Endocrine 06 - Anterior And Posterior Pituitary

Front 1

What is the main function of the hypothalamus?

Back 1

To relay signals from the brain to the pituitary.

Front 2

Describe the pattern of release of hypothalamic hormones.

Back 2

All hypothalamic releasing hormones are secreted in a pulsatile fashion - avoid desensitizing receptors.

Front 3

Continuous release of hypothalamic hormones will ________ the secretion of pituitary hormones.

Back 3

suppress

Front 4

Describe how the cells sizes of target organs are affected by the binding of hypothalamic releasing hormones.

Back 4

Hyperplasia and hypertrophy.

Front 5

A primary endocrine disorder originates in the _________.

Back 5

target organ

Front 6

A secondary endocrine disorder originates in the _________.

Back 6

pituitary gland

Front 7

A tertiary endocrine disorder originates in the _________.

Back 7

hypothalamus

Front 8

What is a hormone pair?

Back 8

A pituitary hormone and the target organ hormone that it stimulates to secrete (i.e. ACTH/Cortisol).

Front 9

What is stimulation testing?

Back 9

Hypofunctioning target organ? Stimulate target organ to increase hormone secretion in order to try and deduce the origin of disorder.

(i.e. clomiphene increases GnRH levels, and so increases FSH/LH release from pituitary thus inducing ovulation.)

Front 10

What is suppression testing?

Back 10

Suspect a hyperfunctioning target organ - inhibit the target organ from oversecreting. Testing origin of disorder.

(i.e. dexamethasone blocks ACTH release in pituitary.)

Front 11

How can hormone pairs diagnose endocrine disorders?

Back 11

1) Low Pituitary Hormone level + Low Target Organ Hormone level = Pituitary failure or Hypothalamus failure.
2) High Pituitary Hormone level + Low Target Organ Hormone level = Target Organ failure.
3) Low Pituitary Hormone level + High Target Organ Hormone level = Autonomous Secretion of Target Gland Hormone (possibly ectopic cancer)

Front 12

Name the major functions of Growth Hormone (GH).

Back 12

1) Growth
2) Maintaining lean body mass.
(GH is a somatotropin.)

Front 13

To what 2 hormones is GH structually similar?

Back 13

*Prolactin mainly, and also human Chorionic Somatomammotropin (hCS)

Front 14

What class of molecules inhibit GH and why?

Back 14

Somatomedins - IGF-1 and IGF-2 (Insulin-like Growth Factor) inhibit GH at the pituitary level because they are homologous to proinsulin.

Front 15

For what hormone does somatomedin stimulate increased secretion?

Back 15

Somatostatin, which also inhibits GH.

Front 16

GH sensitizes the gonads to what hormones?

Back 16

FSH and LH, promoting pubertal sexual maturation.

Front 17

Hypersecretion of GH will result in what pathological condition, besides acromegaly?

Back 17

Diabetes because it is homologous to glucagon, thus causing insulin resistance.
(Impotence because it is homologous to prolactin.)

Front 18

The main target of GH is _______.

Back 18

the liver

Front 19

What are the 3 mechanisms for dwarfism (GH deficiency disease)?

Back 19

1) Somatotroph destruction - secretory cells of the anterior pituitary for GH are nonfunctional.
2) Defective GH ligand or receptor.
3) Defective hypersecretion of somatomedin, a GH suppressant.

Front 20

Name 3 symptoms of GH hypersecretion (gigantism or acromegaly).

Back 20

1) Enlarged organs
2) Suppressed gonadal function (impotence in males) due to high structural homology to prolactin.
3) Often diabetic due to glucose intolerance.

Front 21

What is the prescribed treatment for GH hypersecretion diseases?

Back 21

Administer somatostatin to suppress GH.

Front 22

Name all the anterior pituitary hormones.

Back 22

Prolactin, ACTH, FSH, LH, GH, TSH.
(FLAT PiG)

Front 23

Describe the normal regulation of prolactin secretion.

Back 23

Prolactin is normally tonically suppressed by its dopamine receptors.

Front 24

Describe the situation where prolactin production is increased.

Back 24

Pregnancy causes an increase in estrogen, which blocks dopamine and results in prolactin secretion.

Front 25

What is the main function of prolactin?

Back 25

Initiation and maintenance of lactation.

Front 26

What is one benefit of prolactin in a lactating mother?

Back 26

Suppression of GnRH from the hypothalamus inhibits mother's ovulation because high prolactin inhibits FSH/LH - less chance for pregnancy.

Front 27

Detail the 4 main causes for hypersecretion of prolactin.

Back 27

1) Adenoma
2) Drug-induced (dopamine inhibitors)
3) Pathological nipple stimulation (herpes zoster)
4) Primary hypothyroidism resulting in high TRH levels from hypothalamus resulting in high PRL from pituitary.

Front 28

Describe 3 results of hypersecretion of prolactin.

Back 28

1) *Females: Galactorrhea (inordinate milk production) and Amenorrhea (stop menstruations because of negative inhibition on FSH/LH).
2) Males: Gynecomastia/impotence.
3) Possible headaches/visual impairment due to tumor in anterior pituitary.

Front 29

Describe the stimulation test for PRL.

Back 29

Block dopamine centrally with TRH or chloropromazine.

Front 30

Describe the suppression test for PRL.

Back 30

Administer a dopamine analog (L-Dopa).

Front 31

POMN is a precursor for which proteins?

Back 31

ACTH, MSH, and opioid peptides.

Front 32

What hypothalamic releasing hormone stimulates the release of ACTH in the pituitary?

Back 32

CRH.

Front 33

What is the result of ACTH released from the anterior pituitary on the hypothalamus?

Back 33

Negative feedback for CRH.

Front 34

What is the result of Cortisol on hormone regulation?

Back 34

Negative feedback of ACTH secretion at both the hypothalamus and pituitary levels. Cortisol is used for suppression testing of the CRH/ACTH hormone pair.

Front 35

In what way is estrogen secretion from the gonads unique?

Back 35

Estrogen may exert both positive and negative feedback for gonadotropin (FSH/LH) release, like during the female cycle.

Front 36

How does regulation of ADH relate to diabetes insipidus (not milletus)?

Back 36

Too little ADH action results in large urine loss and polydispia. Diabetes insipidus is simply very dilute urine caused by a loss or lack of ADH function.

Front 37

What are the 3 main actions of oxytocin?

Back 37

1) Milk ejection as part of the suckling reflex.
2) Uterine contraction during delivery.
3) Aiding of sperm transport during intercourse.

Front 38

What negative feedback loops is gonadal hormones (estrogen and testosterone) involved with?

Back 38

Negative feedback to both the hypothalamus and the pituitary.

Front 39

What influences the release of GnRH from the hypothalamus?

Back 39

Higher brain centers.

Front 40

What is the correlation between ADH and plasma osmolality in humans?

Back 40

As osmolality levels goes up, so do levels of ADH to reabsorb more water.

Front 41

What is the correlation between ADH and mean arterial blood pressure?

Back 41

As mean arterial blood pressure drops, ADH levels will increase to maintain blood pressure.