Osmolality Flashcards
Ions capable of carrying an electric charge
Electrolytes
Electrolytes with a positive charge is called? And it move towards the _____ in an electric field
Cation
Cathode
Electrolyte with a negative charge is called? And it move toward the _______ in an electric field?
Anion
Anode
Ions capable of carrying an electric charge
Electrolytes
Electrolytes involve in volume and osmotic regulation
Sodium, chloride, potassium
Electrolyte involved in regulation of adenosine triphosphatase ion pumps
Magnesium
Electrolyte involved in neuromuscular excitability
Potassium, calcium and magnesium
Electrolyte involved in production and use of ATP from glucose
Magnesium and phosphate
Electrolyte involved in myocardial rhythm and contractility
Potassium, magnesium and calcium
Electrolyte involved in cofactors in enzyme activation
Magnesium, calcium and zinc
Electrolyte involved in regulation of acid-base balance
Bicarbonate, potassium and chloride
Electrolyte involved in blood coagulation
Calcium and magnesium
True or false
Women have lower average water content than men
True
Due to higher fat content
Water content of the human body
40% to 75% of total body weight
It is the solvent for all processes in the body
Water
Where is water located in the body?
Intracellular and extracellular compartments
Cite functions of water
Transports nutrients to cell
Determines cell volume
Remove waste products through urine
Act as the body’s coolant through sweating
It is the fluid inside the cell
Intracellular fluid (ICF)
It accounts for one third of total body water
Extracellular fluid (ECF)
Accounts for two thirds of total body water
Intracellular fluid
ECF can be subdivided into….
Intravascular ECF (plasma) and interstitial cell fluid
Fluid that surrounds the cells in the tissue
Interstitial fluid
True or false
Plasma is 98% water
False
93% water
The concentration of ion within cells ansd in plasma are maintained by…
Active transport and diffusion (or passive transport) processes
Passive movement of ions across a membrane
Diffusion
Mechanism that requires energy to move ions across cellular membranes
Active transport
Diffusion depends on what factors?
Size and charge of ion
Nature of membrane
True or false
Most biologic membranes are freely permeable to water, ions and proteins
False
Only permeable to water
Distribution of water is controlled by maintaining what?
concentration of electrolytes and proteins
Factors influencing flow of water
Sodium
Other ions and proteins
Blood pressure
Basis for routine measurements of osmolality. Also, these are considered as the two most frequently used method of analysis
Vapor pressure decrease (dew point) and freezing point depression
It is a physical propertyof a solution that is based on the concentration of solutes per kilogram of solvent
Osmolality
A term occasionally used and is reported as miliosmoles per liter
Osmolarity
Osmolarity is inaccurate in cases of
Hyperlipidemia or hyperproteinemia
Presence of osmotically active substances (mannitol or alcohol)
Formerly called Antidiuretic hormone (ADH)
Arginine vasopressin hormone (AVP)
AVP and sensation of thirst are stimulated by the ____________ in response to ___________
Hypothalamus
Increased osmolality of blood
Important mechanism in mediating fluid intake
Thirst
AVP is secreted by the ______________ and acts on the cells of the ___________ to increase water reabsorption
Post pituitary gland Collecting duct (medullary and cortical collecting tubules)
Cite Natural responses to thirst sensation
Consume more fluid
Increase water content of ECF
Diluting the elevated sodium level
Decrease osmolality of plasma
When water is conserved, what happens to osmolality and AVP?
Osmolality decreases
AVP secretion ceases
Regulation of osmolality affects what ion concentration?
Sodium
An important parameter to which the hypothalamus responds
Osmolality in plasma
It accounts for 90% of the osmotic activity in plasma
Sodium
Important regulatory processes affecting Na concentration
Regulation of blood volume and osmolality
Osmolality is regulated by changes in?
Water balance
Blood volume is regulated by changes in?
Na balance
Receptors in hypothalamus that responds quickly to small changes in osmolality, thus, essential to maintain plasma osmolality.
Osmoreceptors
1% to 2% decrease in osmolality leads to
Shutting off of AVP production
Half life of AVP in the circulation
15-20 minutes
1% to 2% increase in osmolality leads to
Increase in circulating concentration of AVP
Mechanism that is More important in controlling water excess
Renal water excretion
Renal water regulation is done by
avp and thirst
Mechanism that is more important in preventing water deficit or dehydration
Thirst
Excess intake of water results to
Lower plasma osmolality
Suppression of AVP and thirst
Water excreted when there is an excess intake of water
10 to 20 L daily
It usually occur in patients with impaired renal excretion of water
Hyponatremia and hypoosmolality
Major defense against hyperosmolality and hypernatremia
Thirst
Increase plasma osmolality, activated AVP and thirst
These happens in what condition?
Water deficit
Osmotic stimulation of thirst progressively diminishes in people who are older than?
60 yrs old
True or false
In older patients ( with diminished mental status and illness), dehydration becomes increasingly likely
True
True or false
Hyponatremia is a concern in infants, unconscious patients, or anyone who is unable to either drink or ask for water
False
Hypernatremia
How does a patient wt diabetes insipidus prevent dehydration and have normal plasma sodium levels?
Thru thirst
Intake matches the output and therefore retains normal plasma sodium level
Regulation of ______________ and ________ is interrelated in controlling blood volume
Sodium and water
It is essential in maintaining blood pressure and ensure good perfusion to all tissue and organs
Adequate blood volume
This mechanism responds primarily to a decreased blood volume
RAAS
Renin-angiotensis-aldosterone system
This hormone is secreted near the renal glomeruli in response to decreased renal blood flow
Renin
Renin converts what to angiotensin I then later on to angiotensin II?
angiotensinogen
This activated form causes vasoconstriction, which quickly increases blood pressure and secretion of aldosterone
Angiotensin II
This receptor detects changes in blood volume
Stretch receptors
Stretch receptors are located in
Cardiopulmonary circulation
Carotid sinus
Aortic arch
Glomerular arterioles
Stretch receptors activate aseries of responses that restore volume by
Varying vascular resistance, cardiac output, and renal sodium and water retention
4 Factors that affect blood volume
Atrial natriuretic peptide (ANP)
Volume receptors independent of osmolality (stimulate the release of AVP)
Glomerular filtration rate
Increased plasma sodium
Released from myocardial atria in response to volume expansion and promotes sodium excretion in kidney
ANP
Two peptides that act together in regulating blood pressure and fluid balance
ANP and B-type natriuretic peptide
True or false
GFR increases wt volume depletion and decreases wt volume expansion
False
Inc. = volume expansion Dec = volume depletion
True or false
Inc plasma sodium will increase urinary Na excretion (and vice versa)
True
Vol of glomerular filtrate produced daily and is conserved by the tubules
150 L
True or false
98 to 99% of water is filtered by the tubules
False
Sodium
True or false
1% to 2% increase in tubular reabsorption of Na can increase water loss by several liters per day
False
1% to 2% reduction
Urine osmolality is increased in what type of condition
Syndrome of inappropriate ADH secretion
Hypovolemia
Urine osmolality is decreased in what conditions
Diabetes insipidus
Polydipsia
Spx used in measuring osmolality
Urine or serum
What are the major electrolyte concentrations which provide the largest contribution to serum osmolality values
Sodium, chloride and bicarbonate
True or false
Plasma can also be used in detecting osmolality
False
Osmotically active substances may be present in the anticoagulant
True or false
Increase in osmolality, decreases the freezing point temp and vapor pressure
True
Samples to be measured for osmolality should be free of what to obtain accurate results?
Particulate matter
A turbid serum should be _____ before analysis
Centrifuged
Equipment used in measuring freezing point depression
Osmometer
Osmometers are standardized using
Sodium chloride
In freezing point depression, the sample is supercooled to what temp?
-7 degree celsius
Freezing point depression is reported as
Milliosmoles per kilogram
It is the difference between the measured osmolality and the calculated osmolality
Osmolal gap
Calculation of osmolality is used to
Determine osmolal gap or
Provide estimate of the true osmolality
Osmolal gap indirectly indicates the presence of osmotically active substances (other than Na, urea and glucose) such as
BLEEM
Methanol Ethanol Ethylene glycol Lactate B-hydroxybutyrate