Posterior Pituitary Hormones Flashcards
What is Diabetes Insipidus (DI)?
Having too little or ineffective ADH
What is Central DI?
When the CNS is affected and produces too little ADH
What organ is affected in central DI?
Posterior pituitary gland
What are two signs/symptoms of central DI?
Polyuria and Polydipsia
How can we treat central DI?
Synthetic ADH
What is nephrogenic DI?
When the kidneys are affected and do not recognize/respond to ADH
What can cause nephrogenic DI?
Disease or drugs
What is gestational DI?
When the placenta releases an enzyme that destroys the mother’s ADH
What is Syndrome of Inappropriate ADH (SIADH)?
When there is too much ADH which causes CNS swelling (euvolemic hyponatremia) and can alter CNS function
What is euvolemic hyponatremia?
Swelling of the CNS organs (cerebral in particular) due to fluid shifts that can cause altered function of the CNS
What can caused SIADH?
Diabetes Mellitus
Head trauma or meningitis
Medications
Bronchogenic tumors
What does hyponatremia mean?
Decreased sodium levels
How do bronchogenic tumors cause SIADH?
Bronchogenic tumors are typically made up of neuroendocrine cells which release hormones. Since the cancerous cells in this case are neuroendocrine cells they produce ADH in excess (without proper regulation) which causes SIADH
How can SIADH cause euvolemic hyponatremia?
Too much ADH means increased blood volume
ADH signals the kidneys to retain/reuptake water back into circulation BUT NOT SODIUM
The result is very low osmolarity/osmolality
The high water content in the body stimulates the kidneys to get rid of the excess water
This causes total body water (TBW) to return to normal but hyponatremia worsens
What class of hormone is oxytocin?
Hydrophilic peptide hormone
What is oxytocin’s target tissue?
Mammary glands and uterus
Some sex organ in males
What is oxytocin’s function?
Lactation and uterine contractions
sperm motility in males
What stimulates oxytocin?
Nursing, cervical distension, sex, positive emotions
What inhibits oxytocin?
D/C of stimuli and negative emotion
What is synthetic oxytocin used for?
Inducing labor
What class of hormone is ADH?
Hydrophilic peptide hormone
What is the target tissue of ADH?
Collecting ducts of kidneys
Smooth muscle of vessels
What is the function of ADH?
Regulates blood plasma concentration by regulating reuptake of water by the kidneys
What are stimuli of ADH?
Increased osmolarity (increased concentration)
Dehydration/salt intake (heat/stress/drugs that cause xerostomia)
Angio
How does angio II stimulate ADH?
angio II stimulates sodium reuptake which increases plasma concentration, stimulating ADH
A 10% decrease in blood pressure will stimulate what kind of ADH response?
A small ADH release
A 10% increase in plasma osmolarity will stimulate what kind of ADH response?
A large ADH release
What inhibits ADH?
Decreased blood plasma
Increased blood volume
Caffeine/alcohol
