ENDOCRINE SYSTEM

Basic Glands in the Body:

1. Exocrine gland

Its secretions are carried to a specific

location by tube or duct.

2. Endocrine gland

Its secretions diffuse with the blood and are

transported via the circulatory system to the

target cells.

They are fondly called “ductless glands”.

HORMONES

Chemical messengers secreted by the

endocrine glands and tissues which are

carried throughout the body by the blood that

have stimulatory, inhibitory, and regulatory

effects to the target cells.

Effects of hormone

stimulation or inhibition of growth

Mood swings

induction or suppression of apoptosis (programmed

cell death)

activation or inhibition of the immune system

regulation of metabolism

preparation of the body for fighting, sex, fleeing,

mating, and other activity

preparation of the body for a new phase of life, such

as puberty, parenting, and menopause

control of the reproductive cycle

hunger cravings

TYPES OF HORMONES

1. Steroid hormones

Lipids or derivatives of cholesterol

Have complex of four carbon rings but with

different side chains.

E.g. Sex hormones (estrogen &

progesterone)

2. Peptide hormone

Peptides, proteins, glycoproteins, or modified

amino acids.

MECHANISMS OF HORMONAL

ACTION

1st messenger model

accomplished by the steroid hormone.

2nd messenger model

accomplished by the peptide hormone.

1st messenger model

Steroid hormone after crossing the cell

membrane, combines with a receptor protein in

the cytoplasm to form a hormone-receptor

complex.

This complex moves into the nucleus and

interacts with the nuclear DNA which promotes

mRNA synthesis that moves into the cytoplasm

and serves as template for the synthesis of

proteins, usually enzymes.

The synthesized enzymes, in turn, enable

reactions that produce the effect that is

characteristic of a particular hormone.

2nd messenger model

This model of hormonal action involves two messengers.

The 1st messenger is the hormone that binds to a

receptor protein the cell membrane to form a hormone-

receptor complex which in turn activates a certain enzyme

called adenylate cyclase that stimulates the conversion of

ATP into cyclic AMP (cAMP) or cyclic adenosine

monophosphate.

This cAMP serves as the 2nd messenger that sets in

motion an enzyme cascade, that is, each enzyme in turn

activate another enzyme.

This enzyme activation carries the necessary

characteristic effects of the hormone to its target cells.

http://upload.wikimedia.org/wikipedia/commons/d/da/Illu_endocrine_system.png

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY

OR EXCESS

PITUITARY GLAND

OR HYPOPHYSIS

A. Anterior Pituitary TSH or thyroid

stimulating hormone

Regulates production of

the thyroid gland

ACTH or

adrenocorticotropic

hormone

Stimulates adrenal cortex

to secrete its hormones

FSH or follicle-

stimulating hormone

Promotes dev’t. of ovarian

follicles and mature sperm

LH or luteinizing

hormone

Evokes ovulation,

formation of corpus luteum,

and production and release

of estrogens and

progesterone.

Gland/Source

HORMONES

FUNCTIONS

EFFECTS OF

DEFICIENCY/

EXCESS

Prolactin or

Lactogenic hormone

Stimulates milk

secretion by

mammary glands.

Growth hormone or

somatotropin

Promotes cell

metabolism

Dwarfism (deficiency)

Gigantism (excess in

early youths)

Acromegaly (excess

later in life)

MSH or melanophore

stimulating hormone

Controls adjustable

skin pigment cells ( as

in frogs)

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY/

EXCESS

A. Posterior

Pituitary

Vasopressin

(antidiuretic

hormone or ADH)

Increases absorption of

water by the kidney

tubules; causes

constriction of the

smooth muscles of the

arterioles.

Oxytocin Causes contraction of the

smooth muscles in the

uterus; also causes

ejection of milk from the

mammary gland.

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY OR

EXCESS

THYROID Thyroxine

Triiodothyronine

Calcitonin

These hormones

regulate the general

body metabolism,

growth and sexual

dev’t.

Regulates blood

calcium (antagonizes

bone resorption by

osteoclasts.

Deficiency:

Simple Goiter

Cretinism

Myxedema

Excess:

Exophthalmic goiter.

PARATHYROID Parathormone Controls Ca and

phosphate

concentration in blood

plasma and their

metabolism

Muscular twitchings

and spasmodic

contractions of

increasing violence ,

leading to severe

convulsions.

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY OR

EXCESS

ADRENAL

CORTEX

Mineralococorticoids

(e.g.aldosterone)

Glucocorticoids

(cortisol and cortisone)

Androgen

Affects the metabolism

of water and

electrolytes and the

serum concentrations of

Na and K.

Influencing the

metabolism of

carbohydrates and

proteins

Affects sexual dev’t.

Addison’s disease

In excess caused

masculinizing effects

for women

ADRENAL

MEDULLA

Adrenaline

Noradrenaline

“ fight or flight” reaction Ex. raises BP, heart

rate, blood sugar level

Inability to cope with

stress

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY OR

EXCESS

PANCREAS

(Islets of

langerhans)

Insulin

glucagon

Glucose to glycogen

Conversion

Glycogen to glucose

conversion

Diabetes mellitus

DUODENUM Secretin

Pancreozymin

Stimulates pancreatic

Juice secretion

STOMACH Gastrin Stimulates gastric

juice secretion

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY

OR EXCESS

TESTIS Testosterone other

Androgens

Anabolic: growth of muscle

mass and strength, increased

bone density, growth and

strength,

Virilizing: maturation of sex

organs, formation of scrotum,

deepening of voice, growth of

beard and axillary hair.

Atrophy of

reproductive

system

OVARY OR

FOLLICLE

Estradiol other

estrogen

Stimulates sex characteristics,

sex urge

Decline of

secondary sex cha

racteristics

(deficiency)

OVARY OR

CORPUS

LUTEUM

Progesterone Promotes thickenings of the

endometrium; induce mammary

gland enlargement; inhibits

further ovulation by

antagonizing FSH secretion

Abortion during

pregnancy

(deficiency)

Gland/Source HORMONES FUNCTIONS EFFECTS OF

DEFICIENCY OR

EXCESS

PLACENTA

(pregnancy)

progesterone Maintains thickenings of

the endometrium.

PINEAL GLAND melatonin Concentrates the pigment

of melanophores of fishes

and amphibians; inhibits

gonadal dev’t. and is

involved in the regulation

of circadian rhythms