2. ENDOCRINOLOGY INTRODUCTION PITUITARY & HYPOTHALAMUS
DR SYED SHAHID HABIB
MBBS FCPS DSDM

4. INTRODUCTION PITUITARY & HYPOTHALAMUS

5. Endocrinology is the study of hormones, their receptors and the intracellular signalling pathways they invoke

6. Hormone
A chemical substance that is secreted into the internal body fluids by one or a group of cells and exerts a physiological control effect on other cells of the body.
Local hormones: they have specific local effects.
examples of local hormones: secretin, CCK.
General hormones: they are secreted by specific endocrine glands.
they are secreted in the blood and cause physiological actions in distant tissues.
few of general hormones affect all cells of body. ex: growth hormone and thyroid hormone.

7. Two systems control all physiologic processes:
THE NERVOUS SYSTEM exerts point-to-point control through nerves, similar to sending messages by conventional telephone. Nervous control is electrical in nature and fast.
THE ENDOCRINE SYSTEM broadcasts its hormonal messages to essentially all cells by secretion into blood and extracellular fluid. Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond.

8. CONTROL SYSTEMS
DURATION
SPEED

9. OVERVIEW OF ENDOCRINE GLANDS

12. CLASSIFICATION Chemical Structure Solubility Mechanism Of Action
Peptides and proteins
Amino acid derivatives
Steroids
Solubility
Water Soluble
Lipid Soluble
Mechanism Of Action

13. Large inactive protein molecules Endoplasmic Reticulum
SYNTHESIS OF PEPTIDES
Ribosomes on Rough ER
Prepro Hormones
Large inactive protein molecules
Cleaved in
Endoplasmic Reticulum
Pro Hormones
Packed in Golgi App to
Secretory Vesicles
Active Hormones
Inactive Fragments
Exocytosis
Active Hormones

15. MECHANISM OF ACTION RECEPTORS INTRACELLULAR SIGNALLING CELL MEMBRANE
CYTOPLASM
NUCLEUS
INTRACELLULAR SIGNALLING
CHANGE IN MEMBRANE PERMEABILITY
ACTIVATION OF INTRACELLULAR ENZYMES
ACTIVATION OF GENES TO PRODUCE NEW PROTEINS

17. R ENDOCRINE GLAND TARGET CELL Changes channel permeability
HORMONE R
Changes channel permeability
Activates Enzymes (Adenyl Cyclase and PLC)
Activation of genes
TARGET CELL
PHYSIOLOGIC EFFECTS

18. Inactive c AMP dependant Protein + ATP ADP + Protein PO4H
ECF R
Adenyl
Cyclase
Gs Protein
ICF
Cell’s
Response
ATP
c AMP
Inactive c AMP dependant
Protein Kinase
Active c AMP dependant
Protein Kinase
Protein + ATP ADP + Protein PO4

19. H R ECF ICF ER Ca++ Phospholipase C G Protein PIP2 DAG + IP3
Active
Protein Kinase C
Inactive
Protein Kinase C ER
Ca++
Protein PO Protein
Cell’s Response
Cell’s Response

20. Binding to Enhancer like
Activation of genes
Binding to Enhancer like
Segment in DNA
DNA
Transformation of
Receptor to expose
DNA binding Domain
Pre mRNA
mRNA R
mRNA
Response
Protein

21. Pituitary & Hypothalamus

24. Hormones of the Hypothalamus
Thyrotropin-releasing hormone (TRH)
Gonadotropin-releasing hormone (GnRH)
Growth hormone-releasing hormone (GHRH)
Somatostatin (GIH)
Corticotropin-releasing hormone (CRH)
Prolactin Inhibiting Hormone (PIH) Dopamine
Prolactin Releasing Hormone (PRH)
Antidiuretic hormone (ADH)
Oxytocin

25. THE ANTERIOR LOBE Thyroid Stimulating Hormone (TSH) Gonadotropins
Follicle Stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Growth Hormone (GH)
Adrenocorticotropic Hormone (ACTH)
Prolactin (PRL)
Alpha Melanocyte-Stimulating Hormone

26. Hormones of the Hypothalamus
TRH
GnRH
GHRH
GIH
CRH
PIH
PRH
ADH
Oxytocin
TSH
Gonadotropins FSH & LH GH
ACTH
PRL

27. THE POSTERIOR LOBE Antidiuretic Hormone (ADH) Oxytocin no known effect
PARS INTERMEDIA
α β γ-MSH , γ LPH
no known effect

28. Ushu

29. HORMONES-SECRETING CELLS OF THE HUMAN ANTERIOR PITUITARY GLAND
Cell Type
Hormones Secreted
% of Total
Stain Affinity
Diameter of Secretary Granules
Somatotrope
Growth hormone 50
Acidophlic
Lactotrope
Prolactin
(10-30)
200
Corticotrope
ACTH 10
Basophilic
Thyrotrope
TSH 5
Gonadotrope
FSH, LH 20
Chromophobes
These are cells that have minimal or no hormonal content. may be acidophils or basophils that have degranulated
may be stem cells that have not yet differentiated into hormone-producing cells.

30. OXYTOCIN Source Hypothalamus(Primarily Paraventricular Nucleus
Released from Posterior Pituitary (Gonads, Adrenal Cortex, Thymus)
Chemistry Peptide 9 aa
Half Life 6-20 min
Daily Output
Basal Levels 1-10 pg/ml
Transport Neurophysins
Pattern of Secretion Synchronous high frequency
discharge

31. Physiologic Effects
Stimulation of uterine smooth muscle contraction at birth
Stimulation of milk ejection (milk letdown)
Establishment of maternal behavior
Facilitate Sperm transport in Female Genital Tract
Increased Contraction of Vas Deferens (Ejaculation)
Curb salt appetite
Physicians and veterinarians sometimes
administer oxytocin ("pitocin")
to further stimulate uterine contractions

33. ADH (AVP) Source Hypothalamus Posterior Pituitary
(Primarily SupraOptic Nucleus)
(Gonads, Adrenal Cortex)
Chemistry Peptide 9 aa
Half Life 2-3 minutes
Basal Levels 1pg/ml
Transport Neurophysins
Pattern of Secretion
Initial steady increase in discharge
Prolonged Phasic Bursting

34. Physiologic Effects Water retention in excess of solutes
Blood Pressure homeostasis (Vasoconstriction)
Glycogenolysis in Liver
Neurotransmitter in brain & spinal cord
Lowers body temperature
Facilitate memory Consolidation & Retrieval

35. ADH High Osmolality Low ECF Volume Low Pressure Osmoreceptors
Pain
Nausea
Vomiting
Surgical
Stress
Emotions
Standing