MYP Integrated Sciences Body Systems Key Definitions

The minimum amount of energy required for reactant molecules to start a chemical reaction.

The region of an enzyme where the substrate binds and the reaction takes place.

The force that holds atoms together in molecules.

Attraction between water molecules due to hydrogen bonding.

A system where water and blood move in opposite directions to maximize oxygen diffusion.

A gland that makes and releases hormones directly into the bloodstream.

A biological catalyst that speeds up chemical reactions by lowering the activation energy.

The transfer of oxygen into the body and carbon dioxide out across a specialized surface.

The regulation of internal conditions to maintain a stable environment for optimal cell function.

A chemical messenger released by glands that travels in the bloodstream to target organs, where it produces a specific response.

A solution with lower water concentration than the cell contents (more concentrated). Water moves out of the cell by osmosis.

A solution with higher water concentration than the cell contents (more dilute). Water moves into the cell by osmosis.

A solution with the same water concentration as the cell contents. No net water movement occurs.

Receptors that bend when sound vibrations move through the inner ear.

All chemical reactions in living organisms, both building up molecules and breaking them down.

A mechanism that reverses a change to maintain stability.

A chemoreceptor in the nose that detects airborne chemicals.

The control of water content in the body.

The net movement of water molecules from an area of higher water concentration (dilute solution) to an area of lower water concentration (concentrated solution), across a partially permeable membrane.

How the brain interprets sensory signals to create an experience.

Transports sucrose and organic molecules in both directions through translocation.

Light-sensitive cells that convert light into electrical signals.

A specialized cell or structure that notices a change (stimulus) and sends a signal telling the body what to do next.

A molecule on a target cell that detects and responds to a specific hormone.