Endocrine - Pituitary Flashcards

1
Q

What is the “master gland”?

A

pituitary gland

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2
Q

What is responsible for brain-endocrine interactions?

A

Hypothalamic pituitary axis (HPA)

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3
Q

Coordinating center of the endocrine system

A

hypothalamus

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4
Q

The hypothalamus consolidates signals from what 4 sources?

A
  1. Upper cortical inputs
  2. Autonomic fx
  3. Environmental cues
  4. Peripheral endocrine feedback
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5
Q

T/F: The hypothalamus delivers vague signals to the pituitary gland which will release hormones that influence other endocrine systems.

A

False. the hypothalamus delivers PRECISE signals

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6
Q

Where is the pituitary gland located?

A

Sella tursica (area of the the sphenoid bone)

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7
Q

4 divisions of the pituitary gland

A
  1. anterior pituitary / adenohypophysis (largest)
  2. Pars intermedius (gone after baby develops)
  3. Pars tubular (highly vascular, no known hormones secreted)
  4. Neurohypophysis
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8
Q

Name three ways in which the anterior and posterior portions of the pituitary are distinct from one another

A
  1. different connections to the hypothalamus
  2. different cell types
  3. secrete different hormones
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9
Q

What is another name for the anterior pituitary?

A

adenohypophysis

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10
Q

How is the anterior pituitary connected to the hypothalamus?

A

portal venous network (the anterior pituitary is highly vascularized)

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11
Q

The adenohypophysis is responsible for the regulation of which 6 things?

A
  1. thyroid gland
  2. adrenal glands
  3. mammary glands
  4. growth hormone
  5. gonads
  6. melanocytes
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12
Q

Type of anterior pituitary cell that is the most abundant and secretes growth hormone

A

Somatotropes

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13
Q

Type of anterior pituitary cell that secretes adrenocorticotropic hormone (ACTH)

A

Corticotropes

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14
Q

Type of anterior pituitary cell that secretes thyroid stimulating hormone (TSH)

A

Thyrotropes

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15
Q

Type of anterior pituitary cell that secretes lutenizing and follicle stimulating hormones (FSH and LH)

A

Gonadotropes

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16
Q

Type of anterior pituitary cell that secretes prolactin (PRL)

A

Lactotropes

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17
Q

What is another name for the posterior pituitary gland?

A

Neurophypophysis

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18
Q

T/F: The posterior pituitary is largely a collection of axonal projections from the hypothalamus.

A

True

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19
Q

What 2 hormones are produced by the posterior pituitary? What do they regulate?

A
  • Oxytocin and vasopressin

- Uterine contractions and water balance

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20
Q

After hormones are synthesized in the hypothalamus, how are they transported to the posterior pituitary for secretion?

A

intracellularly

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21
Q

Where is vasopressin primarily synthesized?

A

supraoptic nucleus

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22
Q

What are the actions of vasopressin, and what are the results of those actions?

A
  • Increases permeability of collecting ducts –> increased free water reabsorption
    1. increased urine osmolality
    2. decreased plasma osmolality
    3. increased ECF volume
  • Causes contraction of vast smooth muscle
    1. vasoconstriction
    2. more prevalent in larger doses
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23
Q

What do effects do the V1 and V2 receptors have?

A

V1 - pressor effect; prevalent w extreme increases in circulating levels, i.e. hemorrhage

V2 - ADH effect

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24
Q

What is the stimulus for vasopressin release?

A

Osmoreceptor in hypothalamus (HT) activated by plasma osmolality >290 mOsm/kg

(other receptors in HT send sensation of thirst)

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25
Q

_____________ activates stretch receptors in the great veins, atria, and pulm veins for ADH release

A

Decreased ECF volume

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26
Q

Name 5 things (other than osmolality >290) that stimulate ADH release

A
angiotensin II
nicotine
nausea
pain 
stress
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27
Q

How is release of ADH depressed?

A
  • decreased plasma osmolality
  • increased ECF volume
  • ETOH
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28
Q

How are baroreceptors in the carotid sinus and aortic arch activated?

A

large volume changes

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29
Q

Describe SIADH

A

Autonomous release from pituitary (or tumor) cause water retention, low Na with concentrated urine, and hypoosmolar (dilute) plasma

30
Q

Causes of SIADH

A
  • CNS disorders
  • Cold stress
  • Trauma
  • Drug induced
  • Squamous cell lung CA
31
Q

How to treat SIADH

A
  1. Find cause

2. Limit fluid intake

32
Q

T/F: Symptoms of hyponatriema relate to rapidity of onset

A

True

33
Q

A hyponatremic pt is usually asymptomatic until Na is ____ mEq/L, with serious symptoms below ____ mEq/L

A

125

120

34
Q

Mild, mod, and severe s/s of hypoNa

A

Mild: anorexia, nausea, weakness
Moderate: lethargy, confusion
Severe: sz, coma, death

35
Q

Na >____ is safe for elective procedures

A

130

36
Q

Na < ____ may lead to cerebral edema, and elective procedures should be held.

A

130

37
Q

If doing an emergent procedure on a pt with Na <130, what would you expect to see intra-op and post-op related to the hypoNa?

A

Intra-op: decrease MAC

Post-op: agitation, confusion, somnolence

38
Q

Why must hypoNa be corrected slowly?

A

Risk for Central Pontine Myelinolysis

39
Q

What is Central Pontine Myelinolysis?

A
  • demyelinating lesions in the pons R/T rapid correction of hypoNa
40
Q

Central Pontine Myelinolysis is seen with a change in Na > ____ mEq/L/hr

A

0.5

41
Q

What are some of the possible outcomes of central pontine myelinolysis?

A
  • Serious permanent neurologic sequelae
  • Death
  • Spastic quadriplegia
  • pseudo bulbar palsy (inability to control facial movements)
  • varying degrees of encephalopathy or coma from acute, noninflammatory demyelination that centered within the basis pontis
42
Q

Conditions that predispose its to CPM

A
  • alcoholism
  • liver disease
  • malnutrition
  • hypoNA
43
Q

Risk factors for CPM in the hyponatremic pt

A
  • serum Na <120 mEq/L for >48hrs
  • aggressive IVF therapy with hypertonic saline solutions
  • development of hyperNa during tx
44
Q

Symptoms of CPM usually occur within _____ hours post therapy

A

48-72

45
Q

2 causes of diabetes insipidus (DI)

A

ADH deficiency caused by:

  • inability to release ADH (central/most common)
  • inability of kidney to respond to ADH (renal)
46
Q

Results of DI

A

Excretion of lg acts of hypoosmotic urine withhyperosmotic plasma and polydipsia
polyuria w/o hyperglycemia

47
Q

What keeps DI its from severe dehydration?

A

Water intake

48
Q

Tx for DI

  • central
  • renal
A

central: exogenous ADH (desmopressin nasal spray)
renal: demeclocycline (decreases responsiveness of collecting tubules to ADH)

49
Q

When is transient central DI common?

A
  • post head injury or surgery
50
Q

Causes of nephrgenic DI

A
  • CKD
  • lithium toxicity
  • hypercalcemia
  • hypokalemia
  • tubulointerstitial disease (Drugs)
  • hereditary (rare)
51
Q

Anesthetic considerations for DI/hypernatremia

A
  • increased MAC
  • decreased uptake of IAs from decreased CO
  • decreased doses of IV agents (b/c of hypovolemia)
52
Q

Elective surgery should be postponed for Na >____

A

150

53
Q

S/S of hyperNa

A
  • restlessness
  • lethargy
  • hyperreflexia
  • sz
  • coma
  • death
54
Q

T/F symptoms of hyperNa correlate w rapidity of development

A

true

55
Q

Rapid correction of hyperNa results in:

A
  • sz
  • brain edema
  • permanent neurologic damage
  • death
56
Q

Oxytocin is secreted from the _______

A

supraoptic nucleus of the posterior pituitary

57
Q

What are the actions of oxytocin

A
  • contraction of the uterus during labor

- contraction of myopeithelial cells of the lactating breast and sm muscle of the uterus

58
Q

Labor effects and breast feeding effects of oxytocin are an example of _________ feedback.

A

positive

59
Q

How is oxytocin used in OB?

A

to increase contraction of the uterus to organize labor

to contract the uterus and decrease blood loss after birth

60
Q

Complications of oxytocin (pitocin)

A
  • fetal distress r/t hyperstimulation
  • uterine tetany
  • maternal water intoxication (ADH effects, rare)
61
Q

Rapid IV infusion of pitocin can cause:

A
  • HTN
  • Tachycardia
  • N/V
  • Sz (rare)
62
Q

How to reconstitute Pitocin

A

Add 20 units (no more than 40 units) of Pitocin to 1 L crystalloid and titrate to uterine contraction

63
Q

How are pituitary tumors often found?

A

as a result compression on adjacent structures, such as visual changes with impingement of optic chiasm

64
Q

Compression of the optic chiasm can result in ________

A

bitemoral hemianopsia (seeing only the medial half of both visual fields)

65
Q

T/F: Pituitary tumors can manifest with systemic effects due to hormonal changes.

A

True

66
Q

Patients undergoing pituitary resection should undergo evaluation of their hormonal function to detect either:

A

hypersecretion or panhypopituitarism

67
Q

Anesthetic implications of pre-existing hormonal disorders:

  1. GH
  2. TSH
  3. ACTH
  4. Panhypopituitarism
A
  1. GH - acromegaly, difficult airway
  2. TSH - hyperthyroid, tachycardia, wt loss
  3. ACTH - Cushing’s disease, difficult airway and access
  4. Panhypopituitarism - need HRT with cortisol, synthroid, or DDAVP (vasopressin)
68
Q

T/F: Most pituitary resections are done with trasnsphenoidal approach, tho some may require craniotomy

A

True

69
Q

Patients undergoing pituitary surgery may develop _____ but to loss of ADH

A

DI - may be temporary or permanent; may be evident intra-op or post op

70
Q

Intraoperatively, what would cause an anesthetist to suspect DI in a pt undergoing pituitary surgery?

A

high UOP; confirm w specific gravity <1.005

71
Q

Intraoperative tx of DI during pituitary surgery

A

DDAVP 0.5-1 mcg IV or SQ with volume replacement