Lesson 1 Homeostasis.notebook
Unit 1 - The Endocrine System
Homeostasis - what is it? Write a
definition
You've decided to go for a 5 km run. You're
in decent physical condition. With your
neighbour (introduce yourself if need be)
predict what will happen to the following
body parameters as you run:
1. Body temperature - normal is 37o C
2. Heart rate - normal average is 72 beats/
minute
3. Perspiration Levels - varies person to
person
4. Blood Pressure - normal is 120/80
5. Breathing rate - varies person to person
6. Blood Sugar Level - between 4 and 11
mmol/l
Lets discuss - be able to give some
reasoning behind your decision.
Lesson 1 Homeostasis.notebook
Lesson 1
• Homeostasis ­ what is it?
• "homoios" ­ means similar or like
• "stasis" ­ means standing still
• keeping the body in a steady state ­ proper temperature, blood sugar levels, blood pH
• involves a feedback inhibition or negative feedback • same way a thermostat works
Complete reading assignment questions
Lesson 1 Homeostasis.notebook
Answers
1. We have basically 2 internal environments:
- inside your skin (interstitial fluid/space between cells)
- inside the cells and organs
2. The Nervous and Endocrine systems
maintain homeostasis.
Nervous - short term responses - nerve cells
(neurons), brain, spinal cord, eyes, ears etc.
are used for quick reponses
Endocrine system - long term responses uses glands that produce hormones that
travel through the blood stream
The hypothalamus connect these 2 systems
See the flashing lights of a police car
behind you (nervous system), message sent
to hypothalamus, sends message to adrenal
glands - produce epinephrine (adrenalin),
your heart rate speeds up, body
temperature increases etc.
Lesson 1 Homeostasis.notebook
3. If homeostasis is not maintained
organs, tissues , cells begin to shut down
and die. Hypothermia would be an example
of this.
4. Reacting to the cold
- muscle contract - shiver
- hair stands up - insulation
- blood vessels constrict - blood is
diverted from ears, fingers, toes etc.
Normal body conditions
Temperature - 37oC
Blood Pressure - 120/80
Blood Sugar - between 4 - 6 mmol/l
Salvia pH - between 6 - 7.4
Lesson 1 Homeostasis.notebook
Watch the following video and explain the difference between a negative feedback loop and a positive feedback loop
https://www.youtube.com/watch?x­yt­ts=1421914688&v=CLv3SkF_Eag&x­yt­
cl=84503534&list=PLCC2DB523BA8BCB53