Circulatory system

Circulatory System

Responsible for transporting blood, nutrients, and oxygen throughout the body, and maintaining homeostasis.

Vein Structure

Thin less elastic walls with valves; consists of thin wall, endothelium, large lumen, and valves.

Role of Valves

Controls the flow of blood between the chambers of the heart and prevents backflow.

Coronary Arteries

Supply blood to the heart muscle; they are the first branches off the aorta.

Aorta

The largest artery in the body, distributing oxygen-rich blood from the heart to the body.

Chambers of the Heart

Four main chambers: left atrium, right atrium, left ventricle, right ventricle, involved in blood circulation.

Pulmonary Circuit

Circulates deoxygenated blood to the lungs for oxygenation.

Systemic Circuit

Circulates oxygenated blood from the heart to body tissues.

Heart Tissue Layers

Three layers: pericardium (outer protective layer), myocardium (middle cardiac muscle layer), endocardium (inner lining).

Superior Vena Cava

Carries deoxygenated blood from the upper body to the right atrium.

Inferior Vena Cava

Carries deoxygenated blood from the lower body to the right atrium.

Pulmonary Arteries

Carry deoxygenated blood from the right ventricle to the lungs.

Pulmonary Veins

Carry oxygenated blood from the lungs back to the left atrium.

Deoxygenated Blood

Travels through the pulmonary circuit to the lungs.

Oxygenated Blood

Returns to the heart via the pulmonary veins and is distributed through the systemic circuit.

Tricuspid Valve

Prevents backflow from the right ventricle to the right atrium.

Pulmonary Semilunar Valve

Pumps blood from the right ventricle into the pulmonary artery.

Mitral (Bicuspid) Valve

Ensures oxygenated blood flows into the left ventricle without regurgitating.

Aortic Semilunar Valve

Opens to allow oxygen-rich blood to be pumped into the aorta and prevents backflow.

SA Node

Initiates the heartbeat and sends signals for atrial contraction.

AV Node

Receives signals from the SA Node and relays them to the ventricles through Purkinje fibers.

Blood Circulation Sequence

Body tissues → Vena cavae → Right atrium → Tricuspid valve → Right ventricle → Pulmonary valve → Pulmonary artery → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Body tissues.