Chapter 16

1. Chapter 16 Endocrine System

2. Introduction Maintains homeostasis through hormone regulation throughout the body Comparable to the nervous system and the controls previously learned Regulation – chemical messages to the cells (glands or neurons) Target cells and tissues receive hormones from various glands throughout the body How are hormones taken to these target cells?

3. Hormones Effect the body slowly, but lasts long time Secreted by ductless (endocrine)glands Exocrine glands excrete products into ducts (oil, sweat, hydrochloric acid, etc) Some glands contain neurosecretory tissue – modified neurons that secrete chemicals into the blood rather that across a synapse

4. Hormone classification Tropic – target other endocrine glands to stimulate growth and secretion Sex – reproductive tissues Anabolic – stimulate anabolism (cells making hormones from chemicals) OR Steroid Nonsteroid

10. Corticosteroids Indications (usages) Reduce swelling Reduce inflammation Pros Asthma Poison Ivy Cons Thin skin Increased HDL

11. Prednisone True or False Quiz

12. Anabolic steroids“ROIDS” Indications Slow physiological development Low testosterone levels Pros Muscle mass production at a rapid rate Increased self-esteem Cons Increased emotional response Increased cancers/growths Increased heart/liver disease

13. IT IS ILLEGAL !!!!!!

16. Steroid hormones Made from cholesterol that can pass through plasma membranes to target cells Examples: cortisol, aldosterone, estrogen, progesterone, testosterone

17. Steroid hormone action Lipid-soluble and found in target cell cytosol After diffusion into target cell, it binds to receptor molecule to form hormone receptor complex (hypothesis)Activates a gene in the nucleus to transcribe mRNA to ribosomes and makes protein molecules that produce the effect of the hormone The amount of steroid hormone determines intensity of effect Slow process

18. Non-steroidal hormones Made from amino acids (proteins and glycoproteins) Insulin, parathyroid hormone, oxytocin, antidiuretic hormone, epinephrine, nor-epinephrine

19. Non-steroidal action Fixed membrane receptor hypothesis NS hormone is first messenger and delivers chemical message to the target cell’s plasma membrane Message passed by G proteins to second messenger triggers and appropriate cellular changes occur

20. Hormone function Signal target cells receptors Various receptors produce different regulatory functions/chemical reactions Hormone glands produce more than is necessary and left-overs are excreted Combined hormone actions allow for special function

21. Combined hormone actions Synergism – many working together on target cells for better performance Permissiveness – small amounts of one hormone allows for another to have full effect on target cell Antagonism – opposing effects to “fine tune” activity of target cell

22. Hormone regulation Negative feedback loop (endocrine reflex) Physiological changes Regulation by another gland Nervous system input

23. Prostaglandins Lipid molecules Tissue hormones Diffuses to neighboring cells in the tissue Examples: PGA – intraarterial infusion – creates hypotension PGE- vascular regulation (RBC, thrombocyte), GI system (hydrochloric acid) PGF – uterine contractions, GI motility

24. Secretion of protaglandins: kidney, lung, iris, brain, thymus

25. Pituitary

26. Master gland

27. Master gland/hypophysis: ½ “ in size, weight 0.5 g Ventral surface of the brain Stem connects the pituitary to the hypothalmus Contains two glands – Anterior – adenohypophysis Posterior - neurohypophysis

28. Anterior Two parts – pars anterior/pars intermedia Irregular clumps of secretory cells supported by fibers and interweaved with great vascularity Three types of cells Chromophobes – do not stain Acidophils – stain with acids Basophils – basic stains

29. Five functions Somatotrophs – GH Corticotrophs – ACTH Thyrotrophs – TSH Lactotrophs – prolactin – PRL Gonadotrophs – LH/FSH

30. GH – growth hormone Also – STH (sonatotropin) Promotes growth of: bone, muscle, other proteins to cells Stimulates USE of lipids – speeds up catabolism of lipids Shifts cells from glucose catabolism and toward lipid catabolism as an energy source – THIS LEADS TO INCREASED BLOOD GLUCOSE LEVELS

31. Prolactin Released during pregnancy, after birth, during disease Stimulates milk production from the mammary gland

32. TSH Thyrotropin Growth and development of the thyroid Causes secretion of thyroxin

33. ACTH Adrenocorticotropic hormone Normal growth and development of cortex of the adrenal gland and secrete adrenaline

34. FSH Graafian follicles to grow to maturity Estrogen secretion – female Spermatogenesis - male

35. LH Female – stimulates the corpus luteum which then secretes progesterone /estrogen Also assists FSH for egg maturation Male – enables testes to develop and secrete testosterone

36. FSH and LH called gonadotropins because they stimulate the growth and maintainance of the gonads.

37. Adenohypophysis Hypothalamus releases hormones into the blood which are then carried to the hypophyseal portal system The hypothalamus adjusts secretions of the adenohypophysis which then adjusts the secretions of the target cells During stress, the hypothalamus translates nerve impulses into hormone secretions by the endocrine glands

38. Neurophyophysis Serves as storage and release site for ADH and oxytocin which are made in the hypothalamus Release into the blood is stimulated by nerve impulse ADH – regulates fluid content in the blood by regulation of filtration in the kidney Dehydration will trigger ADH release OT – lactation, uterine contraction for birth

39. Pineal gland Part of the nervous and endocrine system Located in the brain Looks like a pine cone Biological clock Secretion of melatonin (happy hormone) – puberty, responds to light (inhibits production) – can cause seasonal affective disorder (winter depression)

41. Thyroid Two large lobes 1 oz. Anterior/lateral surface of trachea below larynx Thyroid hormone synthesized in follicles

43. Thyroid hormones Stores hormones – only endocrine gland that does this Regulates metabolism, cell growth and tissue differentiation Three hormones produced: T-3, T-4, calcitonin Calcitonin – processing of Ca by bones,blood T-3 – three iodine atoms – More potent than T-4 The main thyroid hormone T-4 – four iodine atoms – 20 times more released than T-3 When released to the target cells, it becomes T-3

44. Thyroid abnormalities hyperthyroisdism hypothyroidism • Graves disease • Hashimoto’s Disease • Wt. loss • Exopthalmos • Nervousness • Increased heart rate • Increased respiratory rate • Increased metabolism • Cretinism • Slow metabolism • Retarded growth • Retarded sexual development • Occ. Mental retardation • Occ. Deformed dwarfism (unproportionate) • Sluggish • Loss of hair • Jaundice • Myxedema

45. Graves

46. Cretinism

47. Parathyroid Four embedded to the posterior lateral surface of the thyroids PTH – parathyroid hormone – antagonist to calcitonin PTH acts on bone and kidney cells to release Ca into the blood

49. Adrenal glands Above the kidney Outer – adrenal cortex Inner – adrenal medulla

50. Cortex Three layers each producing a specific hormone Outer – mineralocorticoids – electrolytes Aldosterone – regulates Na, K, and blood pH and regulates BP (pg.507) Middle – glucocorticoids – reg. BP, immune response Cortisol– TMT of inflammation, regulates serum glucose Inner – glucocorticoids and gonadocorticoids – releases sex hormones from the adrenal cortex (androgen)