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Endocrine-Week 1/2 > Posterior Pituitary > Flashcards

Posterior Pituitary Flashcards

1
Q

What hormones are STORED and RELEASED by the Posterior Pituitary (2 total)

A

Vasopressin (Arginine vasopressin = AVP = ADH)

Oxytocin

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2
Q

Where in the Hypothalamus are Oxytocin and ADH produced?

A

Supra-Optic nuclei (oxytocin)

Paraventricular nuclei (ADH)

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3
Q

Function of Oxytocin

A

Uterine contraction

Milk letdown (Contraction of mammary smooth muscles)

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4
Q

Function of ADH (Vasopressin)

A
  1. Antidiuretic FX
    - H2O retention by stimulating H2O movement across renal tubular cell membranes
    - V2
  2. Vasopressor FX
    - Increase ACTH by augmenting ACTH response to CRH
    - V1 & V3
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5
Q

The (V1/V2/V3) ADH receptor stimulates vasoconstriction and vWF release

A

V1

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6
Q

The (V1/V2/V3) ADH receptor has antidiuretic activity

A

V2

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7
Q

The (V1/V2/V3) ADH receptor stimulates ACTH secretion from the pituitary

A

V3

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8
Q

Oxytocin and ADH act via what kind of receptor

A

G-protein coupled receptors

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9
Q

What are some triggers for ADH release

A

Dehydration
Blood loss
Nausea

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10
Q

(Hypertension/Hypotension) triggers ADH release

A

Hypotension (need to reabsorb water to improve blood pressure)

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11
Q

(Osmo/baro)receptors are much more sensitive for the release of ADH

A

Osmoreceptors (osmolality is most effective regulator of plasma AVP)

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12
Q

Excess urinary loss of water due to deficiency or insensitivity to ADH (vasopressin)

A

Diabetes Insipidus (DI)

  • Central
  • Nephrogenic
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13
Q

Possible causes of Polyuria (at least 3 liters of urine per day)

A
  1. Primary polydipsia (excessive water intake with normal pit. fx)
  2. Central DI
  3. Nephrogenic DI
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14
Q

How to help diagnose Diabetes Insipidus

A

Water Deprivation test

  • Administer desmopressin (DDAVP) and withhold water intake
  • Assess urine osmolality
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15
Q

Treatment for Central Diabetes Insipidus

A

Desmopressin (DDAVP)
Synthetic AVP
Chlorpropamide

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16
Q

Why might Desmopressin be the best tx for those with Central DI + CAD

A

Selective for V2 (so no effect on V1 or vascular smooth muscle)

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17
Q

An inappropriate retention of water due to excess ADH; characterized by hyponatremia, high urine osmolality (urine Na+ >20), euvolemia (normal BP), and urine osmolality > plasma osmolality

A

SIADH (Syndrome of Inappropriate ADH)

*hypotonic hyponatremia

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18
Q

4 main causes of SIADH

A
  1. CNS disease/neoplasm (meningitis, abscess)
  2. Pulmonary disease (TB, pneumonia)
  3. Pulmonary neoplasm (small cell carcinoma, squamous cell carcinoma)
  4. Drugs (chlorpropamide, narcotics)
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19
Q

Treatment for SIADH

A

Asymptomatic: fluid RESTRICTION (cheap and safest)

Symptomatic: HYPERTONIC SALINE

20
Q

Examples of Vasopressin antagonists (expensive and only used short term to treat SIADH)

A

Conivaptan
Tolvaptan

*-vaptan ending

21
Q

The pathway from the hypothalamus to the posterior pituitary is called

A

hypothalamic-neurohypophyseal system

22
Q

The pathway from the hypothalamus to the anterior pituitary is called

A

hypothalamic-hypophyseal system

23
Q

Precursor of vasopressin

A

propressophysin

24
Q

Precursor of oxytocin

A

Prooxyphysin

25
propressophysin must be cleaved to form vasopressin + _________, which is noncovalently bonded to vasopressin.
neurophysin (different from oxytocin's)
26
Prooxyphysin must be cleaved to form oxytocin + _________, which is noncovalently bonded to vasopressin.
neurophysin (different from vasopressin's)
27
What are some triggers for oxytocin release
1. Uterine/vaginal distention | 2. Tactile stimulation from nipple suckling
28
Patients with polydipsia (excessive thirst), polyuria, and nocturia indicate
AVP deficiency, insufficiency, or insensitivity * diabetes insipidus
29
What can cause primary polydipsia?
1. drugs that cause dry mouth 2. Psychiatric illness 3. Hypothalami damage in the thirst center
30
What electrolyte conditions can cause nephrogenic DI?
Hypercalcemia | Hypokalemia
31
What drugs can cause nephrogenic DI?
lithium amphotericin B gentamicin cisplatin
32
Describe urine volume, urine osmolality, and serum Na+/osmolality of central DI
Urine volume: inc. Urine osmolality: dec. Serum Na+/Osmolality: inc.
33
Describe urine volume, urine osmolality, and serum Na+/osmolality of Nephrogenic DI
Urine volume: inc. Urine osmolality: dec. Serum Na+/Osmolality: inc.
34
Describe urine volume, urine osmolality, and serum Na+/osmolality of Primary polydipsia
Urine volume: inc. Urine osmolality: dec. Serum Na+/Osmolality: normal or dec.
35
Urine osmolality will _____ in CDI after water deprivation and DDAVP administration
increase
36
Low plasma osmolality with appropriately low plasma AVP describes what condition?
Primary polydipsia
37
Abnormally high AVP regardless of serum osmolality
Nephrogenic DI
38
Abnormally low AVP even with high serum osmolality
Central DI
39
What tx might be the best option for partial vasopressin deficiency?
Chlorpropamide *b/c it potentiates the effects of endogenous vasopressin
40
Treatment for Nephrogenic Diabetes Insipidus
HCTZ | Amiloride
41
What is the antidote for lithium-induced nephrogenic DI b/c of it blunts lithium uptake in the DCT and CD.
Amiloride
42
Formula to figure out how much water needs to be replaced as an ACUTE DI tx
Water Deficit = 0.6 x weight (in kg) x [(serum Na+/140)-1]
43
Symptoms of SIAD/SIADH
HA, confusion, nausea, personality changes
44
What must NOT be given to treat SIADH
ISOTONIC SALINE
45
Swelling of myelin sheaths around CNS nerves that can lead to necrosis and irreversible neurologic damage; occurs when hyponatremia is corrected too quickly via hypertonic saline (> 12 mEq/L in 24 hous); symptoms include LETHARGY, ATAIXA, and MUTISM (unable to speak); can lead to COMA and DEATH!!
Osmotic Demyelination Syndrome (ODS) AKA. Central Pontine Myelinolysis

Endocrine-Week 1/2 (18 decks)

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