The Circulatory System
The Heart & Blood Vessels
Arteries: Responsible for carrying oxygenated blood away from the heart to the rest of the body.
Veins: Responsible for carrying blood to the heart.
Valves: These structures separate the heart chambers and prevent the backflow of blood, ensuring it
flows in one direction.
Blood: Functions & Composition
Blood acts as the body’s primary transport system, moving hormones, nutrients, and gases (oxygen
and carbon dioxide) to where they are needed.
1. Plasma (The Liquid Portion)
Makes up the fluid base of blood and consists of:
Water
Proteins
Salts
Lipids
2. Cellular Components
Red Blood Cells (Erythrocytes): Transport gases throughout the body. They contain hemoglobin, an
iron-rich protein that gives blood its red color and binds to oxygen.
White Blood Cells (Leukocytes): The body’s primary defense system used to fight infections and
pathogens.
Platelets (Thrombocytes): Small cell fragments that help the blood clot to stop bleeding after an injury.
The Heart & Blood Vessels
Arteries: Responsible for carrying oxygenated blood away from the heart to the rest of the body.
Veins: Responsible for carrying blood to the heart.
Valves: These structures separate the heart chambers and prevent the backflow of blood, ensuring it
flows in one direction.
Blood: Functions & Composition
Blood acts as the body’s primary transport system, moving hormones, nutrients, and gases (oxygen
and carbon dioxide) to where they are needed.
1. Plasma (The Liquid Portion)
Makes up the fluid base of blood and consists of:
Water
Proteins
Salts
Lipids
2. Cellular Components
Red Blood Cells (Erythrocytes): Transport gases throughout the body. They contain hemoglobin, an
iron-rich protein that gives blood its red color and binds to oxygen.
White Blood Cells (Leukocytes): The body’s primary defense system used to fight infections and
pathogens.
Platelets (Thrombocytes): Small cell fragments that help the blood clot to stop bleeding after an injury.
