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34 Cards in this Set

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What are the 4 ways cells communicate with each other?
Gap Jxns: direct cell-cell
Nerve Synapses - Neurotrans.
Paracrine - Local regulation
Endocrine - Secreted hormones into circulation
What is the hypothalamus composed of?
Collection of nuclei which control pituitary function.
What two nuclear regions are involved in POSTERIOR PITUITARY control?
Supraoptic and paraventricular nuclei
What are the ONLY TWO HORMONES BY POSTERIOR PITUITARY?
ADH and oxytocin.
Which pituiary region is of neural origin?
POSTERIOR!

Anterior originates from ectodermal evagination of orophranyx and migrates to join posterior pituiary.
How is the ANTERIOR PITUITARY NEUROREGULATED?
Hormones are secreted into the PORTAL CIRCULATION (primarily via ARCUATE NUCLEUS) to Anterior Pituitary
The PORTAL CIRCULATION IS PARTICULARLY INVOLVED IN WHAT PITUITARY?
ANTERIOR!
What hormones are secreted by each cell type?

Somatotrophs?
Lactotrophs?
Thryotrophs?
Corticotrophs?
Gonadotrophs?
Somatotrophs - Growth Hormone
Lactotrophs - Prolactin
Thyrotrophs - TSH
Corticotrophs - ACTH
Gonadotrophs - LH & FSH
What TWO TRANSCRIPTION FACTORS control PRIMORDIAL ANTERIOR PITUITARY DIFFERENTIATION?
PROP1, PIT1
Individuals deficient in PROP1, PIT1 exhibit what symptoms?
They exhibit panhypothyroidism. Stunted growth, delayed puberty, hypothyroidism, amenorrhea
What is the hypothalamus in relation to anterior pituitary?
HYPOTHALAMUS IS FINAL COMMON PATHWAY for multiple systems to reach the anterior pituitary.

Hypothalamus also interacts with other areas of the CNS.
How do sterior/thyroid hormones elicit actions DIFFERENTLY than hormones in circulation?
Steriod/thyroid hormones interact directly with cells. Cross blood-brain barrier and produce specific receptor-mediated actions

Hormones in circulation elicit changes INDIRECTLY.
Where are the cell bodies of GnRH-synthesizing neurons located?
Since GnRH is involved in ANTERIOR PITUITARY, then cell bodies are in ARCUATE NUCLEUS (of the hypothalamus) and travel VIA PORTAL CIRCULATION
Where do GnRH-synthesizing cells originate from?
They originate in OLFACTORY PLACODE (from ectorderm).
What is Kallman's Syndrome

(hint, involved in GnRH production?)
Failed migration of GnRH-producing cells from olfactory placode to Arcuate Nucleus.

The result is an ABSENCE of PUBERTAL DEVELOPMENT AND IMPAIRED SMELL.

These patients have pubic hair because this ADRENAL responsible for this.
What is the role of GnRH?
Determines the onset of puberty, basal levels of gonadotropin secretion, phasic release of gonadotropins for folliculogenesis and ovulation.
GnRH is pulsatile OR continuous secretion?

What are GnRH amplitude/frequency relations between follicular and luteal phase of menstrual cycle?
Luteal cycle = Higher amplitude, lower frequency

Follicular cycle = Lower amplitude, higher freuqncy.

These amplitude/frequency changes result from FSH/LH release from pituitary
What is the difference between a LONG-ACTING GnRH AGONIST and a GnRH PUMP?
LONG-ACTING GnRH AGONIST: Will intially increase levels of FSH and LH, but CAN eventually SHUT DOWN testes/ovary system due to GnRH receptor downregulation on pituitary gonadotrophs.

GnRH AGONIST is good for IVF, precocious (early onset) puberty, estogen-sensitive conditions like fibroids/endometriosis

GnRH PUMP is pulsatile (LIKE IS SUPPOSED TO BE), which can INDUCE folliculogenesis and ovulation in GnRH-deficient patients. In men, can induce puberty/spermatogenesis
Are FSH/LH secreted in pulsatile or continuous fashion?
PULSATILE!
Alpha-subunit for LH and FSH is identical to what other hormones?
TSH, hCG. It is the B-subunit involved in unique biologic activity.

LH VERY SIMILAR TO hCG. Can replace LH with hCG to induce ovulation.
What cells produce INHIBIN in men/women?
INHIBIN in men is produced by SERTOLI cells. (Testes - Laydig cells make testosterone)

INHIBIN produced in granulosa cells in women. Granulosa cells also produce estradiol
What are the 3 FUNCTIONS OF FSH in females?
1) Increases FSH receptor numbers

2) Stimulates granulosa cell ESTRADIOL production by aromatase induction

3) Stimulates growth and proliferation of granulosa cells
What are the 3 FUNCTIONS OF LH in females?
1) Stimulate THECA CELLS to produce ANDROGENS which are CONVERTED TO ESTROGENS in GRANULOSA CELLS

2) LH surge induces ovulation

3) LH triggers estrogen and progesterone secretion by granulosa cells AFTER ovulation
What are 3 FUNCTIONS OF FSH in males?
1) Testicular growth

2) Stimulates SERTOLI cells - essential for spermatogenesis

3) Sertoli cells PRODUCE ANDROGEN BINDING PROTEIN, which concentrates testosterone in the testis.
What are 2 FUNCTIONS OF LH in males?
1) Stimulates Leydig cell testosterone production

2) Required for maturation of spermatozoa
What are the roles of following hormones in REGULATION OF GnRH?

Prolactin?
CRH?
LEPTIN?
OPIATES?
MELATONIN?
NEUROPEPTIDE Y/KISSPEPTIN?
Prolactin - SUPRESSES GnRH (lactating amenorrhea)
CRH - SUPRESSES GnRH (stress-related amenorrhea)
LEPTIN - INCREASES GnRH (satiation-related hormone. Anorexica are lepin deficient)
OPIATES - SUPPRESSES GnRH - (naltrexone can fix this)
MELATONIN - SUPPRESSES GnRH (pineal gland)
NEUROPEPTIN Y, KISSPEPTIN - BOTH STIM/INHIB.
What are PEAK LEVELS in GONADOTROPIN IN LIFETIME?
MIDGESTATION (2nd trimester) - fetus' H-P axis is fully functional

POST-BIRTH: Surge in Gonadotropin due to LACK OF INHIBITION FROM PLACENTAL STEROIDS.

Puberty-reproyears - Increase in pubtery and fluctuations during menstruations

Menopause - LOSS OF INHIBITORY FEEDBACK FROM OVARIES. INCREASE IN FSH AND LH
HYPOTHYROIDISM can lead to what repro abnormalities?

HINT: All menstrual cycle related
ALL MENSTRUAL CYCLE RELATED

1) Anovulation

2) Menstrual irregularities

3) Amenorrhea
A-subunit of TSH is similar to A-subunit of which other hormones?
FSH, LH, hCG.

TSH stimulates Iodide uptake, production and release of thyroxine (T4) and triiodothyronin (T4), increased gland vascularity and size.
What are levels of TRH during hypothyroidism and hyperthyroidism?
TRH is ELEVATED if TSH levels are low (HYPOTHYROIDISM)

Conversely, TRH is DECERASED if TSH levels are high (HYPERTHYROIDISM)
What is TRH's relation to PROLACTIN?
TRH STIMULATES PROLACTIN. PROLACTIN SUPPRESSES GnRH.
TRUE/FALSE?

HYPERPROLACTINEMIA LEADS TO HYPOGONADISM?
TRUE. Although NOT DIRECTLY.

Increased prolactin suppresses GnRH (remember lactating amenorrhea).

This results in anovulation, amenorrhea, infertility in women and decreased libido, infertility, impotence in men.
What is the MAJOR INHIBITOR OF PROLACTIN?
DOPAMINE.

Remember, antipsychotics that block D2 receptor have HYPERPROLACTINEMIA as a side-effect. "Disinhibition of inhibition"
What are the MAJOR STIMULATORS OF PROLACTIN?
1) Chest-wall nerve stimulation (suckling, nipple stim)

2) TRH (hypOthyroidism)

3) Estrogen

4) STRESS!