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HORMONE

ENDOCRINE SYSTEM

-

LEARNING OUTCOMES

gland

Name the endocrine glands and the

-

-

hormones secreted by each
...


-

in the secretion of hormones from the

particular hormone

pituitary gland
...


-

State the functions of the hormones of the

the

stimulus

for

-

their

-

Explain how parathyroid hormone and
Explain how insulin and glucagon work as
antagonists
...

Explain what prostaglandins are made of,
and state some of their functions
...

-

controls & integrates the functions of
other organ systems in the body

-

GENERAL EFFECTS OF HORMONES
1
...
Synthesis of proteins or certain regulatory
molecules (i
...
, enzymes) in the cell
4
...
Activation or inactivation of enzymes

secretion of each
...

cortisol, and describe the stimulus for

-

response

a

organs/tissues

calcitonin work as antagonists
...

-

cell,

organ

State the functions of thyroxine and T3,
describe

on

preprogrammed

stimulus for secretion of each
...
Steroidal Hormones
-

formed from cholesterol

-

are lipid-soluble

-

examples: cortisol, aldosterone

-

receptor is located in the target cell’s
nucleus

MECHANISM OF ACTION:
a
...
once in ICF, enters the nucleus & binds to
a receptor protein to form a hormonereceptor complex

c
...
certain genes are activated to transcribe

-

example: PTH & calcitonin

2
...
new proteins
2
...
g
...
g
...
the nervous &
endocrine system

MECHANISM OF ACTION:

-

although NOT a gland, it regulates the
secretory activity of the pituitary gland

a
...
a reaction starts inside the cell that
converts ATP into cAMP
...
cAMP activates several proteins
releasing hormones

d
...
Humoral regulation
-

-

- PRH

glands secrete their hormones in direct
response to changing levels of ions or

- GHIH or somatostatin

nutrients in the blood

- PIH

example: parathyroid gland

PITUITARY GLAND

2
...
Negative Feedback
the

divided into 2 lobes - the anterior &

hypophyseal portal veins: blood vessels

FEEDBACK MECHANISMS

-

lies in the sella turcica of the sphenoid

hypothalamus

example: thyroid gland

(refer to Unit 1)

-

posterior pituitary glands

glands secrete their hormones in response

-

also called, “hypophysis”

-

to hormones released by other endocrine
-

-

bone at the base of the brain

example: adrenal medulla

3
...
Oxytocin

hormones of the hypothalamus (hormonal

-

plays a role in childbirth & lactation

-

primarily regulated via positive feedback

-

partly responsible for the feelings of sexual

regulation)

pleasure during and after intercourse

-

FSH & LH)
-

target tissue: smooth muscles in the
walls of the uterus
stimulus: pressure on cervix

-

also called “somatotropin”

-

its release is promoted by GHRH & inhibited
by GHIH from hypothalamus (hormonal

response: uterine contraction to expel
fetus &

stimulus:

mammary

stimulating/

regulation)
-

b
...
liver & adipose tissue

mother’s nipples

specific action: lipolysis or breakdown

response: milk ejection or “let down”

of fat for energy & ↑ glucose synthesis
by the liver

2
...
Melanocytestimulating hormone (MSH)
-

stimulus: excess CRH secretion from
hypothalamus (hormonal regulation)

a) kidneys
action:

retention/reabsorption

↑

water

by

kidney

tubules
response: less water loss from the blood
into the urine, & ↓ urine volume
b) sweat glands

or

b
...
Growth Hormone (GH)

a
...
Prolactin (PRL)
-

promotes lactation

its release is promoted by PRH & inhibited

-

by PIH from hypothalamus (hormonal
regulation)
-

target tissue: mammary glands

-

response: milk production

also called “thyrotropin”

-

stimulus:

TRH

-

isthmus:

narrow,

central

portion

of

thyroid gland dividing it into left & right
-

thyroid follicles: microscopic sacs that
make up most of the gland

4
...
the follicles &
produce calcitonin

-

target organ: thyroid gland

-

response: release of thyroid hormones

THYROID GLAND HORMONES
1
...
Adrenocorticotropic hormone (ACTH)
-

also called “corticotropin”

-

stimulus:

CRH

from

-

produced from iodine

-

stimulus: release of TSH from anterior
pituitary (hormonal regulation)

hypothalamus

(hormonal regulation)

-

target cells: various body cells

-

target organ: adrenal cortex

-

effects/response: ↑ ATP production → ↑

-

response: release of hormones from

basal metabolic rate (BMR) → ↑ energy

adrenal cortex

consumption from all food types & ↑
oxygen consumption → ↑ body temp
...
Follicle-stimulating hormone (FSH)
stimulus:

-

GnRH

from

hypothalamus

ovaries

blood stimulates release of TRH from
hypothalamus

egg cells & secretion of estrogen

b) TRH is carried along hypophyseal

males: development of sperm cells

portal veins

7
...


hypothalamus

(hormonal regulation)

d) TSH is released into circulation
...


target organ: interstitial cells of testicles &

-

f) T3 & T4 is released into circulation & ↑

follicles of ovaries

metabolic rate

response:

-

protein

a) ↓ metabolic rate & ↓ T3 & T4 in the

females: development or maturation of

stimulus:

of

control of T3 & T4 secretion:

response:

-

rate

development together w/ GH)

target organ: testicles & follicles of

-

↑

synthesis (maintains normal growth &

(hormonal regulation)
-

effects/response:

g) elevated levels of T3 & T4 inhibit

females: release of mature egg cell

release of TRH & then of TSH (negative

(ovulation) & secretion of progesterone

feedback)

males: secretion of testosterone
THYROID GLAND
-

butterfly-shaped organ on anterior neck

-

located inferior to the larynx (voicebox) &

2
...
Glucagon
-

PARATHYROID GLAND
-

Four (4) small glands embedded on

-

-

target cells: liver

-

specific actions:

Parathyroid Hormone (PTH)

-

also called “parathormone”

-

important for Ca++ homeostasis

-

stimulus: hypocalcemia or i Ca++ levels in

-

-

target cells: osteoclasts & kidneys

-

specific actions:

-

to

↑

response: glucose level of blood h &
negative feedback: glucagon release is
return to normal

2
...


PANCREATIC HORMONES

-

negative

feedback:

insulin

release

is

a
...
CRH

secrete cortisol

located on top of each kidney • also called

d
...
elevated levels of cortisol inhibit

medulla

release of CRH & then of ACTH

ADRENAL CORTEX
-

outer shell of adrenal gland

-

subdivided into 3 zones:
-

zona glomerulosa (outer zone)

-

zona fasciculata (middle zone)

-

zona reticularis (inner zone)

(negative feedback)
f
...
Androgens
-

converted to estrogen or testosterone in
peripheral tissues

stimulus: angiotensin II (as a result of ↓

specific actions:
-

↑ Na+ reabsorption by the kidneys to

-

pubic hair in males & females
ADRENAL MEDULLA
-

inner core of adrenal gland

↑ K+ excretion by the kidneys

-

innervated by sympathetic division of

response: Na+ level of blood, blood
negative feedback: aldosterone release
is inhibited once blood volume, Na+ & BP
return to normal

ANS
HORMONES OF ADRENAL MEDULLA
1
...
Estrogen & Progesterone

levels
-

keeps blood glucose levels high
enough to support brain’s activities

control of cortisol secretion:

produces the fight or flight response
(refer to Unit 8)

stimulus: ACTH from anterior pituitary
gland (hormonal regulation)

stimulus: impulses from hypothalamus
(neural regulation) in response to short-

2
...
Aldosterone

pituitary

c
...
Estrogen
-

secreted by the follicle cells of the ovary

-

stimulus: FSH from anterior pituitary
(hormonal regulation)

-

functions:

-

female secondary sex characteristics

-

hormone produced: thymosin

-

promotes

-

fxn:

maturation

of

egg

cell/ovum a)

1
...
GnRH is released from hypothalamus

-

contraction of the uterus

b
...
FSH & LH stimulate ovaries
d
...
Presence of estrogen & progesterone
inhibits GnRH & then FSH & LH
(negative feedback)
TESTES- male gonads; located in scrotum

2
...
GI hormones

1
...
Progesterone
-

promotes

from

anterior

pituitary

(hormonal regulation)

-

produced by: GI tract

-

examples:

gastrin,

secretin,

cholecystokinin
-

response: regulate digestive functions by
influencing the activity of the stomach,
intestines, liver, & pancreas

FUNCTIONS OF TESTOSTERONE

4
...
Human chorionic gonadotropin (hCG)
-

superior to the heart
-

extends from lower neck to anterior
thorax

placenta

(during

fxn: maintains pregnancy by stimulating
the

ovaries

to

continue

producing

estrogen & progesterone
-

located posterior to the sternum, and

by:

pregnancy)

THYMUS
-

produced

the hormone tested during a pregnancy
test



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