Notes from Grade 11 bio class on homeostasis

1. Sir Charles Blagden
What are effects of
extreme heat on the
body?
How do we resist heat?
See the video

2. Thermoregulation

3. Thermoregulation
Too hot

4. Thermoregulation
Too hot
cc licensed flickr photo by Finizio: http://flickr.com/photos/finizio/492955038/

5. Thermoregulation
Too hot
Too cool
cc licensed flickr photo by Finizio: http://flickr.com/photos/finizio/492955038/

6. Thermoregulation
Too hot
cc licensed flickr photo by MaryLane: http://flickr.com/photos/marylane/520905761/
Too cool
cc licensed flickr photo by Finizio: http://flickr.com/photos/finizio/492955038/

7. Homeostasis of house temperature
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055

8. Homeostasis of house temperature
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055

9. Homeostasis of house temperature
Too cold
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055

10. Homeostasis of house temperature
Too cold
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055
cc licensed flickr photo by Xystance: http://flickr.com/photos/xystance/4278997785/

11. Homeostasis of house temperature
Too cold
Too hot
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055
cc licensed flickr photo by Xystance: http://flickr.com/photos/xystance/4278997785/

12. Homeostasis of house temperature
Too cold
Too hot
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055
cc licensed flickr photo by Xystance: http://flickr.com/photos/xystance/4278997785/

13. Homeostasis of house temperature
Too cold
Too hot
cc licensed flickr photo by rustybrick: http://flickr.com/photos/rustybrick/2151548025/
return temp to
normal range
cc licensed flickr photo by slworking2: http://flickr.com/photos/slworking/394991055
cc licensed flickr photo by Xystance: http://flickr.com/photos/xystance/4278997785/

14. Thermoregulation is an example of homeostasis
def’n - the property of a system that regulates its internal
environment and tends to maintain a stable, constant condition
despite changing external conditions

15. Thermoregulation is an example of homeostasis
def’n - the property of a system that regulates its internal
environment and tends to maintain a stable, constant condition
despite changing external conditions
All living things exhibit homeostasis!

16. Homeostatic systems require:
a receptor - monitors and responds to changes
in the system
a control center - sets the range for the
condition
an effector - produce an action which moves
the system back into the desired range
feedback - the results of the effector are
detected by the receptors

17. Thermoregulation Receptors
Blood temperature is monitored by
the hypothalmus.

18. Thermoregulation Receptors
Blood temperature is monitored by
cc licensed flickr photo by Andres Rueda: http:// the hypothalmus.
flickr.com/photos/andresrueda/3407340937/

19. Thermoregulation Receptors
Blood temperature is monitored by
cc licensed flickr photo by Andres Rueda: http:// the hypothalmus.
flickr.com/photos/andresrueda/3407340937/
http://commons.wikimedia.org/wiki/File:Primary_central_nervous_system_B-
cell_non-Hodgkin_lymphoma.jpg

20. Thermoregulation Receptors
Blood temperature is monitored by
cc licensed flickr photo by Andres Rueda: http:// the hypothalmus.
flickr.com/photos/andresrueda/3407340937/
http://commons.wikimedia.org/wiki/File:Primary_central_nervous_system_B-
cell_non-Hodgkin_lymphoma.jpg

21. Thermoregulation Receptors
External temperature is measured by
receptors in the skin

22. Thermoregulation Effectors
if too hot
Sweat
Dilation of blood
vessels in skin, allowing
blood to flow to
surface. Heat from the
cc licensed flickr photo by RLHyde: http://flickr.com/photos/breatheindigital/
4668093768/ blood can be lost
through the surface of
the skin.

23. Thermoregulation Effectors
if too cold, part 1

24. Thermoregulation Effectors
if too cold, part 1
Goosebumps -
erector pili muscles
cc licensed flickr photo by MaryLane: http://flickr.com/photos/marylane/520905761/

25. Thermoregulation Effectors
if too cold, part 1
Goosebumps -
erector pili muscles
cc licensed flickr photo by MaryLane: http://flickr.com/photos/marylane/520905761/
Shivering
cc licensed flickr photo by Beat Machine:
http://flickr.com/photos/bqwec/212277755/

26. Thermoregulation Effectors
if too cold, part 2

27. Thermoregulation Effectors
if too cold, part 2
• vasoconstriction (blood vessels close up so heat isn’t
lost through the skin)
• adrenal and thyroid glands - increase overall
metabolism

28. Blood sugar regulation
cc licensed flickr photo by EUSKALANATO:
http://flickr.com/photos/
17657816@N05/1971827663/
Receptor (hypothalmus) responds
to high blood sugar level
Control center (hypothalmus)
Sends
signal to
the pancreas releases insulin
cc licensed flickr photo by djneight: http://flickr.com/photos/thedjneight/4119439462/

29. Effects of insulin
• cells absorb more glucose (blood sugar)
• liver stores glucose as glycogen
• fat storage
Lower blood sugar level

30. Water balance
Another example of homeostasis

31. Kangaroo Rat
lives in hot desert
cc licensed flickr photo by ucumari: http://flickr.com/photos/ucumari/3955842320/

32. Little water in environment. Does not drink water!
All water comes from breakdown of nutrients.
cc licensed flickr photo by ucumari: http://flickr.com/photos/ucumari/3955842320/

33. Needs to conserve water. How?
cc licensed flickr photo by ucumari: http://flickr.com/photos/ucumari/3955842320/

34. Behavioural - nocturnal (active at
night, sleeps during the day
cc licensed flickr photo by ucumari: http://flickr.com/photos/ucumari/3955842320/

35. Physiological - miminum water lost from urination.
(5 times more concentrated that human urine)
cc licensed flickr photo by ucumari: http://flickr.com/photos/ucumari/3955842320/

36. Also need to avoid having too much water.
Excess water leads to thinner blood.

37. Thinner blood leads to reduced concentration of red blood
cells (a.k.a. anemia). Not enough oxygen gets to the cells.
cc licensed flickr photo by kingdesmond1337: http://flickr.com/photos/kingdesmond/2872482711/

38. If blood is really dilute, the red blood cells can rupture
cc licensed flickr photo by kingdesmond1337: http://flickr.com/photos/kingdesmond/2872482711/

39. Water balance is maintained homeostatically.
Sensor
Control centre
Effector

40. Sensors
Hypothalmus - senses
concentration of blood.
Blood vessels - sense
blood volume.
If concentration is too
cc licensed flickr photo by EUSKALANATO: http://
flickr.com/photos/17657816@N05/1971827663/ high or blood volume is
low, sends signal to the ...

41. Controller
Pituitary gland (right next to
hypothalmus)
If blood concentration is too
high, it secretes vasopressin
cc licensed flickr photo by EUSKALANATO: http://
flickr.com/photos/17657816@N05/1971827663/
(a.k.a. antidiuretic hormone
a.k.a. ADH), a hormone that
acts on the ...

42. Effector
Kidneys
ADH causes the kidney to
reduce urine production. Water
loss through kidneys is
reduced.
Caffeine and alcohol are both ADH inhibitors
Brain
The hypothalmus activates parts
cc licensed flickr photo by Kaptain Kobold: http://
flickr.com/photos/kaptainkobold/273001185/
of brain that cause thirst.

43. What if there’s too much water?
Hypothalmus
The hypothalmus stops sending signals to
thirst centres and to pituitary.
Pituitary decreases ADH secreted.
Kidneys release more water into urine