in only one direction when each chamber contracts.

Atria

Right Atrium

Upper cavity of the heart where deoxygenated blood is received from the veins and pumped into the right ventricle.

Left Atrium

Upper cavity of the heart where oxygenated blood is received from the veins and pumped into the left ventricle.

Ventricles

Right Ventricle

A chamber in the heart that forces blood into the arteries. It does not need to be as strong or have as thick of a muscle as the left ventricle because it pumps blood into the lungs in the pulmonary circuit.

Left Ventricle

A chamber in the heart that forces blood into the arteries. It has the thickest muscle because it needs to pump blood throughout the entire body through the systemic circuit.

Septum

Separates the right and left ventricles