The Importance of Receptors in Living Organisms_ A level biology essay (A*).

The Importance of Receptors in Living Organisms . A level biology checklist AQA. Receptors are proteins which bind to specific substances in living organisms. Not only is it important for regulating bodily functions it is also vital for plants in response to a stimulus to survive. Immune Response The Immune Response in living organisms prevents any harmful pathogens from invading precious organisms within the body. Receptors are involved in detection of harmful substances and initiate a response in a according manner. T cells are one of the major components of the immune system and rely on receptors to carry out their functions. Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response. Their T cell receptors are located on the surface of T lymphocytes and identify specific, complementary antigens presented by phagocytes, activating the T cells in which influences the immune response by T helper cells, cytotoxic T cells and phagocytes are released which kill abnormal and foreign cells. If the receptors were not present on the T cells then an immune response would not occur causing detrimental effects on the health of the organism. Survival and Response Smaller organisms such as receptors such as insects utilise receptors in order to detect changes in their environment. Whether it is temperature or humidity. This is called taxis and kinesis. Responding to these environmental changes are important as it leads to organisms having a more desirable environment in which they can thrive. However, without these receptors, they would not be able to find their optimum environment and could decrease survival chance. Homeostasis This study source was downloaded by from CourseH on :11:55 GMT -05:00 This study resource was shared via CourseH Homeostasis is a living organism's way of maintaining a steady internal environment, the control of glucose is important for an organism's life as an unbalance can affect many other processes including respiration. Without the use of the specific receptors, glucose would be unable to enter the liver's cell membrane, cells will be unable to carry out respiration as the energy they require to carry out respiration is from glucose so would therefore die. Not only that but, glucose will affect the water potential in the blood causing water to leave the blood by osmosis and cause cell death by lysis. Hence without receptors, there will be no specific bonding sites that insulin can bind to causing glucose build up and eventual downfall of the organism. Control of Heartbeat Two receptors which are vital in the control of the heart rate are Chemoreceptors and Baroreceptors. Located on the aorta and carotid bodies, chemoreceptors monitor pH levels, carbon dioxide levels and oxygen levels. When pH, oxygen are low and carbon dioxide levels rise or the opposite method over a significant level these chemoreceptors respond by sending an electrical impulse to the sensory neuron and through to the medulla in which more chemoreceptors are located and then sends a signal to the effector. This then increases the heart rate or decreases the heart rate in order to regain the balance. If receptors did not have this vital role, the body could become oxygen deprived therefore metabolic and cell functions would slow and eventually cause the death of the organism. Blood pressure within the body is also an entity that needs to be maintained, baroreceptors detect this change by sending impulses the same route as chemoreceptors, once again this will send a signal to a effector which will decrease the heart rate if the pressure is too high and increase the heart rate if the pressure is too low, if these receptors did not exist, blood pressure would become unstable and can cause heart attacks, strokes and other life threatening side effects to organisms. Nervous Impulses This study source was downloaded by from CourseH on :11:55 GMT -05:00 This study resource was shared via CourseH A single retina contains millions of photoreceptors, these detect light and convert this light into electrical impulses, allowing the brain to interpret the image, without these two photoreceptors, rods and cones, light energy could not be converted into electrical impulses and therefore no image would be formed, the organism would be completely blind. Within the skin there are mechanoreceptors called pacinian corpuscles. They detect pressure once the stimuli has put enough pressure on the lamellae and have reached the nerve surrounded in this connective tissue a action potential is triggered, this makes the being aware of the stimulus and potential harm, protecting them from injury. Conclusion In conclusion, if living organisms did not have receptors , they would be at risk of death or a disadvantage to competition and would not be capable of being the strongest to survive and reproduce or gain nutrients, therefore, receptors are a vital part of all living organisms.