ENDOCRINE SYSTEM Hormones Selfregulating system Production Extremely small

ENDOCRINE SYSTEM

Hormones • Self-regulating system • Production – Extremely small amounts – Highly potent • Affect: – Growth – Metabolism – Behavior • Two categories: – Lipid (Steroid) – Amino acid

Pituitary • Also known as hypophysis • Located beneath brain • Divided into two lobes: – Anterior • Releases six hormones – Posterior • Releases two hormones

Thyroid and Parathyroids • Thyroid gland – Located on either side of larynx and upper trachea – Two lobes – Secretes mixture of hormones • Parathyroid glands – Located at posterior surface of thyroid – Affect calcium metabolism

Adrenal Glands • Hormones produced involved in body’s response to stress • Located atop each kidney • Divided into two regions – Outer cortex produces: • Steroid hormones • Cortisol • Aldosterone • Sex hormones – Inner medulla produces • Epinphrine • Norepinephrine

Pancreas • Islet cells produce two hormones: – Insulin • Increases cellular use of glucose • Decreases sugar levels in blood – Glucagon • Decreases cellular use of glucose • Increases sugar levels in blood

Other Endocrine Tissues • Thymus – Secretes thymosin • Gonads – Secrete sex hormones • Prostaglandins – Group of hormones produced by many cells – Variety of effects • Uterine contractions • Inflammatory response • Vasomotor activities

Clinical Aspects of Endocrine System • Endocrine diseases result from: – Hypersecretion – Hyposecretion – Secretion at wrong time – Failure of target tissue to respond • Causes may originate: – In gland itself – With hypothalamus or pituitary failing to release proper amount of hormone stimulators

Pituitary • Pituitary adenoma usually increases secretion of growth hormone – Excess in children causes gigantism – Excess in adults causes acromegaly • Treatment – Surgery – Drugs to reduce hormone level in blood

Pituitary (con’t) • Panhypopituitarism – Hypofunction of pituitary – Caused by tumor or interruption of gland’s blood supply – Widespread effects • Lack of ADH – Results in diabetes insipidus • Kidneys with diminished ability to conserve water • Symptoms include: – Polyuria – Polydipsia

Thyroid • Deficiency of thyroid hormone causes: – In infants • Physical retardation • Mental retardation • Congenital hypothyroidism – In adults • Myxedema • Hyperthyroidism – Common form is Graves disease – May result in goiter (enlarged thyroid) • Not always results from thyroid malfunction

Parathyroids • Overactivity causes high level of calcium in blood – Calcium obtained from bones – Possible development of kidney stones • Underactivity results in decreased calcium – May cause: • Tingling • Numbness • Tetany

Adrenals • Addison disease = hypofunction of adrenal cortex – Caused by: • Autoimmune destruction of gland • ACTH deficiency – Results in: • • • Water loss Low blood pressure Electrolyte imbalance Weakness Nausea Increase of brown pigmentation

Adrenals (cont’d) • Cushing syndrome = excess of adrenal cortisol hormones – Caused by: • Therapeutic administration of steroid hormones • Tumor – Results in: • • • Moon-shaped face Localized obesity Weakness Hirsutism Fluid retention

Pancreas and Diabetes • Diabetes mellitus – Most common endocrine disorder – Failure to use glucose effectively – Excess glucose causes hyperglycemia – Two types: • Type 1 (juvenile-onset or insulin-dependent) • Type 2 (adult-onset or non-insulin dependent)

Type 1 Diabetes • Usually appears in children and teenagers • Caused by failure of pancreatic islets to produce insulin • For proper management: – Monitor blood sugar levels – Give insulin in divided doses – Regulate diet

Type 2 Diabetes • Initiated by cellular resistance to insulin • May result in: – Metabolic syndrome – Hypoglycemia – Insulin shock • Diagnosed by measuring levels of glucose in blood plasma • Most cases linked to obesity • Another form is gestational diabetes mellitus