1. ENDOCRINE SYSTEM
Chapter 16

2. ENDOCRINE GLANDS
Ductless glands that produce hormones that are released directly into the bloodstream and are transported throughout the body to regulate the metabolic function of other cells in the body.
Types of hormones:
Paracrine
Autocrine

3. Chemical Nature of Hormones
Amino-acid based hormones
Amines=simple hormones derived from tyrosine (example: Epinephrine)
Protein and peptides=chains of amino acids hooked together (example: ADH or Oxytocin)
Steroid-based hormones
Progesterone
Testosterone
Eicosanoids
Hormone-like substances that act only on cells in the immediate vicinity (example: prostaglandin)

4. Functions of Hormones
Integrative
Homeostatic
Growth

5. Mechanisms of Hormone Action
Lipid-soluble hormones
Diffusion occurs
Binds to intracellular receptors
Forms hormone-receptor complexes
Hormone-receptor complex binds to specific receptor proteins on DNA
Initiates transcription of certain genes

6. Mechanisms of Hormone Action
Cyclic AMP signaling
Hormone binds to cell membrane receptor
Hormone-receptor complex binds to inactive G protein
G protein becomes active by GTP to GDP
G protein binds adenylate cyclase producing Cyclic AMP
Cyclic AMP activates protein kinase enzymes

7. Mechanisms of Hormone Action
PIP-calcium signaling
Hormone binds to cell membrane receptor
Hormone-receptor complex binds to inactive G protein
G protein becomes active and binds to phospholipase
Phospholipase splits to form IP3 and DAG which activate protein kinases and calcium

8. Control of Hormones Feedback Mechanisms Responsiveness to target cells
Negative feedback
Positive feedback
Responsiveness to target cells
Concentrations of hormones
Number of receptors
Interaction of other hormones

9. Control of Hormones

10. Major Endocrine Glands
Pituitary Gland
Thyroid Gland
Parathyroid Gland
Adrenal Gland
Thymus Gland
Pineal Gland
Other endocrine tissue

11. Pituitary Gland (Hypophysis)
Posterior lobe
Oxytocin
ADH
Anterior lobe GH
TSH
ACTH
FSH LH
PRL
MSH

12. Thyroid Gland Follicles and follicle cells Thyroglobulin Colloid
Thyroxine (T4)
Triiodothyronine (T3)
Calorigenic effect
Calcitonin produced by parafollicular cells

13. Parathyroid Gland Produces parathyroid hormone (PTH)
Regulates calcium levels by targeting:
Bones
Intestine
Kidneys

14. Adrenal Gland Adrenal Cortex
Zona glomerulosa produces mineralcorticoids
Zona fasciculate produces glucocorticoids
Zona reticularis produces androgens or adrenal sex hormones

15. Adrenal Gland (continued)
Adrenal Medulla
Chromaffin cells
Epinephrine
Norepinephrine
Associated with stress or “Fight or Flight” responses

16. Thymus and Pineal Gland
Thymus Gland
Thymosin stimulates T-cell maturation
Immune system
Pineal Gland
Pinealocytes
Melatonin

17. Pancreas Alpha Cells Beta Cells Delta Cells Acinar Cells
Produce glucagon
Glycogen>>Glugacon>>Glucose
Beta Cells
Produce insulin
Enhances uptake of glucose by cells as well as inhibits glycogenolysis and gluconeogenesis
Delta Cells
Somatostatin
Acinar Cells
Produces pancreatic enzymes but are exocrine

18. Pancreas (continued)

19. Other Endocrine Tissues
Ovaries=produce estrogen and progesterone
Testes=produce testosterone and inhibin
Placenta=produces HCG
Heart=secretes ANP
Kidneys=secrete erythropoietin
Skin=produces choleocalciferol
Adipose tissue=releases leptin
Gastrointestinal tract=releases gastrin, secretin, serotonin, cholecystokinin and others

20. Homeostatic Imbalances
Gigantism
Acromegaly
Progeria
Pituitary dwarfism
Galactorrhea
Gynecomastia
Myxedema
Goiter
Cretinism
Grave’s disease
Hyperparathyroidism
Hypoparathyroidism
Diabetes insipidus
Diabetes mellitus
Aldosteronism
Addison’s disease
Cushing’s disease
Masculinization

21. Thyroid Gland (continued)

22. Thyroid Gland (continued)

23. Cushing’s Disease

24. Cushing’ Disease

25. Acromegaly

26. Gigantism and Pituitary Dwarfism

27. Addison’s Disease