checkpoint 1

http://www.school.eb.com/comptons/article-9274943?query=what%20is%20a%20hormone&ct=null
http://www.biology-online.org/3/3_hormone_production.htm
http://www.ftmguide.org/hormonebasics.html

• Hormones are basically chemical messengers that flow through the blood

• Hormones are made in "ductless endocrine glands." 

• Hormones "float" to certain organs where they "turn biochemicals reactions on or off."

• It is responsible for secreting release factors which instruct the pituitary gland to secret certain hormones. 

• Almost all living things produce hormones.  
• Hormones are always circulating throughout the body and come in contact with so many cells, but only effect certain cells called "target cells."              
• Hormones have a certain shape, and thus will fit into only certain receptors, but not others. 

Questions 

1. What is a biochemical reaction?
2. what happens when a biochemical reaction is turned on or off?
3. Why are the hypothalamus and pituitary gland important when talking about hormones?