1. communication basics

• animals respond to internal and external environments to increase their chances of survival
• receptors detect stimuli and are specific and only detect one type of stimulus e.g. light

  there are many types of receptor that detect a different type of stimulus
• some receptors are cells e.g. photoreceptors are receptor cells that connect to the nervous system.
• some receptors are proteins on cell surface membranes e.g. glucose receptor proteins are found in the cell membrane of some pancreatic cells
• Effectors are cells that respond to a stimulus to produce an effect. They include muscle cells and cells found in glands, such as the pancreas.
• To make a response, receptors need to communicate with effectors, which need to communicate with other cells. This happens via cell signalling.
• cell signalling can occur between nearby cells or distant cells e.g. cells in the nervous system communicate by secreting chemicals called neurotransmitters, which signals to nearby cells such as other nerve cells
• the hormonal system works by releasing hormones which travel in the blood, acting as a signal to distant cells. Cell surface receptors allow cells to recognize the chemicals involved in cell signalling
• its important that organisms respond to stimuli so that they can coordinate the activities of different organisms and increase their chances of survival
• Types of receptors:

  • cells - e.g. photo receptors are receptor cells that connect to the nervous system
  • proteins on cell surface membranes - e.g. glucose receptors are proteins found in cell membranes of some pancreatic cells