Bio 30S

Bio 30S

Bio 30S

Negative Feedback Exercise

Directions: As a class, complete three negative feedback mechanism flow diagrams for each of the following processes. These are three critical homeostatic systems in the body.

Waste Management (in this case ammonia, a by-product of protein digestion, acceptable levels between 15-45 micrograms per decilitre)

Osmoregulation (water balance – you must consume fluids daily) Thermoregulation (the maintenance of internal body temperature – set point 36.7°C)

Scenario 1: You have skipped several meals in a row and your body needs to depend on the breakdown of protein for energy. Amino Acids (the building blocks of protein) start to be broken down in your body. This releases ammonia into your blood and the interstitial fluid. Your hypothalamus detects the increased ammonia in your blood. The hypothalamus releases a hormone that tells your liver to combine the ammonia with carbon dioxide and eliminate it from your body.

Scenario 2: You have spent the day working in the hot sun. As a result your blood water levels have dropped. The osmoreceptors have detected fluid drop (dehydration) and the hypothalamus instructs the kidneys to increase water absorption (you also start feeling really thirsty).

YOU TRY THE NEXT ONE!

Scenario 3: During scenario 2 your body starts to sweat. Refer back to Thermoregulation in Humans to complete the negative feedback mechanism flow diagram.

Bio 30S

Scenario 1 – Waste Management

Bio 30S

Scenario 2 – Osmoregulation

Bio 30S

Scenario 3 – Thermoregulation