Good morning

ENDOCRINOLOGY

Introduction Hormones

-chemistry of hormones

-hormone receptors

-mechanism of action Pituitary gland Thyroid gland Endocrine functions of Pancreas Adrenal cortex Adrenal medulla Endocrine functions of other organs Local hormones

CONTENTS

The various physiological activities in our body are controlled by

some chemical substances called chemical messengers or

Chemical mediators.

Chemical messengers

Secreted by Endocrine glands, nerve endings, cells of other

tissues carry the message (signal) from the controlling cells

(signaling cells) to the target cells.

Introduction

Chemical messengers

Classical hormones local hormones

Recent classification of these messengers

-Endocrine messengers

-Neurocrine messengers

-Paracrine messengers

-Autocrine messengers

Endocrine glands

Is a chemical substance that is secreted into internal body

fluids by one cell or a group of cells and has a physiological

control effect on other cells of the body.

Chemistry of hormones

- Hormones are classified depending on the chemical nature

Steroid hormones

Protein hormones

Derivatives of the amino acid- tyrosine

Hormones

Hormone receptors The receptors of the hormones are

large proteins present in the target cells.

Each receptor is highly specific for one single hormone

Situation of hormone receptors

-Cell membrane

-Cytoplasm

-Nucleus

Regulation of hormone receptors

-Up regulation

-Down regulation

Mechanism of hormonal action

1. By altering the permeability of cell membrane

2. By altering the intracellular enzyme

3. By activating the gene

The neurotrasmitter substances in a synapse or neuromuscular junction act by changing the permeability of postsynaptic membrane.

example: NMJ

1. By altering the permeability of cell membrane

Protein hormones and catecholamines The hormone, which acts on the target cell, is called first

messenger HR-complex activates the enzymes of the cell and causes the

formation of another substance called second messenger or intracellular hormonal mediator.

- Cyclic AMP- Calcium Ions and Calmoduline- Inositol triphosphate (IP3)- Diacylglycerol (DAG)- Cyclic Guanosine Monophosphate (cGMP)

2. By Activating the Intracellular enzymes

Thyroid and steroid hormones

3. By Activating on genes

Also known as HYPOPHYSIS

PITUITARY GLAND

Regulation of secretion

HYPOTHALAMO HYPOPHYSEAL PORTAL SYSTEM

Releasing and Inhibitory hormones

GH-RH

GHRP

TRH

CRH

GnRH

GHIH

PIH

Growth hormone

Secreted by the acidophils, known as somtotropes

Is a protein, having a single chain polypeptide with

191 amino acids, 21,500mol wt

Responsible for general growth of the body

Anterior pituitary hormones

Effects of GH

Effects of GH on protein metabolism

Increases the amino acid transport through the cell membrane

Increases the RNA translation

Increases transcription of DNA to RNA

Decreases catabolism of protein

Effects of GH on fat metabolism

Excess GH

Fat mobilization from adipose tissues

Large quantities of acetoacetic acid formed by liver and released into body fluids

(Ketosis)

Resulting in fatty liver

Effects of GH on carbohydrate metabolism

GH causes conservation of glucose, by following mechanisms

-Decrease in the peripheral utilization of glucose for the production of energy

-Increase in the deposition of glycogen in the cells

- Diabetogenic effect of GH

Effect of GH on bones

GH increases the growth of the skeleton

Increase in the protein deposits by chondriocytes and osteogenic cells

And it causes conversion of chondriocytes into osteogenic cells

Mode of action GH on Bones and Metabolism

Thyroid Stimulating Hormone (TSH)

Necessary for the growth and secretory actions of thyroid gland

Adrenocorticotropic Hormone (ACTH)

Necessary for the structural integrity and the secretory activity of adrenal cortex

Follicle Stimulating Hormone

In males it accelerates spermeogenesis in combination with

testosterone

In females it is responsible for development of graafian follicle from primordial follicle

Secretion of estrogen

Luteinizing Hormone

In males it is known as ICSH

In females along with FSH it causes maturation of vesicular follicle

Ovulation

Formation and secretory functions of corpus luteum

Prolactin

Secretion of milk

β-Lipotropin

Mobilizes fat from adipose tissue and promotes lipolysis

Anti Diuretic Hormone (vasopressin) Secreted by supra optic nucleus, and paraventricular nucleus Is a polypeptide with 9 amino acids

Actions Reabsorption of water from DCT and Collecting duct In large amounts, it causes constriction of arteries

Posterior pituitary hormones

Oxytocin Secreted by paraventricular nucleus and in small quantity by

supraoptic nucleus Is a ploypeptide with 9 aminoacids

Actions Causes contraction of myoepithelial cells- ejection of milk On pregnant uterus causes contraction and helps in the

expulsion of fetus Causes contraction in non pregnant uterus and facilitate the

transport of sperms in female genital tract

Anterior pituitary Posterior pituitary

DISORDERS OF PITUITARY GLAND

HypersecretionGigantism

AcromegalyAcromegalic

gigantismCushing’s disease

Hyposecretiondwarfism

AcromicriaSimmond’s disease

orPituitary cachexia

HypersecretionSyndrome of inappropriate

hypersecretion of ADH (SIADH)

HyposecretionDiabetes insipidus

Pre-puberty: Gigantism

An overproduction of growth hormone before epiphyseal closure.

These children grow to be over 7 ft (213 cm) in height and have disproportionately long limbs

-bone growth, > 7 ft. tall

Post-puberty: Acromegaly

Some tissues still grow even after puberty :

cartilage in nose, hands, feet, ridges of eyebrow,

chin, tongue

Metabolic effects:

constant increase in blood sugar

increased insulin type 2 diabetes.

Increase muscle in tunica media narrowing of arteries,

heart attack

Excess growth hormone produced after puberty has little effect on

the growth of the skeleton, but it results in a disease affecting

terminal skeletal structures known as acromegaly

Dwarfism

Deficiency of GH in immature

individual. A deficiency of growth hormone secretion before

puberty results in pituitary dwarfism.

Pituitary dwarfs, who can be as little as 3 to 4 ft (91–122 cm) tall,

are generally well proportioned except for the head, which may be

relatively large when compared to the body.

Unlike cretins, whose dwarfism is caused by a deficiency of

thyroxine, pituitary dwarfs are not mentally retarded;

They are often sexually immature.

They can be treated by injections of synthetic growth hormone,

somatropin, which are produced by genetically engineered

bacteria.

Eruption timing and the shedding is delayed

Clinical crowns appear smaller than normal

The dental arch is smaller than normal so crowding

There is no shortening in length of anatomic crown as expected though the roots may be smaller

Dwarfism due to deficiency of somatomedin C known as Lorain dwarfism

Recombinant human GH (RnGH)

First used to treat GHD

Supply of RnGH has made it possible to supply GH for general shortness

Metabolic side effects:

- Acceleration of puberty

- Pancreatitis

- Intracranial hypertension

- May ↑ risk of leukemia and stroke

Acromicria

Deficiency of GH in adults

Due to atrophy of acidophilic cells, tumor of chromophobes and panhypopituitarism

Atrophy or thinning of extremities

Persons become lethargic and obese

Loss of sexual functions

Simmond’s disease (pituitary cachexia)

Occurs mostly in panhypopituitarism

Due to atrophy or degeneration of anterior pituitary

Rapidly developing senile decay

Loss of hair and tooth

Skin of face becomes dry and wrinkled

Syndrome of inappropriate Hypersecretion of ADH (SIADH)

Excessive secretion of ADH

The cells during cerebral tumors, lung tumors and lung

cancers secrete ADH

Sodium concentration in ECF reduced to 110 mEq/L. (Normal-142mEq/L)

When it falls below, patient may die because of convulsions and coma

Thyroid is an endocrine gland situated at the root of the neck on either side of trachea.

THYROID GLAND

Composed of large number of follicles Follicular cavity is filled with a colloidal substance known as

thyroglobulin from which secretes T3 and T4 Between the follicles, the parafollicular cells are present,

which secretes calcitonin

Histology

Thyroid hormones

T4- tetraiodothyronine

(thyroxine) T3- triiodothyronine is more potent Calcitonin

Regulation of secretion

Effect on basal metabolic rate

-It increases the metabolic rate as much as 60%-100% above

normal in all tissues except brain, retina, spleen, testes and lungs

-T3 stimulates increase in Oxygen uptake by all tissues

( metabolism of all tissues is increased)

Functions of thyroid hormones

Effect on protein metabolism

The protein synthesis is accelerated by the following ways:

-increasing the Translation of RNA

-increasing the Transcription of DNA to RNA

-increasing the activity of Mitochondria

-increasing the activity of cellular enzymes

Effect on carbohydrate metabolism

absorption of glucose from GIT uptake through cell membrane glycogenolysis, gluconeogenesis

Effect on fat metabolism

Mobilization of fat from adipose tissues and fat depots. Increases deposition of fat in liver, decreases plasma

cholesterol level

Decrease in vitamin levels due to their utilization during formation of enzymes

Increase in body temperature due to increased metabolic processes and BMR

Is important hormone to promote growth and development of brain during fetal and few years of postnatal life

Effects on CVS- HR

Force of contraction

BP

Effect on respiration Increases rate and force of respiration

Effect on GIT Increases appetite and food intake Increases secretions and movements

Effect on skeletal muscle With slight increase, muscle work with more vigor

Excessive secretion causes thyrotoxic myopathy

Effect on sleep Hypo secretion causes excessive sleep (somnolence)

Effect on sexual function Hyposecretion causes complete loss of libido Hypersecretion causes impotence

Disorders of thyroid hormones

1. Hyperthyroidism

Causes:- Grave’s Disease (commonest cause)

- Multinodular Goiter

- Thyroiditis and Others

Dental considerations

Patients with untreated hyperthyroidism can be difficult to deal with a result of heightened anxiety and irritability.

The sympathetic overactivity may lead to fainting.

Local anesthesia is the main means of pain control.

Conscious sedation is frequently desirable to control excessive anxiety. Benzodiazepens may potentiate antithyroid drugs, and therefore nitrous oxide, which is more rapidly controllable is probably safer.

Povidone iodine and similar compounds are avoided

Carbimazole occasionally causes agranulocytosis, which may cause oral or oropharyngeal ulcerations.

Otherwise treated thyrotoxic patient presents no special problems in dental treatment.

After treatment of hyperthyroidism the patients are at risk for developing hypothyroidism, which may pass unrecognized.

2. Hypothyroidism

I. Primary Hypothyroidism

Secondary Hypothyroidism

II Cretinism

Myxedema.

Cretinism

Signs like sluggish movement and croaking sound while

crying.

Retarded mental, physical and sexual growth

Because of large tongue, guttural breathing may present which

sometimes choke the baby

Myxedema

-Swelling of the face

-Bagginess under the eyes

-Non pitting type of edema due to accumulation of proteins with

hyaluronic acid and chondroitin sulfate

-Other symptoms of hypothyroidism-

Dental considerations :

The main danger is of precipitating myxoedema coma

by use of sedatives (including diazepam or midazolam), opioid

analgesics or tranquilizers.

Therefore these should be avoided or given in low dose.

Local anesthesia is satisfactory for pain control.

Conscious sedation can be carried out with nitrous oxide and oxygen.

General anesthesia may be complicated because of possible

ischemic heart disease and the danger of coma.

GA must be delayed until thyroxine has been started.

Endocrine function of pancreas is performed by the islets of Langerhans

4 types of cells of islets of langerhans

- A (alpha) GLUCAGON

- B (beta) INSULIN

- D (delta) SOMATOSTATIN

- F (PP) PANCREATIC POLYPEPTIDE

PANCREAS

Insulin is secreted by β- cells of islets of langerhans

Is a polypeptide with mol wt 5808, has two amino acid chains linked by disulfide bridges, alpha chain contains 21 and beta chain contains 30 amino acids.

Insulin

Effect on carbohydrate metabolism

High carbohydrate diet

Insulin secretion

Increased permeability of cell membrane

Transport of glucose from blood into cell

Promotes conversion of glucose to glycogen and stored in

muscle and liver Inhibits glycogenolysis, gluconeogenesis

Actions

Effect on protein metabolism Insulin accelerates synthesis and storage of proteins

Effect on fat metabolism Insulin activates the enzymes which converts glucose into

fatty acid and triglycerides Promotes the storage of fat in adipose tissue

Effect on growth Anabolism of protein -> promotes growth

Secreted by α-ells of islets of langerhans

It is a polypeptide contains 29 amino acids, mol wt 3485.

Actions of glucagon Increases glycogenolysis, gluconeogenesis

Shows lipolytic and ketogenic actions

Secretion of bile Secretion of gastric juice

Glucagon

Secreted by Hypothalamus, δ-cells of islets of langerhans, δ-cells in stomach, small intestine

Is a polypeptide, 14(pancreas) and 28(intestine) amino acids

Inhibits- glucagon, insulin, GH

Decreases the motility of stomach, duodenum, gallbladder

Increased secretion seen with increase in glucose, amino acids, cholecystokinin

Somatostatin

Secreted by Fcells or PPcells

Polypeptide with 36 amino acids

Increase secretion of glucagon

Increase secretion stimulated by presence of chyme containing more proteins

Pancreatic polypeptide

Type-1 (IDDM)

Due to deficiency of insulin

Not associated with obesity but associated with acidosis or ketosis

Occurs before 40 years- juvenile diabetes

Causes degeneration, destruction by viral infection, congenital disorder, auto immune disease of beta cells

Diabetes mellitus

Type-2 (NIDDM)

Occurs after 40 years- maturity onset diabetes

Associated with obesity

Causes- absence or reduced number of insulin receptors

Endocrine disorders like gigantism, acromegaly and cushing’s syndrome- secondary diabetes

Loss of glucose in urine

Osmotic diuresis

Polyuria, polydipsia, polyphagia

Asthenia(loss of strength)

Acidosis, circulatory shock, coma

Chronic diabetes- diabetic retinopathy- diabetic nephropathy- diabetic neuropathy

Signs and symptoms

Excessive secretion of insulin

Occurs due to tumor of beta cells

Signs and symptoms- hypoglycemia, neuroglycopenic symptoms like clonic convulsions and unconsciousness, coma

Hyperinsulinism

Good morning

There are two endocrine organs in the adrenal gland, one surrounding the other

Situated on the upper pole of each kidney (Suprarenal glands)

Each gland weighs about 4 gms

Adrenal glands

Histology

Is formed by three layers of structures

Hormones- Mineralocorticoids (Life Saving Hormone)- Glucocorticoids (Life Protecting Hormone)- Sex hormones

Are steroid in nature and synthesized mainly from cholesterol

Mineralocorticoids binds to plasma protein- globulins, glucocorticoids combine with plasma protein glucocorticoid-binding globulin or transcortin

Adrenal cortex

Mineralocorticoids- Aldosterone- 11-Deoxycorticosterone

These are C21 steroids

90% of mineralocorticoid activity is provided by aldosterone

Functions of Mineralocorticoids

Mineralocorticoids

K+ in ECF

Na+ and Cl-

ECF volume & Blood volume

Cardiac Dysfunction Shock Death

On sodium ions Acts on DCT and collecting duct and increase the reabsorption

of sodium

On extra cellular fluid volume Along with sodium water also reabsorbed- increase in ECF

volume

On blood pressure Increase in ECF causes increase in BP

Aldosterone escape or Escape phenomenon

Aldosterone

Reabsorption of Na+ and Water

ECF, Blood Pressure

ANP (Atrial Natriuretic Peptide)

Na+ & Water excretion through urine

70.3

Regulation Of Secretion

Glucocorticoids

- Cortisol

- Corticosterone

- Cortisone

Secreted mainly by zona fasciculata, small quantity by zona reticularis

C21 Steroids having 21 carbon atoms

Life protecting hormone as it helps to withstand the stress and trauma in life

Functions of glucocorticoids

On carbohydrate metabolism Increases blood sugar level (Adrenal Diabetes)- By promoting gluconeogenesis- By inhibiting glucose uptake & utilization by peripheral cells

On protein metabolism Promotes catabolism of proteins Except for liver cells, it causes decrease protein synthesis by

inhibiting amino acid transport into cells & by inhibiting RNA formation

On fat metabolism Causes mobilization and redistribution of fats Increases ketone bodies in blood- ketogenic effect

On mineral metabolism Retains sodium, excretes potassium Inhibits calcium absorption from intestine – excretion of

calcium through urine

It accelerates excretion of water- in adrenal insufficiency causes water retention and water intoxication after water load

On CNS Insufficiency of these causes personality changes like

irritability and lack of concentration

Permissive action of glucocorticoids The actions of some hormones are executed only in the

presence of these hormones- Calorigenic effect of glucagon- Lipolytic, brochodilation & pressor action of catecholamines

- On Resistance to stress It is assumed that they enhances the resistance

- Immediate release & transport of amino acids from tissues to liver for synthesis of new proteins which are essential to withstand the stress

- Release of fatty acids produces more energy during stress- Enhancement of vascular reactivity of catecholamines

Anti- inflammatory effects Prevent the inflammatory changes in the cells caused by injury

or infection by acting at all stages of inflammation

Anti-allergic actions Prevent the various reactions in allergic conditions

Immunosuppressive effects Suppress the immune system by decreasing the number of

circulating T lymphocytes, also prevent release of inerleukin-2 by T cells

Regulation Of Secretion

Most of the hormones secreted are male sex hormones (Androgens) and in small amounts of estrogens and progesterone also secreted

The androgens are- Dehydroepiandrosterone

- Androstenedione

- Testosterone

Androgens in general are responsible for masculine feature of the body

Adrenal sex hormones

Hyperactivity Hypoactivity

Disorders of Adrenal cortex

Cushing's syndrome

Hyperaldosteronism

Adrenogenital syndrome

Addison’s diseaseAddisonian crisis

Congenital adrenal

hyperplasia

Any condition that produces an elevation in glucocorticoid levels.

Etiology Primary hypothalamic – pituitary diseases associated with

hypersecretion of ACTH (Cushing Diseases).

Microadenomas

Corticotroph cell hyperplasia.

Cushing’s syndrome (Hypercortisolism)

Primary adrenal neoplasms (ACTH independent)

Adrenal adenoma

Adrenal Carcinoma

Primary pigmented nodular adrenal hyperplasia

Carney Complex

McCune Albright Syndrome

Ectopic ACTH by a non endocrine neoplasm

Clinical Features

Obesity – centripetal, buffalo lump,

moon like facies

Reproductive dysfunction – Menstrual irregularity, loss of libido,

hirsuitism, acne

Psychiatric abnormalities – agitated depression & lethargy,

psychosis, memory and cognition affected, Insomnia.

Bone – Children – poor linear growth and weight gain.

Osteoporosis – Vertebral collapse

Pathologic fractures – rib and vertebral compression fracture

Skin – Skin thinning, separation and exposure of the subcutaneous vascular tissue.

Liddles Sign – dorsum of land Plethoric appearance Red – Purple livid striae Increase skin pigmentation

Muscle – Proximal myopathy

- Bruising Cardiovascular–Hypertension – 75% Infections – more common Fungal infections – tinea

versicolor, candidiasis. Poor wound healing

Treatment

Surgical removal of adrenal tumors & pituitary tumors. Benign tumors causing ectopic ACTH syndrome.

Medical Treatment

Metapyrone, Aminoglutethimide, Ketaconazole, Mitotane

Increased secretion of aldosterone Based on cause

Primary hyperaldosteronism

-Tumors in zona glomerulosa

Secondary hyperaldosteronism

- CCF

- Nephrosis

- Toxemia of pregnancy

- Cirrhosis of liver

Hyperaldosteronism

Signs & Symptoms

Increase in ECF & Blood volume Hypertension Prolonged depletion of K+ causes renal damage leads to

polyuria, polydipsia Muscular weakness due to K+ depletion Due to excretion of large amount of H+ ions causes metabolic

alkalosis, which in turn reduces blood calcium- tetany

Abnormal quantities of adrenal androgen secretion develops andrenogenital syndrome

Cause

Tumor of zona reticularis

Symptoms in females (Adrenal virilism)

-Increased muscular growth

-Deepening of voice

-Amenorrhea

-Enlargement of clitoris

-Male type hair growth

Andrenogenital syndrome

Symptoms in males

-Feminization

-Gynacomastia

-Atropy of testis

Due to failure of adrenal cortex to secrete all corticosteroids

Classified into

Primary – Due to adrenal cause

Secondary – Due to failure of ant pituitary to secrete ACTH

Tertiary – Due to failure of hypothalamus to secrete CRF

Addison’s disease or Chronic Adrenal Insufficiency

Signs and symptoms

Pigmentation of skin and mucus membrane

Muscular weakness

Dehydration with loss of sodium

Hypotension & Hypoglycemia

Decreased cardiac output leading to decreased size of heart

Nausea, vomiting and diarrhea

Susceptibility to any type of infection

Inability to withstand any stress

Characterized by sudden collapse associated with an increase in need for large quantities of Glucocorticoids

Causes

-Exposure to even mild stress

-Hypoglycemia due to fasting

-Trauma

-Surgical operation

-Sudden withdrawal of glucocorticoid treatment

Sudden collapse occurs, the condition becomes fatal if not treated in time

Addisonian Crisis or Adrenal Crisis or Acute Adrenal Insufficiency

Medulla is the inner part of the adrenal gland Made up of interlacing cords of cells known as Chromaffin

cells, Pheochrom cells or chromophil cells

Hormones of Adrenal medulla

-Adrenaline or Epinephrine

-Noradrenaline or Norepinephrine

-Dopamine

Adrenal medulla

Synthesis of catecholamines

Mode of action of these hormones are executed by binding with receptors called Adrenergic receptors

- Alpha adrenergic receptors (α-1 α-2 )

receptors mediate more of noradrenaline action than the adrenaline action

- Beta adrenergic receptors (β1 β2 )

β1- equal actions of both adrenaline, noradrenaline

β2- more adrenaline action than noradrenaline

On metabolism (via alpha and beta receptors )

General metabolism: Adr increases oxygen consumption, CO2

removal, BMR – calorigenic hormone

Carbohydrate metabolism: Increases glycogenolysis

Fat metabolism: Mobilization of free fatty acids from adipose

tissues

On blood (via beta receptors )

Adr decreases coagulation time, increases RBC count

Actions

On Heart (via beta receptors ) Adr has stronger effect on heart It increases Heart rate (Chronotropic effect )

Force of contraction (Ionotropic effect)

Excitability of heart muscle (Bathmotropic effect)

On Blood vessels (via alpha and beta 2 receptors) Noradr- Constriction (alpha) – Increase peripheral resistance Adr - Dilatation in skeletal muscle, liver and heart (beta 2)-

Decrease peripheral resistance

On Blood Pressure

Adr increases systolic BP, decreases diastolic BP

Noradr increases both systolic & diastolic BP

On respiration

Adr increases force and rate of respiration

Adrenaline secretion increases Fight or Flight reactions of brain

Causes contraction of smooth muscle

Increases secretion of many glands

Dopamine

Secreted by medulla and by dopaminergic neurons in some

areas of brain particularly, basal ganglia

It acts as neurotransmitter

Deficiency of dopamine, basal ganglia produces nervous

disorder called Parkinsonism

Is a condition characterized by Hypersecretion of catecholamines

Cause Tumor of chromophil cells in adrenal medulla Tumor of sympathetic ganglia (extra adrenal

pheochromocytoma)

Pheochromocytoma

Signs and symptoms

Hypertension- characteristic feature

Others- Anxiety

Chest pain

Fever, Headache

Hyperglycemia

Palpitation

Sweating and Flushing

Tachycardia

Weight loss

Pineal gland :

- secretes melatonin (inhibits onset of puberty)

Thymus :

- Endocrine glands ( secretion of Thymosin and Thymin )

Endocrine function of Kidney:

- Secretion of Erythropoietin, Thrombopoietin,Prostaglandins,

Renin, 1,25 – Dihydroxy cholecalciferol

Endocrine function of heart:

- Secretion of Atrial Natriuretic Peptide

Endocrine functions of other organs

Local hormones are the substances which act on the same area of their secretion or in immediate neighborhood

Classified into two types

Hormones synthesized in tissues-Prostaglandins and related substances, others like Acetylcholine, Serotonin, Histamine, Substance P, Heparin, Leptin, GI hormones

Hormones synthesized in Blood- Serotonin, Angiotensinogen, Kinins

Local hormones

Prostaglandins

Are unsaturated fatty acids with a cyclopentane ring & 20 carbon atoms

Synthesized from Arachidonic acid Types- PGD2, PGE2, PGF2

Actions

-Vasodilatation

-Gastric secretion

-Inhibit release of free fatty acids from adipose tissue

-Increase the velocity of sperm transport in female genital tract

-Induce abortion if injected intra-amniotically

-Stimulate jaxtaglomerular apparatus to secrete Renin

Thromboxanes (A2 & B2) Important in hemostasis by accelerating aggregation of

platelets

Prostacyclin Causes vasodilation and inhibits plate aggregation

Leukotrienes These are the mediators of allergic responses, and promote

inflammatory reactions

Lipoxins (A & B) Lipoxin A causes dilation of minute blood vessels, both inhibit

the cytotoxic effects of killer T cells

Acetylcholine It is the neurotransmitter substance at the NMJ Inhibits cardiac function & causes vasodilation

Serotonin (5-hydroxytryptamine) Inhibits impulses of pain sensation in posterior gray horn of

spinal chord, causes mood depression and sleep, vasoconstriction

Histamine During allergic condition, inflammation or damage of tissues-

vasodilation- entry of fluid and proteins from blood into affected tissue

Substance P Is a neurotransmitter substance, increases the mixing and

propulsive movements of small intestine

Heparin Produced by mast cells and basophils, is a natural

anticoagulant

Leptin Secreted by adipocytes in adipose tissue Inhibits feeding center resulting in stoppage of food intake Stimulates the metabolic reactions involved in utilization of

fat stored in adipose tissue

Kinins

Kinins are biologically active protein hormones which are circulating in blood

Two kinins in humans are- Bradykinin

- Kallidin Actions of bradykinin

-Dilates blood vessels decreases BP

-Increases permeability of capillaries edema

Kallidin is a vasodilator hormone Plasma Kallikrein activates factor XII during blood

coagulation, and are potent vasodilators

Textbook of physiology, 3rd edition Ganong

Textbook of medical physiology,7th edition Guyton

Textbook of human Physiology, Sembulingam

Davidson. TextBook of Medicine 20th ed., Elsevier Publishers

www.endocrinology.org

References

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