1. GOOD AFTERNOON

2. Getting Introduced To Endocrine Physiology Neelambikai.N

3. General Principles of Endocrinology

4. Cell-to-cell signaling
Local mol.
Local mol..
Neurohormone
Cell-to-cell signaling

5. Nervous Vs endocrine systems
Control
Of secretion
Nervous system ??
Typical nerve
cell
Neuro-endocrine
cell
Typical endocrine
cell
axon
Blood
hormone
neurotransmitter
Target
tissue
To target tissues
Which tissues?

6. First Chemical Messengers
Neurotransmitter
Neurohormone
Hormone
Released:
On target tissues
In blood
Carry:
To all tissues
Affect only tissues which………..!

7. The two major regulatory systems
Nervous system
Endocrine system
What are the characteristics
Of responses?
What are the characteristics
Of responses?
Rapid and precise
Prolonged
Give examples
Give examples

8. Solely endocrine function
Mixed function
Complete function uncertain
Pineal
Hypothalamus
Pituitary
Parathyroid
Thyroid
Thymus
Testes
in male
Heart
Stomach
Adrenal gland
Pancreas
Duodenum
Kidney
Skin
Ovaries in female
Placenta in
pregnant female

9. Overall functions of the endocrine system
Regulate metabolism
Regulate water& electrolyte
balance
Homeostasis
Adaptive changes
To cope with stress
Regulate growth
Control reproduction
Regulate RBCs production
Regulate CVS and GIT functions

10. Targets other endocrine
Hormones
Tropic
Non-tropic
Targets other endocrine
Glands
Targets other
tissues

11. Tropic hormones _ _ deficiency of tropic hormone Endocrine gland
Anterior
pituitary
gland _ _
Thyroid stimulating
hormone
Tropic
hormone
Endocrine
gland
Thyroid
gland
hormone
Thyroid hormone
deficiency of tropic hormone
1- secretion from target gland decreases
2- target gland atrophy

12. Endocrine
gland
Hormone
Binding
with
receptor
(Target cell)
Binding of hormone with receptor triggers
one of the following intracellular events:
Acting on pre-existing proteins
(channel, enzyme..etc) or
2. Activates specific genes to cause
formation of new proteins
Physiologic
response

13. H R HR + # of HR in target cell depends on:
Hormone receptor interaction
hormone
receptor
Hormone receptor complex H R HR +
Final effect of hormone depends on: # of HR in target cell
# of HR in target cell depends on:
{H} free in blood
# of receptors in target cell
affinity of receptors to H

14. General properties of endocrine function
Single gland
Single hormone
Single cell
May affect
>one type
of cell
May be secreted
By > one gland
May be affected
By > one hormone
May produce
> One hormone
Anterior pituitary gland
ADH
Somatostatin
hepatocyte

15. Patterns of hormone secretion
Cyclical
Non-cyclical
(steady)
Temporal coordination
Of function
Thyroid hormone
Menstrual cycle

16. Peptides Amines Steroids Chemical structures of hormone catecholamines
Thyroid hormone
Water soluble
(hydrophylic)
Fat soluble
(lipophylic)
Dissolve in plasma
Bind to plasma proteins
Receptors on cell membranes
Why?
Receptors inside cells

17. Hdrophylic hormone
lipophylic hormone
free hormone
receptor
Second messenger
Gene

18. Typical synthesis/secretion of peptide hormones
signal
Large molecule
Rapid response

19. Biosynthesis of steroid hormones
In ester form
Synthesized by cell
Derived from food
Rate of secretion totally controlled by rate of synthesis
(Delayed onset)
Once synthesizedReleased immediately from the cell by diffusion
Transported in blood bound to plasma proteins
Biosynthesis of steroid hormones

20. 17 11 15 14 9 1 10 5 3 7

21. Transport of hormones in blood
Hhydrophilic hormones
lipophylic hormones
Bound to plasma proteins
Dissolved in plasma

22. Dynamic equilibrium Protein bound hormone Free Hormone (active) Gland
Factors affecting
concentration
of free hormone
Dynamic
equilibrium
Protein bound
hormone
Free
Hormone
(active)
Target tissue
Activation
Degradation in
Liver etc …
(inactivation)
Excretion
(urine)
Question: what will happen if the concentration of the binding increases?

23. second messengers!

28. The cell membrane phospholipid second messenger system by which some hormones exert their control of cell function

30. Epinephrine can act through two second –messenger systems

31. The mechanism of action of a steroid hormones on the target cells

32. Receptors for Steroid hormones

33. Mechanism of action of thyroid hormones on the target cells

34. Receptor for insulin

35. Enzyme-linked receptor-the leptin receptor

36. Mechanisms of interaction of lipophilic hormones

37. Receptors & Down stream effectors of Peptide hormones

38. Possible fates and actions of a hormone following its secretion by an endocrine cell. Not all paths apply to all hormones

39. General regulation of hormone secretion
Cortisol as an example
Regulation of hormone secretion
Maintain basal
levels of hormones
Negative feedback
Diurnal or
circadian rhythm
Neuroendocrine reflexes
Response to stress

40. Negative feedback Anterior pituitary Thyroid-stimulating hormone
Thyroid hormone
Thyroid gland

41. Circadian rhythm
N = noon
M = midnight
Light
Dark

42. Endocrine disorders
Hormone excess
Hormone deficiency

43. Response of a target cell to a hormone may be varied by:
The hormone it self
1- down regulation
2- up regulation or
Other hormones
1- permissiveness
2- synergism
3- antagonism

44. Permissiveness Basic mechanism Example Epinephrine Hormone 1 Thyroid
Makes cell responsive to
Hormone 1
Target cell
Target cell
Epinephrine/cortisol
Is another example

45. (uterine smooth muscle)
Antagonism
Basic mechanism
Example
estrogen
Hormone 1
Makes cell less
responsive to Hormone 1
progesterone
Hormone 2
Target cell
Target cell
(uterine smooth muscle)

46. Synergism testosterone Follicle stimulating hormone Hormone 1
Target cell
Spermatogenesis
Precursor cells
Combined action > sum of actions
Combined action > sum of actions

47. Basic principles of the enzyme-linked immunosorbent assay (ELISA) for measuring the concnetration of a hormones

48. Principles of Radioimmunoassay

49. THANK YOU