1. The Endocrine System
Dr. Tamie Lieto

2. Endocrine Endo=within Krino= separate
The word implies that intercellular chemical signals are produced within and secreted from endocrine glands, but that the chemical signal have effects at locations that are away from or or separate from the endocrine glands that secrete them. The chemical signals are transported by way of the blood

3. Hormones
Hormones – the intercellular chemical signals that are secreted by the endocrine glands
Hormone means “set in motion” because hormones set things in motion
Hormones are distributed in the blood to all parts of the body BUT only certain tissues called Target tissues respond

4. Regulation of Hormone Secretion
Negative Feed Mechanism based on the following: blood levels of chemicals
eg glucose and insulin
hormones
eg some hormones control other hormones
Nervous System
eg epinephrine is released from adrenal medulla because of nervous stimulation

7. Endocrine Glands and Their Hormones
Look at Table 10.3 Endocrine Glands, Hormones and their Target Tissues

8. Classification of Hormones
Proteins/ Amino Acids
thyroid
posterior pituitary
Lipids
Steroids
Eicosanoids

9. Pituitary Gland
The pituitary gland is located posterior to the optic chiasm and beneath the hypothalamus.
It is connected to the hypothalamus by a stalk called the infundibulum
It is divided into anterior and posterior parts
It is part of the Hypothalamus Pituitary Axis

10. Pituitary Gland

12. Pituitary The Pituitary Gland is divided into
Anterior and Posterior Parts
Hormones from the pituitary control control the function of many other endocrine glands
such as the ovaries , testes, thyroid gland and adrenal coortex
Also secretes hormones that affect growth, kidney function, birth and milk production by the breast
Release of Hormones from the Pituitary is under the control of the Hypothalamus

13. Hormones secreted by the Pituitary
Growth Hormone- stimulates growth of bone and organs by increasing protein synthesis
It resists protein breakdown during food deprivation and promotes fat breakdown instead
Growth hormone is under the control of Growth hormone releasing factor (GHRF) and Growth Hormone Inhibiting Factor)

14. Hormones secreted from the pituitary gland
AnteriorPituitary Posterior Pituitary
Antidiuretic Hormone
Growth Hormone Oxytocin
Thyroid stimulating hormone
(TSH)
Adrenocorticotrophic hormone
( ACTH)
Melanocyte Stimulating hormone
Luteinizing Hormone
Follicle Stimulating Hormone
Prolactin

15. Growth Hormone (GH)
Growth Hormone- increases protein synthesis and growth of tissue and organs, breakdown of lipids, and release of fatty acids, increase blood glucose levels
Target Tissue : Most Tissue

16. Deficient of Growth Hormone Pituitary Dwarfism

17. Excess Growth Hormone Gigantism
Exces growth hormone can
result from hormones secreting
tumors of the pituitary gland

18. Acromegaly
IF growth hormone continues to be in excess after the growth plates are closed bones will grow wider . This condition is called acromegaly

19. Thyroid Stimulating Hormone (TSH)
Target tissue: binds to the receptors on the thyroid gland and causes the thyroid gland to secrete thyroid hormone
Too much TSH over stimulates the Thyroid gland ( enlarges)
Too little TSH under stimulates the Thyroid gland (Shrinks)
TSH is under the control of the Thyroid Releasing Hormone released form the hypothalmus

21. Adrenocorticotropic Hormone ACTH
Target Tissue: Binds to receptors on the adrenal cortex gland and stimulates release of the Glucocorticoid hormones such as cortisol
Target Tissue: Binds to melanocytes in the skin and increase skin pigmentaion
ACTH is under the control of the ACTH releasing hormone secreted by the hypothalmus

22. Gonadotropins
Target Tissue: Bind to the receptors on the gonads(ovaries and testes)
Luteinizing Hormone
Follicle Stimulating Hormone
Under control by the GNRH or gonadotropin releasing hormones of the hypothalamus

23. Luteinizing Hormone (LH)
Females- target tissue ovary, promotes ovulation and progesterone in the ovary
Males- target tissue testis, causes testosterone synthesis and supports sperm cell production in testis t

24. Follicle Stimulating Hormone (FSH)
-Female
Target tissue :Follicles in ovary. Promotes follicle maturation and estrogen secretion in ovary.
- Male
Target tissue- Seminiferous tubules in male causing Sperm production

25. Prolactin Female- Target Tissue: receptors in the breast and ovary
Helps promote breast development during pregnancy and stimulates the production of milk. Prolongs progesterone secretion following ovulation and during pregnancy.
Male - Target tissue-testis increses sensitivity to LH
Under control of the releasing hormones from the hypothalamus

26. Site of Prolactin Action is the Mammary Gland

27. Melanocyte Stimulating Hormone (MSH)
Target Tissue: MSH binds to receptors on the skin and increase the production of melanocytes causing them to synthesize melanin
Causes the skin to darken
Under the control of releasing hormones that increase or decrease its production

28. Antidiuretic Hormone ADH
Target Tissue: binds to receptors in the kidney that increase water reabsorption by kidney tubules. This results in less water loss as urine.

29. Oxytocin
Target Tissue: Binds to membrane bound receptors in uterus and mammary glands.
Causes contraction of the smooth muscle in the uterus and milk let down in breast

30. The Thyroid
made up of two lobes connected by a narow band called the ithmus
lobes are on either side of the trachea
highly vascular
contains follicles filled with the protein hormone
Secretes Thyroid Hormone

32. Thyroid Hormone Target Tissue : most cells of the body
regulates your rate of metabolism
also important for growth and development
The thyroid gland requires iodine to synthesize thyroid hormone
deficiency of iodine in the diet can lead to thyroid hormone deficiency
regulation is through feed back mechanism Fig10.14

33. Hypothalamus-Pituitary- Thyroid Axis

34. Lack of thyroid hormone is called Hypothyroidism

35. Excess amout of thyroid hormone can lead to
GRAVES DISEASE

36. Parathyroid Gland
Four glands that are embedded in the posterior wall of the thyroid
Secretes
Parathyroid hormone
Calcitonin
hormones which regulates calcium metabolism

38. Parathyroid Hormone Target tissue : bone and kidney
PTH binds to membrane bound receptors of cells and increases the absorption of calcium from the intestines which increases active Vitamin D
PTH also causes the resorption by incresing the rate of bone breakdown by osteoclasts of bone tissue to release Ca (calcium) into the circulation and decreases the rate at which Ca is lost in the urine
PTH acts on tissue to raise blood Calcium Levels to normal

39. Calcitonin Target Tissue – Bone
Decreases the rate of bone breakdown, prevents large increase in blood calcium levels following a meal

41. Adrenal Gland Divided into Adrenal Cortex (outer)
Glucocorticoids (cortisol)
Aldosterone
Adrenal Androgens
Adrenal Medulla
Epinephrine and Norepinephrine

42. Layers of the Adrenal Gland

43. Arenal Cortex Hormones
Mineralocorticoids- Aldosterone – regulation of NA and K and water balance.
Glucorticoids- Cortisol – decreases inflammation, increases glucose
Adrenal Androgens DHEA- axillary and pubic hair in females

44. Excess Adrenal Androgens (DHEA) in females

45. Cushing Syndrome ( excess cortisol)

46. The Pancreas Both Endocrine and Exocrine Gland The Endocrine part
pancreatic Islets which secrete
insulin (beta cells)
glucagon( alpha cells)

47. Pancreatic Islet cells

48. Blood Glucose control Under the control of insulin and glucagon
It is very important to maintain blood glucose levels within a normal range of values.
A decline in blood glucose level below its normal range causes the nervous system to malfunction because glucose is the nervous system’s main source of energy

49. Insulin
Insulin is released from the beta cells primarily in response to the elevated blood glucose levels and increased parasympathetic stimulation that is associated with the digestion of a meal.
Increased blood levels of certain amino acids also stimulate insulin secretion.
Decreased insulin secretion results from decreasing blood glucose and from stimulation by the sympathetic division of the nervous system This allows blood glucose to be conserved to provide the brain with glucose.

50. Glucagon
Binds to receptors on liver cells and causes the release of glucose from glycogen
The glucose is then released in the blood to increase blood glucose levels
Glucagon secretion is reduced after a mealb

51. Diabetes Mellitus Two Types
Type I - secretion of too little insulin from the pancreas
- onset childhood, very thin , require insulin
Type 2 - insufficient numbers of insulin receptors on target cells or defective recepetors
- adult onset, usually overweight, can take medications that help increase endogenous insulin activity.

52. Diabetes Mellitus Type I The signs and symptoms
As a result, tissues can not take up glucose and the blood becomes Hyperglycemic
Satiety center responds as if there is no glucose and patients feeel hungry
Excess glucose is secreted in urine and they become dehydrated
Fats and protein become energy source and body wasting occurs

53. Table 10.4
Effects of Insulin and Glucagon on Target Tissue

54. Testes and Ovaires
Testes secrete testosterone- growth of male and development of male reproductive structures, muscle enlargement, hair, voice change and male sexual drive
Ovaries secrete estrogen and progesterone- female characteristics
Both are under control of FSH and LH form the pituitary

55. Pineal Gland Small gland superior and posterior to the thalamus
Secretes a hormone called melatonin which decreases LH and FSH by decreasing GNRH which may help regulate the onset of puberty by acting on the hypothalmus

56. Thymus
Secretes thymosin which enhances the ability of the immune system
Thymosin helps in the production of the white cells ( called T cells)

57. Other Hormones Prostaglandins- role in inflammation
Erythropoietin-comes from kidney and stimulates red blood cell production
HCG ( human chorionic gonadotropin) – secreted by the placenta during pregnancy to maintain the pregnacy.

58. Age Related Changed in the Endocrine System
Age related changes include a gradual decrease
GH inpeople who do not exercise
Melatonin
Thyroid Hormone
Reproductive Hormones
Thymus Hormones
Increase in Diabetes