Characteristics of Living Organisms and Body Systems

Vocabulary flashcards covering characteristics of living organisms, structural levels of organization, body organ systems, and feedback loop mechanisms.

Cellular composition

A property of life stating that cells are the basic units of life and all organisms are composed of cells.

Metabolism

The collective chemical reactions carried out by living organisms.

Growth

A process in living organisms where building processes outweigh breaking down processes.

Excretion

The elimination of potentially harmful waste products created by metabolic processes.

Responsiveness

The ability to sense and react to changes or stimuli in the environment (also referred to as irritability).

Movement

The motion of an entire organism, individual cells within an organism, or materials within or between cells of an organism.

Reproduction

The process occurring in two forms in multicellular organisms: individual cells reproduce during growth and to replace damaged/old cells, or the organism itself reproduces to yield similar offspring.

Structural levels of organization

A series of progressively larger building blocks constructing the body, ordered from smallest to largest: chemical level, cellular level, tissue level, organ level, organ system level, and organism level.

Cardiovascular System

An organ system composed of blood vessels and the heart that pumps and delivers oxygen-poor blood to the lungs and oxygen-rich blood to the tissues, removes wastes from tissues, and transports cells, nutrients, and other substances.

Integumentary System

An organ system composed of hair, skin, and nails that protects the body from the external environment, produces vitamin D, retains water, and regulates body temperature.

Lymphatic System

An organ system composed of tonsils, lymph nodes, thymus, spleen, and lymphatic vessels that returns excess tissue fluid to the cardiovascular system and provides immunity against disease.

Endocrine System

An organ system composed of glands (pineal gland, hypothalamus, pituitary gland, thyroid gland, thymus gland, adrenal glands, pancreas, ovaries, and testes) that regulates body functions and tissue activities through the secretion of chemicals called hormones.

Urinary System

An organ system composed of kidneys, ureters, urinary bladder, and urethra that removes metabolic wastes from the blood, maintains fluid, electrolyte, and acid-base balance, and stimulates blood cell production.

Negative feedback loop

A feedback mechanism that opposes the initial change in a regulated variable and reduces output to return conditions to normal.

Positive feedback loop

A feedback mechanism in which effector activity increases and reinforces the initial stimulus, shutting off when conditions return to normal range.

Receptor

A component of a feedback loop (such as sensory nerves in skin) that detects changes in a regulated variable and sends information to the control center.

Control Center

A component of a feedback loop (such as brain cells) that processes a stimulus and determines if a regulated variable is outside normal range.

Effector

A component of a feedback loop (such as skeletal muscle cells activated to shiver) that responds to signals from the control center to alter the regulated variable.