Overview
This lecture introduces the circulatory (cardiovascular) system, focusing on the heart’s structure, function, and its double circulatory circuits in mammals.
The Circulatory System
- The circulatory system (cardiovascular system) transports substances like oxygen, nutrients, and waste throughout the body.
- It is made up of the heart, blood vessels, and blood.
- The heart pumps blood; blood vessels direct it; blood carries substances.
Double Circulatory System
- Mammals have a double circulatory system with two circuits: pulmonary and systemic.
- The pulmonary circuit moves blood from the heart to the lungs and back.
- The systemic circuit moves blood from the heart to all body tissues and back.
- Blood cycles from heart to lungs, back to heart, then to the body, repeating continuously.
Heart Structure and Function
- The heart is a muscular organ with four chambers: two atria (upper) and two ventricles (lower).
- Right and left sides of the heart are labeled from the heart owner’s perspective (mirror image in diagrams).
- The right atrium receives deoxygenated blood and sends it to the right ventricle.
- The right ventricle pumps blood to the lungs via the pulmonary artery.
- The left atrium receives oxygenated blood from the lungs and sends it to the left ventricle.
- The left ventricle pumps oxygenated blood to the body via the aorta.
- The left ventricle’s wall is thicker because it pumps blood further (to the whole body) than the right ventricle (to lungs).
Blood Vessels of the Heart
- The vena cava brings deoxygenated blood from the body to the right atrium.
- The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
- The pulmonary vein brings oxygenated blood from the lungs to the left atrium.
- The aorta carries oxygenated blood from the left ventricle to the body.
Coronary Arteries
- Coronary arteries branch from the aorta and provide the heart muscle with oxygen and nutrients.
- Blockage of coronary arteries can cause disease or heart attacks.
Key Terms & Definitions
- Circulatory System — transports blood, nutrients, and waste in the body.
- Pulmonary Circuit — blood flow between heart and lungs.
- Systemic Circuit — blood flow between heart and body tissues.
- Atrium (plural: Atria) — upper chambers of the heart.
- Ventricle — lower chambers of the heart.
- Vena Cava — largest vein, returns deoxygenated blood to heart.
- Pulmonary Artery — carries deoxygenated blood to lungs.
- Pulmonary Vein — returns oxygenated blood from lungs to heart.
- Aorta — largest artery, carries oxygenated blood to body.
- Coronary Arteries — supply heart muscle with blood.
Action Items / Next Steps
- Review diagrams of the heart and circulatory system to identify structures and blood vessels.
- Prepare for future lessons on the components of blood and blood vessels.