1. ENDOCRINE SYSTEM

2. Endocrine - General Major Control System of Homeostasis Negative Feedback Ductless Glands; Produce Hormones Diffuse into Blood Slow Initial Effects, but Effects Persist much longer Hormones act on specific Targets

3. Classification of Glands Endocrine – ductless glands that secrete hormones into the blood stream Exocrine – ducted glands that secrete their products onto a surface

4. Types of Exocrine Glands -Merocrine - secrete via exocytosis (most common) -Holocrine – accumulate products then rupture (sebaceous glands) -Apocrine – products accumulate near surface then part of cell pinches off (mammary glands?)

5. Hormones – Definition Definitions -Literal: To spur on, to set in motion -Physiological: A chemical messenger that affects another tissue or organ (the target)

6. Hormones - General Function Modify activity of target cells Targets have specific receptors for the particular hormone Distributed by blood

8. Location of Receptors Cell Surface -cell membrane Intracellular -Cytoplasm -Nucleus

9. Mechanisms of Hormone Action Steroids (Synthesized from Cholesterol) -Hormone enters cell -Hormone forms complex with receptor -Hormone/receptor complex enters nucleus -Complex binds to DNA -Protein synthesis occurs -Protein alters cell function (i.e. produces the effect) -E.g. Testosterone

11. Mechanisms of Hormone Action continued Non-Steroids (Proteins/Peptides/Amine) Hormones -Hormone does not enter cell -Hormone is 1st messenger -Hormone binds to receptor on cell membrane -Triggers formation of 2 nd messenger (cyclic AMP) -2 nd messenger alters cellular activities (i.e. produce the effect) -E.g. Pituitary hormones

13. Regulation by Receptors Changeable Number of receptors on target -Up Regulation *Low hormone levels *Number of receptors increases *Target’s responsiveness increases -Down Regulation *Excess hormone levels *Number of receptors decreases *Target’s responsiveness decreases

14. Secretion Stimuli Hormonal -Tropic hormones regulate activity of other endocrine glands -Most common Humoral -Changing levels of ion or nutrients trigger release of hormones Neural -Stimulated by nerve fibers

15. Hormonal Stimuli of Endocrine Glands Slide 9.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Endocrine glands are activated by other hormones Figure 9.2a

16. Humoral Stimuli of Endocrine Glands Slide 9.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 9.2b  Changing blood levels of certain ions or nutrients stimulate hormone release

17. Neural Stimuli of Endocrine Glands Slide 9.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nerve impulses stimulate hormone release  Most are under control of the sympathetic nervous system Figure 9.2c

18. Endocrine Organs Hypothalamus Pituitary -Anterior -Posterior Thyroid Gland Parathyroid Glands Adrenal Glands -Cortex -Medulla Pancreas Pineal Gland Thymus Gonads

20. Hypothalamus Integrates Nervous System & Endocrine Portal Circulation carries hormones to Anterior Pituitary Releasing Factors (hormones) stimulate secretion by Anterior Pituitary Inhibiting Factors (hormones) are antagonistic to Releasing Nervous tissue carries hormones to Posterior Pituitary

22. Pituitary Gland Attached to Hypothalamus via infundibulum Protected by sella turcica of sphenoid Divided into 2 lobes: -Anterior (glandular) -Posterior (neuroendocrine)

23. Anterior Pituitary (Adenohypophysis) “Master Gland” (makes & secretes various tropic hormones) Tropic Hormones -Act on other Endocrine Glands -Serve as Hormonal Stimuli -Stimulate release of another hormone

24. Anterior Pituitary (Adenohypophysis) -Human Growth Hormone (GH): *Target: All/Most Body Cells (esp. Bone & Muscle) *Action: Promotes Growth & Repair, *Increases Blood Glucose -Prolactin (PRL): *Target: Mammary Tissue *Action: Promotes milk secretion

25. Anterior Pituitary continued Thyroid Stimulating Hormone (TSH) -Target: Thyroid Gland -Action: Stimulates production of Thyroxine

26. Anterior Pituitary continued Adrenocorticotropic Hormones (ACTH) -Target: Adrenal Cortex -Action: Controls production/secretion adrenal cortex hormones Gonadotropic Hormones -Follicle Stimulating Hormone (FSH) *Target: Gonads (Ovaries/Testes) *Action: Production of gametes & sex hormones

27. Anterior Pituitary continued -Luteinizing Hormone (LH/ICSH) *Target: Gonads *Functions:  Production of sex hormones  Prepare uterus for implantation  Develop corpus luteum

29. Hormones of the Anterior Pituitary Slide 9.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 9.4

30. Posterior Pituitary (Neurohypophysis) Does NOT synthesize Hormones Neural rather than glandular Stores & Releases two hormones produced by hypothalamus -Oxytocin *Target: Uterus & Mammary Glands *Action: Stimulates Contractions to eject fetus & milk

31. Posterior Pituitary continued -Antidiuretic Hormone (ADH) also called vasopressin *Target: Kidneys *Action:  Conserve Water (decrease urine volume)  Increase BP

32. Hormones of the Posterior Pituitary Slide 9.22b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 9.5

33. Thyroid Gland Thyroid Hormone -T3 (Triiodothyronine), T4 (Thyroxine) -Target: Most body cells -Action: Increase metabolic rate, regulate body temperature Calcitonin -Target: Bone/Osteoclast Inhibition -Action: Decrease blood Ca 2+ (Hypocalcemia if excessive)

35. Parathyroid Glands Parathyroid Hormone -Target: Bone/Stimulation of Osteoclasts -Action: Increase blood Ca 2+ (Hypercalcemia if excessive)

36. Parathyroid Glands Slide 9.26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Tiny masses on the posterior of the thyroid  Secrete parathyroid hormone (PTH)

37. Adrenal Glands Adrenal Cortex (outer/glandular) -Cortisol *Target: Many tissues *Action: make glucose, decrease inflammation -Aldosterone *Target: Kidneys *Action: Maintain Na+/K+ blood levels

39. Adrenal Glands continued Adrenal Medulla (inner/nervous) -Epinephrine/Adrenalin (Fear/Flight) -Norepinephrine/Noradrenalin (Anger/Fight) -Targets:Heart, Liver, Muscles, Blood Vessels, etc. -Functions: Prepare for sudden threat

40. Pancreas Endocrine (Islets of Langerhans) & Exocrine Glucagon (from Alpha Cells) -Target: Liver -Action: Release glucose from glycogen (increases blood glucose) Insulin (from Beta Cells) -Target: Most/All Cells -Action: Promotes glucose transport into cells (decreases blood glucose)

42. Pineal & Thymus Glands Pineal Gland (Endocrine & CNS) -Melatonin *Target: Hypothalamus *Action: Sets Diurnal Clock/Circadian rhythm & promotes sleep Thymus (atrophies at puberty) -Thymosins *Target: T cells of immune system *Action: T cell maturation (immunocompetence)

44. Gonads Ovaries -Estrogen *Target: Uterus, Ovaries, other *Action: prepare for fetus, secondary sexual characteristics -Progesterone *Target: Uterus *Action: maintains pregnancy, prevents uterine contractions

45. Gonads continued Testes -Testosterone *Target: Various body parts *Action: Secondary sexual characteristics

46. Endocrine Disorders Hypersecretion -GH  Gigantism or Acromegaly -TH  Grave’s Disease -ACTH  Cushing’s Disease

47. Endocrine Disorders Hyposecretion -GH  Pituitary Dwarfism -TH  Cretinism or Hypothyroidism -Insulin  Diabetes mellitus (Type 1)