HESI A2 - Circulatory System - Key Terms and Concepts

Circulatory system

The body system is responsible for transporting blood, oxygen, nutrients, and waste products throughout the body.

Cardiovascular system

A body system made up of the heart and blood vessels that works to transport blood throughout the body.

Pulmonary circulation

The pathway in which blood travels from the heart to the lungs for oxygenation and then back to the heart.

Systemic circulation

The circulation of blood from the heart to the rest of the body, delivering oxygen and nutrients.

Coronary circulation

The movement of blood through the vessels supplying the heart muscle with oxygen and nutrients.

Artery

A blood vessel that carries oxygen-rich blood away from the heart to the body tissues.

Vein

A blood vessel that returns oxygen-depleted blood from the body to the heart.

Capillary

The smallest blood vessel where the exchange of gases, nutrients, and waste occurs between blood and tissues.

Endothelium

The thin layer of cells lining the interior surface of blood vessels, playing a role in vascular function.

Vasodilation

The widening of blood vessels that increases blood flow and reduces blood pressure.

Heart

A muscular organ that pumps blood throughout the body via the circulatory system.

Atrium

The heart's upper chamber that receives blood from the veins and pumps it into the ventricles.

Ventricle

The heart's lower chamber pumps blood to the lungs or the rest of the body.

Endocardium

The inner lining of the heart chambers that helps maintain smooth blood flow.

Pericardium

A protective membrane surrounding the heart that reduces friction during heartbeats.

Septum

A thick wall of tissue separating the heart's left and right sides.

Aortic valve

The heart valve that prevents blood from flowing backward from the aorta into the left ventricle.

Pulmonary valve

The heart valve that prevents blood from flowing backward into the right ventricle from the pulmonary artery.

Mitral valve

The valve between the left atrium and left ventricle that ensures one-way blood flow.

Myocardium

The heart’s thick, muscular middle layer responsible for the forceful contractions that pump blood.

Blood

A fluid that transports oxygen, nutrients, hormones, and waste throughout the body.

Plasma

The liquid component of blood that carries cells, hormones, nutrients, and waste products.

Red blood cell

A type of blood cell that carries oxygen from the lungs to the body and returns carbon dioxide to the lungs.

Hemoglobin

A protein in red blood cells that binds oxygen and facilitates transport.

White blood cell

A blood cell that plays a key role in defending the body against infections.

Platelet

A cell fragment in the blood that helps clot and prevent excessive bleeding.

Agglutination

The clumping of blood cells due to an immune reaction, often occurring in mismatched blood transfusions.

Fibrin

A protein that forms the structural framework of a blood clot to stop bleeding.

Hematopoiesis

The bone marrow's process of producing blood cells.

Erythropoietin

A hormone that reacts to low oxygen levels by promoting the synthesis of red blood cells.

Aorta

The largest artery in the body that carries oxygen-rich blood from the heart to the systemic circulation.

Pulmonary artery

The artery that carries deoxygenated blood from the heart to the lungs for oxygenation.

Pulmonary vein

The vein that carries oxygenated blood from the lungs back to the heart.

Superior vena cava

The vein that returns blood from the upper body to the heart.

Arteriole

A small artery that leads into capillaries, helping regulate blood pressure.

Collateral circulation

An alternate route for blood flow that develops when normal pathways are blocked.

Vascular resistance

The opposition to blood flow within the vessels, which plays a role in determining blood pressure levels.

Vena cava

The largest vein in the body, returning deoxygenated blood to the heart.

Inferior vena cava

The vein that supplies the heart with blood from the lower body.

Venule

A little vein that carries blood to bigger veins after collecting it from capillaries.

Hypertension

A condition characterized by persistently high blood pressure, increasing the risk of heart disease.

Hypotension

A condition where blood pressure is lower than normal, potentially causing dizziness or fainting.

Atherosclerosis

A disease in which plaque builds up inside arteries, reducing blood flow.

Arrhythmia

An irregular heartbeat caused by abnormal electrical activity in the heart.

Ischemia

A condition in which a reduced blood supply limits oxygen delivery to tissues.

Stroke

A medical emergency caused by a blockage or rupture of blood vessels in the brain.

Myocardial infarction

A condition commonly known as a heart attack, occurring when blood flow to the heart is blocked.

Aneurysm

A weakened and bulging area in a blood vessel that can rupture and cause life-threatening bleeding.

Varicose veins

Enlarged and twisted veins that result from malfunctioning valves, allowing blood to collect and back up.

Deep vein thrombosis (DVT)

The development of a blood clot in a deep vein, frequently in the lower limbs, which, if ignored, can cause major problems.

Hematocrit

The percentage of red blood cells (RBCs) in total blood volume.

Bone marrow

Spongy tissue situated in bones, which is responsible for the production of RBCs, WBCs, and platelets.

Granulocytes

A type of white blood cell with phagocytic properties, including neutrophils, eosinophils, and basophils.

Agranulocytes

A type of white blood cells without granules, including lymphocytes and monocytes.

Blood component percentage

55% Plasma

45% Formed Elements (RBCs, WBCs, and Platelets)

Never Let Monkeys Eat Bananas (5 different types of WBCs from most to least abundant)

1. Neutrophils

2. Lymphocytes

3. Monocytes

4. Eosinophils

5. Basophils

Atrioventricular valves

These valves consist of the tricuspid and mitral valves, which are responsible for preventing the backflow of blood from the ventricles to the atria.

Semilunar valves

Consisting of the pulmonary and aortic semilunar valves that prevent blood from flowing back into the ventricles.

Tricuspid valve

It is found between the right atrium and the right ventricle.

Bicuspid valve

It is found between the left atrium and left ventricle.

Systolic

A blood pressure during heart contraction.

Diastolic

A blood pressure during heart relaxation.

Left ventricle

Pushes oxygenated blood into the systemic circulation.

Right ventricle

It pushes deoxygenated blood into the pulmonary circulation.

Blood flow through the heart (from deoxygenated blood to pulmonary circulation)

Superior/Inferior Vena Cava → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonary Valve → Pulmonary Artery → Lungs

Blood flow through the heart (from oxygenated blood to systemic circulation)

Oxygenated blood from the lungs → Pulmonary Vein → Left Atrium → Mitral Valve → Left Ventricle → Aortic Semilunar Valve → Aorta → Body

Unidirectional

Describes blood flowing in a single direction through the heart, regulated by valves that prevent backflow.