1. Endocrine (hormone) System
Hendra Wijaya

2. Hormones are chemical messengers secreted by certain tissues into the blood or institial fluid, serving to regulate the activity of other tissues.

3. Chemical Classification of Hormones
Amine hormones are derived from tyrosine or tryptophan
Include NE, Epi, thyroxine, melatonin
Polypeptide/protein hormones are chains of amino acids
Include ADH, GH, insulin, oxytocin, glucagon, ACTH, PTH
Glycoproteins
Long polypeptide bound to a carbohydrate group
Include LH, FSH, TSH
Steroids are lipids derived from cholesterol
Include testosterone, estrogen, progesterone & cortisol
11-7

4. Chemical Classificaton of Hormones
Steroid Hormones:
Lipid soluble
Diffuse through cell membranes
Endocrine organs
Adrenal cortex
Ovaries
Testes
placenta

5. Chemical Classification of Hormones
Nonsteroid Hormones:
Not lipid soluble
Received by receptors external to the cell membrane
Endocrine organs
Thyroid gland
Parathyroid gland
Adrenal medulla
Pituitary gland
pancreas

6. Regulatory Systems Target cells~ body cells that respond to hormones
Endocrine system/glands~ hormone secreting system/glands (ductless); exocrine glands secrete chemicals (sweat, mucus, enzymes) through ducts
Neurosecretory cells~ actual cells that secrete hormones
Feedback mechanisms ~ negative and positive

7. Endocrine System

8. Major Endocrine Glands
Pineal Gland
Hypothalamus
Pituitary Gland
Anterior
Posterior
Thyroid Gland
Parathyroid Glands
Adrenal Glands
Cortex
Medulla
Thymus Gland
Pancreas
Gonads
Ovaries
Testes
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9. There is a hierarchical chain of command in hormonal signaling.
Coordination center
of the endocrine
system.
Via direct neuronal connection

10. Hypothalamus-pituitary axis

11. Feedback control

12. Feedback control of thyroid function

13. Mode of Action: Chemical Signaling
1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones)
2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators

14. Hypothalamus Part of brain
Regulates ANS, emotions, feeding/satiety, thirst, body temperature, etc.
Hormones related to these functions
“Releasing hormones”
Axonal transport to posterior lobe

15. Hypotalamus
Hypothalamus and pituitary gland secrete hormones and regulate other endocrine organs. They are the main regulatory organs of the endocrine system.

16. Hypothalamus
Located below the thalamus and above the pituitary gland (=epiphysis)
Regulates the pituitary gland secretions through two different mechanisms

17. Hypothalamus - neurohypophysis
1- Neurons, receiving information from receptors, fire APs which travel down to the post pituitary gland and stimulate the release of stored neurohormones – Oxytocin (OT) and anti-diuretic hormone (ADH)

18. Pituitary Gland Releasing and inhibiting hormones Anterior pituitary:
Growth (GH)~bones √gigantism/dwarfism √acromegaly
Prolactin (PRL)~mammary glands; milk production
Follicle-stimulating (FSH) &
Luteinizing (LH)~ovaries/testes
Thyroid-stimulating (TSH)~ thyroid
Adrenocorticotropic (ACTH)~ adrenal cortex
Melanocyte-stimulating (MSH)
Endorphins~natural ‘opiates’; brain pain receptors

19. Hormones of the Anterior Pituitary

20. Hypothalamus & Pituitary Gland

21. Posterior Region of the Pituitary Gland
The posterior pituitary:
Oxytocin~ uterine and mammary gland cell contraction
Antidiuretic (ADH)~ retention of water by kidneys

23. The Pineal, Thyroid, & Parathyroid
Melatonin~ pineal gland; biological rhythms
Thyroid hormones: Calcitonin~ lowers blood calcium Thyroxine~ metabolic processes
Parathyroid (PTH)~ raises blood calcium

24. The thyroid gland - Chp 21 p 623-625
Located in the neck, just below the larynx
Secrete 2 types of hormone:
- thyroid hormones  stimulate cell metabolism, triiodothyronine (T3) and thyroxine (T4) – iodine is needed to synthesize these hormones
- calcitonin  decrease blood calcium
Figure 6.8a

25. Thyroid hormones T3 and T4 secreted by the follicular cells
Stored as colloid
Parafollicular cells (C cells) secrete calcitonin (Chp 19)

26. Thyroid Hormones T3 and T4
Target organs: all cells
Role: Increase cell metabolism, oxygen consumption
Permissive role for some other hormones (growth hormone)

27. Thyroid hormone regulation
Figure 6.7

28. Goiter Both hypo and hyperthyroidism can have goiter as a symptom
Goiter is a swelling of the neck due to hypertrophy of the thyroid gland
How can one explain that?

29. Goiter in hypothyroidism
Most often due to a lack of dietary iodine
The thyroid hormone is unable to synthesize a functional thyroid hormone (T3 and T4)
The person express symptoms of hypothyroidism
The nonfunctional T3/T4 cannot promote a negative feedback on TRH and TSH
 the hypotalamus and pituitary gland increase their secretions  the thyroid gland is stimulated to secrete more T3 and T4 …
In children, the lack of functional T3/T4 result in cretinism, a form a mental retardation

30. Goiter in hyperthyroidism
The cells secreting TRH or TSH on the hypothalamus and pituitary gland (respectively) have become abnormal and no longer are sensitive to the negative feedback  they continue to secrete TRH or TSH  continuous stimulation of the thyroid gland with excess thyroid hormones being formed
 symptoms of hyperthyroidism

31. Parathyroid glands
Four nodules located in the back of the thyroid gland
Secreted parathyroid hormone or parathormone or PTH
Action of PTH opposes action of calcitonin
Both hormones play a role in calcium metabolism

32. Roles of calcium Most calcium ions are stored in the bones
Calcium is an important cofactor for enzymatic activity, plays a role in blood coagulation and action potentials.
Calcitonin and PTH participate in calcium regulation
Vitamin D helps PTH activity

33. Calcium regulation: Calcitonin promotes blood calcium decrease, by:
1. calcium deposition on bone
2. calcium dumping by the kidney
PTH promotes blood calcium increase by:
1. bone resorption
2. calcium reabsorption by kidney
3. increase calcium absorption by intestine

34. Figure 23-20: Calcium balance in the body
Calcium Metabolism:
Figure 23-20: Calcium balance in the body

35. Figure 19.20

36. The Pancreas Islets of Langerhans
Alpha cells: •glucagon~ raises blood glucose levels
Beta cells: •insulin~ lowers blood glucose levels
Type I diabetes mellitus (insulin-dependent; autoimmune disorder)
Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness in insulin targets)

37. The pancreas Located in the left upper abdominal cavity
Exocrine and endocrine glands
The endocrine function is due to the cells of the islets of the Langerhans
-- α cells  glucagon
-- β  insulin
-- δ  somatostatin

38. Glucose regulation Glucose level controlled by insulin and glucagon
Insulin promotes a decrease in blood glucose
Glucagon promotes an increase in blood glucose

39. Glucose regulation

40. Fate of glucose
Figure 3.21

41. Diabetes mellitus
Type I: autoimmune disease  beta cells of the islets of Langerhans are destroyed by antibodies
Type II: The cells become insulin-resistant  glucose does not enter the cells as readily

42. The Adrenal Glands
Adrenal medulla (catecholamines): •epinephrine & norepinephrine~ increase basal metabolic rate (blood glucose and pressure)
Adrenal cortex (corticosteroids): •glucocorticoids (cortisol)~ raise blood glucose •mineralocorticoids (aldosterone)~ reabsorption of Na+ and K+

44. The Gonads Steroid hormones: precursor is cholesterol
Androgens (testosterone)
sperm formation
male secondary sex characteristics; gonadotropin
Estrogens (estradiol)
uterine lining growth
female secondary sex characteristics
gonadotropin
Progestins (progesterone)

45. The Gonads Steroid hormones: precursor is cholesterol
androgens (testosterone)~ sperm formation; male secondary sex characteristics; gonadotropin
estrogens (estradiol)~uterine lining growth; female secondary sex characteristics; gonadotropin
progestins (progesterone)~uterine lining growth

46. Revision: Major endocrine conditions
Endocrine Gland
Hormones
Endocrine Disorders
Hyper
Hypo
Anterior Pituitary
Growth Hormone
Gigantism, acromegaly
Dwarfism
Thyroid
Thyroxine (T4)
Triodothronine (T3)
Thyrotoxicosis
Goitre
Exopthalmos
Hypothroidism
Cretinism
Myxoedema
Parathyroid
Parathormone
Osteoporosis
Kidney stones
Tetany
Adrenal Cortex
Glucacorticoids
Cushings syndrome
Addisons disease
Adrenal Medulla
Epinephrine Norepinephrine
Increased metabolism
Hypertension
Pancreatic Islets
Insulin
Diabetes mellitus

47. Pituitary Dwarfism

48. Hyper secretion of Growth hormone: Gigantism