1. Ch.21.3 Endocrine System
Chemical Control: similar to nervous control, coordinate body processes by transmitting messages from one part of the body to another ~ achieved through hormonal action

2. Regulation How we maintain homeostasis nervous system endocrine system
nerve signals control body functions (faster & short-lasting)
endocrine system
hormones
chemical signals control body functions (slower & longer-lasting)

3. Endocrine System:function to maintain homeostasis
Endocrine glands: synthesize and secrete hormones (ductless)
Hormones: chemicals secreted in one area of body which affect responses in other areas.
The circulatory system aids in the distribution of these hormones
Delivered to target tissue which recognize specific hormones by receptor cells
Hormones have specific shape that fit the receptors

4. Hormones Why are hormones needed?
chemical messages from one body part to cells in other parts of body
communication needed to coordinate whole body
maintaining homeostasis
growth hormones

5. Endocrine System Endocrine system releases hormones
glands which secrete (release) chemical signals into blood
chemicals cause changes in other parts of body
growth hormones
sex hormones
response hormones
metabolism hormones
and more….
Hormones coordinate slower but longer–acting responses to stimuli such as stress, dehydration, and low blood glucose levels. Hormones also regulate long–term developmental processes by informing different parts of the body how fast to grow or when to develop the characteristics that distinguish male from female or juvenile from adult. Hormone–secreting organs, called endocrine glands, are referred to as ductless glands because they secrete their chemical messengers directly into extracellular fluid. From there, the chemicals diffuse into the circulation.

6. Responding to hormones
Lock and key system
hormone fits receptor on “target” cell
target cell
secreting cell
non- target cells
can’t read signal
can’t read signal

7. Major glands of the Endocrine system
The hypothalamus integrates endocrine and nervous function

8. Maintaining homeostasis
Feedback
hormone 1
gland
lowers body condition
high
specific body condition
low
raises body condition
gland
hormone 2

9. Negative Feedback Response to changed body condition
if body is high or low from normal level
signal tells body to make changes that will bring body back to normal level
once body is back to normal level, signal is turned off
hormone 1
gland
lowers body condition
high
specific body condition

10. Regulation of Blood Sugar
Endocrine System Control
Regulation of Blood Sugar
Feedback
insulin
body cells take up sugar from blood
liver stores sugar
reduces appetite
pancreas
liver
high
blood sugar level
(90mg/100ml)
low
liver releases sugar
triggers hunger
pancreas
liver
Diabetes: insulin deficiency-results in an elevated blood sugar level (glucose)
glucagon

11. Regulation by chemical messengers
Neurotransmitters released by neurons
Hormones release by endocrine glands
endocrine gland
neurotransmitter
axon
hormone carried by blood
receptor proteins
receptor proteins
target cell

12. Body Regulation Nervous system & Endocrine system work together
hypothalamus
“master nerve control center”
receives information from nerves around body about internal conditions
communicates with pituitary gland
“master gland”
releases many hormones
sexual development, growth, milk production, pain-relief
hormones

13. Comparison of Nervous & Endocrine Systems
Nervous system
Brings about a response in effector organs when a receptor is activated
Message is an electrical- chemical impulse that travels along neurons, and between neurons by neurotransmitters.
Nervous communication is quick, but short-lasting
Endocrine System
Brings about a response in target tissues when a receptor is activated
Hormone messenger travels via the bloodstream
Chemical communication is slower, but longer-lasting