Assignment:
Introduction: In biology, a feedback mechanism is a physiological loop that brings the body either toward or away from the normal, steady state. The feedback mechanism, also referred to as a feedback loop, either amplifies a certain biological pathway or inhibits it. These pathways most commonly return the body to homeostasis.
Title: Observing Feedback Mechanisms in Excretion
Aim: To observe excretory feedback control
Apparatus: hormone levels data, pencil, graph paper
Methods/Procedure:
? collect blood hormone level data for a patient who is thirsty
? record their levels of ADH, over a period of time
? discuss the relationship between increase in thirst [over time] and ADH production
? draw a graph to show the levels of ADH in the plasma as thirst increases
|
Plasma ADH (pg/ml)
|
Time (mins.)
|
|
0.5
|
0
|
|
0.5
|
1
|
|
2
|
2
|
|
4.5
|
5
|
|
5
|
6
|
|
6
|
7
|
|
9
|
10
|
|
11.5
|
13
|
Discussion:
? Discuss the function of ADH
? Define osmoregulation
? What is feedback control?
o Why are feedback mechanisms important?
o Discuss negative vs. positive feedback
? What trends do you identify from the graph?
o hints: what is the relationship between thirst and increased ADH? Is this an example of negative or positive feedback?