A hormone is any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour. Hormones have diverse chemical structures, mainly of 3 classes: eicosanoids, steroids, and amino acid/protein derivatives. The glands that secrete hormones comprise the endocrine signaling system. The term hormone is sometimes extended to include chemicals produced by cells that affect
The use case model consists of two artifacts: the use case diagram, which is a graphical representation showing which actors can operate which use cases, and the use case description (sometimes called the use case narrative), which is the text-based, detailed, step-by-step interactions and dialogue between the actor and the system.
Use case elaboration. Usage scenarios describe a way the system may be used by its actors. The UML sequence diagram can be used to flesh out the details of one or more use cases by illustrating visually how the system will behave in a particular scenario.ML sequence diagrams are used to represent or model the flow of messages, events and actions between the objects or components of a system. Time is represented in the vertical direction showing the sequence of interactions of the header elements, which are displayed horizontally at the top of the diagram.