Biology Assignment 5 Question 1 The pancreas is a large gland, situated in the peritoneal cavity, in the curve of the duodenum. It is the pancreas that is responsible for aiding the body’s endocrine system. (Darlington College 2011). The pancreas releases two endocrine hormones and it is these hormones that ensure the blood glucose levels within the body are constantly controlled. These hormones are glucagon and insulin and they are secreted from tiny clusters of cells within the pancreas, know as the islets of Langerhans. Glucagon is a hyper- glycaemic hormone, secreted by the islets alpha cells.
Its main function is to increase the level of glucose in the blood. This is a vital process when blood sugar levels become low. Glucagon stimulates the liver to break down its excess glycogen into glucose. The glucose then passes into the blood stream and the homeostasis of blood glucose level is restored. Insulin is a hypo- glycaemic hormone that is secreted by the islets beta cells, in response to high blood glucose levels. Insulin decreases the level of glucose in the blood by stimulating its uptake by the skeletal muscles, liver and adipose cells.
The skeletal muscles uptake glucose, to give energy for movement and the glucose that travels to the liver is converted into glycogen, and stored here until it is needed. The adipose cells use glucose for cell metabolism. Once sufficient glucose has been removed from the blood, the beta cells slow the secretion of insulin, so that homeostasis is again restored. (Glenn, 2005, pg84). Both insulin and glucagon are vital to ensure that the body constantly has enough fuel to supply its cells with the energy needed to enable them to function normally. Question 2 Peter’s normal blood glucose concentration will be approximately 4. mmol. After he eats his balanced meal his blood sugar levels will rise to around 8. 0mmol. This is because Peter’s meal will contain carbohydrates. In response to this rise in blood sugar levels insulin is secreted by Peter’s pancreas’s beta cells. The release of insulin facilitates the entry of glucose into his body cells and this vital process maintains the energy levels within the cell. When glucose is absorbed in the cells, the blood sugar levels fall again. This occurs because the excess sugar, present in the carbohydrates in Peter’s meal, that caused his blood sugar levels to rise, has been used up.
This is what allows the blood glucose concentration to return to normal. (Glenn, 2005, pg85). When peters blood sugar levels drop, because he needs more food, glucagon is released from the pancreas alpha cells in response. Glucagon is a hormone that calls on the liver, which has its own glucose store, in the form of glycogen. Glycogen will release from the liver to allow the blood sugar to rise until it returns back to its normal rate. (Bowen, 2002). It is vital that Peter’s blood glucose levels are maintained at a normal rate, in-between his meals as large fluctuations in these levels can cause convulsions and could even induce a coma.
Question 3 The body’s internal environment is constantly controlled and balanced by homeostasis. Homeostasis is the condition of equilibrium that is maintained through the body’s response to a change in conditions. There are many regulating systems within the body that work together to constantly control the internal environment. The nervous system and the endocrine system work very closely alongside one another to keep the body normal and in balance. Feedback systems are vital in keeping the body regulated. All feedback systems are made up of a receptor, a control centre and an effector.
The receptor is able to detect any changes that may have occurred and send a message to the brain to tell it that it needs to respond. The brain acts as the control centre and is responsible for evaluating the messages it receives from the receptors. Once the messages have been processed the control centre generates a command, if one is needed. The commands are received by the effectors, which produce a response that is then able to change the controlled condition. (Darlington College 2011). A negative feedback system reverses the change in a controlled condition.
When the body’s blood glucose levels fall too low, specialised receptors pick up this information and relay it the hypothalamus part of the brain, which forms the control centre. The hypothalamus then activates the response of the effector that allows the body’s blood glucose level to rise. When the levels become within normal range the receptors stop picking up the messages and no longer send them to the hypothalamus. This prevents the blood glucose levels then becoming too high and enables homeostasis of the internal environment to be restored. (Darlington College 2011). Question 4
The body’s endocrine and nervous systems work very closely together to form the body’s major communication system. If a problem arises with one of these systems, homeostasis is upset. For instance: If the islets beta cells do not produce any insulin, such as in diabetes, the blood sugar levels will just continue to rise. This would cause extremely high blood sugar levels which would in turn go on to affect the body’s nervous system and could result in a coma occurring. The nervous system works in conjunction with the endocrine system by using nerve impulses and rapidly responding to stimuli, in order to adjust body processes.
The integration of these systems is what enables homeostasis to constantly be maintained. (Facey, 2002). Reference List Bowen, R. (2002)The Endocrine Pancreas. http://www. vivo. colostate. edu/hbooks/pathphys/endocrine/pancreas/index. html [10. 5. 2011]. Darlington College (2011) The Endocrine System. [21. 5. 2011]. Facey, D. (2002) The Nervous System. http://www. cartage. org. lb/en/themes/sciences/zoology/animalphysiology/nervoussystem/nervoussystem. htm [31. 5. 2011]. Glenn, J. (2005) Black’s Concise Atlas of Human Anatomy. London: A&C Black Publishers Ltd.