KULIAH 1:

ENDOKRINOLOGI DASAR

Krishna W. Sucipto, dr, SpPDDivisi Endokrinologi & Metabolisme

Bag./SMF Penyakit Dalam FK Unsyiah/ RSUZA

Banda Aceh

KONSEP DASAR

Ilmu yang mempelajari tentang keadaan klinik yang disebabkan oleh karena gangguan

sekresi hormon pada sistim kelenjar endokrin

Content

• Function of hormones• Interaction• Chemical nature of hormones• Hormone synthesis,storage,and release• Transport• Feedback relationship• Biorhytme• Endocrine pathology• Assessment of endocrine function

Systems Of Extracellular Communication

NERVOUS SYSTEM

ENDOCRINESYSTEM

IMMUNE SYSTEM

Transmit electro- chemical signalstwo way traffic

between thebrain and peripheral tissues or

between tissues

Releases chemi-cal mediators into the circu-

lation for actionaway from theirsites of origin

Protect organism against externalAnd internal threats

No Clear distinction between the 3 systems

Duct

Blood Circulation

• PARACRINE HORMONES When hormones act on neighboring non-hormone-producing cells ( Sex Steroid on ovary, Angiotensin II in the Kidney, etc)– JUXTACRINE HORMONES

Variant from Paracrine Hormones, Peptide hormone can remain in the membrane of one cell and interact with a receptor on a juxtaposed cell (The action of some hemopoietic GF)

• AUTOCRINE HORMONES Hormone is released and acts on receptors located on the same cell. (hormones to unregulated growth of cancer cells)– INTRACRINE HORMONES When hormones act inside the cell without being released

(Insulin can inhibit its own release from pancreatic islet B cells)

HH

H

HH

R H

H

R H

R H

RH

R H

Intracrine Autocrine

Paracrine

Paracrine

Hormon Target Cell

Endocrine Cell

Juxtracrine

H

R

Hormon Target Cell

H

H

Juxtracrine

Up And Down Regulation

DOWN REGULATIONHormone Serum Level Receptor Number

UP REGULATIONHormone serum level Receptor Number

Sensitivity to Hormone(Hormone Resistance)

Sensitivity to Hormone

HORMONES

REPRODUCTION

MAINTENANCE OFINTERNAL ENVIRONMENT

ENERGY PRODUCTION,UTILIZATION & STORAGE

GROWTH & DEVELOPMENT

Function of Hormones

Reproduction

• All hormones are present in both sex• Sexual dimorphism result of differences in the

amounts of individual hormones and their pattern of secretion

• Sexual reproduction requires a precise genetic programming

• Hormones regulates gametogenesis• Control dimorphic anatomic, functional, and

behavioural development of males and females

Growth and Development

• Growth and limitation of growth involve interaction hormones of all classes (peptide, steroid, catecholamine, thyroid)

• Hormones influence growth in several ways (i.e thyroid induced the formation if IGF 1)

Maintenance (and adaptation) of Internal Environment

• Regulate the volume and electrolyte content of body fluid

• Blood pressure and heart• Acid base balance• Body temperature• Mass of bone, muscle, and fat

Energy Production, Utilization, and Storage

• Mediators of substrate flux and utilization of food (glucagon and insulin)

• Oxidation of fatty acid and ketones for maintaining a save level of plasma glucose level to protect CNS function

• Leptin regulates food intake• Thyroid regulates oxygen consumption (BMR)

Action of Hormones. A single hormone may act independently or in concert with other hormones

Hormone 1

Action 1

Action 2

Action 3

Hormone 2

Action 1

Action 2

Action 3

Multi HormonalProcess

Hormone 3

Action 1

Action 2

Action 3

One Hormone, Multiple Action

• Testosterone effects– Fusion of labioscrotal folds during embryogenesis– Induction of male differentiation of Wolfian duct– Regression of embryonic breast– Growth of the male urogenital tract– Control spermatogenesis– Growth of bread and body hair– Promotion of muscle growth etc.– Antiestrogen– Anabolic

One Function, Multiple Hormones

InsulinGlucagon,

Epinephrin, Cortisol,GH, Thyroxin, etc

Blood Glucose Homeostasis

Characteristic of Hormones

• Low concentration– Steroid and thyroid pmol – micromol – Peptides 1 pmol/L - 1µmol/L

• Directed to site of action– By specific mechanisms (receptors that recognize and bind

the hormone)– Delivered within restricted circulation– Direct diffusion – Local formation within a tissue from circulating

• Concept of target tissue

The Chemical Natures of Hormones

• Peptides (Amino acids)– Complex polypeptides

(LH,CG)– Intermediate-sized

peptides (insulin)– Small peptides (TRH)– Dipeptides (T3,T4)– Single amino acids

(actecholamine, serotonin, histamin)

• Steroids– Intact steroid nucleus

(adrenal & gonadal)– Broken steroid nucleus

(Vit. D & Metabolites)

Receptors

• Lypophilic Hormones – Hormon dengan molekul yang kecil– Masuk kedalam sel dengan difusi– Reseptor dalam inti (nuclear receptornuclear receptor)– Berikatan dan memodulasi gene tunggal– Yang termasuk: hormon derivat steroid, retinoic

acid, tiroid, vitamin D., Cholesterol dan asam lemak

Receptors

• Hydrophilic Hormon– Bersifat semipermeabel, tidak dapat menembus membran

sel– Mempunyai reseptor di membran sel (Membrane Membrane

ReceptorReceptor)– Ikatan hormon dan membran akan mensintesa mediator

intra sel ( 2nd messenger atau intracellular signal transducers)

– Yang termasuk: hormon derifat Peptida, Growth Factors dan Cytokines

Hormone Synthesis, Storage And Release

• Peptide hormones are synthesized as other protein• Steroid hormones and catecholamines are

synthesized from smaller precursor molecule• Synthesizes of some hormones can occur in diverse

tissue (i.e hCG in almost every tissue; estrogen can be formed from testosteron and androstenedione in ovary, brain, adipocytes, hair follicle)

• Thyroid hormone to be restricted to thyroid cells

Fundamental Characteristics Distinguish Endocrine From Nonendocrine Tissues

• Rates of synthesizes are greater in the endocrine organ

• There is an appropriate processing machinery to complete conversion of pro hormones to hormones

• Contain mechanisms for regulating the release of the hormone into the circulation (specialized vesicle)

Hormone Release

• The rate of hormone release is limited by the rate of its synthesizes

• Only limited quantities of hormones are stored within the body

• Exceptions to the generalization are T4 and 1,25-idydroxyvitamin D

Transport

• Water soluble hormones require no specific transport mechanism (transported in solution)

• Hormones inasoluble in water require carrier mechanisms (transport protein)

• Transport protein are two types: albumin an transthyretin (prealbumin)

Feedback Relationship

• Hormone produced in peripheral organs feedback on the hypothalamic-pituitary system

• All hormones are under feedback control, some by the peripheral hormone themselves, some by cations (Ca and PTH), some by metabolites (glucose-insulin-glucagon), some by other hormones (somatostatin, on insulin and glucagon), some by osmolality/extracellular fluid volume (vasopressin-renin-aldosteron)

-

Hypothalamus

TRH

Pituitary

TSH

Thyroid

T4

rT3 T3

The clasic feedback system:Control of thyroid hormone release

HYPOPHYSIS ANTERIOR

(trophic hormone)

(Portal System)

cortisolaldosteron

T3T4

estrogenprogesteron

testosteron

HYPOTHALAMUS

(releasing factors)

ACTH TSHFSHLH

FSHICSH

ADRENAL TIROID OVARIUM TESTES

+ + + +

HYPOTHALAMUS

(Paraoptic Nuclei)

HYPOPHYSIS POSTERIOR

(Neurohypophyse)

A.D.H (Oxytocine)

Collecting Duct of Kidney

(water reabsorbtion)Contraction of uterus

(HT- HP TRACT)

Not Related With Feedback Mechanism

• Insulin• Glucagon • Catecholamines • Parathyroid Hormone (P.T.H) • Intestinal Hormones

– (Secretin Glp, Etc)

Biorhytms

• Common feature of all endocrine systems• Common cause of endocrine pathology• Can vary over minutes, hours, days, weeks,

seasonal

Endocrine Pathology

• Excess• Deficiency

– Sub normal production– Receptor disorder– Abnormalities of transport or metabolism

• Tumors of endocrine glands– Functioning– Non functioning

Thank You