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2020.02.25. 1 The The Endocrine Endocrine System System Judit Rosta 21. 02. 2020 Evening seminar Evening seminar- Physiology Physiology Learning Obj.: 71,72,73 Evening seminar-Physiology-Endocrin. The Endocrine System From: Costanzo, Physiology, 5th Edition Elsevier

The The Endocrine Endocrine SystemSystemEndocrine Feedback Loop Gastric acid secretion- cephalic/oral phase (endocrine, paracrine, neural components) from Prof.Sáry (Phys.lecture

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2020.02.25.

1

The The EndocrineEndocrine SystemSystem

Judit Rosta

21. 02. 2020

Evening seminarEvening seminar-- PhysiologyPhysiology

Learning Obj.: 71,72,73

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

2020.02.25.

2

MulticellularMulticellular LifeLife

1) Hormone synthesis, storage, release

2) Define neurosecretion.

3) Hormone secretion control

4) Hormonal effects: stimulatory, inhibitory, permissive effects

Learning Obj.: 71,72,73

Cell-cell

Paracrine

Endocrine (vs.exocrine)

Principles of endocrine control systems

Evening seminar-Physiology-Endocrin.

Synthesis Storage Release Receptor/

Target

Glycoproteins/Peptides

trophichormones…

In advance Vesicles Exocytosis Membranereceptor

Steroids cortisol, aldosterone

On demand No (cholesterol/HD

L,LDL)

Diffusion Intracellular/Nuclear receptor

Aminehormones

T3,T4 In advance Vesicles/follicle Transporter NuclearTR/Transporter(B

BB)

The Classification of Hormones

Based on chemical structure

Hormone synthesis, storage, release

2020.02.25.

3

Evening seminar-Physiology-Endocrin.

Learn.Obj.2. State Fick’s law of diffusion. Transport rate:

driving forces (chemical and electrical gradient)

membrane properties

secretion rate of a hormone depends on its synthesis

Hormone synthesis, storage, release

Steroids - release

Cholesterol+enzyme activity

Bound hormones : Free hormones

e.g. hepatic failure: TBG ↓= free hormone↑

1 picogr-1 microgram/ml

Hormones in circulation:

HYPOTHALAMOHYPOTHALAMO--HYPOPHYSEAL PORTAL SYSTEMHYPOPHYSEAL PORTAL SYSTEM

Neurosecretion

Trophic hormones(their presence or absence causesother

organs to grow or atrophy)

The synthesis and release of hormones by neurons (neurohormones)

Hypothalamus: neurons receive nerve impulses

from other parts of the brain but transmit signals

to the pituitary gland by neurohormones that are

released into the blood

neurotransmitter vs. neurohormone

Portal vessels (after passing through one

capillary bed, conveyed through a second

capillary network- e.g. hepatic portal system)

CRH

GnRH

PIH

FSH,LH GH

ACTH

PRL

TSH

Ad

en

oh

yp

op

hysis

:

tro

ph

ic h

orm

on

es

neu

roh

yp

op

hysis

Optic chiasma

Neu

rosecre

tory

cells

:

rele

asin

gh

orm

on

es

Neurosecretory cells:ADH,oxytocin

Su

p.h

yp

op

hys.a

rt.

Portal veins

2020.02.25.

4

Evening seminar-Physiology-Endocrin.

Hormone Secretion Control

Learning Obj.

1. Principles of control theory.

Regulation (humoral, neural): Guidance vs. Control

Positive Feed Back: blood clotting, Ferguson (oxytocin) reflex

Negative feed back: HCO3--secretin

Feed forward:

Endocrine Feedback Loop

Gastric acid secretion- cephalic/oral phase

(endocrine, paracrine, neural components)

from Prof.Sáry (Phys.lecture 1st)

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

2020.02.25.

5

Hormone Secretion Control

Negative Feedback

e.g. pancreas and parathyroid gland

controlled by the regulated variable

(e.g. blood glucose and calcium)

Gardner DG, Shoback D.: GreenspanBasic & Clinical Endocrinology, 9thEdition

PTH ↑

Calcium Feedback to Regulate Parathyroid Hormone (PTH)

Secretion

Endocrine Feedback Loop

Osteoclasts, distal tubules, kidney (vitamin D)

Ca++-sensor on parathyroid cells

↓ Blood calcium

-

Blood calcium ↑

-

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

2020.02.25.

6

Hormone Secretion Control

Hypothalamic Releasing and Inhibiting Hormones

Endocrine Feedback Loop

Thyroid gland

1. how the hypothalamus

controls the anterior

pituitary through

hormone secretion

2. how the anterior pituitary

controls the target tissue

through hormone

secretion.

3. how tissue hormones

provide negative feedback to the

hypothalamus and

anterior pituitary

TRHTRH-receptor

Released TSH

Hormone Secretion ControlEndocrine

Feedback Loop

Thyroid gland

Graves’ Disease-TSH

receptor autoantibodies-

excess negative feed

back, supresses TSH

TSH:thyrotropin

2020.02.25.

7

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

Hormone Secretion Control

Hypothalamic Releasing

and Inhibiting Hormones

Endocrine Feedback Loop

Positive feedback

causes additional

secretion of the

hormone-until an

appropriate

concentration

Hormonal Profile of

EstradiolEstradiol, , LH LH and FSHand FSH

Sustained increase in estradiol in the late follicular phase triggers

the massive burst of LH secretion that just precedes ovulation

Estradiol has + Feedback on LH

2020.02.25.

8

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

Regulation of Prolactin Secretion

Prolactin inhibits itsown secretion byincreasing the secretionof dopamine

Hormone Secretion Control

Hypothalamic Releasing

and Inhibiting Hormones

Endocrine Feedback Loop

Prolactin has + Feedback on PROLACTIN

INHIBITING FACTOR (dopamine)

2020.02.25.

9

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

consequence of feedback control

Gardner DG, Shoback D.: Greenspan Basic & Clinical Endocrinology, 9th Edition

ACTHACTH--CortisoCortisol

Pulsatory Pattern: burst-like manner

Hormone Secretion Control

by Pascale M Y Smets

ACTH � Cortisol � metabolic effectsmin hours

CORTISOL has – Feedback on

ACTH Hypothalamic Releasing and Inhibiting Hormones

Endocrine Feedback Loop

stress

2020.02.25.

10

Evening seminar-Physiology-Endocrin.

The Endocrine System

From: Costanzo, Physiology, 5th Edition Elsevier

Hormone Secretion- Regulation Inefficiency

ADH ADH SecretionSecretion

ADH neurons

Plasma osmolarity

increases

Plasma osmolarity

decreases

Water reabsorption

in collecting ducts

Nucl.

supraopticus

ADH ADH releaserelease

Posterior

pituitary

Plasma osmolality ↑

ANP

alcohol

baroreceptors

Na+ cc.

Case report:

56-year-old man with

lung carcinoma

experienced a grand mal

seizure and became

semicomatose

Tests:

serum Na+, Cl-:low

serum K+: normal

urine Na+, Cl-:normal

Osmolarity: 225 mOsm/L

Hypothalamic

osmorceptors

2020.02.25.

11

Explanation:

Seizure caused by swelling of brain cells-excess water reabsorbed by the kidney was

distributed throughout the ICF-water flowed into the cells, their volume increased-(fixed

cavity the skulll)

Treatment:

Hypertonic NaCl is infused�raise the osmolarity; administration of ADH antagonist

Small cell carcinoma: ADH

secreting tumor cells

Low osmolality: Na+-reabsorption ↓ or water reabsortion ↑

Inappropriate secretion of the

antidiuretic hormone (ADH)

(Aldosteron)

Urine Na+: normal

(ADH)

?

Ectopic production of ADH

Hormone Secretion- Regulation Inefficiency

the presence of one hormone, at a certain

concentration, is required in order to allow a

second hormone to fully affect the target cell

Hormones which exert permissive effect on:

Estrogen the formation of receptor proteins for progesterone in

uterus

Parathyroid hormone the synthesis of vitamin D3

(via stimulation of the production of the hydroxylating

enzymes in the kidneys and liver)

Cortisol: glucagon induced gluconeogenesis

Thyroid hormones: anabolic and metabolic effects of Growth Hormone

Hormonal effects: permissive effect

2020.02.25.

12

• Increase adrenergic receptor synthesis

• Enhanced binding of the receptor to the G-protein

• Increased catecholamine-induced cAMP formation

• Prolonged effect of catecholamine on smooth muscles

Hormonal effects: permissive effect

Vasoconstriction, positive inotropic effect

Glucocorticoids are needed to the

maintenance of normal blood

pressure!

CORTISOL exerts permissive

effect on the actions of

catecholaminesatecholamines

keeps vasculatura and arterioles partially

constricted and this maintains blood

pressure

(regulating amount of blood flow into the

capillaries)

α1

BLOOD VESSELS

WITHOUT DUAL

INNERVATION-SYM

TONE

2020.02.25.

13

Evening seminar-Physiology-Endocrin.

Glucocorticoid ↑= Cushing syndrome: Hypertension vasoconstriciton

Hormonal effects:

CORTISOL

46. The regulation of local blood flow.

Cortisol -

hormones work together to

produce a particular result

epinephrine+norepinephrine on cardiac rate- together even greater

increase than the sum of their individual effects (additive)

testosterone+FSH-each stimulates different stages of

spermatogenezis, both needed to complete sperm development

(complementary)

Hormonal effects: Synergistic Effect

2020.02.25.

14

Synergism between THYROID

Hormones and Catecholaminesatecholamines

increases β1 adrenergic

receptor induced cAMP

formation

Hormonal effects:

thyroid hormones

α,β adrenergic receptors

cAMP

increases β1 adrenergic receptor mediated cAMP formation

Hormonal effects:THYROID Hormones

Tachycardia: clinical importance- whether a patient has

excessive or diminished thyroid hormone production

increased heart strength via formation of myosin

Na/Ca-exchanger inhibition

CHRONOTROPIC EFFECTCHRONOTROPIC EFFECT

pulse pressure is increased (systolic pressure is

elevated 10 to 15 mm Hg)

INOTROPIC EFFECTINOTROPIC EFFECT

Hyperthyroidism:

Cardiovascular effects

+/− heart effects

LUSITROPIC EFFECTLUSITROPIC EFFECT SERCA upregulation

Appropriate thyroid hormone level is

required for optimal heart functions

2020.02.25.

15

Hormonal effects:THYROID Hormones

Phys Heart I. Prof.Sáry Obj.35.

increases β1 adrenergic receptor mediated cAMP formation

increased heart strength via formation of myosin

Na/Ca-exchanger inhibition

CHRONOTROPIC EFFECTCHRONOTROPIC EFFECT

INOTROPIC EFFECTINOTROPIC EFFECT

LUSITROPIC EFFECTLUSITROPIC EFFECT SERCA upregulation

Evening seminar-Physiology-Endocrin.