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Endocrine > Hypothalamus and Pituitary > Flashcards

Hypothalamus and Pituitary Flashcards

1
Q

The hypothalamus and pituitary gland form a unit that exerts control over the function of:

A

Thyroid
Adrenals
Gonads

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2
Q

The pituitary is the:

A

“master gland”

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3
Q

The hypothalamic-pituitary axis (HPA) is responsible for:

A

Brain-endocrine interactions

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4
Q

The hypothalamus is the:

A

coordinating center of the endocrine system

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5
Q

They hypothalamus consolidates signals from:

A

-Upper cortical inputs
-autonomic function
-environmental cues
-Peripheral endocrine feedback

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6
Q

The hypothalamus delivers precise signals to the _____ gland which releases hormones that influence other endocrine systems

A

Pituitary gland

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7
Q

The pituitary gland rests in the _____ bone in the area called the _____ ____

A

Sphenoid bone
Sella tursica

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8
Q

4 divisions of the pituitary gland:

A

1.) Anterior pituitary/ adenohypophysis
-largest

2.) Pars Intermedius
-gone after fetal development

3.) Pars tubularis
-highly vascular, no known hormones secreted

4.) Posterior pituitary/ neurohypophysis

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9
Q

The anterior and posterior portions of he pituitary are ____ from one another

A

Distinct

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10
Q

The anterior and posterior pituitary have different:

A

Connections to the hypothalamus

cell types

Secrete different hormones

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11
Q

The anterior pituitary is highly vascularized and connected to the hypothalamus via a:

A

Portal venous network

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12
Q

The anterior pituitary is responsible for the regulation of the _____, ____, and _____ glands

A

Thyroid
Adrenal
Mammary

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13
Q

The anterior pituitary also regulates ____ ___, _____, and ____

A

Growth hormone
Gonads
Melanocytes

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14
Q

Somatotropes

A

30-40%
-Most abundant
-Growth hormone (GH)

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15
Q

Corticotropes

A

20%
Adrenocorticotropic hormone (ACTH)

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16
Q

Thyrotropes

A

3-5%
Thyroid-stimulating hormone (TSH)

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17
Q

Gonadotropes

A

3-5%
Luteinizing hormone (LH)
Follicle-stimulating hormone (FSH)

goes right to site of action

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18
Q

Lactotropes

A

3-5%
Prolactin (PRL)

goes right to site of action

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19
Q

The posterior pituitary is largely a collection of ____ ___ from the hypothalamus

A

axonal projections

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20
Q

The posterior pituitary produces what 2 hormones

A

Oxytocin
Vasopressin (ADH)

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21
Q

What does Oxytocin do?

A

Regulates uterine contractions

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22
Q

What does Vasopressin (ADH) do?

A

Regulates water balance

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23
Q

Where are the hormones synthesized before being transported intracellularly for secretion from the pituitary?

A

Hypothalamus

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24
Q

The posterior pituitary is fed by which artery?

A

inferior hypophyseal artery

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25
Q

The hypothalamus is supplied by which artery?

A

superior hypophyseal artery

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26
Q

How is the anterior pituitary supplied blood?

A

Venous by way of long portal vessels

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27
Q

Which nerve fiber supplies oxytocin?

A

Paraventricular nucleus

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28
Q

Which nerve fiber supplies antidiuretic hormone (vasopressin)?

A

Supraoptic nucleus

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29
Q

What is the mechanism of action of vasopressin?

A

Increases permeability of the collecting ducts, increasing free water absorption.

-increased urine osmolality
-decreased plasma osmolality
-Increased ECF volume

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30
Q

How does Vasopressin (ADH) produce vasoconstrictive/pressor effects?

A

Causes contraction of vascular smooth muscle

-more prevalent in large doses

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31
Q

V1 receptor:

A

Pressor effect

-vasoconstriction = increased arterial pressure
-prevalent w extreme increases in circulating levels (hemorrhage)

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32
Q

V2 receptor:

A

ADH effect

  • renal fluid reabsorption= increased blood volume = increased arterial pressure
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33
Q

Vasopressin is released from the posterior pituitary d/t :

A

Angiotensin 2
Sympathetic stimulation
Hyperosmolarity
Hypovolemia
HoTN

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34
Q

Stimulus for release of vasopressin (ADH):

A

Osmoreceptor in the hypothalamus is activated by plasma osmolarity > 290 mosm/L

-other receptors in the hypothalamus send sensation of thirst

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35
Q

Decreased ECF volume activates ____ receptors in the ____ ____, _____, and _____ ____ for ADH release

A

stretch receptors
-great veins
-atria
-pulmonary vessels

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36
Q

Other stimulators of ADH release:

A

-High sodium
-Low BP
-angiotensin 2
-nicotine
-nausea
-pain
-stress
-PPV

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37
Q

Release of ADH is depressed by:

A

-Decreased plasma osmolality
-Increased ECF volume
-Alcohol

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38
Q

Large volume changes activate:

A

baroreceptor in the carotid sinus and aortic arch

39
Q

Diabestes insipidus (DI)

A

excessive thirst= dilute urine

40
Q

What is Diabetes insipidus caused by?

A

ADH deficiency caused by an inability to release (neurogenic/central- most common) or inability of kidney to respond (nephrogenic)

41
Q

What are the results of Diabetes Insipidus?

A

Excretion of large amounts of hypoosmotic urine w hyperosmotic plasma

polydipsia, polyuria w/o hyperglycemia

42
Q

What keeps DI pts from severe dehydration?

A

Water intake

43
Q

Treatment for DI:

A

Limit sodium intake

Give ADH (1-Deamino-8-D-arginine vasopressin/ DDAVP for central

44
Q

What is Hypernatremia a result of?

A

Loss of H2O, an excess of Na or retention of large quantities of sodium.

45
Q

When is transient central DI commonly seen?

A

Post-head injury or surgery

46
Q

What can cause Nephrogenic DI?

A

Chronic renal disease

Lithium toxicity

Hypercalcemia

Hypokalemia

Tubulointerstitial disease (drugs)

47
Q

Above what sodium level should elective surgery be cancelled?

A

> 150

48
Q

What are symptoms of hypernatremia?

A

Restlessness
Lethargy
Hyperreflexia
Seizure
Coma
Death

49
Q

Is MAC increased or decreased w hypernatremia?

A

Increased

50
Q

Is MAC increased or decreased w hypernatremia?

A

Increased (decreased potency)

51
Q

Is the uptake of inhalation agents increased or decreased with hypernatremia?

A

Decreased from decreased CO

52
Q

What can rapid correction of hypernatremia result in?

A

-Seizures
-Brain edema
-Permanent neurologic damage
-Death

53
Q

What is Syndrome if inappropriate ADH (SIADH)?

A

ADH overload

54
Q

What causes SIADH?

A

Autonomous release from the pituitary (or tumor)

CNS disorders

Head trauma

Squamous cell lung cancer
(SCC of lung)

Pulmonary infection

Pituitary signs and symptoms

55
Q

What are the symptoms of SIADH?

A

Water retention

dilutional hyponatremia

Concentrated urine

Hypoosmolar (dilute plasma)

Water intoxication

Brain edema= CNS effects –> lethargy, seizure, coma

56
Q

Treatment for SIADH

A

Tx underlying cause

restrict fluid

Demeclocycline

57
Q

What causes hyponatremia?

A

Low Na+ reflects water retention either from an absolute increase in total body water (TBW) or Na+ loss in excess of H2O

58
Q

Until what level is hyponatremia asymptomatic?

A

125 mEq/L

59
Q

When can you see serious symptoms with hyponatremia

A

Below 120 mEq/L

60
Q

Mild hyponatremia:

A

anorexia, nausea, weakness

61
Q

Moderate hyponatremia:

A

lethargy, confusion

62
Q

Severe hyponatremia:

A

seizures, coma, death

63
Q

Above what sodium level is safe for elective procedures?

A

> 130

64
Q

Anesthetic implications for a sodium level less than 130:

A

May lead to cerebral edema

Decreased MAC
Post-op agitation, confusion, somnolence

Tx: Hypertonic 3% saline, furosemide

65
Q

What can happen is hyponatremia is corrected too quickly?

A

Central pontine myelinolysis
-demyelinating lesions in the pons

66
Q

What are the recommended correction guidelines for hyponatremia?

A

1-2 mEq /hr

<12 mEq /24 hrs

67
Q

What are symptoms associated w Central Pontine Myelinolysis?

A

Spastic quadriplegia

pseudobulbar palsy (inability to control facial movements)

varying degrees of encephalopathy or coma from acute, noninflammatory demyelination that is centered within the basis pontis

68
Q

Conditions predisposing pts to CPM:

A

Alcoholism

Liver disease

Malnutrition

Hyponatremia

69
Q

Risk factors for CPM in the hyponatremic pt include:

A

Serum sodium less than 120 mEq for more than 48 hrs

Aggressive IV fluid therapy w hypertonic saline solutions

Development of hypernatremia during tx

70
Q

How often should serum Na+ be monitored?

A

Every 1-2 hrs.

71
Q

Where is Oxytocin (Pitocin) secreted from?

A

paraventricular nucleus of posterior pituitary

72
Q

What does oxytocin do?

A

Causes contraction of myoepithelial cells of the lactating breast and smooth muscle of the uterus

decreases blood loss after birth d/t uterine contractions

73
Q

When does the secretion and sensitivity of oxytocin increase

A

late pregnancy

74
Q

What causes the milk ejection reflex?

A

stimulation of touch receptors in the breast by infant suckling

activation of afferent fibers sends signals to the supraoptic and paraventricular nuclei to release oxytocin , contraction of myoepithelial cells and ejection of milk

75
Q

Labor effects and breastfeeding are examples of what?

A

Positive feedback

76
Q

Is the blood-brain barrier intact to the hypothalamus?

A

NO

77
Q

Complications of oxytocin?

A

Fetal distress d/t hyperstimulation

Uterine tetany

Maternal water intoxication (ADH effects, rare)

78
Q

Rapid IV infusion of oxytocin can cause:

A

HTN

Tachycardia

N/V

Seizures (rarely)

79
Q

How are intracranial neoplasms found most often?

A

d/t hypersecretion of pituitary hormones

80
Q

Galactorrhea

A

High prolactin secretion

81
Q

Cushing disease

A

High ACTH

High cortisol

82
Q

Acromegaly

A

High growth hormone secretion

83
Q

How are pituitary tumors often found?

A

As a result of compression on adjacent structures

  • visual changes w impingement of the optic chiasm
84
Q

What can the compression of the optic chiasm result in?

A

Bitemporal hemianopsia

(Impaired peripheral vision in the outer temporal halves of the visual field of each eye.)

85
Q

Anesthetic implications for Acromegaly (increased GH)

A

-difficult mask
-difficult intubation
-Large tongue and epiglottis
-enlarged mandible
-distorted facial features
-subglottic narrowing and vocal cord enlargement.
-May consider downsizing ETT.
-OSA is common.
-High risk of HTN, cardiomyopathy, LVH, arrhythmias.
-Enlarged spleen, heart, liver, kidneys
-Skeletal overgrowth
-Glucose intolerance
-Preferred surgery is pituitary tumor removal

86
Q

Anesthetic implications for Hyperthyroid (TSH)

A

Tachycardia
Wt. loss

87
Q

Anesthetic implications for Cushing’s (ACTH)

A

Difficult airway and access

88
Q

Panhypopituitarism

A

Need hormone replacement w cortisol, levothyroxine (synthetic T4), DDAVP (vasopressin)

89
Q

What kind of tube would you use for pituitary surgery?

A

ETT oral Rae

90
Q

Implications for pituitary surgery:

A

Head pins

Deep extubate

Procedure 2-4 hrs

Dura is opened to expose tumor and repaired w fat or bone graft

EBL 20-200 ml

Keep pt normotensive and normocapneic

91
Q

Why should you avoid hypocapnia in pituitary surgery?

A

Hypocapnia lowers ICP and pulls pituitary tumor further into brain

92
Q

Which hormones are released by the anterior pituitary gland?

Prolactin

Luteinizing hormone

Antidiuretic hormone

Oxytocin

Corticotropin-releasing hormone

Growth Hormone

A

Prolactin

Luteinizing hormone

Growth Hormone

(anterior pituitary releases 6 hormones: “FLAT PiG)

-Follicle-stimulating hormone
-Luteinizing hormone
-Adrenocorticotropin
-Thyroid-stimulating hormone
-Prolactin
-Ignore
-Growth hormone

93
Q

If overhydrated urine specific gravity

A

If overhydrated (SIADH) = <1.005

94
Q

If dehydrated (DI) urine specific gravity

A

= >1.030

Endocrine (7 decks)

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