Communication and Homeostasis

Communication and Homeostasis

(a)    The need for communication systems in multicellular organisms

·         Animals increase chances of survival by responding to internal (making sure conditions are optimal for metabolism) and external (avoiding dangerous situations) stimuli. Plants also increase chances of survival by responding to stimuli.

·         Receptors are specific, so each one can only detect a certain kind of stimulus eg light or pressure. Some receptors are cells that connect to the nervous system whilst others are proteins on cell surface membranes.

(b)   The communication between cells by cell signalling

·         To produce a response, receptors need to communicate with effectors.

·         Cell signalling allows communication between cells, it can occur between nearby cells or distant cells. For example the nervous system send neurotransmitters to nearby cells whilst in the hormonal system hormones are sent in the blood to distant cells.

·         Cell surface receptors allow cells to recognise chemicals involved in cell signalling

(c)    The principles of homeostasis

·         Receptors are glycoproteins that bind to chemical signals which invoke a response by the cell.

·         Effectors are muscles or glands that carry out body’s response to a stimulus, includes muscle cells and cells found in glands…