Body Systems

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Anatomy Noun

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[uh-nat-uh-mee]

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Anatomy

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The scientific study of the structure, shape, and parts of living organisms and their relationships to one another.

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Example: This image shows the anatomy of the human skeletal system by labeling several key bones, like the humerus and pelvis, on a complete skeleton.

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Physiology Noun

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[fiz-ee-ol-uh-jee]

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Physiology

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The scientific study of the functions and mechanisms that work within a living system to sustain life.

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Example: Physiology is the study of function. This diagram shows the respiratory system and its functional units, the alveoli, where the key function of gas exchange happens.

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Homeostasis Noun

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[hoh-mee-oh-stey-sis]

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Homeostasis

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The body's ability to maintain a stable, constant internal environment despite changes in external conditions.

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Example: This diagram shows how red blood cells transport oxygen from the lungs to the body's cells, a key process for maintaining a stable internal environment.

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Neuron Noun

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[noor-on]

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Neuron

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A specialized cell that functions as the basic working unit of the nervous system by transmitting nerve impulses.

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Example: This diagram shows a neuron, or nerve cell, the basic unit of the nervous system, labeling its main parts: dendrites, soma, nucleus, axon, and myelin sheath.

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Neurotransmitter Noun

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[noor-oh-trans-mit-er]

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Neurotransmitter

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A chemical messenger that transmits signals across a synapse from one neuron to another target cell or organ.

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Example: This diagram shows neurotransmitters as chemical messengers released from one neuron (axon) that travel across a gap to send a signal to another neuron (dendrite).

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Tendon Noun

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[ten-duhn]

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Tendon

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A tough, flexible band of fibrous connective tissue that functions to connect a muscle to a bone.

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Example: This diagram shows a tendon, a tough connective tissue, attaching a skeletal muscle to a bone in the arm.

Front

Ligament Noun

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[lig-uh-muhnt]

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Ligament

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A short band of tough, flexible fibrous connective tissue that connects two bones to hold a joint together.

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Example: This diagram shows a ligament, a tough band of tissue, connecting the femur (thigh bone) to the tibia (shin bone) within the knee joint.

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Bone Marrow Noun

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[bohn mar-oh]

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Bone Marrow

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The soft, spongy tissue found inside most bones where new blood cells, including red and white cells, are produced.

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Example: This diagram shows a cross-section of a bone, highlighting the two types of bone marrow: red marrow, which produces blood cells, and yellow marrow.

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Pathogen Noun

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[path-uh-jen]

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Pathogen

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A bacterium, virus, fungus, or other microorganism that has the potential to cause disease in a host organism.

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Example: A pathogen is a disease-causing agent, which can be cellular (living) like bacteria and fungi, or acellular (non-living) like viruses and prions.

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Enzyme Noun

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[en-zahym]

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Enzyme

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A protein that acts as a biological catalyst, accelerating the rate of specific chemical reactions within the body.

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Example: This diagram shows how an enzyme has a specific active site that fits a substrate, like a lock and key, to create new products.