Alterations in Fluids and Solutes

Question 1

OSMOSIS

Answer 1

Movement of water, fluid shifts, between plasma, interstitial, and cell. Ruled by osmolality. Water will always want to move from a more dilute compartment to a more concentrated compartment

Question 2

OSMOLALITY

Answer 2

A measurement of how concentrated a compartment is, the proportion of solutes-to-water that are in the compartment’s fluid

High concentration = more solutes, less H2O
Low concentration = less solutes, more H20

Question 3

TONICITY

Answer 3

Interchangeable with salinity. How much NaCl compared to H20.

Normal tonicity is 0.9%

Hypertonic/hyperosmolar = more NaCl concentration
Hypotonic/hypoosmolar = less NaCl concentration

Question 4

ISOTONIC

Answer 4

Any fluid that has a saline concentration (tonicity) of 0.9% is isotonic to blood. Anything lower is hypotonic, anything higher is hypertonic

Question 5

OSMOTIC PRESSURE

Answer 5

The pressure exerted by all the solutes in a compartment, correlates with osmolality.

Question 6

ONCOTIC PRESSURE

Answer 6

Colloidal osmotic pressure, pressure exerted by all protein molecules in a compartment, correlates with osmolality

Question 7

PATHOLOGIC WATER LOSS

Answer 7

Increased blood osmolality

Water loss can occur via:
Inadequate intake
Increased output (vomiting, diarrhea, increased urination)

Disease causing water loss from body –> water loss from blood –> increased blood osmolality –> water loss from cells –> overall dehydration

Question 8

TISSUE-TO-BLOOD, FLUID SHIFT S&S

Answer 8

Dehydration, known as fluid volume deficit

Tissue cells have their water “pulled out” into vascular system, high serum osmolality, hyperosmolar.

Leads to:
Dry mucus membranes
Poor skin turgor (state of flexibility or tightness of the skin cells)
Sunken eyes
Sunken fontanels in babies
Diminished urinary output (oliguira), urine concentration increases
Low blood pressure
Acute CNS changes - restlessness, confusion, unconsciousness, convulsions

Question 9

Renin-Angiotensin-Aldosterone System

Answer 9

RAAS, increased renin is secreted by the kidneys when:
Blood osmolality is high
When fluid volume in circulation is low due to blood loss
Blood pressure is lower

Secretion of angiotensin I –> becomes angiotensin II with help of ACE (angiotensin converting enzyme) –> peripheral vasoconstriction/secretion of aldosterone –> less total blood flow in periphery, kidney tubules hold on to Na+ –> urine output decreases, circulatory volume increases

Question 10

Antidiuretic Hormone (ADH)

Answer 10

Hormone that is secreted to assist RAAS. Retains water and decreases urine output

Question 11

PATHOLOGIC WATER GAIN

Answer 11

Decreased blood osmolality

Excess fluids are pulled from the blood into the tissues (edema) and loss of solutes, namely protein

Water gain can occur via:
Psychotic water drinking (water intoxication)
Too much IV fluid
Low output (inability, or kidney failure)
Hormonal problems (SIADH)

Disease causing overall body water gain –> water gain to blood –> decreased osmolality –> water gain to tissue (edema) –> fluid overload

Question 12

SIADH

Answer 12

Syndrome of inappropriate antidiuretic hormone - high levels of ADH, hold onto water too much by decreasing urination

Etiologies:
Ectopicallly-produced ADH such as small-cell bronchogenic cancer
Various drugs, general anesthetics
Trauma to brain (tumors, trauma, swelling, pressure on pituitary gland)

S&S:
Decreased urine output (oliguria), and other fluid volume overload signs and systems

Question 13

SOLUTE LOSS

Answer 13

Solutes lost and affected by fluid shifts, generally sodium (Na+) and/or proteins via excess sweating, disease processes, or loss in blood

Question 14

HYPOPROTEINEMIA

Answer 14

Protein loss in the blood.

Caused by:
Diminished protein production (cirrhosis)
Diminished protein intake - protein malnutrition (kwashiorkor)
Plasma protein loss via kidney diseases (glomerulonephritis)

Question 15

GLOMERULONEPHRITIS

Answer 15

Glomeruli of kidneys lose ability to appropriately keep proteins molecules in the blood, cause protein to spill into the urine (proteinuria)

Sequela:
Less proteins in blood, hypoproteinemia
Water pulled form blood to tissue, causing edema
Also, nutritional problems

Question 16

BLOOD-TO-TISSUE, FLUID SHIFT S&S

Answer 16

Known as fluid volume overload or excess

Tissue cells pull in water from diluted vascular system, show water overload as edema anywhere in the body

Can cause:
Skin appears tight and puffy, can cause indentation (pitting edema)
Pulmonary edema (wet lungs) - cough, shortness of breath, or crackles
Swelling brain cells - restlessness, confusion, unconsciousness, convulsions

Low serum osmolality

Question 17

NATRIURETIC PEPTIDE SYSTEM (NPS)

Answer 17

Compensatory mechanism to correct fluid overload. Right atrium and left ventricle detect it and secrete ANP (atrial natriuretic peptide) and BNP (b-type natriuretic peptide), stimulation increases urination (diuresis)