Anatomy of pituitary

Question 1

Where is the pituitary?

Answer 1

Sits in the hypopheseal fossa in the sella turcica in the sphenoid bone. Below the 3rd ventricle which is b/w two halves of hypothalamus. Right close to optic chiasm

Question 2

How can you remove a pituitary gland tumour?

Answer 2

Transnasal approach. Don’t need to do craniotomy

Question 3

Parts of pituitary and fn

Answer 3

Pars tuberalis: ant.; infundibulum: post., aka stalk; Pars intermedia: also makes some hormones. Pars distalis/anterior pituitary/adenohypophysis: produces hormones. Pars nervosa/posterior pituitary/neurohypophysis: releases hormones made in hypothalamus. Picture.

Question 4

Histology of pituitary and fn of cell types

Answer 4

Neurohypo. looks like nerve tissue, adenohypo. more capsules, basophilic cells make hormones that stimulate other glands, acidophilic cells make hormone that act directly on target cells

Question 5

Hormones and fn from the neurohypophysis

Answer 5

1. ANTIDIURETIC HORMONE (ADH, vasopressin): in response to rise in electrolytes or fall in BP or blood volume; Decreases H2O lost at kidneys; Causes constriction of peripheral blood vessels -> increase in BP. 2. OXYTOCIN: uterine smooth muscle contraction (parturition); contraction of myoepithelial cells (lactation); Male – smooth muscle contractions in prostate gland

Question 6

Which hormones are secreted by adenohypophysis?

Answer 6

Thyroid-stimulating hormone (TSH). Adrenocorticotropic hormone (ACTH). Follicle-stimulating hormone (FSH, follitropin). Luteinizing hormone (LH, lutropin). Prolactin (PRL, leutotropic hormone). Growth hormone (GH) (Human growth hormone, somatotropin).

Question 7

Which hormones are secreted by pars intermedia?

Answer 7

Melanocyte-stimulating hormone (MSH, melanotropin)

Question 8

How does the hypothalamus communicate with neurohypophysis?

Answer 8

Paraventricular nucleus makes oxytocin, supraoptic nucleus makes ADH; descend in granules along axons of neurosecretory neurons via Hypothalamo-hypophyseal tract, and are released from neurohypophysis

Question 9

How does the hypothalamus communicate with adenohypophysis?

Answer 9

Hypo. releases hypothalamic releasing factors, travel via hypophyseal portal system (hypophyseal arteries/veins); stimulate endocrine cells in ant. pituitary; hormones released into hypophyseal veins (!)

Question 10

What would you expect as symptoms of a pituitary tumour?

Answer 10

Pituitary tumour causes vision problems (tunnel vision) because it presses right on the optic chiasm.

Question 11

Summary of functions of pituitary hormones

Answer 11

Picture.