Lab Homeostasis in Systems Feedback Mechanisms

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Alaina Carpenter
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Name: SHS Living Environment Date: Lab Homeostasis in Systems Feedback Mechanisms Introduction: Homeostasis a stable internal environment (equilibrium). How does our body maintain homeostasis?

1 Name: SHS Living Environment Date: Lab Homeostasis in Systems Feedback Mechanisms Introduction: Homeostasis a stable internal environment (equilibrium). How does our body maintain homeostasis? Through two systems: the nervous and endocrine systems. They work together to constantly self check and make sure all life functions are working properly. If some aspect of our body is not in homeostasis, these systems work together to adjust that system so we may be brought back into balance. For example, if bacteria enter our system, our lymph nodes, bone marrow and spleen are signaled to make more white blood cells to get rid of the infection. Once the infection is gone, a normal white blood cell count will develop. If homeostasis is not achieved, the organism will fall sick and could potentially die. The self checking of all systems is called FEEDBACK. The brain is the central control region for the nervous system. For example when carbon dioxide levels in the blood become too high (and the ph of the blood becomes too acidic), the brain will increase the respiratory rate. As breathing the breathing rate increases, carbon dioxide is exhaled and the blood level of carbon dioxide drops. This drop in carbon dioxide levels will now trigger the brain to allow the breathing rate to slow down and return to normal. The control center for the nervous system is the brain. The control center for the endocrine system is the endocrine glands. The endocrine gland will respond by either increasing or decreasing the amount of hormone secreted into the blood. Purpose: Students will understand negative feedback mechanisms with the aid of graphic organizers using real world and human physiology examples. They will also learn the difference between a receptor, control center and effector. Procedure: Part A: Homeostasis Watch the Brainpop movie on Homeostasis and answer the questions on the next page 1

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3 Part B: Feedback Mechanisms Feedback mechanisms work to keep a system in balance, within a Set Point Normal Range. If values increase above the Set Point Normal Range, receptors will detect the increase. They will send a message to the control center (brain or endocrine gland) which will respond by sending a message to the effector. The result will be a lowering or decrease in the value of the substance. If values decrease below the Set Point Normal Range, receptors will detect the decrease. They will send a message to the control center (brain or endocrine gland) which will respond by sending a message to the effector. The result will be an elevation or increase in the value of the substance. Control Center Receptors detect values higher than the set point normal and send a message to the control center Control Center responds by sending a message to the effector which will decrease values Set Point Normal Receptors detect values lower than the set point normal and send a message to the control center Control Center responds by sending a message to the effector which will increase values Control Center 3

4 1. Go over the Generic Negative Feedback Mechanism with your teacher. Make sure you understand the difference between the Set Point Normal Range and Control Center. Control Center responds 2 Increase is detected 1 Decrease because 3 Set Point Normal Range Decrease detected 4 Increase because 6 Control Center responds 5 4

5 2. Example 1-Regulation of Oven Temperature: Cut out the stimulus and response ovals on page 11. With your teacher, place the stimulus and response ovals in the correct sequence on the Feedback Mechanism chart below. Once you are sure the feedback mechanism is correct have you teacher check it. Then glue or scotch tape the ovals onto the feedback mechanism. Feedback Mechanism Set Point Normal Range 5

6 3. Example 2- Body Temperature Regulation: Cut out the stimulus and response ovals on page 11. Place the stimulus and response ovals in the correct sequence on the Feedback Mechanism below. Once you are sure the feedback mechanism is correct have you teacher check it. Then glue or scotch tape the ovals onto the feedback mechanism. Feedback Mechanism Set Point Normal Range 6

7 4. Example 3 Blood Pressure Regulation: Cut out the stimulus and response ovals on page 10. Place the stimulus and response ovals in the correct sequence on the Feedback Mechanism below. Once you are sure the feedback mechanism is correct have you teacher check it. Then glue or scotch tape the ovals onto the feedback mechanism. Feedback Mechanism Set Point Normal Range 7

8 5. Example 4- Blood Glucose Regulation: Cut out the stimulus and response ovals on page 10. Place the stimulus and response ovals in the correct sequence on the Feedback Mechanism below. Once you are sure the feedback mechanism is correct have you teacher check it. Then glue or scotch tape the ovals onto the feedback mechanism. Feedback Mechanism Set Point Normal Range 8

9 Analysis and Conclusions: 1. What is homeostasis? 2. Explain how feedback helps maintain homeostasis. 3. Exposure to extreme temperatures can be very dangerous, even lethal to living organisms. Explain using feedback how organisms respond to both an increase and a decrease in body temperature in order to maintain homeostasis. Explain how insulin helps regulates blood sugar. What happens to individuals who cannot produce insulin? How do pathogens challenge an organism s stability? 9

10 Blood Pressure Regulation Brain s control center responds which increases in heart rate Decrease in heart rate causes a decrease in blood pressure Brain s control center responds which decreases heart rate Decrease in blood pressure detected Increase in blood pressure detected Increase in heart rate causes an increase in blood pressure Blood Glucose Regulation Decreased blood glucose causes decreased insulin Increase in insulin because of increase in blood glucose Increase in blood glucose detected after a meal Response is a decrease in blood glucose Response is an increase in blood glucose Decrease in blood glucose detected 10

11 Regulation of Oven Temperature at 375 F Heating unit is activated Open oven door-cold air goes in, temperature falls Temperature inside oven decreases because heating unit is off Temperature in oven rises Oven temperature rises above 375 Heating unit shuts off Body Temperature Regulation Brain senses a decrease in body temperature Shivering occurs to increases body temperature Sweating increases which decreases body temperature Brain senses an increase in body temperature Body temperature increase is detected by receptors in skin and brain Body temperature decrease is detected by receptors in the skin and brain 11

Laughter and the Body Systems

Laughter and the Body Systems Laughter causes the lungs to pump out carbon dioxide, the eyes to cleanse themselves with tears, the muscles to relax, the flow of adrenaline to increase, and the cardiovascular