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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
Q

propressophysin must be cleaved to form vasopressin + _________, which is noncovalently bonded to vasopressin.

A

neurophysin (different from oxytocin’s)

26
Q

Prooxyphysin must be cleaved to form oxytocin + _________, which is noncovalently bonded to vasopressin.

A

neurophysin (different from vasopressin’s)

27
Q

What are some triggers for oxytocin release

A
  1. Uterine/vaginal distention

2. Tactile stimulation from nipple suckling

28
Q

Patients with polydipsia (excessive thirst), polyuria, and nocturia indicate

A

AVP deficiency, insufficiency, or insensitivity

  • diabetes insipidus
29
Q

What can cause primary polydipsia?

A
  1. drugs that cause dry mouth
  2. Psychiatric illness
  3. Hypothalami damage in the thirst center
30
Q

What electrolyte conditions can cause nephrogenic DI?

A

Hypercalcemia

Hypokalemia

31
Q

What drugs can cause nephrogenic DI?

A

lithium
amphotericin B
gentamicin
cisplatin

32
Q

Describe urine volume, urine osmolality, and serum Na+/osmolality of central DI

A

Urine volume: inc.
Urine osmolality: dec.
Serum Na+/Osmolality: inc.

33
Q

Describe urine volume, urine osmolality, and serum Na+/osmolality of Nephrogenic DI

A

Urine volume: inc.
Urine osmolality: dec.
Serum Na+/Osmolality: inc.

34
Q

Describe urine volume, urine osmolality, and serum Na+/osmolality of Primary polydipsia

A

Urine volume: inc.
Urine osmolality: dec.
Serum Na+/Osmolality: normal or dec.

35
Q

Urine osmolality will _____ in CDI after water deprivation and DDAVP administration

A

increase

36
Q

Low plasma osmolality with appropriately low plasma AVP describes what condition?

A

Primary polydipsia

37
Q

Abnormally high AVP regardless of serum osmolality

A

Nephrogenic DI

38
Q

Abnormally low AVP even with high serum osmolality

A

Central DI

39
Q

What tx might be the best option for partial vasopressin deficiency?

A

Chlorpropamide

*b/c it potentiates the effects of endogenous vasopressin

40
Q

Treatment for Nephrogenic Diabetes Insipidus

A

HCTZ

Amiloride

41
Q

What is the antidote for lithium-induced nephrogenic DI b/c of it blunts lithium uptake in the DCT and CD.

A

Amiloride

42
Q

Formula to figure out how much water needs to be replaced as an ACUTE DI tx

A

Water Deficit = 0.6 x weight (in kg) x [(serum Na+/140)-1]

43
Q

Symptoms of SIAD/SIADH

A

HA, confusion, nausea, personality changes

44
Q

What must NOT be given to treat SIADH

A

ISOTONIC SALINE

45
Q

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!!

A

Osmotic Demyelination Syndrome (ODS)

AKA. Central Pontine Myelinolysis

Endocrine-Week 1/2 (18 decks)

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