1. Interactions in the Human Body Notes and Lab

2. Your Task Design and test a model of a negative feedback system to maintain the temperature of water in a beaker at 37°C.

3. Maintaining Equilibrium The ability to sense and respond to conditions or changes in the environment distinguishes living organisms from nonliving things. The cells of living organisms function best in a constant, balanced internal environment. Organisms must maintain a “steady state” called homeostasis to survive.

4. Cells, tissues, organs, and organ systems in an organism must work together to adjust to changing conditions. When humans experience cold temperatures, they respond by shivering to increase body temperature by muscle movement. In extremely hot temperatures, humans may respond by sweating to cool off. These responses automatically occur when body temperatures rise above or fall below a human’s normal temperature of 37°C.

5. Interactions to Maintain Homeostasis To remain in balance, systems must be monitored and adjusted. The temperature feedback system you will make in the beaker is a model of a negative feedback system to maintain a constant temperature In order for organisms to maintain homeostasis, every cell, tissue, organ, and organ system in an organism must work together to adjust to changing conditions. Systems in the human body use negative feedback systems to maintain a balance of sugar in the blood, body temperature, heart rate, water content, and blood flow.

6. The nervous and endocrine systems coordinate the activities of all of the other body systems to maintain homeostasis and control body responses to environmental changes The nervous system consists of cells called neurons which are able to sense and help the body respond to changes in the environment. Neurons have the ability to quickly send electrical messages or impulses to each other. Many neurons bundled together make up nerves, which send messages to the brain. The brain, the major control center of the nervous system, responds to messages sent in from all areas of the body.

7. Have your ever noticed the changes that occur in your body during exercise or physical education class? Exercise causes an increased need for oxygen. The brain detects low levels of oxygen in the blood and sends signals to increase the heart rate and the breathing rate. Your pulse is a measure of your heart rate. Nerves carry messages to parts of the brain that control involuntary activities, such as heart rate. These nerves send messages when blood pressure, or the force of blood pushing on the walls of blood vessels, becomes too high. The high blood pressure is sensed, and feedback mechanism sends a message to the brain to slow down the heart rate.

8. Instructions 1.Under most conditions, normal human body temperature is maintained at 37°C. 2.Using the materials provided at the station,your group must design a system and procedures to keep 200-300 mL of water at a constant temperature of 37°C. 3.Heat 200-300 mL of water to a temperature of 37°C and maintain that temperature for ten minutes. 4.Record the temperature readings in the chart in thirty second intervals. 5.Construct a graph of the data. 6.Remember to label the independent variable on the x axis, the dependent variable on the y axis, and add an appropriate title.

9. TimeTemperature (°C) 30 seconds 1 minute 1 minute 30 seconds 2 minutes 2 minutes 30 seconds 3 minutes 3 minutes 30 seconds 4 minutes 4 minutes 30 seconds 5 minutes 5 minutes 30 seconds 6 minutes 6 minutes 30 seconds 7 minutes 7 minutes 30 seconds 8 minutes 8 minutes 30 seconds 9 minutes 9 minutes 30 seconds 10 minutes

10. Questions 1.If the temperature of the water went above 37°C, what did your group do to bring it back to the set point of 37°C? 2.If the temperature of the water went below 37°C, what did your group do to bring it back to the set point of 37°C? 3.Did you notice a pattern in the data? If yes, explain the pattern. 4.What are some practical examples of other systems that regulate temperature to a certain setting? 5.Which part of the system acts as the thermostat to detect temperature changes? 6.Which system in your body has cells that sense changes in body temperature? 7.Which systems in your body help to regulate body temperature?

11. Blood –The Link to All Body Systems The main task of the cardiovascular system, or circulatory system, is transportation. The cardiovascular system delivers needed materials to body cells. These substances all travel in blood. The heart pumps blood through blood vessels that reach all parts of the body. Since every cell in the body depends on the cardiovascular system to deliver needed materials to it ad to remove wastes, al body systems interact with the cardiovascular system.

12. Interactions in Transporting Oxygen The organ system responsible for delivering oxygen to your cells is the respiratory system. The respiratory system could not deliver oxygen to your body cells or remove CO2 without the cardiovascular and muscular systems.

13. Air enters the body through the nostrils. It travels to the lungs through a tube called the trachea. The lungs, which are the main organs of the respiratory system, contain hundreds of round sacs called alveoli. The alveoli are the structures through which oxygen moves from the air into the blood. CO2 moves through alveoli in the opposite direction: from the blood into the air. The Role of the Respiratory System

14. The Role of the Cardiovascular System Each alveolus is surrounded by capillaries. Capillaries are the smallest blood vessels in the cardiovascular system. Inside each lung, oxygen in the air moves through the walls of the alveoli and into the capillaries. In the capillaries, the oxygen binds to red blood cells, which are carried in the bloodstream through the rest of the body. As the oxygen rich red blood cells move through the cardiovascular system, they release the oxygen to body cells. As oxygen in the alveoli passes into the bloodstream, CO 2 is moving in the opposite direction. CO 2 passes from the blood, through the walls of the alveoli, and into the air inside the alveoli. From the alveoli, CO 2 leaves your body. The CO 2 is expelled when you breath out.

15. How would homeostasis be affected by the absence of the organs pictured on the left?

16. What role does the nervous system play in the proper functioning of the following systems? Skeletal Immune Muscular Endocrine Circulatory Respiratory Digestive