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Cardiovascular system
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Acyanotic congenital heart defects: Pathology review
Aortic dissections and aneurysms: Pathology review
Atherosclerosis and arteriosclerosis: Pathology review
Cardiac and vascular tumors: Pathology review
Cardiomyopathies: Pathology review
Coronary artery disease: Pathology review
Cyanotic congenital heart defects: Pathology review
Dyslipidemias: Pathology review
Endocarditis: Pathology review
Heart blocks: Pathology review
Heart failure: Pathology review
Hypertension: Pathology review
Pericardial disease: Pathology review
Peripheral artery disease: Pathology review
Shock: Pathology review
Supraventricular arrhythmias: Pathology review
Valvular heart disease: Pathology review
Vasculitis: Pathology review
Ventricular arrhythmias: Pathology review
Cushing syndrome
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Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome p. 354
in Cushing syndrome p. 221, 354
Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome and p. 354
in Cushing syndrome p. 354
acanthosis nigricans and p. 495
anovulation with p. 669
corticosteroids p. 118
hirsutism p. 354
paraneoplastic syndrome p. 221
small cell lung cancer p. 709
Cushing syndrome diagnosis p. 354
Cushing syndrome diagnosis p. 354
Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome p. 354
Cushing syndrome and p. 354
Cushing syndrome p. 354
Cushing syndrome, named after the famous neurosurgeon, Harvey Cushing who first described it, is an endocrine disorder with elevated cortisol levels in the blood. In some cases, Cushing syndrome results from a pituitary adenoma making excess ACTH, and in those situations it’s called Cushing disease.
Normally, the hypothalamus, which is located at the base of the brain, secretes corticotropin-releasing hormone, known as CRH, which stimulates the pituitary gland to secrete adrenocorticotropic hormone, known as ACTH. ACTH, then, travels to the pair of adrenal glands, on top of each kidney, where it specifically targets cells in the adrenal cortex.
The adrenal cortex is the outer part of the adrenal gland and is subdivided into three layers- the zona glomerulosa, the zona fasciculata, and the zona reticularis. Zona fasciculata is the middle zone and also the widest zone and it takes up the majority of the volume of the whole adrenal gland.
The ACTH specifically stimulates cells in this zone to secrete cortisol, which belongs to a class of steroids, or lipid-soluble hormones, called glucocorticoids. Glucocorticoids are not soluble in water, so most cortisol in the blood is bound to a special carrier protein, called cortisol-binding globulin, and only about 5% is unbound or free. In fact, only this small fraction of free cortisol is biologically active, and its levels are carefully controlled. Excess free cortisol is filtered in kidneys and dumped into the urine.
Free cortisol in the blood is involved in a number of things and it’s part of the circadian rhythm. Cortisol levels peak in the morning, when the body knows we need to “get up and go” and then drop in the evening, when we’re preparing for sleep. In times of stress, the body needs to have plenty of energy substrates around, so cortisol increases gluconeogenesis, which is the synthesis of new glucose molecules, proteolysis, which is the breakdown of protein and lipolysis, which is the breakdown of fat.
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