Hypothalamic pituritary axis

Question 1

what are the features of endocrine glands

Answer 1

ductless
may be endocrine, paracrine or autocrine
very vascular with fenestrated capillaries
some are discrete organs and some are associated with other tissues
may have complex embryology

Question 2

what stimulated secretion of parathyroid hormone

Answer 2

low Ca blood conc

Question 3

what hormone is released by the pineal gland

Answer 3

melatonin

Question 4

what hormone is released by the thymus

Answer 4

thymopoietin

Question 5

what hormone is released by adipose tissue

Answer 5

leptin

Question 6

what structure encloses the pituritary gland superiorly

Answer 6

diaphragma sellae

Question 7

what structures are the pituitary gland related to

Answer 7

optic chiasma and spenoid sinus

Question 8

what is the neurohypophysis

Answer 8

posterior pituitary gland

Question 9

what is the adenohypophysis

Answer 9

anterior pituitary gland

contains the pars anterior, pars tuberalis and pars intermedia

Question 10

what is the pars intermedia derived from

Answer 10

rathke’s pouch

lies between the ant and post lobes
contains colloid filled, epithelial lined follicles
obscure function
contains basophilic cells

Question 11

how does the anterior pituitary gland develop

Answer 11

up growth of epithelium from the oral cavity (Rathke’s pouch)
Rathke’s pouch loses contact with the oral cavity

Question 12

how does the posterior pituitary develop

Answer 12

down growth from the brain infundibulum as a diverticulum

Question 13

what is a craniopharyngioma

Answer 13

slow growing tumour which may develop along the track of Rathke’s pouch (benign)

Question 14

how can secretory cells of the anterior gland be classified

Answer 14

how they stain

chromophils: acidophils (GH and prolactin)
Basophils (the others)

chromophobes do not stain

Question 15

what neurohormones are released by the hypothalamus

Answer 15

Thyrotropin releasing hormone
corticotropin releasing hormone
growth releasing hormone
somatostatin growth hormone release inhibiting hormone
gonadotrophin releasing hormone
prolactin releasing factor
prolactin release inhibiting factor (PIF)

Question 16

what neurohormones are released from the posterior pituitary

Answer 16

vasopressin
antidiuretic peptide
oxytocin

Question 17

what are trophic hormones

Answer 17

act on other endocrine glands

Question 18

what trophic hormones are released by the anterior pituitary

Answer 18

thyrotropin (thyroid stimulating hormone)
corticotropin (adrenocorticotropic hormone, ACTH)
Lutinising hormone
follicle stimulating hormone

Question 19

what hormones acting on peripheral targets are released by the anterior pituitary gland

Answer 19

somatotropin (growth hormone)
prolactin (PL)
melanotropin (melanocyte stimulating hormone)

Question 20

describe the release of growth hormone

Answer 20

cells in the arcuate nucleus secrete growth hormone releasing hormone that is released into the hypophyseal portal blood supply
this causes somatotrophs to release GH

in order to inhibit growth hormone somatostatin is released by cells in the periventricular region

Question 21

when is growth hormone release greatest

Answer 21

during sleep

Question 22

what are the functions of growth hormone

Answer 22

inhibits growth hormone release
increases cartilage and bone growth
increased protein synthesis, cell growth and proliferation
increased lipolysis
increased blood glucose and other anti insulin effects

Question 23

how does growth hormone increase cartilage, bone, protein synthesis

Answer 23

by stimulating insulin like growth factors from the liver

Question 24

what are the consequences of growth hormone release

Answer 24

increased linear growth and lean body mass
important for post natal development and rapid growth throughout puberty
maintenance of protein synthesis and tissue function in adults

Question 25

what are the effects of GH deficiency in children

Answer 25

dwarfism decreased availability of lipids and glucose for energy (treatment is effective with human growth hormone)

Question 26

what is the effect of GH excess before puberty

Answer 26

gigantism due to excess stimulation of epiphyseal plates

Question 27

what is the effect of GH excess after puberty

Answer 27

periosteal bone growth causing enlarged hand, jaw and feet soft tissue growth leading to enlarged tongue, and coarse facial features insulin resistance (diabetes) can be treated with somatostatins (octreotide) varying success

Question 28

what are the signs and symptoms of acromegaly/ gigantism

Answer 28

``` enlargement of hands and feet rapid growth soft tissue swelling skin tags muscle weakness fatigue skin changes hirsutism coarsening of facial features joint pain amenorrhea hyperhidrosis sleep apnea headaches paraesthesia/ carpal tunnel impotence hypertension goiter visual field defects ```

Question 29

where is vasopressin synthesised

Answer 29

neurosecretory cells in the supra optic nucleus and paraventricular nucleus

Question 30

what stimulates ADH release

Answer 30

increase in blood osmolality decrease blood volume angiotensin 2 release

Question 31

what are the effects of ADH

Answer 31

recruitment of APQ channels | water retention

Question 32

what are the causes of ADH deficiency (diabetes insipidus)

Answer 32

tumours, trauma, disease induced, familial disorders | nephrogenic - sex linked genetic defect in collecting tubule

Question 33

what are the symptoms of diabetes insipidus

Answer 33

polyuria and polydipsia

Question 34

where is oxytocin produced

Answer 34

hypothalamic neurons in the paraventricular and supraoptic nuclei

Question 35

where is oxytocin released

Answer 35

``` posterior pituitary (stored in vesicles in the expanded ends of the axons) release is controlled by impulses from the hypothalamus ```

Question 36

describe the hypothalamic control of milk production and ejection

Answer 36

sucking stimulus travels from breast to hypothalamus dopamine release from the arcuate nucleus is inhibited dopamine normally inhibits lactotrophs in the anterior pituitary. prolactin is released which stimulates milk production oxytocin is released from the paraventricular and supraoptic nuclei, it then travels to the posterior pituitary and is released into the blood it travels to the breast and myoepithelial cells GnRH is inhibited which inhibits the menstrual cycle

Question 37

where is the pineal gland

Answer 37

midline of the posterior part of the roof of the 3rd ventricle

Question 38

what hormone is melatonin derived from

Answer 38

tryptophan

Question 39

what are the features of melatonin

Answer 39

``` secreted in darkness regulates circadian rhythms regulates onset of puberty effects on aging and immune system accumulates calcium phosphate with time - 'brain sand' visible on x-ray ```