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Jardine Jade Albert C. Valdez, RMT
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ENDOCRINOLOGY
The science of the structure and
function of the endocrine glands and the
diagnosis and treatment of disorders of
the endocrine system
Endo: within
Crino: to secrete
Logy:study of
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ENDOCRINE GLANDS
Pituitary gland
Thyroid gland
Parathyroid gland
Adrenal gland Pineal gland
Secrete hormones Hormone: mediator molecule that is released
in one part of the body but regulatesactivity
of cells in other parts of the body
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NON ENDOCRINE
GLANDS Hypothalamus
Thymus
Pancreas
Ovaries Testes
Kidneys
Stomach
Liver Adipose tissue
Placenta
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Hormones
Chemical signals produced by
specialized cells secreted into the blood
stream and carried to a target tissue.
They play an important role in thegrowth and development of an organism
They are regulated by the metabolic
activity either positive or negativefeedback mechanism
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Positive feedback systeman
increased in the product also increases
the activity of the system and the
production rate
Negative feedback system - an
increased in the product decreases theactivity of the system and the production
rate
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Types of hormone action
Endocrine
Paracrine
Autocrine
Juxtacrine
Exocrine
Neurocrine Neuroendocrine
Cl ifi i f H
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Classification of Hormones
according to composition or
structure: Peptides and proteins Synthesized and stored within the cells in
the form of secretory granules and are
cleaved as needed Steroids
Are lipid molecules that have cholesterol as
a common precursor
Water insoluble, bound to carrier protein
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Amines
They are derived from amino acid and they
are intermediary between steroid andprotein hormones.
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Hypothalamus
Is the portion of the brain located in
the wall and floor of the third ventricle.
It is above the pituitary gland, and is
connected to the posterior pituitary by
the infundibulum (pituitary stalk)
The link between the nervous system
and the endocrine system
Hypothalamic cell bodies synthesize
oxytocin and ADH
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Releasing hormones regulateAnterior Pituitary
Growth hormone-releasing H.
Growth hormone-inhibiting H.
Thyrotropin-releasing H.
Corticotropin-releasing H.
Gonadotropin-releasing H.
Prolactin-releasing H.
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Endocrine glands
PINEAL GLAND
Other name: Epiphysis Cerebri
Anatomical structure: Is a small organ,
weighing little more than 0.1 gram
A pinecone shaped gland.
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Hormone secreted
: MELATONIN
It is known as
dracula of hormonebec. of the pattern
of hormone
Produce/ increase
during Late night
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Target tissue : blood vessel, ovaries,GIT, brain
Functions of melatonin: Generates the fight or flight response
Regulates mood
Lowers body temperature, release stress.
Regulates sexual development
Regulates daily cycles in response to theamount of light in the environment.
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GLAND Is known as the MASTER GLAND
It is located in a small cavity in the
sphenoid bone of the skull called the
SELLA TURCICA or TURKISH SADDLE
All pituitary hormones have circadian
rhythms
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ANTERIOR PITUITARY
HORMONES
Hormones are larger and more complex
as compared to the hormones released
by the hypothalamus
Hormones are either tropic or direct
Tropic: actions are specific for another
endocrine gland
Direct: acts directly on peripheral tissue
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TROPIC HORMONES
LH: directs testosterone production from
Leydig cells in men and ovulation in women
TSH: directs thyroid hormone production
form the thyroid
FSH: folliculogenesis in women and
spermatogenis in men
ACTH: regulates adrenal steroidogenesis
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DIRECT HORMONES
GH: has direct effect on substrate
metabolism in numerous tissues
Prolactin
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ANTERIOR PITUITARY SECRETION CONTROL
1STneurosecretory cells in the hypothalamus secretes 5
releasing hormones and 2 inhibiting hormones which
suppress secretion of anterior pituitary hormones
Hormone Secreted
by
Stimulates
secretion/
Releasing
hormone
Suppress secretion
/
Inhibiting hormone
GH/Somatotropin Somatotrophs GHRH/Somatocrini
n
GHIH/Somatostatin
TSH/Thyrotropin Thyrotrophs Thyrotropin
releasing hormone
GHIH
FSH Gonadotrophs Gonadotrophicreleasing
hormone(GnRH)
___
LH Gonadotrophs GnRH ___
Prolactin Lactotrophs PRH PIH
ANTERIOR PITUITARY SECRETION
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2ndnegative feedback in the form of hormones
releases by target glands decrease secretion ofanterior pituitary cells
ANTERIOR PITUITARY SECRETION
CONTROL
Anterior Pituitary
Hormone
Target
gland
Feedback
hormone
LH Gonad Sex steroids
FSH Gonad Inhibin
TSH Thyroid T3 T4
ACTH Adrenal Cortisol
GH Multiple IGF-1
Prolactin Breast __
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Anterior Pituitary
Adenohypophysis
Regulates the released and productionof hormones such as:
Growth H. (hGH) Prolactin
Melanocyte-stimulating H. (MSH)
Thyroid-stimulating H. (TSH)
Adrenocorticotropic H. (ACTH)
Follicle-stimulating H. (FSH)
Luteinizing H. (LH)
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Growth hormones (GH,
hGH) The most abundant of all pituitary
hormones.
Is controlled by GH-RH and
somatostatin
The secretion is erratic and occurs in
short burst
Markedly elevated during sleep (deepsleep)
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Its overall metabolic effect is to
metabolize fat stores while conserving
glucose
Ref. value(fasting)
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Growth hormone
Lack of hGH retards
growth Charles Stratton,1838-1883, adopted &
trained by P.T. Barnum.
General Tom Thumb
~ 33 in. (84 cm) tall
Married Lavinia Warren,
1863.Died of CV disease.
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Growth hormone
Over secretion in
youth produces
giantism Over secretion in
adult produces
acromegaly
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GONADOTROPINS
Follicle Stimulating Hormone (FSH) and
Leutenizing Hormones (LH)
Fertility and menstrual cycle disorder
FSH aids in spermatogenesis (male)
LH helps leydig cells to produce
testosterone (male) and for female, it is
necessary for ovulation and the final
follicular growth
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THYROID STIMULATING
HORMONE (TSH)
Also known as thyrotropin
Stimulates thyroid hormone synthesis
It is main stimulus for the uptake of
iodide by the thyroid gland It acts to increase the number and size
of follicular cells; stimulates thyroidhormone synthesis
Blood level may contribute in theevaluation of infertility
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ADRENOCORTICOCOTROPHI
C HORMONE (ACTH)
Produce in response to low serum
cortisol; regulator of adrenal androgen
synthesis.
Highest level is between 6-8 am; lowestlevel is between 6-11 pm
Increased level: Addisons disease,
ectopic tumors, after protein-rich meals.
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PROLACTIN (PRL)
Prolactinis structurally related to GH
and human placental lactogen. Its amino
acid sequence is similar to that of
growth hormone (GH) and placentalactogen (PL) sharing genomic,
structural and biological features and
belonging to the same PRL/GH/PL
protein family.
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A product of the anterior pituitary
Prolactin (PRL) is mainly synthesized
and secreted by the lactotropes cells of
the pituitary
Considered a stresshormone
It has vital functions in relationship to
reproduction.
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Prolactin is classified as a direct effectorhormone because it has diffuse targettissue and lacks a single endocrine endorgan
Dopamineis the neuroendocrine signalthat inhibits prolactin and is nowconsidered to be the elusive Prolactininhibitory factor (PIF)
It is also regulated by several hormones,including gonadotropin releasing hormone,thyrotropin-releasing hormone andvasoactive intestinal polypeptide.
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Any compound that affects
dopaminergic activity in the median
eminence of the hypothalamus will also
alter prolactin secretion. Stimulation of breasts, as in nursing,
causes the release of prolactin secreting
hormones from the hypothalamus. The physiologic effect of prolactin is
lactation.
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HYPERPROLACTINEMIA
Modest elevations in prolactin (25100
ng/mL)may be seen with pituitary stalk
interruption, use of dopaminergic
antagonist medications, or other medicalconditions such as primary thyroidal
failure, renal failure, or polycystic ovary
syndrome.
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Any disruption of the pituitary stalk (e.g.,
tumors, trauma, or inflammation)
causes an elevation in prolactin as a
result of interruption of the flow ofdopamine from the hypothalamus to the
lactotropes.
Estrogens also directly stimulatelactotropesto synthesize prolactin.
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Significant hyperprolactinemia is also
encountered during pregnancy.
May also be seen in renal failure and
polycystic ovary syndrome
The usual consequence of prolactin
excess is hypogonadism,either by
suppression of gonadotropin secretionfrom the pituitary or by inhibition of
gonadotropin action at the gonad.
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PROLACTINOMA
A prolactinoma is a pituitary tumor that
directly secretes prolactin
Substantial elevations in prolactin (150
ng/mL) indicate prolactinoma, and thedegree of elevation in prolactin is
correlated with tumor size.
Premenopausal women most frequentlycomplain of menstrual
irregularity/amenorrhea, infertility
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Idiopathic Galactorrhea
Lactation occurring in women with
normal prolactin levelsis defined as
id iopathic galacto rrhea.
This condition is usually seen in womenwho have been pregnant several times
and has no pathologic implication.
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HYPOPITUITARISM
The failure of either the pituitary orhypothalamus results in the loss of anteriorpituitary function.
Complete loss of function is termedpanhypopi tu i tar ism
Panhypopituitarism can result fromradiotherapy used to treat a primarypituitary tumor or a pituitary that wasinadvertently included in the radiation port;loss of function, however, may be gradualand may occur over several years
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Pituitary tumors may cause
panhypopituitarismby compressing or
replacing normal tissue or interrupting the
flow of hypothalamic hormones bydestroying the pituitary stalk.
Parasellar tumors (meningiomas and
gliomas), metastatic tumors (breast and
lung), and hypothalamic tumors(craniopharyngiomas or dysgerminomas)
can also cause hypopituitarism
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monot rop ic hormone def ic iency. The
loss of a tropic hormone (ACTH, TSH,
LH, and FSH) is reflected in function
cessation of the affected endocrinegland
primary failure of an endocrine gland
that is accompanied by dramaticincreases in circulating levels of the
corresponding pituitary tropic hormone
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secondary failure (hypopituitarism) isassociated with low or normal levels oftropic hormone. In primaryhypothyroidism, for example, thecirculating levels of thyroxine are lowand TSH levels may exceed 200 U/mL(normal, 0.45.0). As a result of pituitary
failure in hypothyroidism, TSH levels areinappropriately low and typically lessthan 1.0 U/mL.
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POSTERIOR PITUITARY
Neurohypophysis - CNS
Capable of releasing the hormones
oxytoxin and vasopressin but not
capable of producing it.
The hormones released by
neurohypophysis are synthesized in the
supraoptic (ADH) and paraventricularnuclei (oxytoxin) of the hypotalamus.
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Oxytocin
Stimulates smooth muscle contraction of
uterus & mammary glands.
Antidiuretic H. Stimulates water reabsorption in collecting
ducts.
Stimulates vasoconstriction (vasopressin)
Lackdiabetes insipidus
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THYMUS GLANDAnatomical structure: PINKISH GRAY
COLOR
Pyramidal shape with two lobes connected
by areolar tissue It resembles the leaves of herbal plants
classified under the genus of thymus or
thyme
Increase in size until it reaches its maxduring puberty then progressively atrophies
with age.
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Average size:
Birth : 15 grams
Puberty :30-50 gramsproduce more T
cellsAge 65 : 5-15 grams
Location: located in the upper thoraxbehind the sternum, but below the
thyroid gland.
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Function of thymus gland : processing andmaturation of special lymphocytes called Tcells --- immunity
Hormone secreted : Thymosin
Function of Thymosin: promote the
maturation of lymphocyte within the gland. Promote the growth and activity of lymphocytes
throughout the body.
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