The hypothalamic-pituitary axis

Question 1

Pineal gland

Answer 1

located anterior to medulla above the third ventricle
functions as a third eye, light sensitive, and releases melatonin
promotes sleep
cyclic production over 24 hours

Question 2

Hypothalamus

Answer 2

neuroendocrine glands secreting various tropic hormones from neurons into a portal circulatory system that delivers hormones to the anterior pituitary

Question 3

Tropic hormones

Answer 3

hormones that act on other hormone secreting glands

Question 4

Thyrotropin releasing hormone (TRH/TRF)

Answer 4

stimulates anterior pituitary to secrete TSH

Question 5

Corticotropin releasing hormone (CRH/CRF)

Answer 5

stimulates anterior pituitary to secrete ACTH

Question 6

Growth hormone releasing hormone (GHRH/GHRF/GRF)

Answer 6

works with somatostatin to work on the anterior pituitary to control GH production

Question 7

Gonadotropin releasing hormone (GnRH/LHRH)

Answer 7

stimulates the anterior pituitary to secrete LH/FSH –> ovaries/testes
L for luteinizing

Question 8

Dopamine (DA/PIH)

Answer 8

inhibits release of prolactin from anterior pituitary

prolactin stimulates the breasts to produce milk

Question 9

Adenocorticotropic hormone (ACTH)

Answer 9

Target organ: Adrenal galnd

Synthesis of glucocorticoids

Question 10

Follicle stimulating hormone (FSH)

Answer 10

Target organ: Ovaries/testes

Growth of reproductive system

Question 11

Growth hormone (GH, HGH)

Answer 11

Target: liver, bone, adipose tissue

promotes growth, lipid and carbohydrate metabolism

Question 12

Luteinizing hormone (LH)

Answer 12

Target: ovaries/testes

Sex hormone production

Question 13

Prolactin (PRL)

Answer 13

Target: Ovaries, mammary glands

Secretion of estrogens/progesterone, milk

Question 14

Thyroid stimulating hormone (TSH)

Answer 14

Thyroid gland

Secrertion of thyroid hormones

Question 15

Hormones are produced by

Answer 15

Anterior pituitary by distinct cell types for each hormone

Question 16

Tumors in the anterior pituitary can result in…

Answer 16

overproduction of the hormone derived from that tissue

Question 17

Trans-sphenoidal surgery

Answer 17

through the nose

performed to remove the adenomas

Question 18

Posterior pituitary gland

Answer 18

some neurons of hypothalamus have cell bodies in hypothalamus and axon termini in the posterior pituitary
ex. oxytocin and ADh are produced in the cell body and stored in posterior pituitary and later secreted in a regulated manner

Question 19

Oxytocin

Answer 19

stimulates uterine contraction in females during childbirth
can be administered to induce labor
also stimulates release of milk from the breast

Question 20

Anti-diuretic hormone (ADH)

Answer 20

acts on receptors in the kidney to promote translocation and insertion of water channels (aquaporins) into the PM of the renal collecting ducts
permits reabsorption of water by the kidneys –> more concentrated urine
stimulated by dehydration or low blood pressure
osmoreceptors in hypothalamus sense high osmolarity to stimulate ADH secretion
baroreceptors sense low blood pressure to stimulate ADH secretion from posterior pituitary
serum/urine osmolarity is measured by OSMOMETRY

Question 21

Central Diabetes Insipidus

Answer 21

caused by damage to the hypothalamus or the pituitary
inadequate ADH secretion –> high serum osmolarity and low urine osmolarity
high urine output and thirst
can be treated with ADH analogs

Question 22

Nephrogenic Diabetes Insipidus

Answer 22

results from an impaired ability of kidneys to respond to ADH
can be acquired, medication induced, or inherited
ADH level is usualy high
high serum osmolarity
low urine osmolarity with high urine volume output an thirst

Question 23

Syndrome of inappropriate ADH secretion (SIADH)

Answer 23

overproduction of ADH
caused by some drugs, head injuries, ectopic production)
results in excess water reabsorption –> hyponatremia
concentrated urine
treated by removing underlying cause and fluid restriction