CHAPTER 45 CHEMICAL SIGNALS IN ANIMALS

1. CHAPTER 45 CHEMICAL SIGNALS IN ANIMALS

2. Hormone-chemical signal secreted into the body fluids that communicates a regulatory message Target cell-equipped to respond to a particular hormone Endocrine system-all the hormone secreting cells Endocrine glands-whole organs of large tissues whose major function it is to secrete hormones; ductless Neurosecretory cells-nerve cells that secrete hormones Exocrine glands secrete their chemicals into ducts; sweat, mucus, digestive enzymes

4. Brain hormone controls the release of ecdysone that causes a larvae to become a adult. Juvenile hormone opposes ecdysone

5. Local signals growth factors-peptides and proteins that stimulate cell proliferation; important in tissue culture research nitric oxide-produced by many cells, has varied effects, works in seconds then rapidly breaks down; functions as a neurotransmitter and lowers bp by relaxing smooth muscle prostaglandins-modified fatty acids; many and various affects cause swelling and inflammation; production inhibited by aspirin and ibuprofen

6. receptors in plasma membrane-signal transduction pathway- second messenger- cAMP-animals; calmodulin in plants steroid hormones-lipid soluble pass through cell membranes where they encounter intracellular receptors in target cells; usually activates a transcription factor causing a gene to be transcribed and a protein to be produced

7. Growth factors- peptides and proteins that stimulate cell division Nitrous oxide- produced by many cells with varying effects; acts as a neurotransmitter; when secreted by leucocytes it kills bacteria and cancer cells; when released by endothelium cells, it makes smooth muscles relax and dilates blood vessels Prostaglandins- modified fatty acids; released by most types of cells into interstitial fluid; many different functions and affect different target cells with even opposite reactions; cause swelling and inflammation; production inhibited by aspirin and ibuprofen

8. Same hormone has different effects on different target cells

9. Endocrine Glands

10. Hypothalamus-integrates the nervous and endocrine system; consists of two sets of neurosecretory cells one set has its cell bodies in the hypothalamus but its axons extend into the posterior pituitary where its hormones are released the other set is located entirely in the hypothalamus and releases its releasing or inhibiting hormones into a portal system (two capillary beds) of capillaries that transport them to the anterior lobe of the pituitary where their target cells are located

11. Posterior pituitary-neurohypophysis- axons from the neurosecretory cells in the hypothalamus extend down into the posterior lobe where their hormones are secreted and stored oxytocin-causes muscles of the uterus to contract causing labor & causes mammary glands to eject milk antidiuretic hormone-makes collecting ducts permeable to water, raises B.P., produces less volume but more conc. urine

13. Anterior pituitary-adenohypophysis-

16. Thyroid gland Parathyroids glands

19. Contains light sensitive cells or connections from the eyes regulates functions related to light and seasons; biological rhythms, jet lag and reproductive cycles

21. Adrenal medulla catecholamines-epinephrine, norepinephrine, adrenaline-stress hormone flight of flight

22. Adrenal cortex-corticosteroids- glucocorticoids- cortisol-raise blood glucose; anti-inflammatory Mineralocorticoids-aldosterone reabsorption of Na+ and excrete K+