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11.21: Cardiovascular System

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    What do you do for "cardio"?

    "Cardio" has become slang for aerobic exercise that raises your heart rate for an extended amount of time. Cardio can include biking, running, or swimming. Can you guess one of the main organs of the cardiovascular system? Yes, your heart.

    Functions of the Cardiovascular System

    Your cardiovascular system has many jobs. At times the cardiovascular system can work like a pump, a heating system, or even a postal carrier. To do these tasks, your cardiovascular system works with other organ systems, such as the respiratory, endocrine, and nervous systems.

    The cardiovascular system (Figure below) is made up of the heart, the blood vessels, and the blood. It moves nutrients, gases (like oxygen), and wastes to and from your cells. Every cell in your body depends on your cardiovascular system. If your cells don't receive nutrients, they cannot survive. The main function of the cardiovascular system is to deliver oxygen to each of your cells. Blood receives oxygen in your lungs (the main organs of the respiratory system) and then is pumped, by your heart, throughout your body. The oxygen then diffuses into your cells, and carbon dioxide, a waste product of cellular respiration, moves from your cells into your blood to be delivered back to your lungs and exhaled. Each cell in your body needs oxygen, as oxygen is used in cellular respiration to produce energy in the form of ATP. Without oxygen, lactic acid fermentation would occur in your cells, which can only be maintained for a brief period of time. Arteries carry blood full of oxygen ("oxygen-rich") away from the heart and veins return oxygen-poor blood back to the heart.

    The cardiovascular system also plays a role in maintaining body temperature. It helps to keep you warm by moving warm blood around your body. Your blood vessels also control your body temperature to keep you from getting too hot or too cold. When your brain senses that your body temperature is increasing, it sends messages to the blood vessels in the skin to increase in diameter. Increasing the diameter of the blood vessels increases the amount of blood and heat that moves near the skin's surface. The heat is then released from the skin. This helps you cool down. What do you think your blood vessels do when your body temperature is decreasing?

    The blood also carries hormones, which are chemical messenger molecules produced by organs of the endocrine system, through your body. Hormones are produced in one area of your body and have an effect on another area. To get to that other area, they must travel through your blood. An example is the hormone adrenaline, produced by the adrenal glands on top of the kidneys. Adrenaline has multiple effects on the heart (it quickens the heart rate), on muscles and on the airway.

    The cardiovascular system moves nutrients and other substances throughout the bod
    Figure \(\PageIndex{1}\): The cardiovascular system moves nutrients and other substances throughout the body.


    • The cardiovascular system is made up of the heart, the blood vessels, and the blood.
    • The cardiovascular system moves nutrients, hormones, gases, and wastes to and from your cells.

    Explore More

    Use the resource below to answer the questions that follow.

    1. Where does blood enter the heart? Where does it exit the heart?
    2. How does blood entering the right side of the heart differ from blood entering the left side of the heart?
    3. Why is it important for the heart to have one-way valves? How do you think a leaky valve affects the functioning of the heart?
    4. What are coronary arteries? What are their function? How are they involved in heart disease?


    1. List three components of the cardiovascular system.
    2. List the main functions of the cardiovascular system.
    3. Why does each cell in your body need oxygen?
    4. Complete this sentence: _______ carry blood full of oxygen _______ from the heart and _______ return oxygen-poor blood back to the heart.

    This page titled 11.21: Cardiovascular System is shared under a CC BY-NC license and was authored, remixed, and/or curated by CK-12 Foundation via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.