Pituitary Flashcards
The hypothalmus and pituitary gland form a unit that exerts control over the function of several endocrine glands including…
thyroid, adrenals, gonads
The pituitary is AKA
master gland
The hypothalmic pituitary axis (HPA) is responsible for ___-_____ interaction
brain-endocrine
The _______ is the coordinating center of the endocrine system
hypothalmus
The ________ consolidates signals from the upper cortical inputs, autonomic function, environmental cues, and peripheral endocrine feedback
hypothalmus
The hypothalmus delivers precise signals to the _______ which releases hormones that influence other endocrine systems
pituitary
**The pituitary gland rests in sphenoid bone area called the _____ ______ and has ____ divisions
sella tursica / 4
**What are the 4 divisions of the pituitary?
Anterior pituitary or adenohypophysis, Pars intermedius, Pars tubularis, neurohypophysis
**Anterior pituitary or adenohypophysis is the _________. The pars intermedius is actually gone after ______ development. The Pars tubularis is highly ________, and no known hormones secreted. Then you have the neurohypophysis.
largest, fetal, vascular
The anterior and posterior portions of the pituitary are ______ from one another. They have different connections to the _________. They have different _____ types and they secrete different _______.
distinct / hypothalmus / cell / hormones
The anterior pituitary is also called the __________. It is highly _______ and connected to the hypothalmys via a portal ________ network. It is responsible for the regulation of THYROID, ADRENAL and MAMMARY glands. IT also regulates growth hormone, gonads and melanocytes.
adenohypophysis / vascularized / venous
Thryotopic cells secrete _____
TSH
Mammotropic cells secrete _____
Prolactin
Corticotropic cells secrete __________
Adrenocortocotropic hormone
Somatotropic cells secrete ______
growth hormone
Gonadotropic cells secrete ________
follicle-stimulating hormone and Leutenizing hormone
Pars intermedia cells secrete _________
melanocyte-stimulating hormone
What is the most abundant anterior pituitary cell type?
somatotropes
The posterior pituitary is also called the _________
nuerohypophysis
The posterior pituitary is largely a collection of axonal projections from the _________. It produces only two hormones, _______ and _________. These regulate uterine contractions and water balance. They are synthesized in the hypothalmus and transported intracellularly for secretion from the pituitary
hypothalmus / oxytocin / vasopressin
Supraoptic nucleus, cells secrete _____.
oxytocin (slide 9)
Paraventricular nucleus, cells secrete _____
ADH (slide 9)
**The supraoptic nucleus is the dominant site of synthesis of _______. ADH increases the permeability of the ______ _______, increasing free water reabsorption.
ADH / Colllecting ducts
Net effect of ADH secretion
increased urine osmolaltiy, decreased plasma osmolality, increased ECF volume
ADH can cause contraction of vascular smooth muscle producing vasoconstrictive pressor effect. This is more prevelant at _______ doses.
large
**V1 receptor: PRESSOR EFFECT
prevalent with extreme increases in circulating levels (ex: hemorrhage)
**V2 receptor: ____ Effect
ADH
Stimulus for ADH release: Osmoreceptor in hypothalmus is activated by plasma osmolality greater than
290 mosm/kg
Decreased ECF volume activates stretch receptros in great veins, atria, pulmonary vessels for ____ release
ADH
Other stimulators for ADH release
angiotensin II, nicotine, nausea, pain, stress
ADH release is depressed by what?
decreased plasma osmolality, increased ECF volume, alcohol
osmolality =
number of paricles / vol H20
Large volume changes can activate baroreceptors in ____ ____ and ____ ____
carotid sinus / aortic arch
SIADH is from an autonomous release from pituitary or tumor that causes what?
water retention, hyponatremia with concentrated urine and hypoosmolar (dilute) plasma
Other causes for SIADH
CNS disorders, cold stress, trauma, drug induced, squamous cell lung CA
Treatment for SIADH
find cause and limit fluid intake
Low Na reflects what?
Water retention from an absolute increase in total body water OR Na loss in excess of water
Hyponatremia is usually asymptomatic until level of _____mEq/L, with serious symptoms below _____mEq/L
125 / 120
Symptoms of mild hyponatremia
anorexia, nausea, weakness
Symptoms of moderate hyponatremia
lethargy, confusion
Symptoms of sever hyponatremia
seizures, coma, death
Na level safe for elective procedures
> 130
Na level < 130 may lead to ____ ______
cerebral edema
Na level <130 intraoperatively causes a ______ in MAC. Postoperatively causes what?
decrease / agitation, confusion, somnolence
What can happen from correcting hyponaremia too fast?
Central Pontine Myelinolysis. Seen with change in [Na] > 0.5mEq/L/hr
Central Pontine Myelinolyisis
Serious permanent neurologic sequalae and death can occur. Spastic quadriplegia, pseudobulbar palsy (inability to control facial movements), and varying degrees of encephalopathy or coma from acute, noninflammatory demylenation that centered within the basis of the pontis
Conditions predisposing patients to CPM
alcoholism, liver dz, malnutrition, hyponatremia
Risk factors for CPM in the hyponatremic patient include what?
serum sodium less than 120 mEq/L for 48 hrs. Aggressive IV fluid therapy with hypertonic saline solutions. Development of hypernatremia during treatment
When do symptoms of CPM appear
usually from 48-72 hrs post therapy
Diabetes insipidus is characterized by what?
excessive thirst and dilute urine
DI is where there is ____ ______ caused by inability to release (central-most common) or inability of kidney to respond (renal)
ADH deficiency
DI results in excretion of large amounts of ________ urine with _______ plasma and polydipsia, polyuria without hyperglycemia
hyposmotic / hyperosmotic
What keeps a DI patient for severe dehydration
water intake
Treatment for DI
Give exogenous ADH (desmopressin nasal spray) for central. Give demeclocycline for renal-decreases responsiveness of collecting tubules to ADH
Hypernatremia is a result of loss of ______ in excess of ____ or retention of large quantites of Na
H20 / Na
(Hypernatremia) Transient ________ DI is common post head injury or surgery
central
(Hypernatermia) Nephrogenic DI causes?
chronic renal dz, lithium toxicity, hypercalcemia, hypokalemia, tubulointerstitial dz (drugs), and a rare hereditary form
With Hypernatremia you will have _______ MAC, with decreased uptake of inhalation agents from decreased ____
increased / CO
Someone that is hypernatremic and hypovolemia would require _____ doses of IV agents
decreased
Na <130, what would you do?
postpone elective surgery
Hypernatremia symptoms
restlessness, lethargy, hyperreflexia and can proceed to seizures, coma, death. Symptoms correlate with rapidity of development.
What does rapid correction of hypernatremia result in?
seizures, brain edema, permanent neurologic damage, death
**Where is oxytocin secreted from?
Supraoptic Nucleus of the posterior pituitary
Oxytocin is responsible for _____ of uterus during labor. This includes the myoepithelial cells of the lactating breast and smooth muscle of uterus.
contraction
Secretion and sensitivity to oxytocin increase in ____ pregnancy
late
Milk ejection reflex includes stimulation of touch receptors in the breast by infant suckling, activation of afferent fibers to the supraoptic nuclei and paraventricular nuclei which results in release of ________, contraction of myopeithelial cells and ejection of milk
oxytocin
**Labor effects and breast feeding effects are example of __________ feedback
positive
Oxytocin is used in OB to increase contraction of uterus to organize labor or to contract uterus to decrease ____ _____ after birth
blood loss
Complications of pitocin administratioin
fetal distress due to hyperstimulation, uterine tetany, maternal water intoxication (ADH effects, rare). Rapid IV infusion can cause hypertension, tachycardia, nausea and vomiting and rarely seizures
How is Ptiocin administered?
usually add 20 units (no more than 40 units) to 1 liter of crystalloid and titrate to uterine contraction
**Pituitary tumors are often found as a results of compression on adjacent structures, such as visual changes with impingement of the _____ _____
optic chiasm (lateral visual fields are lost)
Compression of the optic chiasm can result in ______ _______
bitemoral hemianopsia
Pituitary tumors can manifest with systemic effects due to ________ changes
hormonal
Acromegaly from overproduction of Growth Hormone is associated with _______ ______
difficult airways
Hyperthyroid is associated with tachycardia and ____ _____
weight loss
T/F Cushing’s disease is associated with difficult airway?
TRUE
Panyhypopituitarism is treated with what?
cortisol, levothyroxine, DDAVP
Most pituitiary resections are done with _________ approach, though some may require craniotomy
transphenoidal
** T/F Patients undergoing pituitary resection may develop DI due to loss of ADH and it could be temporary or permanent
TRUE
Treatment for DI from loss of ADH
DDAVP 0.5 to 1 mcg IV or SQ and with volume replacement