Endocrines Endocrines & Endocri Endocri nology nology
Jan 04, 2016
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