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

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

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

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

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….

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

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

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

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 high hormone 1 lowers body condition gland specific body condition

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

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

Body Regulation hormones 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

Comparison of Nervous & Endocrine Systems Nervous systemEndocrine System