Diabetes Flashcards
This diabetes disorder is commonly referred to as tasteless.
diabetes insipidus
This diabetes disorder is commonly referred to as sweet.
Diabetes mellitus
This diabetes disorder involves the proteins that regulate plasma and urine osmolarity.
diabetes insipidus
This diabetes disorder involves insulin production and/or sensitivity.
diabetes mellitus
Diabetes insipidus involves a deficiency in this hormone that is released from the posterior pituitary.
Arginine-vasopressin/anti-diuretic hormone
What is the fxn of AVP [Arginine vasopressin]?
Acts on collecting ducts in the kidney to stimulate expression of a water channel called Aquaporin 2
-permits passive transport of water into cells, concentrating urine & diluting plasma [holding water in the body]
True/False: When present in large amounts, AVP has diuretic activity.
True
What is the main physiologic stimulus for AVP secretion?
plasma osmolarity
What is osmolarity?
a measure of the concentration of solutes which depends on the number of particles in solution & not their molecular weight
What are the units for osmolarity?
particles per liter
A 300mM solution of MgCl2 is iso-osmolar with what concentration of a NaCl solution?
3 particles of MgCl2
2 particles of NaCl
300 x 3/2 = 450mM
True/False: Fewer particles = lower osmolarity
False: fewer particles = higher osmolarity
What is the normal contribution of glucose to plasma osmolarity?
6mOsmoles
What are the units for plasma osmolarity?
mOsmoles/liter
What are the consequences of AVP deficiency?
No H2O resorption via apical side of principal cell; decreased urine osmolarity; increased volume of water lost from body; ultimately diabetes insipidus
True/False: Diabetes insipidus patients urinate alot.
True
How many liters per day of fluid do diabetes insipidus patients urinate as opposed to the 1 liter per day for healthy patients?
24 liters
What is cAMP’s role?
stimulate translocation of vesicles containing water channel, aquaporin 2
AVP acts on what receptor in the collecting tubule?
V2 receptor
In diabetes insipidus, plasma osmolarity goes [up/down] while urine osmolarity goes [up/down].
plasma osmolarity goes up
urine osmolarity goes down
The mortality associated with diabetes insipidus in adults is….
rare as long as they have free access to water
What are the two etiologies of Diabetes Insipidus?
Deficiencies in AVP secretion
Deficiencies in AVP action
What are the two types of Diabetes Insipidus that result from deficiencies in AVP secretion?
Cranial DI
Gestational DI
What specifically causes cranial DI?
due to abnormal hypothalamic or pituitary development; genetic mutation in AVP gene, cell loss, abnormal AVP processing
What specifically causes gestational DI?
increased AVP degradation by an aminopeptidase produced by placenta
What type of diabetes insipidus is caused by a deficiency in AVP action?
Nephrogenic DI
What specifically causes Nephrogenic DI?
genetic, caused by drug exposure [aminoglycosides, methoxyflurane, cisplatin, rifampin, foscarnet, lithium, clozapine]
-genetic form usually a mutation in the V2 AVP receptor or aquaporin 2 channel in distal nephron
AVP secretion is typically stimulated at what plasma osmolarity?
280mOsmol/L
What are the two general disorders associated with diabetes?
- Diabetes Insipidus
- Diabetes Mellitus
