1.
The hormone action
The endocrine system uses hormones to convey information between different tissues. Hormones derive from the major classes of biologic molecules, this can be proteins
including glycoproteins, peptides or peptide derivatives, amino acid analogs, or lipids. Endocrine hormones are part of a large complement of small intercellular signaling
molecules.
The system of internal hormone secretion is subject to complex regulatory mechanisms that govern receptor activity and hormone synthesis, release, transport,
metabolism, and delivery to the target cells. Hormones bind specifically to hormone receptors and translate the signal into biologic activity. The receptors can be expressed on
the cell surface or within the cell.
Hormone response is regulated by hormone concentration. This in turn is governed by hormone production, efficiency of delivery and metabolism. The classic disorders of the
endocrine system arise from state of excess or deficiency of hormones, however resistance to hormones also play a role. Disorders of the endocrine system will discuss in each part of
the gland.
2. Pituitary gland and hypothalamus
The pituitary gland lies on the base of the skull in a portion of the sphenoid bone called the sella tursica. The hypothalamus and pituitary gland form a unit which exerts control over the
function of several endocrine glands: thyroid, adrenal, and gonads, as well as a wide range physiologic activities. This unit constitutes a paradigm of neuroendocrinology: brain-
endocrine interactions.
The hypothalamic hormones can be divided into those secreted into hyppophysial portal blood vessels and those secreted by the neurohypophysis directly into the general
circulation. The hypophysiotropic hormones regulate the secretion of anterior pituitary hormones, include growth hormone-releasing hormone GHRH, thyrotropin-releasing
hormone TRH, corticotrophin-releasing hormone CRH, and gonadotropoin-releasing hormone GnRH. The six major anterior pituitary hormones are adrenocorticotropic
hormone ACTH, growth hormone GH, prolactin PRL, TSH, LH, and FSH. The posterior pituitary hormones are antidiuretic hormone ADH and oxytocin.
Hypothalamic and pituitary lesions present with a variety of manifestations, including pituitary hyper- and hyposecretion, sellar enlargement, and visual loss.
PRL hypersecretion is the most common endocrine abnormality due to hypothalamic-pituitary disorders, and PRL is the hormone most commonly secreted in
excess by pituitary adenoma. GH-secreting adenomas are second in frequency to prolactinoma and cause the classic syndromes of acromegaly and gigantism.
The major effect of ADH is to increase the water permeability of the luminal membrane of the collecting duct in the kidney. Diabetes insipidus is a disorder resulting from
deficient ADH action and is characterized by the passage of amounts of very dilute urine.
3. Pancreas and Diabetes mellitus
The pancreas is made up of two functionally different organs: exocrine and endocrine. The major product of exocrine pancreas is the digestive enzims. The endocrine pancreas
consists of 0.7-1 million small endocrine glands – the islets of Langerhans – scattered within the glandular substance of the exocrine pancreas. The product of endocrine pancreas are:
insulin, glucagon, somatostatin, and pancreatic polypeptide.
Udayana University Departement of Medicine Education, DME
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11. CONTENT OUTLINE
Clinical diabetes mellitus is a syndrome of disordered metabolism with inappropriate hyperglycemia due either to absolute deficiency of insulin secretion or a reduction in the
biologic effectiveness of insulin insulin resistance, or both. Type 1 diabetes is the severe form of diabetes mellitus and is associated with ketosis in the untreated state. While type 2
diabetes – previously classified as non-insulin-dependent-diabetes NIDDM afflict patient with insulin resistance who generally have relative insulin deficiency. There are also other
types of diabetes. Patient with diabetes needs a proper diet, exercise, and also pharmacologic agent, such as insulin or oral anti diabetes. Oral anti diabetes fall into three
categories: 1 drugs that stimulate insulin secretion, 2 drug that alter the insulin action, 3 drug that principally affect absorption of glucose.
In most patient with diabetes, a number of pathologic changes occur at variable intervals during the course of the disease. There are also acute complications either cause
by hypoglycemia or hyperglycemia.
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. Lipid metabolism and disorders
The clinical importance of dislipidemia is mainly from the role of lipoprotein in atherosclerosis. Because lipid are relatively insoluble in water, they are transported in
association with proteins. The simplest complexes are those formed between unesterified or free, fatty acids FFA and albumin, which serve to carry the FFA from peripheral adipocytes
to other tissue. Cholesterol in the atheroma originates in circulating lipoprotein. Atherogenic lipoproteins include low-density LDL, intermediate density IDL, very low density VLDL,
and Lpa species.
Initial treatment in all forms of hyperlipidemia is an appropriate diet. Patient with severe hypercholesterolemia will require drug therapy. The increased risk of acute
pancreatitis associated with hypertriglyceridemia is another indication for intervention.
5.
Energy balance and metabolism disorder, obesity and metabolic syndrome
The energy balance equation is dynamic and this may explain why there is a long-term relative stability of body weight and fat stores. The three determinants of body fat stores are
intake, expenditure, and nutrient partitioning, each under complex control. Obesity is a disorder of body composition defined by relative or absolute excess of
body fat and characterized by several remarkable features. It is difficult to certain the relationship between obesity and disease, because it is confounded by many metabolic and
hormonal that either contribute to or derive from excess adiposity. Obesity and abdominal obesity are closely associated with dyslipidemia, hypertension, insulin resistance, and
diabetes. The abdominal adipose tissue has several features of interest in connection with the metabolic syndrome. This is the reason of The ATP III definition of the metabolic
syndrome lists the waist circumference as a diagnostic factor of the metabolic syndrome.
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. Thyroid gland
Thyroid gland is the largest organ specialized for endocrine function in the human body. The major function of thyroid gland is to secrete a sufficient amount of thyroid hormones, which
promote normal growth and development, regulate a number of homeostatic function including energy and heat production.
Patient with thyroid disease will usually complain of thyroid enlargement diffuse or nodular, symptoms of thyroid deficiency hypothyroidism, symptoms of thyroid hormone
excess hyperthyroidism, or complication of specific form of Grave’s disease. Thyrotoxic crisis thyroid storm is one of an acute state that requires vigorous management.
Udayana University Departement of Medicine Education, DME
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7. Mineral metabolism and parathyroid gland
