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41 Cards in this Set

  • Front
  • Back
What is the main function of the hypothalamus?
To relay signals from the brain to the pituitary.
Describe the pattern of release of hypothalamic hormones.
All hypothalamic releasing hormones are secreted in a pulsatile fashion - avoid desensitizing receptors.
Continuous release of hypothalamic hormones will ________ the secretion of pituitary hormones.
Describe how the cells sizes of target organs are affected by the binding of hypothalamic releasing hormones.
Hyperplasia and hypertrophy.
A primary endocrine disorder originates in the _________.
target organ
A secondary endocrine disorder originates in the _________.
pituitary gland
A tertiary endocrine disorder originates in the _________.
What is a hormone pair?
A pituitary hormone and the target organ hormone that it stimulates to secrete (i.e. ACTH/Cortisol).
What is stimulation testing?
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.)
What is suppression testing?
Suspect a hyperfunctioning target organ - inhibit the target organ from oversecreting. Testing origin of disorder.

(i.e. dexamethasone blocks ACTH release in pituitary.)
How can hormone pairs diagnose endocrine disorders?
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)
Name the major functions of Growth Hormone (GH).
1) Growth
2) Maintaining lean body mass.
(GH is a somatotropin.)
To what 2 hormones is GH structually similar?
*Prolactin mainly, and also human Chorionic Somatomammotropin (hCS)
What class of molecules inhibit GH and why?
Somatomedins - IGF-1 and IGF-2 (Insulin-like Growth Factor) inhibit GH at the pituitary level because they are homologous to proinsulin.
For what hormone does somatomedin stimulate increased secretion?
Somatostatin, which also inhibits GH.
GH sensitizes the gonads to what hormones?
FSH and LH, promoting pubertal sexual maturation.
Hypersecretion of GH will result in what pathological condition, besides acromegaly?
Diabetes because it is homologous to glucagon, thus causing insulin resistance.
(Impotence because it is homologous to prolactin.)
The main target of GH is _______.
the liver
What are the 3 mechanisms for dwarfism (GH deficiency disease)?
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.
Name 3 symptoms of GH hypersecretion (gigantism or acromegaly).
1) Enlarged organs
2) Suppressed gonadal function (impotence in males) due to high structural homology to prolactin.
3) Often diabetic due to glucose intolerance.
What is the prescribed treatment for GH hypersecretion diseases?
Administer somatostatin to suppress GH.
Name all the anterior pituitary hormones.
Prolactin, ACTH, FSH, LH, GH, TSH.
Describe the normal regulation of prolactin secretion.
Prolactin is normally tonically suppressed by its dopamine receptors.
Describe the situation where prolactin production is increased.
Pregnancy causes an increase in estrogen, which blocks dopamine and results in prolactin secretion.
What is the main function of prolactin?
Initiation and maintenance of lactation.
What is one benefit of prolactin in a lactating mother?
Suppression of GnRH from the hypothalamus inhibits mother's ovulation because high prolactin inhibits FSH/LH - less chance for pregnancy.
Detail the 4 main causes for hypersecretion of prolactin.
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.
Describe 3 results of hypersecretion of prolactin.
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.
Describe the stimulation test for PRL.
Block dopamine centrally with TRH or chloropromazine.
Describe the suppression test for PRL.
Administer a dopamine analog (L-Dopa).
POMN is a precursor for which proteins?
ACTH, MSH, and opioid peptides.
What hypothalamic releasing hormone stimulates the release of ACTH in the pituitary?
What is the result of ACTH released from the anterior pituitary on the hypothalamus?
Negative feedback for CRH.
What is the result of Cortisol on hormone regulation?
Negative feedback of ACTH secretion at both the hypothalamus and pituitary levels. Cortisol is used for suppression testing of the CRH/ACTH hormone pair.
In what way is estrogen secretion from the gonads unique?
Estrogen may exert both positive and negative feedback for gonadotropin (FSH/LH) release, like during the female cycle.
How does regulation of ADH relate to diabetes insipidus (not milletus)?
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.
What are the 3 main actions of oxytocin?
1) Milk ejection as part of the suckling reflex.
2) Uterine contraction during delivery.
3) Aiding of sperm transport during intercourse.
What negative feedback loops is gonadal hormones (estrogen and testosterone) involved with?
Negative feedback to both the hypothalamus and the pituitary.
What influences the release of GnRH from the hypothalamus?
Higher brain centers.
What is the correlation between ADH and plasma osmolality in humans?
As osmolality levels goes up, so do levels of ADH to reabsorb more water.
What is the correlation between ADH and mean arterial blood pressure?
As mean arterial blood pressure drops, ADH levels will increase to maintain blood pressure.