Endocrinology Lec.1

8/21/2019 Endocrinology Lec.1

1/48

Jardine Jade Albert C. Valdez, RMT


2/48

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


3/48

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


4/48

NON ENDOCRINE

GLANDS Hypothalamus

Thymus

Pancreas

Ovaries Testes

Kidneys

Stomach

Liver Adipose tissue

Placenta


5/48

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


6/48

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


7/48

Types of hormone action

Endocrine

Paracrine

Autocrine

Juxtacrine

Exocrine

Neurocrine Neuroendocrine

Cl ifi i f H


8/48

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


9/48

Amines

They are derived from amino acid and they

are intermediary between steroid andprotein hormones.


10/48

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


11/48


12/48

Releasing hormones regulateAnterior Pituitary

Growth hormone-releasing H.

Growth hormone-inhibiting H.

Thyrotropin-releasing H.

Corticotropin-releasing H.

Gonadotropin-releasing H.

Prolactin-releasing H.


13/48

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.


14/48

Hormone secreted

: MELATONIN

It is known as

dracula of hormonebec. of the pattern

of hormone

Produce/ increase

during Late night


15/48

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.


16/48

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


17/48

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


18/48

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


19/48

DIRECT HORMONES

GH: has direct effect on substrate

metabolism in numerous tissues

Prolactin


20/48

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


21/48

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 __


22/48

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)


23/48

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)


24/48

Its overall metabolic effect is to

metabolize fat stores while conserving

glucose

Ref. value(fasting)


25/48

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.


26/48

Growth hormone

Over secretion in

youth produces

giantism Over secretion in

adult produces

acromegaly


27/48

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


28/48

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


29/48

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.


30/48

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.


31/48

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.


32/48

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.


33/48

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.


34/48

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.


35/48

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.


36/48

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.


37/48

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


38/48

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.


39/48

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


40/48

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


41/48

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


42/48

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.


43/48

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.


44/48

Oxytocin

Stimulates smooth muscle contraction of

uterus & mammary glands.

Antidiuretic H. Stimulates water reabsorption in collecting

ducts.

Stimulates vasoconstriction (vasopressin)

Lackdiabetes insipidus


45/48

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.


46/48

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.


47/48

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.


48/48

THANK YOU!!!

Endocrinology Lec.1

Documents

Transcript of Endocrinology Lec.1