1. Hormonal Regulation
Reference: Pathophysiology by Kathryn
McCance
Mindy Milton, MPA, PA-C
July 29, 2010
1
Mosby items and derived items © 2006 by Mosby, Inc.

2. Hormones
 General characteristics
 Specific rates and rhythms of secretion
 Diurnal, pulsatile and cyclic, and patterns depending
on circulating substances
 Operate within feedback systems
 Most common negative feedback
 Affect only cells with appropriate receptors
 Endocrine communication
 The liver inactivates hormones, rendering the
hormones more water soluble for renal excretion
2
Mosby items and derived items © 2006 by Mosby, Inc.

3. The Endocrine System
 Hypothalamus
 Pituitary
 Adenohypophysis
 Neurohypophysis
 Thyroid
 Parathyroid
 Adrenals
 Pancreas
 Ovaries
 Testes
3
Mosby items and derived items © 2006 by Mosby, Inc.

4. Regulation of Hormone Release
 Hormones are released:
 In response to an alteration in the cellular
environment
 To maintain a regulated level of certain
substances or other hormones
 Hormones are regulated by chemical,
hormonal, or neural factors
 Negative feedback
4
Mosby items and derived items © 2006 by Mosby, Inc.

5. Feedback
5
Mosby items and derived items © 2006 by Mosby, Inc.

6. Hormone Transport
 Hormones are released into the circulatory
system by endocrine glands
 Water-soluble hormones circulate in free,
unbound forms
 short half life
 Peptides, glucoproteins, polypeptides
 Insulin
 PTH
 Pituitary hormones
 Hypothalamic hormones
 Lipid soluble hormones are primarily circulating
bound to a carrier
 Circulate on protein carrier – longer half life
 Steroid hormones
6
Mosby items and derived items © 2006 by Mosby, Inc.

7. Cellular Mechanism of Hormone
Action
 Target cell
 Up-regulation
 Down-regulation
 Hormone effects
 Direct effects
 Permissive effects
7
Mosby items and derived items © 2006 by Mosby, Inc.

8. Cellular Mechanism of Hormone
Action
 Hormone receptors
 Located in or on the plasma membrane or in the
intracellular compartment of the target cell
 Water-soluble hormones
 High molecular weight
 Cannot diffuse across the plasma membrane
 Lipid-soluble hormones
 Easily diffuse across the plasma membrane and
bind to cytosolic or nuclear receptors
8
Mosby items and derived items © 2006 by Mosby, Inc.

9. Cellular Mechanism of Hormone
Action
 Water-soluble hormones
 First messenger
 Signal transduction
 Second-messenger molecules
 Calcium
 Cyclic adenosine monophosphate (cAMP)
 Cyclic guanosine monophosphate (cGMP)
9
Mosby items and derived items © 2006 by Mosby, Inc.

10. Cellular Mechanism of Hormone
Action
10
Mosby items and derived items © 2006 by Mosby, Inc.

11. Cellular Mechanism of Hormone
Action
 Lipid-soluble hormones
 Steroid hormones
 Androgens, estrogens, progestins, glucocorticoids,
mineralocorticoids, and thyroid hormones
 Diffuse across the plasma membrane
 Bind to cytoplasmic or nuclear receptors
 Activate
 RNA polymerase
 DNA transcription and translation
11
Mosby items and derived items © 2006 by Mosby, Inc.

12. Lipid-Soluble Hormones
12
Mosby items and derived items © 2006 by Mosby, Inc.

13. Structure and Function of the
Endocrine Glands
 Hypothalamic-pituitary axis
 Hypothalamus
 Secretes regulatory hormones
 Releasing and inhibiting
 Autonomic center neural control
 Endocrine organ
 Pituitary gland
 Anterior pituitary (adenohypophysis)
 Posterior pituitary (neurohypophysis) neuro-
attachments to adrenal medulla. Has trophic hormones
too.
13
Mosby items and derived items © 2006 by Mosby, Inc.

14. The Pituitary Gland
14
Mosby items and derived items © 2006 by Mosby, Inc.

15. Posterior Pituitary Hormones
 Synthesized with their
binding proteins in the
supraoptic and
paraventricular nuclei of
the hypothalamus
 Secreted by the posterior
pituitary
 Antidiuretic hormone
(ADH)
 Controls plasma osmolality
 Oxytocin
 Uterine contractions and
milk ejection in lactating
women
15
Mosby items and derived items © 2006 by Mosby, Inc.

16. Anterior Pituitary Hormones
 Adrenocorticotropic hormone (ACTH)
 Melanocyte-stimulating hormone (MSH)
 Growth hormone (GH)<-- GHRH
 Prolactin (has “releasing” and
“inhibiting”(Dopamine).
 Thyroid-stimulating hormone (TSH)
 Luteinizing hormone (LH) <-- GRH
 Follicle-stimulating hormone (FSH)<-- GRH
16
Mosby items and derived items © 2006 by Mosby, Inc.

17. Anterior Pituitary Hormones
17
Mosby items and derived items © 2006 by Mosby, Inc.

18. Thyroid and Parathyroid Glands
 Thyroid gland
 Two lobes lateral to the trachea
 Isthmus
 Follicles (follicle cells surrounding colloid)
 Parafollicular cells (C cells)
 Secrete calcitonin
 Stimulus is high serum ionized calcium
 Regulation of thyroid hormone secretion
 Thyrotropin-releasing hormone and thyroid stimulating hormone
18
Mosby items and derived items © 2006 by Mosby, Inc.

19. Thyroid and Parathyroid Glands
 Thyroid hormones
 90% T4 and 10% T3
 T4 converted to T3 in the liver, kidneys, and peripheral tissues
 T3 has greatest metabolic effects
 Bound to thyroxine-binding globulin, thyroxine-
binding prealbumin, or albumin
 Affect growth and maturation of tissues, cell
metabolism, heat production, and oxygen
consumption
19
Mosby items and derived items © 2006 by Mosby, Inc.

20. Thyroid and Parathyroid Glands
20
Mosby items and derived items © 2006 by Mosby, Inc.

21. Thyroid and Parathyroid Glands
 Parathyroid glands
 Small glands located behind the upper and lower
poles of the thyroid gland
 Produce parathyroid hormone
 Regulator of serum calcium
 Stimulus is low serum ionized calcium level
 Antagonist of calcitonin
21
Mosby items and derived items © 2006 by Mosby, Inc.

22. Endocrine Pancreas
 The pancreas is both an endocrine and an exocrine
gland
 Islets of Langerhans
 Secretion of glucagon and insulin
 Cells
 Alpha—glucagon
 Beta—insulin
 Delta—somatostatin and gastrin
 F cells—pancreatic polypeptide
 ANS innervation
 PNS +
 SNS –
22
Mosby items and derived items © 2006 by Mosby, Inc.

23. Endocrine Pancreas
23
Mosby items and derived items © 2006 by Mosby, Inc.

24. Endocrine Pancreas
 Insulin
 Synthesized from proinsulin
 Secretion is promoted by increased blood glucose
levels
 Facilitates the rate of glucose uptake into the cells
of the body
 Anabolic hormone
 Synthesis of proteins, lipids, and nucleic acids
24
Mosby items and derived items © 2006 by Mosby, Inc.

25. Endocrine Pancreas
 Glucagon
 Secretion is promoted by decreased blood glucose
levels
 Stimulates glycogenolysis, gluconeogenesis, and
lipolysis
 Somatostatin
 Possible involvement in regulating alpha and beta
cell secretions
25
Mosby items and derived items © 2006 by Mosby, Inc.

26. Endocrine Pancreas
26
Mosby items and derived items © 2006 by Mosby, Inc.

27. Adrenal Glands
 Adrenal cortex
 80% of an adrenal
gland’s total weight
 Zona glomerulosa
 Zona fasciculata
 Zona reticularis
 Adrenal medulla
 20% of total weight
 Innervated by ANS
 Pre-ganglionic
cholinergic fibers
 SNS and PNS
27
Mosby items and derived items © 2006 by Mosby, Inc.

28. Adrenal Glands
 Adrenal cortex
 Stimulated by adrenocorticotropic hormone
(ACTH)
 Glucocorticoid hormones
 Direct effects on carbohydrate metabolism
 Anti-inflammatory and growth-suppressing effects
 Influence awareness and sleep habits
 Most potent naturally occurring glucocorticoid is
cortisol
28
Mosby items and derived items © 2006 by Mosby, Inc.

29. Adrenal Glands
 Adrenal cortex
 Mineralocorticoid hormones
 Affect ion transport by epithelial cells
 Increase the activity of the sodium pump of the epithelial
cells
 Cause sodium retention and potassium and hydrogen loss
 Most potent naturally occurring mineralocorticoid is
aldosterone
 Regulated by the renin-angiotensin system
29
Mosby items and derived items © 2006 by Mosby, Inc.

30. Aldosterone
30
Mosby items and derived items © 2006 by Mosby, Inc.

31. Adrenal Glands
 Adrenal cortex
 Adrenal estrogens and androgens
 Estrogen secretion by the adrenal cortex is minimal
 The adrenal cortex secretes weak androgens
 Androgens are converted by peripheral tissues to stronger
androgens such as testosterone
31
Mosby items and derived items © 2006 by Mosby, Inc.

32. Adrenal Glands
 Adrenal medulla
 Chromaffin cells (pheochromocytes)
 Chromaffin cells secrete the catecholamine
epinephrine (majority) and norepinephrine
 Release of catecholamine has been characterized
as a “fight or flight” response
 Catecholamines promote hyperglycemia
32
Mosby items and derived items © 2006 by Mosby, Inc.

33. Tests of Endocrine Function
 Radioimmunoassay
 Measures minute quantities of hormone in blood
 Enzyme-linked immunosorbent assay
(ELISA)
 Similar to RIA but less expensive
33
Mosby items and derived items © 2006 by Mosby, Inc.

34. Aging and the Endocrine System
 Thyroid gland
 Glandular atrophy, fibrosis, nodularity, and increased
inflammatory infiltrates
 TSH and TH secretion diminished
 Hypothyroidism
 Parathyroid glands
 Related to alterations in calcium balance
 Inadequate intake, malabsorption, or renal changes
 Adrenal glands
 Decreased clearance of cortisol
 Secondary to decline in liver and renal functions
34
Mosby items and derived items © 2006 by Mosby, Inc.

35. Hormones from other tissues
 Erythropoietin
 Released by kidney
 Stimulus is low oxygen levels
 Increases RBC production in bone marrow
 Renin
 Released by Kidney
 Stimulus is low volume, hypotension, low GFR
 Angiotensin II and Aldosterone – retains sodium, water, and
vasoconstriction increases blood pressure
 ANP
 Released by atrium
 Stimulus is increased wall stretch due to increased blood volume
 Promotes loss of Na+ and water
 Decreases release of Renin, aldosterone, ADH
 Suppresses thirst
 Thysosin
 Released by Thymus
 Maturation of lymphocytes
35
Mosby items and derived items © 2006 by Mosby, Inc.

36. The End
 Questions?
36
Mosby items and derived items © 2006 by Mosby, Inc.