Levels of Organization and Homeostasis in Organisms

Organism

A living thing

Homeostasis

Describes the maintenance of a constant internal environment.

Cell

The basic unit of life.

Atom

The smallest unit of matter held together by chemical bonds.

Molecule

Components of organisms, such as proteins and lipids.

Organelle

The main structures within a living cell (Example: A nucleus is an organelle).

Tissue

Groups of cells working together to carry out a specific function.

Organ

Structures composed of two or more tissues carrying out a specific function.

Organ system

Groups of organs that carry out a specific function in an organism.

Negative feedback

Organism senses a change in the internal environment and organ systems temporarily adjust their functions to return internal environment to the set point.

Positive feedback

Organism senses a change in the internal environment and response to change increases as time progresses.

Example of negative feedback

When human blood pressure is elevated, the brain senses the change and causes the heart to slow until pressure returns to a normal level.

Example of positive feedback

During childbirth, a woman's uterine contractions increase in intensity until her child is delivered.

Levels of organization

Different possible levels of organization that organisms participate in.

Multicellular organisms

Organisms composed of multiple cells that often involve complex homeostasis mechanisms.

Cytosol

The liquid found inside cells, where single cells regulate the amount of water.

Cytoplasm

The material within a cell, excluding the nucleus.

Set point

A certain level that the internal environment is restored to during homeostasis.

Complexity of an organism

Exhibited by the different levels of organization that exist.

Individual living things

Organisms.