The Endocrine System

1. The Endocrine System Chapter 9

2. Communication and Control – slower and long lasting through hormones – chemical messages – that effect a target organ • Diseases (tumors) influence by: • Hyposecretion – too little secretion • Hypersecretion –two much secretion • All organs are glands: • Exocrine – secrete products into ducts • Endocrine – ductless glands • Heterocrine Gland - Both (pancreas)

4. Origin Of Hormones • Hormones affects target cells • Secreted by endocrine glands • Secreted by neurons (neuro-hormones) - neurosecretory cells • Secreted by individual cells or tissues (Growth Factors, prostaglandins, histamine)

5. Chemical Nature of Hormones • Derived from cholesterol • Derived from amino acids • Derived from fatty acids

6. Second Messenger Hypotheses Cause specific affects on target organs only Hormone binds to specialized receptor – “first messenger” Second Messenger is Cyclic Adenosine MonoPhosphate (cAMP) The bonding of the hormone activates activates a G4 protein, which in turn activates adenylate cyclase (enzyme) to react with ATP to produce cAMP Protein Hormones

7. Steroid Hormones • Small – lipid soluble Hormones • Pass directly through the cell membrane of target organs • Go to nucleus, interact with DNA to allow transcription of certain proteins

8. Prostaglandins • PG’s - tissue hormone – produced on a tissue and acts on nearby cells • Three groups PGA, PGE, PGF • Might have a role in asthma, blood pressure disorders, and ulcers

10. Negative Feedback • Reverses a change in a body condition • Insulin – high blood-sugar content after a meal, pancreas secretes insulin to move blood-sugar into cells, thus decreasing levels

11. Other types of Negative Feedback

13. Positive Feedback • More Uncommon than negative feedback • Amplify changes rather than reverse them • Labor – the contractions are amplified through hormone control

20. Pituitary Gland • Gland in hind brain about the size of a pea • Anterior (adrenohypophysis)- gland / Posterior (neurohypophysis) - nervous

21. Anterior (adrenohypophysis)- gland - hypothalamin releasing hormones get anterior to release hormonesPosterior (neurohypophysis) - nervous- nerve endings from hypothalamus cause hormones to be released

23. Hormones of Anterior Pituitary • Tropic Hormones – Stimulates another endocrine gland to grow and secrete its hormone

24. ANTERIOR GLAND - TROPIC • TSH - (thyroid-stimulating) Growth and secretion of the thyroid • ACTH - (adenocorticotropic) Growth of Adrenal cortex and secretions • FSH - (follicle stimulating) Growth and development of Ovarian Follicles - providers of ova (eggs), release of estrogen/progesterone • LH - (Luteinizing) Control ovulation - maturation and bursting of follicle - males - interstitial cells • ICSH - (Interstitial cell)Testosterone secretion of testes

25. MSH - (melanin stimulating hormone) - synthesizes and spreads melanin - pigment • GH - (Growth Hormone) -stimulates growth by protein anabolism (building) - fat and glucose catabolism - enhances the movement of Amino acids across cell membrane • Insufficient GH - dwarfism • Oversecretion - giagntism • Prolactin - (lactogenic) - stimulates milk production, in males excess may decrease sex hormones

26. Posterior Pituitary Hormones • ADH- retention of water by kidneys (diuretic - loss of water by kidneys)- maintained by osmoreceptors in the brain • Oxytocin - stimulates uterine contraction - positive feedback

27. Located in the neck, below the larynx Thyroxin (T4 - four atoms of iodine - accelerates metabolism Calcitonin - decreases blood calcium, puts calcium into bones Triiodothyronine (T3 three atoms of iodine) -energy for metabolism - five times as potent as thyroxin Small (usually 4) found on the back of the thyroid Increases Blood Calcium - breaks down bone Thyroid Gland ---Parathyroid Gland

29. Adrenal Glands • Adrenal Glands - Lie on top of the kidneys • Two separate endocrine glands the adrenal cortex and the adrenal medulla

30. CORTEX Glucocorticoids - maintain blood pressure, sugar, stress - cortisol Mineralocorticoids - increase blood sodium, decrease blood potassium sex hormones - small amount secreted, female converted to estrigens Medulla Produces epinephrine and norepinephrine for stress response - sympathetic inervation The effects include increase heart rate, breathing rate, and all assoisiated sympahtetic responses ADRENAL GLANDS

31. Pancreatic Islets/ Islets of Langerhans • Alpha cells = glucagon, Beta cells = insulin

32. Female and Male Sex Hormones • Ovaries – female, Testis - male • Female characteristics and fertility - release of estrogen and progesterone • Male - secretes testosterone - interstitial cells - controls male sexual development

33. PLACENTA • Temporary endocrine gland • secretes choriongonadotropin hormone - maintains corpus luteum - high in urine = pregnancy • PINEAL • Small pine-coned shaped gland at the roof of the third ventricle of the brain • Also called third eye – responds to senses • Produces melatonin • inhibits ovarian activity • influences menstrual cycle • biorhythms

34. HEART • Atrial Natriuretic Hormone – secreted by the walls of the atria – regulates fluid and electrolytes • THYMUS • Located in mediastinum. Has cortex and medulla • Houses lymphocytes • secretes thymosin - immune regulator

35. Digestive Glands - stomach and small intestines secrete hormones to aid digestion - gastrin, secretin

36. Endocrine Development • Endocrine tissue develops from the ectoderm, epithelial tissue