Adrenal glands

adrenal glands

The small internally secreting (ENDOCRINE) organs which sit like triangular caps one on top of each KIDNEY (hence the name). Each adrenal has two distinct parts, the inner core, which produces ADRENALINE, and an outer layer (the cortex) which produces various steroid hormones. Formerly known as suprarenal glands, which, of course, means the same thing.

Adrenal glands

The two glands that are located on top of the kidneys. These glands secrete several hormones, including the glucocorticoids which, among other things, influence the way the immune system works, and the mineralocorticoids, which affect retention of water and sodium.

Mentioned in: Adrenocorticotropic Hormone Test, Barbiturates, Congenital Adrenal Hyperplasia, Corticosteroids, Inhaled, Cortisol Tests, Hypoglycemia, Thyroid Hormones

adrenal glands

endocrine glands sited above each kidney. The outermost region, the adrenal cortex, secretes steroid hormones: the glucocorticoids (principally cortisol), mineralocorticoids (principally aldosterone) and androgens in both male and female. The inner adrenal medulla secretes the catecholamines, mainly adrenaline and noradrenaline, under the control of the sympathetic nervous system. See also adrenocorticotrophic hormone (ACTH), hormones, steroids; Table 1.

Table 1: Hormones

Site of production	Name of hormone	Main targets	Involved in regulating:	Secretion controlled by:
Hypothalamus	Releasing and inhibiting hormones	Anterior pituitary (via local blood vessels)	Secretion of anterior pituitary hormones	Other brain regions; feedback re regulated hormones and their actions
	Neurohormones released from posterior pituitary:
	Oxytocin	Uterus, breasts	Labour and lactation	Afferent information from target organs
	Antidiuretic hormone (ADH, vasopressin)	Kidneys	Water loss: ECF volume and osmolality	Hypothalamic osmoreceptors
Anterior pituitary	(Human) growth hormone (H)GH	Most cells	Growth and metabolism	Hypothalamic releasing and inhibiting hormones via local blood vessels
	Prolactin	Breasts	Milk production
	Trophic hormones:
	Thyroid-stimulating (TSH)	Thyroid gland	Thyroid secretions
	Gonadotrophins	Ovary or testis	Germ cell maturation and hormone secretions
	Adrenocorticotrophic (ACTH)	Adrenal cortex	Cortisol secretion
Pineal body	Melatonin	Widespread, including brain, thymus, etc.	Sleep/wake cycle Antioxidant Immune system	Hypothalamus; varying light input from retina
Thyroid	Thyroxine Triiodothyronine Calcitonin	Most cells Bone, kidneys, gut	Cellular oxidative metabolism Decreases ECF [Ca2+]	TSH from anterior pituitary. Negative feedback from blood hormone concentration ECF [Ca2+]
Parathyroids	Parathormone	Bone, kidneys, gut	Calcium and phosphorus absorption, secretion and turnover in bone. Increases ECF [Ca2+]	ECF [Ca2+]
Adrenal: Cortex	Cortisol Aldosterone Androgens	Most cells Kidneys Gonads & other tissues	Metabolism Response to stress Na and K balance Sex characteristics and reproductive function	ACTH from anterior pituitary ECF [Na+] [K+] Renin-angiotensin ACTH
Medulla	Adrenaline Noradrenaline	Heart, smooth muscle, glands	Cardiovascular and metabolic adjustments to activity and stress	Sympathetic nervous system
Atrial wall	Atrial natriuretic hormone	Kidneys	Blood volume; increases sodium (therefore also water) loss in urine	Stretch of atrial wall by venous pressure
Gonads: Testis	Androgens (mainly testosterone)	Genitalia and other tissues	Reproductive function and sex characteristics	Anterior pituitary gonadotrophins
Ovary	Oestrogens Progesterone	Uterus, breasts and other tissues	Menstrual cycle, pregnancy, lactation
Pancreas	Insulin, glucagon Somatostatin	Most cells Other secretory cells in the pancreas	Blood levels, storage and cellular uptake of nutrients, notably glucose, but also proteins and fats	Blood levels of nutrients; autonomic nervous system; other gastrointesinal hormones
Alimentary tract
Stomach	Gastrin	Gastric acid-secreting cells	Gastrointestinal functions: motility, digestive juices and other secretions	Local chemical and mechanical factors in the alimentary tract
Small intestine	Secretin Cholecystokinin- pancreozymin (CCK-PZ) Somatostatin, motilin Other peptide hormones including vasoactive intestinal peptide (VIP)	Widespread on GI tract	Several GI functions including bile flow, pancreatic enzyme and exocrine secretions	Ingestion of food, distension of GI tract