Ch. 7.8 Circulatory System Key Terms
1. Aortic Valve
A semilunar valve located between the left ventricle and the aorta (the body's largest artery). It opens to allow oxygenated blood to be pumped to the rest of the body and closes to prevent backflow into the left ventricle.
12. Left Ventricle
The thick-walled, muscular lower chamber on the left side of the heart that pumps oxygenated blood out through the aortic valve into the aorta, distributing it to the systemic circulation (the rest of the body).
15. Myocardium
The thick, muscular middle layer of the heart wall responsible for the powerful pumping action.
6. Circulatory System
The organ system that includes the heart and blood vessels (arteries, veins, and capillaries), responsible for transporting blood throughout the body to deliver nutrients and oxygen and remove waste products.
17. Plasma
The straw-colored, liquid portion of the blood (about 55% of its volume), primarily composed of water, proteins, nutrients, hormones, and waste products.
14. Mitral Valve
An atrioventricular valve (bicuspid valve) with two leaflets located between the left atrium and the left ventricle. It allows oxygenated blood to flow from the atrium to the ventricle and prevents backflow.
19. Right Atrium
The upper chamber on the right side of the heart that receives deoxygenated blood from the body (via the vena cavae).
16. Pericardium
A double-walled sac that encloses the heart, providing protection and anchoring it within the chest.
3. Arteries
Blood vessels that carry oxygenated blood away from the heart to the body's tissues (the pulmonary artery is the exception, carrying deoxygenated blood to the lungs).
9. Erythrocytes
Red blood cells (RBCs); biconcave cells that lack a nucleus and are responsible for transporting oxygen from the lungs to the body's tissues.
18. Pulmonary Valve
A semilunar valve located between the right ventricle and the pulmonary artery. It opens to allow deoxygenated blood to be pumped to the lungs for oxygenation and closes to prevent backflow.
20. Right Ventricle
The lower chamber on the right side of the heart that pumps deoxygenated blood through the pulmonary valve into the pulmonary artery, leading to the lungs.
7. Diastole
The phase of the heartbeat when the heart muscle relaxes and the chambers fill with blood.
25. Veins
Blood vessels that carry deoxygenated blood back to the heart (the pulmonary veins are the exception, carrying oxygenated blood from the lungs to the heart).
10. Hemoglobin
An iron-containing protein found in erythrocytes that binds to oxygen in the lungs and releases it to the tissues. It is responsible for the red color of blood.
24. Tricuspid Valve
An atrioventricular valve with three leaflets located between the right atrium and the right ventricle. It allows deoxygenated blood to flow from the atrium to the ventricle and prevents backflow.
21. Septum
The muscular wall that divides the heart into right and left sides, preventing the mixing of oxygenated and deoxygenated blood.
22. Systole
The phase of the heartbeat when the ventricles contract and pump blood out of the heart (into the aorta and pulmonary artery).
5. Capillaries
The smallest blood vessels, which form a network connecting arteries and veins, where the exchange of oxygen, nutrients, and waste products occurs between the blood and the surrounding tissues.
13. Leukocytes
White blood cells (WBCs); cells of the immune system that protect the body against infectious disease and foreign invaders.
11. Left Atrium
The upper, thin-walled chamber on the left side of the heart that receives oxygenated blood from the lungs (via the pulmonary veins).
8. Endocardium
The smooth, thin inner lining of the heart's chambers and valves.
2. Arrhythmias
Also known as dysrhythmias, these are problems with the rate or rhythm of the heartbeat, meaning the heart beats too fast, too slow, or irregularly.
4. Blood
A fluid connective tissue composed of plasma and cells (red blood cells, white blood cells, and platelets) that circulates through the cardiovascular system, transporting substances throughout the body.
23. Thrombocytes
Platelets; small, irregular cell fragments that are involved in blood clotting and wound healing.