Week 2 Pituitary Flashcards
What is known as the “master gland?”
The pituitary gland
What is known as “the coordinating center of the endocrine system?”
the hypothalamus
What 4 areas does the hypothalamus consolidate signals from?
- Upper cortical limits
- Autonomic Function
- Environmental cues
- Peripheral endocrine feedback
The _________ delivers precise signals to the _________ which releases ________ that that influence other endocrine systems
- Hypothalamus
- Pituitary
- Hormones
Which area of the pituitary is highly vascularized?
The anterior or adenohypophysis
Which type of cell secretes thyroid stimulating hormone (TSH)?
Thyrotropes
What is the posterior pituitary mainly consisted of?
Axonal projections from the hypothalamus
What 2 main things does ADH do? What 4 things does it lead to?
Increases permeability of the collecting ducts —> increasing free water absorption
- Increased urine osmolality
- Decreased plasma osmolality
- Increased ECF
Also causes smooth muscle contraction = vasoconstriction
What happens to plasma osmolality with dehydration?
It increases
What does decreased ECF volume activate?
Stretch receptors in the great veins, atria & pulmonary vessels —> trigger ADH release
Name all the stimulus for ADH release (8)?
Angiotensin II, nicotine, nausea, pain, stress, stretch receptors, baroreceptors (carotids & aortic arch), osmoreceptor in hypothalamus
What depresses the release of ADH(3)? What does this cause?
- Decreased plasma osmolality
- Increased ECF volume
- Alcohol
— increased urine output
What is the treatment for SIADH?
Find the cause & limit fluid intake
What is SIADH and what does it cause?
Autonomous release of ADH from pituitary — water retention, hyponatremia, concentrated urine, hyperosmolar (dilute) plasma
What can cause SIADH? (5)
- CSN disorders
- cold stress
- trauma
- drug induced
- squamous cell lung CA
What does now sodium reflect? (2)
- Absolute increase in total body water (TBW)
2. Na+ loss in excess of water
What are the risk factors of CPM in the hyponatremia patient? (3)
- Serum Na+ < 120 mEq/L for > 48 hours
- Aggressive IVF therapy with hypertonic saline solutions
- Development of hypernatremia during treatment
What is Central Diabetes Insipidus? How is it treated?
ADH deficiency caused by pituitary’s inability to release ADH
MOST COMMON
— exogenous ADH (desmopressin nasal spray)
What is renal Diabetes Insipidus? Treatment?
The inability of the kidneys to respond to ADH
— demeclocycline (decreases responsiveness of collecting tubules) & ADH
What is the most common cause of central DI?
Transient post head injury or surgery
What are causes of Nephrogenic DI?
- Chronic renal disease
- Lithium toxicity
- Hypercalcemia
- Hypokalemia
- Tubulointerstitial disease (drugs)
- Heredity (rare)
What are anesthetic implications of diabetes insipidus?
Hypernatremia & hypovolemia =
- increased MAC - b/c of decreased uptake of inhalation agent and decreased CO
- decreased IV agents due to hypovolemia
What Na+ level would you postpone an elective surgery?
Na+ >150
What are symptoms of hypernatremia (6)?
- Restlessness
- Lethargy
- Hyperreflexia
- Seizures
- Coma
- Death
What does oxytocin do (2)?
- Uterine contractions
2. Myoepithelial cell contraction (milk ejection)
What are complications during labor of too much pitocin (7)?
- Fetal distress (d/t hyperstimulation)
- Uterine tetany
- Maternal water intoxication (ADH effects rare)
- Hypertension
- Tachycardia
- N/V
- Seizures (rare)
What is commonly compressed with pituitary tumors and what does this cause?
Compression of OPTIC CHASM —> Bitemporal hemianopsia (blindness over half field of vision)
What approach is used for most pituitary resection?
Transsphenoidal approach
What is often a symptom following pituitary surgery?
May develop DI due to loss of ADH - temporary or permanent
