Human Body Systems Review

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Atom Noun

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[at-uhm]

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Atom

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The basic unit of a chemical element, which is the smallest particle of matter that retains its unique properties.

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Example: This diagram shows an atom's structure: a central nucleus with protons and neutrons, and electrons orbiting in shells. This is an oxygen atom.

Front

Molecule Noun

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[mol-i-kyool]

Back

Molecule

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A group of two or more atoms chemically bonded together, representing the smallest fundamental unit of a chemical compound.

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Example: This image shows that a water molecule (H₂O) is formed when two hydrogen (H) atoms and one oxygen (O) atom bond together.

Front

Organelle Noun

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[or-guh-nel]

Back

Organelle

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A specialized structure within a living cell that performs a specific function, analogous to an organ in the body.

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Example: This diagram shows the inside of an animal cell, labeling its specialized parts like the nucleus and mitochondria, which are all examples of organelles.

Front

Cell Noun

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[sel]

Back

Cell

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The smallest structural and functional unit of an organism, which is typically microscopic and consists of cytoplasm and a nucleus.

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Example: This diagram shows a cross-section of an animal cell, labeling key parts called organelles, like the nucleus (the control center) and mitochondria (powerhouses).

Front

Tissue Noun

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[tish-oo]

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Tissue

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A group of interconnected cells with a similar structure and function that work together to perform a specific job.

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Example: This diagram shows how a group of similar cells, cardiac muscle cells, join together to form cardiac muscle tissue found in the heart.

Front

Organ Noun

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[or-guhn]

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Organ

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A self-contained group of tissues that performs a specific function in the body, such as the heart or liver.

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Example: This diagram shows the heart, a key example of an organ, which is a structure made of different tissues working together to perform a function.

Front

Organ System Noun

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[or-guhn sis-tuhm]

Back

Organ System

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A group of organs that work together as a biological system to perform one or more complex functions.

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Example: This diagram shows the nervous system, where organs like the brain and spinal cord work with nerves to send and receive signals, controlling the body.

Front

Organism Noun

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[or-guh-niz-uhm]

Back

Organism

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An individual living being, such as an animal, plant, or single-celled life form, that can function independently.

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Example: An elephant is a complex, multicellular organism, which is a single, complete living being composed of many organ systems working together to survive.

Front

Neuron Noun

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[noor-on]

Back

Neuron

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A specialized cell that transmits nerve impulses throughout the body, forming the fundamental unit of the nervous system.

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Example: This diagram shows a neuron (nerve cell) and labels its main parts: the dendrites that receive signals, the soma (cell body), and the axon.

Front

Connective tissue Noun

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[kuh-nek-tiv tish-oo]

Back

Connective tissue

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A type of biological tissue that supports, connects, or separates different types of tissues and organs in the body.

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Example: This diagram shows that connective tissue is made of cells (fibroblasts) and a network of different fibers, like strong collagen and stretchy elastin.