1. The oxygen we inhale is absorbed in the alveoli of the lungs. These tiny air sacs have thin walls lined with simple squamous epithelium, allowing oxygen to diffuse into the surrounding capillaries and enter the bloodstream.

    The oxygen we inhale is absorbed in the alveoli of the lungs. These tiny air sacs have thin walls lined with simple squamous epithelium, allowing oxygen to diffuse into the surrounding capillaries and enter the bloodstream.

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  2. Oxygen is transported to all body cells by binding to hemoglobin in red blood cells. When blood flows through the lungs, hemoglobin binds to oxygen. The oxygen-rich blood is then circulated by the heart through arteries to tissues and cells, where oxygen is released for cellular functions.

    Oxygen is transported to all body cells by binding to hemoglobin in red blood cells. When blood flows through the lungs, hemoglobin binds to oxygen. The oxygen-rich blood is then circulated by the heart through arteries to tissues and cells, where oxygen is released for cellular functions.

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  3. Cells need oxygen for aerobic respiration, a process that generates ATP, the primary energy source for cellular activities. Oxygen helps convert glucose into ATP, powering essential functions like growth, repair, and maintenance.

    Cells need oxygen for aerobic respiration, a process that generates ATP, the primary energy source for cellular activities. Oxygen helps convert glucose into ATP, powering essential functions like growth, repair, and maintenance.

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  4. Blood transports waste products like carbon dioxide and urea from cells to excretory organs. Carbon dioxide is carried to the lungs for exhalation, while urea and other wastes are transported to the kidneys for elimination.

    Blood transports waste products like carbon dioxide and urea from cells to excretory organs. Carbon dioxide is carried to the lungs for exhalation, while urea and other wastes are transported to the kidneys for elimination.

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  5. The combination of nerve and muscle tissue is fundamental to most animals because it enables coordinated movement and response to stimuli, allowing for efficient interaction with the environment, crucial for survival, feeding, and reproduction.

    The combination of nerve and muscle tissue is fundamental to most animals because it enables coordinated movement and response to stimuli, allowing for efficient interaction with the environment, crucial for survival, feeding, and reproduction.

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