1. Entry slip: What is homeostasis?
Lesson 5.4 Negative Feedback Loop
(pp302-303 of McGraw-Hill Ryerson)
I. Terms:
a. Negative Feedback Loop (p302):
i. A process that detects and reverses
deviations from normal internal
conditions of bodies, such as
temperature of 37oC, water levels in
body, blood glucose levels, etc...
II. Negative Feedback Loop:
a.Closely involved in homeostasis. When
there are changes in the body from the
internal environment the body wants, the
N-F-L goes into effect to get the body to
return to its’ desired environment.
b. This process involves three parts:
i. Sensory Receptors (Nerves in tissues
affected): Nerves in certain tissues

2. sense changes and send information
(electronic impulses) to the brain.
Sometimes the information is sensed
in the brain due to compounds in the
blood.
ii. Integrator (Brain): Like the
thermostat in your home, the brain
decides what information to send out
to the body to reverse the deviation.
iii. Effectors (Various tissues and organs):
Receives information from the brain
on how to reverse the deviation, and
puts these instructions “into effect”.
c. Example: Body temperature (deviations:
too hot and too cold)
III.Youtube search:
a.none
IV. Homework: Make up a negative feedback
loop concept map for one of the following
mechanisms:
a.Heart rate

3. i. hint: unit 4 Transportation
ii. deviations: too much CO2/ lowering
amounts of CO2
b.Water balance
i. hint: unit 3/nephron/ADH
ii. deviations: too much water/ not
enough water
c. Blood glucose levels
i. Hint: unit 1/liver/glycogen
ii. Deviations: too much blood glucose/
not enough glucose