ENDOCRINE BASIC HORMONES

1. ENDOCRINE SYSTEM
DR.NILESH KATE.
M.D.
ASSOCIATE PROFESSOR,
DEPARTMENT OF PHYSIOLOGY,

2. OBJECTIVES
 Hormone : definition, classification.
 Hormones general consideration.
 Hormone receptors & mechanism of
action.
 Measurement of hormones.

3. HOMEOSTASIS & CONTROLS
 Successful
compensation
 Homeostasis
reestablished
 Failure to
compensate
 Pathophysiology
○ Illness
○ Death
Figure 1-5: Homeostasis

4. COMPARISON OF ENDOCRINE AND
NERVOUS SYSTEMS.
 NERVOUS SYSTEM
 “WIRED”
 CHEMICAL SIGNAL AT
TARGET CELL
 RAPID
 BRIEF DURATION
 CLOSE ANATOMICAL
PROXIMITY
 ENDOCRINE SYSTEM
 “WIRELESS”
 CHEMICAL SIGNAL IN
BLOOD.
 SLOW
 LONG DURATION
 SPECIFIC RECEPTORS

5. ENDOCRINE SYSTEM
 Hormaein-- Greek word means “to execute
or to arouse”.
Def:- Secretary product of ductless glands
which are released in catalytic amounts into
blood stream & transported to specific target
cells where they elicit physiologic,
morphologic & biochemical responses.

6. LOCATION OF DIFFERENT
ENDOCRINE GLANDS.

7. Long Distance Communication:
Endocrine Hormones
 Signal Chemicals
 Made in endocrine
cells
 Transported via
blood
 Receptors on target
cells
Figure 6-2a: Long distance cell-to-cell communication

8. TYPES OF HORMONES
 Functional
 ENDOCRINE HORMONES – Travel through the
blood to act at a site distant from the secreting cell
or gland
 PARACRINE HORMONES – Act on cells near the
secreting cell
 AUTOCRINE HORMONES – Act on the secreting
cell
 NEUROCRINE HORMONES – Secreted by neural
cells
○ neurotransmitters
○ neurohormones

9. Figure 6-2b, c: Long distance cell-to-cell communication

10. Paracrine and Autocrine
Hormones
 Local communication
 Signal chemicals
diffuse to target
 Example: Cytokines
 Autocrine–receptor on
same cell
 Paracrine–neighboring
cells
Figure 6-1c: Direct and local cell-to-cell communication

11. CHEMICAL CLASSIFICATION OF
HORMONES
Depending upon chemical nature
 Amines or amino acid derivatives:
 Proteins & Polypeptides:
 Steroid hormones
Depending upon mechanism of action.
 Group I hormones.
 Group II hormones. : A,B,C,D.

12. HORMONE : GENERAL
CONSIDERATION.
 Hormones chemistry, synthesis, storage &
release.
1 Amines / amino acid derivatives
2 Protein & polypeptide hormones.
3 Steroid hormones.

13. HORMONE TRANSPOT, PLASMA CONC,
HALF LIFE.
 Hormone transport.
 Unbound.
 Bound .
 Plasma concentrations.
 Peptide hormone 10 -12 mol/ L to 10-14 mol/L
 Epi / Nor Epi = 2× 10-10 to 13 × 10 -10
 Steroid & thyroid 10-9 mol/ L & 10-6 mol/ L.
 Half life.
 Peptide hormone – short
 Steroid, & thyroid – long.

14. FUNCTIONS OF HORMONES.
 Regulation of biochemical reactions
 Regulation of bodily process.

15. HORMONE DISPOSAL.
 Target cell uptake & intracellular degradation.
 Metabolic degradation / inactivation.
 Urinary / biliary secretions.
 Metabolic clearance rate (MCR):-
volume of plasma cleared per unit time.

16. REGULATION OF HORMONE
SECRETION.
 Feedback control
 Neural control.
 Chronotropic control

17. FEEDBACK SYSTEM.
Figure 6-26: Negative and positive feedback

18. Figure 7-14: Negative
feedback loops in the
hypothalamicanterior
pituitary pathway
NEGATIVE FEEDBACK REFLEXES : LONG , SHORT &
ULTRASHORT LOOP.

19. HORMONES RECEPTORS.
 Characteristics
 Specificity .
 Location .
○Internal
○External .
 Regulation of number.
○Down regulation
○Up regulation .

20. STRUCTURE OF RECEPTORS.
 Recognition domain.
 Coupling domain.

21. CLASSIFICATION OF RECEPTORS.
 Receptor kinase
 Receptor linked kinase.
 G-protein coupled receptors.
 Ligand gated ion channels.

22. MECHANISM OF ACTION OF
HORMONES.
 Through change in membrane
permeability.
 Through effect on gene expression.
 Through second messengers.
 Through tyrosine kinase activation.

23. THROUGH CHANGE IN MEMBRANE
PERMEABILITY.
 Hormones bind with external receptors.
Conformational change in protein of
receptors.
Opening of Na, K, Ca channel.
Movement of ions.

24. THROUGH EFFECT ON GENE
EXPRESSION.
Figure 7-7: Steroid hormone action

25. THROUGH SECOND
MESSENGERS SYSTEM.
 Adenyl cyclase- cAMP system.
 Guanyl cyclase –cGMP system.
 Membrane phosplipase- phoapholipid
system.
 Calcium- calmodulin system.

26. ADENYLATE CYCLASE-CAMP (Sutherland
1961)

27. PHOSPHOLIPASE-C-CA2+ (CONTINUED)

28. CA2+- calmodulin system (CONTINUED)

29. THROUGH TYROSINE KINASE ACTIVATION.

30. MEASUREMENT OF
HORMONES.
 BIOASSAY.
 Injecting unknown sample of
plasma in experimental
animals & observing specific
biological effect.
 IMMUNOASSAY.(AG-AB
REACTION)
 RADIOIMMUNOASSAY
○ Mix
Unknown sample of plasma
containing hormone + purified
specific antibody + purified
hormone tagged with
radioactive isotopes.
 ELISA
○ Instead of specific antibody,
stained with suitable dye. &
intensity of colour measured by
spectrophotometer.

31. MEASUREMENT OF HORMONES.
 CYTOCHEMICAL ASSAY.
 Endocrine gland cut in
slices
 Incubate in ascorbate
enriched culture
medium
 Genesis of hormone
detected.
 DYNAMIC TESTS.
 Suppression type.
 Stimulation type.

32. ENDOCRINE REFLEX PATHWAYS:
OVERVIEW
Figure 7-9: Hormones may have multiple stimuli for their release

33. PATHOLOGIES: OVER OR UNDER
PRODUCTION
Figure 7-19: Negative feedback by exogenous cortisol

34. PATHOLOGIES: DUE TO RECEPTORS
Figure 7-20: Primary and secondary hypersecretion of cortisol

35. Thank you