What is homeostasis? (5.1.1 Communication & Homeostasis a-c)

First lesson from 5.1.1 Communication and Homeostasis (spec point a-c):

(a) the need for communication systems in multicellular organisms
To include the need for animals and plants to respond to changes in the internal and external environment and to coordinate the activities of different organs.
(b) the communication between cells by cell signalling
To include signalling between adjacent cells and signalling between distant cells.
© the principles of homeostasis
To include the differences between receptors and effectors, and the differences between negative feedback and positive feedback.

Includes detailed lesson content, a video and summary questions.