Feedback mechanisms
O Are used to either maintain or
amplify (to increase) chemical
systems in the body.
O Note: To determine the type of mechanism
you must be able to determine the stimulus
and response.
Feedback Mechanisms
Identify a Stimulus and
Response
Your dog chases the ball and you say
“Good Boy!”
O Stimulus: __________________
O Response:__________________
Your dog pees on the rug and you say
“Bad Dog!”
O Stimulus:____________________
O Response:____________________
Feedback Mechanisms
Positive Feedback
O The response will
increase the stimulus
O Does not return to
homeostasis but will
cause more of the
stimulus to happen.
Negative Feedback
O The response will
decrease the
stimulus or return
the system back to
homeostasis.
Feedback Mechanisms
?
O The dog pees on the
rug and you say “Bad
Dog!”
O Is this Positive or
Negative Feedback?
?
O The dog chases the
ball and you say
“Good Boy!”
O Is this positive or
Negative Feedback?
You have your head phones in
listening to your favorite
songs.
Positive Feedback
What would be an
example?
Negative Feedback
O What would be an
example?
The Circulatory
System
Functions
O To transport oxygen to the cells of the
body so cells can continue Cell
Respiration
O To Transport nutrients to the cells of
the body
Parts
O Heart
O Blood Vessels
O Blood
Components of Blood
O Red blood cells
O White blood cells
O Platelets
O Plasma
What are Red Blood Cells?
O Also called erythrocytes
O Transport oxygen
O Contain Hemoglobin
O An iron containing protein that binds to
oxygen
O Gives blood a red color
What are White Blood
Cells?
O Also called leukocytes
O Can live for days, months or even years
O Guard against infection, fight parasites,
and attack bacteria
O Can leave the circulatory system and go
into the immune system fighting
infection
What are two kinds of
White Blood Cells?
O Phagocytes (eating cells)
O Engulf and digest bacteria and other
disease causing bacteria
O Lymphocytes
O Produce antibodies that are proteins to
help destroy pathogens
What are platelets?
O Cell fragments needed for clotting
O Clotting process
O Platelet comes in contact with edges of
broken blood vessel and becomes sticky
O A cluster of platelets gathers around
the wound forming a clot (scab)
What is plasma?
O Fluid part of blood (mostly made of
water)
O Straw colored
O Transport fatty acids, hormones and
vitamins
O Regulate osmotic pressure and blood
volume
O Fight viral and bacterial infections
O Aid in blood clotting
What are blood vessels?
O Types of blood vessels
O Arteries (largest)
O Capillaries (smallest)
O Veins
What are arteries?
O Large, thick walled blood vessels
O Carry blood from the heart to the cells
O All arteries except the pulmonary
artery carry oxygen rich blood
What are capillaries?
O Tiny blood vessels with walls that are
only one cell thick
O Oxygen and nutrient absorption take
place in the capillaries
O Also carbon dioxide and waste products
move into the blood through the
capillaries
O Diffusion of Oxygen and Carbon Dioxide
occurs here in the lungs.
What are veins?
O Smaller than arteries but larger than
capillaries
O Return blood to the heart
O Contain valves to keep blood flowing
towards the heart
Parts of the Heart
Aorta
Superior Vena Cava
Right Atrium
Right Ventricle
Inferior Vena Cava
Pulmonary
Artery
Pulmonary
Vein
Left Atrium
Left Ventricle
Septum
Blood Flow Through the
Heart
O Oxygen poor-
O Oxygen rich-
1.) Superior and
inferior vena cava
2.) Right Atrium
5.) Left Atrium
3.) Right Ventricle
7.) Aorta
4.) Lungs
8.) Body
6.) Left Ventricle
Blood Flow Through the
Body
O Pulmonary circulation
O Right side of the heart pumps blood
from the heart to the lungs
O Systemic circulation
O Left side of the heart receives blood
from the lungs and pumps it to the rest
of the body
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:_________
Feedback Mechanisms in the
Circulatory System
O 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.
O Stimulus: ______________
O Response:______________
O Feedback:_______________