P2.1-ELECTROLYTES INTRO Flashcards by Dave U.

Are ions capable of carrying an electric charge

ELECTROLYTES

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ELECTROLYTES Are classified based on the type of charge they carry, what are the two types

Anions
Cations

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have a negative charge and move toward the anode

Anions

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have a positive charge and migrate in the direction of the cathode

Cations

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Electrolytes that are involved in the regulation of blood volume as well as osmotic regulation.

Sodium, Potassium, and Chloride

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Examples of electrolytes that are involved in the regulation of myocardial rhythm and contractility.

Calcium, Potassium and, Magnesium

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Acid base balance electrolytes such as

Bicarbonate, Chloride, and Potassium.

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Average water content of the body

40% - 75% of total body weight

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T or F Men have lower water content than women

F - due to differences in fat content, women typically have lower water content than men

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Is the solvent for all processes in the human body
 Transports nutrients to cells, determines cell volume by its transport into and out of cells, removes waste products by way of urine, and acts as the body’s coolant by way of sweating

WATER

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the fluid inside the cells and about 2/3 of total body water

Intracellular fluid (ICF)

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accounts for the other 1/3 of total body water

Extracellular fluid (ECF)

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Type of extracellular fluid otherwise known as Plasma

Intravascular extracellular fluid

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fluid that surrounds the cells in tissues

Interstitial cell fluid

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Normal plasma composition

93% water, 7% solutes (glucose, lipids,
proteins, NPN, AA, ions)

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NPN examples

creatinine, BUN, and BUA

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Water content of plasma is ___% higher than Whole Blood

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Retention of 3 liters of water is called

edema

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10-20L of water is excreted daily due to deficiency of what enzyme

ADH

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ADH or otherwise known as

Arginine Vasopressin

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Responsible for promoting water reabsorption, therefore, when these are deficient, water excretion maybe 10-20 L per day

ADH

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TRANSPORT MECHANISMS

ACTIVE TRANSPORT
PASSIVE TRANSPORT

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Is a mechanism that requires energy to move ions across
cellular membranes

ACTIVE TRANSPORT

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These pumps move ions extracellularly and potassium ions intracellularly.

Sodium Potassium Pump

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the major intracellular cation

potassium

the major extracellular cation

sodium

Movement of ions across a membrane o Depends on the size and the charge of the ion as well as the nature of the membrane.

PASSIVE TRANSPORT

Is a physical property of a solution that is based on the concentration of solutes (millimoles per kilogram of solvent)

OSMOLALITY

the concentration of solute in plasma

plasma osmolality

the concentration of solute in the urine sample.

urine osmolality

account for approximately 90% of the osmotic activity in plasma

Sodium and its associated anions

Increased osmolality triggers what

Sensation of thirst and AVP or ADH

Response of body to thirst

consume more fluid

Plasma water osmolality Reference range

275– 295 mOsm/kg

A 1%–2% increase in osmolality causes a fourfold increase in the circulating concentration of

AVP or ADH - reabsorbs water

waht happens in 1%–2% decrease in osmolality

shut off AVP production

The normal mechanism when there is an excess of water intake

suppress both thirst sensation and AVP secretion.

WATER LOAD subsequent effects

Hypoosmolality hyponatremia

WATER DEFICIT subsequent effects

hypernatremia hyperosmolality

is the major defense against hyperosmolality and hypernatremia.

Thirst

REGULATION OF BLOOD VOLUME system

RENIN-ANOGIOTENSIN-ALDOSTERONE SYSTEM

responds primarily to a decreased blood volume

RENIN-ANOGIOTENSIN-ALDOSTERONE SYSTEM

is secreted in response to decreased renal blood flow (decreased blood volume or blood pressure).

RENIN

RENIN is secreted by the

juxtaglomerular cells of the kidney

catalyzes the conversion of angiotensinogen to angiotensin I

RENIN

Enzyme converting Angiotensin I to Angiotensin II

Angiotensin Converting Enzyme (ACE)

causes vasoconstriction and promotes secretion of aldosterone

ANGIOTENSIN II

promotes sodium reabsorption.

Aldosterone

FACTORS AFFECTING BLOOD VOLUME

Atrial Natriuretic Peptide (ANP) Volume receptors independent of osmolality Glomerular Filtration Rate (GFR) An increased plasma sodium will increase urinary sodium excretion and vice versa

 Released from the myocardial atria in response to volume expansion (increased blood volume)  Promotes sodium excretion in the kidney in order to decrease blood volume

Atrial Natriuretic Peptide (ANP)

Stimulate the release of AVP – these hormones promote water reabsorption.

Volume receptors independent of osmolality

is a measure on how well the kidney is working.  Reflects filtering capacity of the kidneys  Increases with volume expansion and decreases with volume depletion (decreases with decreased blood volume), in normal conditions

Glomerular Filtration Rate (GFR)

Diseases that causes DECREASED URINE OSMOLALITY

Diabetes insipidus and polydipsia

the problem lies on the AVP – low levels of ADH or AVP will now cause the kidney to excrete too much water producing a diluted urine, resulting to a decreased urine osmolality

Diabetes insipidus

excessive water intake.  Since too much water, kidneys respond by excreting too much water producing diluted urine.

Polydipsia

Diseases causing INCREASED URINE OSMOLALITY

Syndrome of inappropriate ADH secretion (SIADH)

 So urine osmolality is high since more water is reabsorbed causing a decreased urine output in a more concentrated urine sample.  Causes increased urine osmolality; indicated concentrated urine sample

Syndrome of inappropriate ADH secretion (SIADH)

DETERMINATION OF OSMOLALITY samples

o Serum osmolality: make use of serum o Urine osmolality: make use of urine

METHODS of determination of osmolality

Osmometers

principle of osmometers

freezing point depression

In osmometers After calibrating the analyzer with a sodium chloride solution, the sample is pipetted in the sample cuvette and is placed onto the analyzer and the sample is allowed to stay there and it should be incubated at ?

-7 degrees Celsius for freezing

Unit of measurement used in osmometers

Milliosmoles per kilogram

Indirectly indicates the presence of osmotically active substances other than sodium, urea or glucose

Osmolal gap

Formula for osmolality

2Na + (glucose/20) + (BUN/3) or 1.86 Na + (glucose/18) + (BUN/2.8) + 9

Reference Ranges for osmolality

SERUM - 275-295 mOsm/kg URINE - 300-900 mOsm/kg URINE : SERUM ratio - 1.0-3.0 RANDOM URINE - 50-1200 mOsm/kg OSMOLAL GAP - 5-10 mOsm/kg