Fluid & Electrolytes (EXAM 3)

What maintains homeostasis in our body?

Fluids, electrolytes, pH

What do fluids do to maintain homeostasis? (4)

1. transport nutrients

2. transport electrolytes

3. transport oxygen

4. carry waste away from cells

What percent of adult body weight is water?

50-60 %

What percent of older adult body weight is water?

45%

Higher body fat means what for water content

lower

Lower body fat means what for water content

higher

Define intracellular fluid (ICF)

body water in cells

Define extracellular fluid (ECF)

Body water outside of cells

Define interstitial fluid

fluid between cells & lymph

Define intravascular fluid

fluid within blood vessels and lymphatic system (plasma)

Define transcellular fluid

Fluid trapped inside specific body chambers (CSF, synovial, plueral, intraoccular, pericardial)

Define electrolytes

minerals in body that break down in water into ions

Name the cations

1. Na+

2. K+

3. Mg2+

4. Ca2+

Name the anions

1. HCO3-

2. Cl-

3. PO43-

Cations & anions combine with water to do what?

maintain electroneutrality

Define diffusion

movement of molecules to areas of high concentration to low concentration

When does diffusion stop?

When concentration equalizes

Define facilitated diffusion

requires a protein carrier to move molecules that cannot pass membrane

Define active transport

molecules move against concentration gradient from low to high concentration (ATP)

Define osmosis

passive movement of water across semipermeable membrane from low solute to high solute

1. Example of facilitated diffusion

2. Example of active transport

1. glucose transport into cell

2. Na+ to K+ pump

Define hypertonic solutions

solutes are more concentrated than the cells

Define isotonic solutions

osmolality of solution same as cell interior

Define hypotonic solutions

solutes are less concentrated than cells

What effect do isotonic solutions have on RBC’s?

None

What effect do hypertonic solutions have on RBC’s?

Cell can shrink and die

What effect do hypotonic solutions have on RBC’s?

Can cause cell to swell and burst

Explain hydrostatic pressure

force exerted by fluid inside blood vessels, causing fluid to leak into tissues (interstitial space)

Explain oncotic pressure

pulling force of plasma proteins that pull fluid back into blood vessels from tissue (interstitial space)

Interstitial oncotic pressure moves fluid where

Into tissues

Interstitial hydrostatic pressure moves fluid where

Into capillaries

If there are changes in capillary or interstitial pressure what can happen?

Fluid can shift abnormally into one compartment to another, causing dehydration or edema

Explain the relation of hydrostatic pressure in conditions like heart failure or fluid overload

Fluid pressure increases in the blood vessels, causing fluid to leak into tissues

Explain the relation of oncotic pressure and hypoproteinemia in liver disease and malnutrition

The proteins are missing or damaged, so fluid stays in the tissues, causing edema

Interstitial fluid to plasma fluid shift can occur after administering

hypertonic solutions

Blood carries what to the tissues

oxygen, nutrients, electrolytes

Tissues give what to blood

waste & carbon dioxide

Explain first spacing

Normal distribution of fluid in ICF & ECF compartments

Explain second spacing

abnormal accumulation of interstitial fluid (edmea)

Explain third spacing

Abnormal, trapped fluid and unavailable for use (acites)

REGULATION OF WATER BALANCE

Hypothalamic-Pituitary Regulation

1. ______ in hypothalamus sense fluid deficit or increase

2. deficit stimulates _____ & ____ release from pituitary

3. Water excess suppresses _____ release

1. receptors

2. thirst, ADH

3. ADH

REGULATION OF WATER BALANCE

Renal Regulation

1. regulates fluid & electrolyte ______, adjusts fluid urine volume

2. selective ______ of water & electrolytes

3. avg. adult kidneys produce abt. ____ liters per day

4. min. urine output per hour is _____ ml

5. In severely impaired ______, they can’t maintain fluid and electrolyte balance

1. balance

2. reabsorption

3. 1.5

4. 30

5. kidneys

What is the site of action for ADH & aldosterone?

renal tubules

What can severely impaired renal function cause? (4)

1. edema

2. increased K+

3. phosphorus retention

4. acidosis

REGULATION OF WATER BALANCE

Adrenal Cortical Regulation

1. releases _____ to regulate water & electrolytes

2. mineral corticoids - aldosterone causes ____ & _____ retention & _____ excretion

3. Decreased renal perfusion to distal renal tubule activates the _______

1. Hormones

2. Na+, water, K+

3. renin-angiotensin-aldosterone system

REGULATION OF WATER BALANCE

Insensible Water Loss

1. invisible _______ of skin & lungs

2. loss of approx. _____to____ mL/day

3. No _____ loss

4. Excessive perspiration may cause large losses of _____ & ______

1. vaporization

2. 600-900

3. electrolyte

4. water, electrolytes

Avg. fluid intake per day at moderate activity and temperatures (including food)

2,500-3,000 mL

Where is our thirst regulator located?

hypothalmus

Avg. fluid output per day (incl. loss thru. skin, lungs, & feces)

1,400-1500 mL

What is the suggested Na intake per day?

less than or equal to 1,500-2,300 mg

What is the avg. intake of Na per day?

3,400+ mg

Older adults have structural changes in their kidneys, causing what?

decreased ability to conserve water

Older adults have hormonal changes leading to a decrease in what 3 hormones?

renin, aldosterone, ADH

Older adults lose subcu. tissue causing what?

increased moisture loss

Older adults have functional body changes like mental status and mobility, making it hard to do what?

independently get fluids

Older adults have musculoskeletal changes like stiff hands/fingers, making it hard to do what?

hold cups

What might an older adult do to intentionally limit incontinence episodes?

decrease fluid intake

HYPOTONIC Fluids

1. more _____ than electrolytes

2. dilutes & expands ______

3. moves fluid ______ cells

4. typically _____ fluids

5. monitor changes in ______

1. water

2. ECF

3. into

4. maintenance

5. LOC

Excess hypotonic fluids can cause what?

cellular sweating (cerebral edema)

Name an example of a hypotonic fluid

0.45% sodium chloride

ISOTONIC fluids

1. administration of an isotonic solution expands only the _____

2. ideal fluid replacement for pt. w/ _____ ______

1. ECF

2. ECF deficit

Name an example of an isotonic fluid

0.9% sodium chloride

HYPERTONIC fluids

1. increases the osmolality of the _____ initially and expands it

2. useful in treatment of ______ & ______

3. requires monitoring of ____, ____ ____, ______ __ levels due to risk of intravascular excess

1. ECF

2. hypovolemia, hyponatremia

3. BP, lung sounds, serum Na+

Name an example of a hypertonic fluid

3% sodium chloride

Normal Saline

1. What kind of fluid/solution?

2. What does it expand?

3. Risk for what is higher?

4. Compatible w/ most ____

1. isotonic

2. ECF, circulating volume

3. fluid overload

4. meds

What is the preferred fluid for emergent situations?

normal saline

D5W (5% Dextrose in Water)

1. 1L of this solution provides how much dextrose in grams and calories?

2. What kind of fluid is it initially?

3. What kind of fluid does it turn into?

4. Free water does what to renal excretion?

5. Why is this used?

6. Does it have electrolytes?

1. 50g, 170 calories

2. isotonic

3. hypotonic

4. increase

5. replace water loss, treat hypernatremia

6. no

What does free water mean?

free of electrolytes

Why does D5W turn from isotonic to hypotonic?

dextrose metabolizes quickly by the cells and free water remains

Lactated Ringers (LR)

1. what kind of fluid/solution?

2. What does it contain?

3. What does it expand?

4. What is it used to treat?

5. What is contraindicated w/?

1. isotonic

2. Na+, K+, Ca+, Cl-, lactate

3. ECF

4. burns, GI losses

5. hyperkalemia

Dextrose 5% & 45% Sodium Chloride (D5 ½ NS)

1. What kind of solution?

2. It is a common _____ fluid.

3. Does not replace any other electrolytes but which one?

4. It contains free water in addition to?

1. hypertonic

2. maintenance

3. Na+

4. Na+ and Cl-