1. Feedback mechanisms
Are used to either maintain or amplify (to increase) chemical systems in the body.
Note: To determine the type of mechanism you must be able to determine the stimulus and response.

2. Feedback Mechanisms

3. Identify a Stimulus and Response
Your dog chases the ball and you say “Good Boy!”
Stimulus: __________________
Response:__________________
Your dog pees on the rug and you say “Bad Dog!”
Stimulus:____________________
Response:____________________

4. Feedback Mechanisms Positive Feedback Negative Feedback
The response will increase the stimulus
Does not return to homeostasis but will cause more of the stimulus to happen.
The response will decrease the stimulus or return the system back to homeostasis.

5. Feedback Mechanisms ? ? The dog pees on the rug and you say “Bad Dog!”
Is this Positive or Negative Feedback?
The dog chases the ball and you say “Good Boy!”
Is this positive or Negative Feedback?

6. You have your head phones in listening to your favorite songs.
Positive Feedback
Negative Feedback
What would be an example?
What would be an example?

7. The Circulatory System

8. Functions
To transport oxygen to the cells of the body so cells can continue Cell Respiration
To Transport nutrients to the cells of the body

9. Parts
Heart
Blood Vessels
Blood

10. Components of Blood
Red blood cells
White blood cells
Platelets
Plasma

11. What are Red Blood Cells?
Also called erythrocytes
Transport oxygen
Contain Hemoglobin
An iron containing protein that binds to oxygen
Gives blood a red color

12. What are White Blood Cells?
Also called leukocytes
Can live for days, months or even years
Guard against infection, fight parasites, and attack bacteria
Can leave the circulatory system and go into the immune system fighting infection

13. What are two kinds of White Blood Cells?
Phagocytes (eating cells)
Engulf and digest bacteria and other disease causing bacteria
Lymphocytes
Produce antibodies that are proteins to help destroy pathogens

14. What are platelets? Cell fragments needed for clotting
Clotting process
Platelet comes in contact with edges of broken blood vessel and becomes sticky
A cluster of platelets gathers around the wound forming a clot (scab)

15. What is plasma? Fluid part of blood (mostly made of water)
Straw colored
Transport fatty acids, hormones and vitamins
Regulate osmotic pressure and blood volume
Fight viral and bacterial infections
Aid in blood clotting

16. What are blood vessels? Types of blood vessels Arteries (largest)
Capillaries (smallest)
Veins

17. What are arteries? Large, thick walled blood vessels
Carry blood from the heart to the cells
All arteries except the pulmonary artery carry oxygen rich blood

18. What are capillaries?
Tiny blood vessels with walls that are only one cell thick
Oxygen and nutrient absorption take place in the capillaries
Also carbon dioxide and waste products move into the blood through the capillaries
Diffusion of Oxygen and Carbon Dioxide occurs here in the lungs.

19. What are veins? Smaller than arteries but larger than capillaries
Return blood to the heart
Contain valves to keep blood flowing towards the heart

20. Parts of the Heart Aorta Pulmonary Artery Pulmonary Vein
Superior Vena Cava
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
Septum
Inferior Vena Cava

21. Blood Flow Through the Heart
Oxygen poor-
1.) Superior and inferior vena cava
2.) Right Atrium
3.) Right Ventricle
4.) Lungs
Oxygen rich-
5.) Left Atrium
6.) Left Ventricle
7.) Aorta
8.) Body

22. Blood Flow Through the Body
Pulmonary circulation
Right side of the heart pumps blood from the heart to the lungs
Systemic circulation
Left side of the heart receives blood from the lungs and pumps it to the rest of the body

23. Feedback Mechanisms in the Circulatory System
When human tissue, such as skin is torn or cut, all the cells near the damage send out a signal that activates the platelets in that area. A the platelets begin to form a plug, they send out chemical signals calling for more platelets in order to stop the bleeding. Stimulus:__________ Response:_________ Feedback:_________

24. Feedback Mechanisms in the Circulatory System
When muscle cells are active they need more ENERGY (ATP). In cellular respiration, the Mitochondria uses Oxygen to make ATP. After you are done exercising, your breathing returns to a normal rate because the amount of Oxygen required by your cells has decreased.
Stimulus: ______________
Response:______________
Feedback:_______________