anterior pituitary

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anterior pituitary

1. Adenohypophysis.

2. A preparation of dried, defatted, powdered anterior lobe of the pituitary gland of domestic animals.

anterior pituitary

endocrine gland, part of the pituitary gland at the base of the brain. Secretes growth hormone (with widespread actions on growth and metabolism), prolactin (promoting lactation) and 'trophic' hormones that regulate in turn the endocrine secretions of the adrenal cortex, of the thyroid gland, and those from the gonads involved in reproductive function. All these secretory functions are themselves controlled by 'releasing' and in some instances also 'inhibitory' hormones from the hypothalamus via local blood vessels. See also hormones, posterior pituitary; 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

situated at or directed toward the front; opposite of posterior. In quadrupeds the use of the term is limited to parts of the head but is often used to mean cranially. In bipeds such as humans it is synonymous with ventral.

anterior abdomen pain

elicited pain in the anterior abdomen caused, in cattle, by reticulitis, hepatic or splenic abscess, abomasal ulcer and intestinal obstruction.

anterior chamber

the part of the eyeball between the cornea and the iris, filled with aqueous humor.

anterior chamber angle

see iridocorneal angle.

anterior compartment

chamber of the eye bounded by the iris and cornea; contains the aqueous humor as it moves to the filtration angle; called also anterior chamber.

anterior cruciate ligament

see cranial (anterior) cruciate ligament.

anterior (cranial) drawer sign

cranial, nonrotary movement of the proximal tibia in relation to the distal femur. Normally restricted by the cranial (anterior) cruciate ligament and used as a diagnostic test for rupture of that structure.

anterior epithelial layer

of the cornea is a noncornified, stratified, squamous epithelium, continuous with the bulbar conjunctival epithelium.

anterior functional stenosis

achalasia of the reticulo-omasal sphincter causing ingesta to accumulate in the reticulorumen.

anterior limiting membrane

of the cornea is a combination of the basement membrane, a felted layer of fine collagen fibers; substantial only in primates.

anterior pituitary

see adenohypophysis.

anterior pituitary hormones

see adenohypophysis.

anterior station trypanosomes

a section of the genus Trypanosoma in which the infectious stages accumulate in the mouthparts and salivary glands of the intermediate host so that the parasite is transmitted when the insect vector takes a blood meal. Called also Salivaria. See also posterior station trypanosomes.

anterior vena cava

see vena cava.

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