Module 2
1. Module 2
1.46. Module Summary/Assessment
Module 2—The Endocrine System
Module Summary
Human life is possible only if the internal environment of the body is regulated to stay within a very narrow range of parameters. If these parameters are upset or exceeded, the result can be sickness or even death. The endocrine system uses chemical messengers called hormones to communicate with target glands, body cells, and organs to regulate the internal environment. The body then stays within the narrow range of normal values. This maintenance of a steady state is called homeostasis. Homeostasis is achieved through closed-loop systems called feedback—information about the response of the system is “fed back” to the receptor. Negative feedback counteracts or neutralizes the original stimulus and acts to stabilize the system, leading to the re-establishment of homeostasis. Positive feedback reinforces the disruptive stimulus and acts to destabilize the system, which can lead to illness or the development of a disorder.
The principal glands of the endocrine system, including the hypothalamus-pituitary complex, the thyroid gland, the parathyroid gland, the adrenal glands, and the islet cells of the pancreas, produce hormones that maintain homeostasis through negative feedback. Thyroid stimulating hormone, thyroxine, calcitonin, parathyroid hormone, adrenocorticotropic hormone, cortisol, glucagon, insulin, human growth hormone, antidiuiretic hormone, epinephrine, and aldosterone are hormones that all have important physiological functions in the body. Some examples follow.
- Thyroxine plays an important role in metabolism.
- Insulin, glucagon, and cortisol help to regulate blood sugar.
- Calcitonin and parathyroid hormone regulate calcium levels in the blood.
- Human growth hormone controls growth.
- Antidiuretic hormone adjusts water levels in the blood and extracellular fluid.
- Aldosterone maintains a constant sodium concentration in the blood.
- Epinephrine prepares your body for the fight or flight response—a reaction to short-term stress.
Various medical interventions and technologies, such as synthetic insulin, thyroxine, and human growth hormone, have been developed to deal successfully with hormonal imbalances.
Tropic hormones, such as releasing hormone, TSH, and ACTH, produced by the hypothalamus and anterior pituitary control hormonal secretions from the other endocrine glands and exert control over the endocrine system, much like the brain exerts control over the nervous system.
Homeostasis within the body is brought about by the nervous and endocrine systems working together in response to changes in the environment. The two systems are linked together by the hypothalamus. Nervous control is faster, of shorter duration, and precisely targets a muscle or gland; while hormonal control is slower, lasts longer, and is more widespread in its effect.
To review and summarize the concepts of Module 2, you may wish to complete a concept organizer. You may have saved a copy of this document when you encountered it at the beginning of Module 2. If you didn’t, you may download it now. The concept organizer provides an outline of the lessons and the focusing questions for each lesson you studied in Module 2. Fill in the concept organizer with the ideas that you have mastered in each lesson, and show how these ideas helped you answer the focusing questions. You may integrate your Venn diagram from Lesson 6 into this organizer. You can use keywords, point form, or any amount of detail that meets your needs. You may choose to work from the file on your computer, print the document and work from the paper copy, or copy the outline onto a large sheet of poster paper. This is a great tool to review and use for study purposes.
Before you begin the Module Assessment, you may wish to complete some of the questions on pages 464 and 465 in your textbook as a review. Review questions for Unit A are found on pages 468 to 471. Your teacher may suggest questions for you to complete and provide feedback about your responses.
Module Assessment
The Diploma Exam contains two types of written-response questions. Both present a problem based on current research. The written-response question in this Module Assessment will be completed in the form of an expository (explanatory) essay in which you are expected to explain concepts, describe processes, and evaluate or identify technological solutions to real biological problems. It requires you to make connections between biological concepts, technologies, and social issues. The response to this question is expected to be in complete sentences, use correct biological terminology, and contain well-structured and organized paragraphs. Use the bulleted parts of the question as a guide for structuring your response.
This type of question is scored using two scoring scales. The “science” scale assesses your response to the scientific aspects of the question, while the “technology and society” scale assesses your response to these aspects of the question.
Go to www.education.gov.ab.ca to view the Biology 30 Information Bulletin for the past school year and see an example of this type of question as well as the key and marking rubric used to evaluate the response. The publication called The Key provides additional examples, keys, and rubrics. You may want to view these examples and address any questions with your teacher before completing the Module Assessment. For this question, the marking rubrics for the science, the technology, and the society scales are included with the question for your guidance. When you have completed the response, submit it to your teacher for assessment.
Use the following information to answer the open-response question that follows.
The following table shows blood glucose concentration data for two people, designated as Person A and Person B. One of these people is Emily, who has developed diabetes-like symptoms as a result of her endocrine disorder. The blood glucose concentrations were monitored over 15 h for both subjects. Both people ate identical meals at the same times, and exercised equal amounts at the same times. Neither of these people was taking any medication for diabetes at the time the data was collected.
A healthy range for blood glucose is between 4.5–5.0 mmol/L. In general, a person with moderate diabetes would take medication if the blood glucose level went above 13–15 mmol/L.
The so called “dawn phenomenon” increases blood sugar levels in the early morning hours through the stimulation and release of hormones by other endocrine glands.
Blood Glucose Levels over 15 h Taken for Person A and Person B
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- Using the grid provided, plot both sets of data on the same graph and draw a line of best fit for each set of data. Label the graph appropriately.
- Using the data in the graph, predict which person is Emily, who is a diabetic. Explain how the data supports your prediction.
- Draw and label negative feedback loops that show how high and low blood glucose levels are normally maintained by pancreatic hormones.
- Identify several symptoms, other than blood glucose level, that the diabetic person (Emily) would exhibit, and explain why these symptoms would be present.
- Identify two additional hormones, other than the pancreatic hormones, that can raise blood glucose levels, and outline their mode of action.
- Describe two medical technologies that might be used in the maintenance of blood glucose levels by a diabetic, such as Emily, and explain how these treatments would work.
Rubrics
Science Score |
Scoring Criteria |
5 Excellent |
|
4 |
|
3 |
|
2 |
|
1 |
|
Technology and Society Score |
Scoring Criteria |
5 Excellent |
|
4 |
|
3 |
|
2 |
|
1 |
|
Science Score: x/5 X 2 = 10 marks X 2 = 20 marks
Technology and Society Score: x/5 X 2 = 10 marks
Total: 30 marks