Blood and Blood Vessels

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Plasma Noun

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[plaz-muh]

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Plasma

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The fluid portion of blood that distributes nutrients, removes wastes, and transports substances like carbon dioxide, hormones, and heat.

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Example: Blood separates into layers in a test tube; the top yellow liquid is plasma, making up 55% of blood and carrying water, proteins, and gases.

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Erythrocytes Noun

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[uh-rith-roh-sytes]

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Erythrocytes

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Red Blood Cells (RBCs) that contain hemoglobin and are responsible for carrying oxygen from the lungs to the body's cells.

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Example: This image shows many erythrocytes (red blood cells) under a microscope, highlighting their disc shape with a lighter center, known as the central pallor.

Front

Hemoglobin Noun

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[hee-muh-gloh-bin]

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Hemoglobin

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The specific oxygen-carrying protein contained within red blood cells, which binds to oxygen in the lungs and releases it in tissues.

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Example: This diagram shows that hemoglobin is a protein found inside red blood cells, and it is made of smaller parts including iron.

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Leukocytes Noun

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[loo-koh-sytes]

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Leukocytes

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White Blood Cells (WBCs) that are part of the immune system, helping the body fight infection and disease by ingesting pathogens.

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Example: Leukocytes, or White Blood Cells (WBC), are a group of different cells in the blood that are part of the body's immune system.

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Thrombocytes Noun

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[throm-boh-sytes]

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Thrombocytes

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Cellular fragments, also known as platelets, found in the blood that help in blood clotting to stop bleeding at injury sites.

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Example: This diagram shows both smooth, inactive platelets (thrombocytes) and spiky, activated platelets, illustrating how they change shape to become sticky and form blood clots.

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Artery Noun

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[ar-ter-ee]

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Artery

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A type of blood vessel with thick, muscular walls that carries blood away from the heart, typically under high pressure.

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Example: This image shows a cross-section of an artery, revealing its thick, layered, and muscular walls which are built to withstand high-pressure blood flow.

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Vein Noun

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[vayn]

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Vein

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A type of blood vessel with thin walls and internal valves that carries blood toward the heart, typically under low pressure.

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Example: This image compares a normal vein with a varicose vein, showing how correctly functioning valves in a healthy vein prevent the backflow of blood.

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Capillaries Noun

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[kap-uh-lair-eez]

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Capillaries

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Microscopic blood vessels, only one cell thick, where the exchange of gases and nutrients occurs between blood and body tissues.

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Example: This diagram shows a capillary, a tiny blood vessel, wrapped around an air sac (alveolus) in the lung, demonstrating how oxygen enters the blood.

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Alveoli Noun

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[al-vee-oh-lye]

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Alveoli

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Tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide between the air and the blood takes place.

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Example: This diagram shows an alveolus (air sac) surrounded by a capillary (tiny blood vessel), where oxygen (O2) moves from the air into the blood.

Front

Vasoconstriction Noun

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[vay-soh-kun-strik-shun]

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Vasoconstriction

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The decrease in the diameter, or narrowing, of a blood vessel, which results in a reduction of blood flow.

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Example: This diagram shows blood vessels near the skin constricting (narrowing) to reduce blood flow to the surface, which helps the body conserve heat.