Endocrines Endocrinology Endocrines & Endocrinology

Endocrines Endocrines &

EndocriEndocrinologynology

The functions of the endocrine system cover a broad range of action.

Endocrine activity affects the entire body: growth and development, metabolism, sexual activity, mental ability and emotions.

The endocrine system is a means of communication between one body part and another.

Physiology

Homeostasisstate of equilibrium

Hormones (chemical messengers)Target Tissues or Target OrgansHypersecretionHyposecretion

Hormones

chemical substances produced by specialized cells (glands)

released slowly, minute amounts, circulate in blood

some hormones effect the entire body, some effect target organs

most hormones are inactivated or excreted by the liver and kidneys

one pituitary glandone thyroid glandfour parathyroid glandstwo adrenal glandsone pancreasone pineal gland

Pituitary or Master Gland

posterior lobeneurohypophysis

anterior lobeadenohypophysis

Anterior Lobe

growth hormone GH somatotropinthyroid-stimulating hormone TSHlactogenic hormone Prolactin adrenocorticotropic hormone ACTHfollicle-stimulating hormone FSHluteinizing hormone LH

Posterior Lobe

antidiuretic hormone ADHdecrease ADH causes increase urine outputincrease ADH causes decrease urine output

oxytocin stimulates contraction of pregnant uterus,

labor, and childbirthstimulates milk secretionerection/orgasm

Pituitary Pathology

Growth Hormone GHdwarfism - hyposecretiongiantism, acromegaly - hypersecretion

Thyroid Stimulating Hormone TSHcretinism (infants) - hyposecretionmyxedema (adults) - hyposecretiontoxic goiter (adults) - hypersecretion

exophthalmos

Thyroid

thyroxine, T4triiodothytonine, T3regulates rate of cellular

metabolism influences physical and

mental developmenteuthyroidism

Stimulates cellular metabolism by increasing the rate of oxygen use with subsequent energy and heat production

Faster cellular metabolism increases the cell’s demand for oxygen, so more O2 must be circulated.Increase demand on circulatory system leads

to increase pulse rate and heart activity.

Parathyroid Glands

four glandsparathyroid hormone PTHregulates the level of circulating calcium

and phosphatetarget organs: bones, intestines, kidneys

Calcium is essential to blood-clotting mechanism

Calcium increases the tone of heart muscle

Calcium plays a significant role in muscle contraction

When blood calcium levels drop, PTH is secreted to increase calcium levels

Pathology of Parathyroid

Hypoparathyroidismhypocalcemia

lowers electrical threshold causes neurons to depolarize easier

tetanysustained muscular contractionlaryngeal muscle spasms leading to

respiratory tract obstruction and deathsharp flexion of some skeletal muscles

Hyperparathyroidism

often due to benign tumordemineralization of bones (osteitis fibrosa

cystica)osteoporosis

Adrenal Glands

Suprarenal glands (glandulae suprarenales)

adrenal cortexadrenal medulla

Adrenal Cortexstimulated by ACTH from anterior pituitarymineralocorticoids - regulates water & salts

aldosterone

glucocorticoids - regulates carbohydrate, lipid, and protein metabolismcortisol

sex hormonesandrogens - maleestrogen - female

Adrenal Medulla

epinephrine or adrenalinesecreted in stress situationsstimulates sympathetic nervous systemincreases HR, blood glucose, stimulates

BPvasoconstriction to shunt blood

norepinephrine or noradrenalinepowerful vasopressor to increase BP

Adrenal Pathology

Pheochromocytoma adrenal medulla tumorincrease BP due to release of

catacholamines

Addison’s disease - decrease cortisolhyponatremia, dehydrationhyperkalemia

Cushing’s disease - increase cortisolmoon face, hirsutism

Pineal Gland

melatonin-may control biological cyclesserotonin-neurotransmitter,

vasoconstrictorstimulates smooth muscles and inhibits

gastric secretion

Diabetes Insipidus

Insufficient ADHInability of kidneys to respond to ADH

extreme polydipsia and polyuria

Pancreas

Endocrine and exocrine functionsislets of Langerhansglucagon (Alpha cells)

stimulates liver to convert glycogen to glucose

insulin (Beta cells)transports glucose into cells for

metabolism and energy source

Diabetes Mellitus

inadequate amount of insulin secretedin absence of insulin; glucose cannot enter

the cells for normal metabolismresults in hyperglycemiablood sugar may increase from 300 to 1200

mg/dl of blood and even highercells deprived of principal nutrient, glucoseglycosuria, diuresis, polydipsia, polyphagia

Insulin-dependent diabetes mellitus IDDMType IJuvenile diabetesdestruction of Beta cellsmore serious formrequires daily insulin injections

Non-insulin-dependent diabetes mellitusNIDDMtype IImaturity onset diabetesless severe, often diet controlledoral hypoglycemic agents

A prolonged, excessively high carbohydrate diet over time stimulates the beta cells to secrete insulin.

Result: beta cells “burn out”.

diabetic ketoacidosis (acidosis)due to insulin deficiency, stressmetabolic shift results in excessive

accumulation of ketones

gestational diabetes mellitusdeficiency of insulin during pregnancy