Different tissues are joined together in order to form organs. For example, the human heart contains

• muscle tissue for contraction.
• connective tissue in the valves and blood vessel walls.
• nerve tissue that regulates the rate of heartbeat.

Organs form systems that fulfil specific functions in our bodies. For example, the heart and the blood vessels form the circulatory system, which is in charge of transporting oxygen, nutrients, waste products, water and heat throughout the body.

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