The Endocrine System

1. The Endocrine System By Evil Mr. Bleecker

2. Endocrine vs Nervous System NERVOUS ENDOCRINE • Uses chemical hormones released from glands into the blood • Uses impulses sent along axons and chemical neurotransmitters at synapses • Receptors are on the plasma membranes of target cells or intercellular • Receptors are on post-synaptic membrane • Signals are very fast (milliseconds) • Signals are slower (seconds to days) • Response is immediate but short-lived • Response is delayed but more sustained

3. Characteristics of Hormones • Hormones: • exert their effects some distance from where they are produced • are active under very low (nanogram 10-9) concentrations in the blood • usually have a short half-life in the body - several seconds to 60 mins. They are degraded by enzymes in their target cells or in the kidney or liver.

4. Characteristics of Hormones • Hormones bring about their effects by altering cell activity. The precise response depends on the target cell type. • Typical cellular effects include: • Altering membrane permeability • Stimulating protein synthesis • Activating enzymes • Inducing cells to secrete materials • Stimulating mitosis

5. Control of Hormone Release • Synthesis and release of most hormones are regulated by a Negative Feedback System. As hormone levels rise, they cause target organ effects which inhibit further hormone release.

6. Hormone - Target Cell Specificity • Hormones circulate to virtually all tissues but influence the activity of only certain tissue cells, known as its target cells.

7. The Hypothalamus Contros the Anterior Pituitary • Hypothalamus “tastes blood” for hormone levels. It sends orders to the anterior/posterior pituitary to regulate the release of hormones. • Hormonal control rather than by nerves • Hypothalamus neurons synthesize releasing and inhibiting hormones. • Hormones secreted regulate the secretions of the anterior pituitary

10. CONTROL OF RELEASE TARGET ORGAN HORMONE GLAND EFFECTS OF HYPER- AND HYPOSECRETION NORMAL EFFECTS OF HORMONE

11. pituitary gland • Pituitary gland is located in the diencephalon below the hypothalamus • Structurally and functionally divided into: • Anterior lobe • Posterior lobe

13. Anterior Pituitary – Master Gland • growth hormone - GH • prolactin- PRL • adrenocorticotropic hormone - ACTH • thyroid stimulating hormone - TSH • lutenizing hormone - LH • follicle-stimulating hormone - FSH

14. posterior pituitary • antidiuretic hormone – ADH • oxytocin - OT

15. pituitary glandgrowth hormone • Direct effects are the result of GH binding its receptor on target cells. • Target cells then believe they should take in more nutrients and grow, then divide

16. GROWTH HORMONE DISORDERS • Gigantism (Acromegaly) refers to a condition characterized by extreme physical size and stature due to a hyper-secretion of growth hormone during infancy, childhood or adolescence 12 year-old with mother

17. Remember Andre the Giant? (WWF)At the Start of his Career

18. By the End of his Career  Topping out at 625 lbs! Click for the action------>

19. GROWTH HORMONE DISORDER #2 • Dwarfism results from a GH deficiency in childhood, leading to a maximum height of 4 feet typically with normal body proportions. If diagnosed before puberty, hormone replacement therapy can promote nearly normal growth. Dwarfed brothers with researcher in India

20. THE THYROID GLAND • Thyroid gland is a large gland located in the neck, just below the larynx. Needs IODINE to work properly. • Thyroid follicle cells stimulated by the anterior pituitary gland hormone TSH =Thyroid-stimulating Hormone • Secretes THRYOXIN = adjusts metabolism for all body cells – ie. Burning more glucose

21. Goiter - Due to iodine deficiency

22. Hypothyroid in Infants • Cretinism: • Hypothyroid from end of 1st trimester to 6 months after birth. • Severe mental retardation • Short disproportionately sized body with a thick neck and tongue

23. Hypothyroid in Adults • In adults, it is called Myxedema: • Accumulation of proteins and fluid in subcutaneous tissue. • Symptoms: • Decreased metabolic rate. • Weight gain. • Decreased ability to adapt to cold. • Lethargy (= fatigue)

24. Hyperthyroid in Adults • Grave’s disease • Elevated metabolic rate (rapid heartbeat, sweating, nervousness) and bulging eyeballs (expophthalmia)

25. HORMONES OF CALCIUM BALANCE • Calcitonin - protein • Produced by thyroid • Reduces blood serum calcium levels by stimulating calcium uptake in bone • Important only in childhood when bones are quickly growing

26. Parathyroid Glands – Calcium II • Parathyroid Hormone (PTH) • Produced by parathyroid glands • Opposite effect to Calcitonin  Increases blood calcium levels by enhancing absorption of calcium in the small intestine, bone and promoting Ca2+ reabsorption in the kidney

28. Adrenal Gland • Paired organs that cap the kidneys. • Each gland consists of an outer cortex and inner medulla.

29. Adrenal Cortex • Adrenal cortex • Stimulated hormonally (ACTH = Adrenal CorticoTropic Hormone) • Secretes corticosteroids • Glucocorticoids – raises blood glucose, increases protein breakdown. Another is cortisone = anti-inflammatory • Aldosterone (Mineralcorticosteroid) – sodium reabsorption in kidneys • Sex Hormones – stimulates sex organs, development of reproductive organs

30. Negative Feedback Loop • Low blood sodium sensed by kidneys  enzyme Angiotensin secreted which turns on secretion of aldosterone by kidney • Increased H20 absorbed to raise pressure

31. GLUCOCORTICOIDS • At high concentrations, cortisol has pronounced anti-inflammatory and anti-immune effects including: • Depressing cartilage and bone formation • Inhibiting inflammation

32. GLUCOCORTICOIDS in Excess • Cushing’s disease = glucorticoid excess • Symptoms include hyperglycemia (high blood sugar), loss of muscle and bone protein, moon face, and a redistribution of fat to the abdomen and posterior neck (causing a “buffalo hump”) • Excess of aldosterone causes excessive Na reabsorption, flooding tissues with water = edema

33. GLUCOCORTICOIDS – Insufficiencies • Addison’s disease is the major hypo-secretory disorder of the adrenal cortex, usually involving of both glucocorticoids and mineralcorticoids. Victims lose weight, demonstrate hypoglycemia and reduced levels of sodium, and show an increase in skin pigmentation (bronzing) JFK had Addison’s, which he kept from public knowledge

34. Adrenal Medulla • Synthesizes and secretes • Epinepherine and some NorEpinepherine • Sympathetic Nervous System hormones made here!!! Fight or Flight!!!

35. ANTIDIURETIC HORMONE • Antidiuretic Hormone (ADH; vasopressin) The main regulator of body’s water (osmotic)balance • ADH increases the reabsorption rate of water in kidney • Secretion is regulated in the hypothalamus by osmoreceptors, which sense water concentration

36. Pancreas • Islets of Langerhans secrete insulin into the bloodstream • Insulin tells cells to absorb sugar and store it • Huge storage in liver as GLYCOGEN and in muscles!!!

37. Homeostatis & Regulating Blood Sugar Levels • Negative feedback loops • If blood sugar rises, insulin is secreted to bring it down • If blood sugar lowers, glucagon is secreted to place sugar into the blood

39. INSULIN • Diabetes mellitus results from hypo-secretion of insulin or hypo-activity of insulin. When insulin is absent or deficient, blood sugar levels remain high after a meal because glucose is unable to enter most tissue cells.

40. DIABETES • Type I diabetes mellitis (insulin-dependent) afflicts 750, 000 Americans. • Autoimmune disease (the insulin secreting beta cells of the Islets of Langerhans are attacked by immune cells) • Insulin is not produced or secreted, requiring regular insulin injections.

41. DIABETES • Type II diabetes mellitis (non-insulin-dependent) afflicts 7.5 million Americans • Insulin resistance - Insulin is usually produced but the receptors do not respond. Loss of receptors possible – can have all the insulin there, but can’t absorb it.

42. DIABETES & HEREDITY • Heredity plays a role - an estimated 30% of Americans carry a gene that predisposes them to Type II diabetes. • Lifestyle play a role - Type II diabetics are almost always obese and sedentary. Adipose tissue produces a hormone-like chemical that may prevent uptake of insulin

43. PINEAL GLAND • Secretes melatonin: • Production stimulated by the hypothalamus • Sets daily = circadian rhythms. • Melatonin secretion increases with darkness and peaks in middle of night.

46. MELATONIN • Melatonin secretion has been linked to seasonal affective disorder (SAD) in people living in northern latitudes like Alaska. Melatonin is elevated in the winter months, and it may lead to depression, long bouts of sleeping, and eating binges. Sun lamps with a full spectrum of light are helpful therapy for some people. The Midnight Sun

47. Thymus Gland & Hormones of the Immune System • Secretes thymosins that aid in the maturity of lymphocytes inside the lobules of the thymus.

48. Hormones of Digestion & Sex • Digestion- gut hormones – ex Gastrin & fullness • Sex hormones . . . . • Testes • produce androgens (testosterone) • Puberty - secondary sexual characteristics such as • Pubic hair, Muscular strength, Deepening of voice • Ovaries • produce estrogens and progesterone. • Puberty - secondary sexual characteristics such as • Pubic hair, Breast development, Widening of hips, onset of menstrual cycle

49. Effects of Anabolic Steroids 1995 1997 2002 2005 Gynecomastia Severe Acne Accelerated Balding