2. The Glands and Hormones of the Endocrine System

3. Endocrine System Regulation of Body Temperature Regulation of Body’s H 2 O Content Regulation of Serum Glucose Levels Regulation Ca ++ Metabolism Regulation of Rate of Metabolism Hormones steroids peptides (proteins) prostaglandins catecholamines “little ones” “big ones” “really big ones”

5. Main Function:  it secretes hormones (chemical messengers) into the blood to signal other cells to behave in certain ways.  it is a slower form of communication compared to the nervous system, but it has longer lasting effects. More free powerpoints at http://www.worldofteaching.comhttp://www.worldofteaching.com

6. Endocrine glands  secrete hormones into the bloodstream.  pituitary, pineal, thyroid, parathyroid, and adrenal glands are solely endocrine glands  hypothalamus, thymus, pancreas, testes, and ovaries have other functions Hormones:  over 200 different ones Consists of:

7. The word “hormone” comes from the Greek meaning “to excite or to set into motion” There are two types: o Steroid hormones: lipid-soluble molecules made form cholesterol (e.g. male and female sex hormones, cortisol) o Water-soluble hormones: derived from amino acids or chains of amino acids (e.g. insulin, growth hormone, thyroxine)

8. Delivery Systems autocrine system – chemicals made by a cell to affect itself paracrine system – chemicals made to affect cells nearby juxtacrine system – chemicals made to signal along a cell membrane (own cell or neighbouring cells)

9. Hormone Action on Target Cells How do they know where to go? –Target cells have protein receptors for hormones

10. Steroid Hormones Steroid hormones are lipids (and hydrophobic) –Made from cholesterol –Not soluble in water 1.diffuse through the lipid bilayer of the membranes of the target cells 2.Diffuse into target cells & bind to receptors 3.Often moves into nucleus to affect transcription This binding activates specific genes, causing changes in the cells such as cell growth. Steroid Hormone Action

11. R R H H

12. binding area R H R H

13. Protein Hormones Short peptide sequences Water soluble 1. transported from cell of origin (secretory vacuoles) 2. attach to surface receptors of target cells 3. activates enzymes to make other internal signals – cascade of reactions (amplifies) protein hormone action

14. Protein Hormone Action R H ATP cyclic AMP + PPi other enzymes

15. The Hypothalamus located in the brain, this region controls most endocrine secretions link between the nervous system and the endocrine system mainly regulatory hormones are produced here most control the pituitary gland

16. PITUITARY GLAND This is known as the master gland because it controls a lot of other endocrine glands. A small sac connected to the hypothalamus. Pituitary gland stores hormones while the hypothalamus stimulates it to release them.

17. PITUITARY GLAND The pituitary gland has two lobes: – The posterior lobe stores and releases hormones produced by the hypothalamus (ex. ADH, oxytocin) – The anterior lobe produces and stores its own hormones (ex. TSH, prolactin)

18. Regulating the Regulators After receiving signals from sensors in the body, the hypothalamus secretes releasing hormones. These hormones stimulate the pituitary gland to secrete other hormones that act on other endocrine glands. Hormones that target endocrine glands to secrete other hormones are called tropic hormones. Continued…

19. Regulating the Regulators A specific example of hormone regulation is the negative feedback system that controls thyroid- stimulating hormone (TSH), shown in diagram A, below.

20. Working Together The nervous system and the endocrine system work together to maintain homeostasis. The functions of these two systems often overlap: some nervous system structures (such as cells in the hypothalamus) release hormones some chemicals (epinephrine) act as both neurotransmitters and hormones both the endocrine and nervous systems are regulated by feedback loops some physiological processes require both systems to operate (e.g., breastfeeding a baby involves nerve messages and the hormone oxytocin)