Chapter 17: Fluid and Electrolytes

homeostasis

the basis for understanding most physiologic processes

feedback

the relaying of information to the appropriate organ or system

negative feedback

when the body reverses an original stimulus to regain physiologic balance

positive feedback

the body enhances or intensifies an original stimulus

systems involved in feedback

nervous system, endocrine system

nervous system

regulates homeostasis by sensing system deviations and sending nerve impulses to appropriate organs to restore balance

endocrine system

uses the release and action of hormones to maintain homeostasis

fluids

make up a large portion of the body. composed of water and electrolytes.

intracellular fluid (ICF)

fluid inside the cells, helps maintain shape, constitutes about 2/3 of the total body fluid in an adult

extracellular fluid (ECF)

fluid outside the cells, constitutes about 1/3 of the total body fluid in an adult

interstitial fluid

found between the cells

intravascular

watery fluid of the blood known as plasma. includes sodium (Na), chlorine (Cl), and carbonate.

body fluid balance

the volume of ECF is the most important aspect of _______

drop

a significant loss of ECF volume can ____ blood pressure to a life-threatening point where cells can no longer function due to a lack of oxygen and nutrients

high

too much ECF can place a person in a fluid overload state, leading to a ____ blood pressure and risk for conditions such as congestive heart failure

brain, kidneys, pituitary gland

the body monitors extracellular fluid volume closely and sends messages to the

hypothalamus

thirst center in the ________ of the brain stimulates or depresses the desire for a person to drink

1:1 ratio

normal intake and output

overhydration

an excess of water in the body

edema

excess accumulation of fluid in the interstitial (tissue) spaces

edema is due to

a disruption of the filtration and osmotic forces of the body’s circulating fluids

ascites

excess amount of fluid in the peritoneal cavity

anasarca

severe generalized edema

dehydration

deficiency of body water or an excessive loss of water from the body

greater

body’s output of water is _____ than its intake

fluid volume deficit

nursing terminology referring to dehydration

dehydration can be caused by

potassium, increase in sodium, or a disturbance of certain other electrolytes

outside

sodium lives _____ the cells

45-77%

the human body is ______ water

difference

a great ______ in temperature is needed to bring about a physical change in water

water

directly and indirectly participates in all chemical reactions that occur in the body

oxidation

process through which the body uses oxygen to form needed new substances

solvent

liquid that dissolves solutes

solute

substance dissolved in a solvent

solutes

nutrients and wastes are transported as _____ in water

electrolytes and non-electrolytes (proteins, glucose, carbon dioxide, oxygen)

suspension

water functions as a _______ agent

pressure

water exerts _______ against the walls or vessels that contain it

osmotic pressure

develops when a semipermeable membrane separates two solutions containing different concentrations of solutes

osmosis

water will move from an area of lower concentration of solutes (such as Na, glucose, ect.) to an area of higher concentration to even out the concentration

isotonic

solutions exerting equal pressures on opposite sides of the membrane (no change in the size of cell)

hypertonic

stronger solutions, compared to those on opposing sides of a membrane (causes blood cells to shrink because osmosis draws fluid out of the cell)

hypotonic

weaker solutions, compared to an opposing solution (causes blood cells to swell)

electrolyte

an element or a compound that will dissociate into ions when dissolved in water

ions

atoms or groups of atoms that are in search of a bonding partner

cation

positively charged ion

anion

negatively charged ion

ionization

dissociation of compounds into their respective ions

sodium chloride / NaCl

one of the most common compounds in the body

normal level of Sodium (Na)

135 - 145 mEq/L

normal level of Potassium (K)

3.5 - 5 mEq/dl

normal level of Calcium (Ca)

8.9-10.1 mg/dL

normal level of Magnesium (Mg)

1.8-2.3 mg/dL

normal level of Phosphorus (P) and Phosphate (PO4)

1.7-2.6 mEq/L

normal level of Chloride (Cl)

95-108 mEq/L

permeability

the ability of a membrane to allow molecules to pass through

factors that affect permeability include

• the size of the pores in the membrane

• the external and internal pressures exerted on the molecule (osmotic pressure)

four ways to move across the cellular membrane

• molecules move through the cell membrane, including oxygen, carbon dioxide, and steriods

• substances pass through membranes channels. these channels are of various sizes and allow only a certain size range and electrical charge to traverse the membrane

• carrier molecules in the membrane assist substances across the barrier

• a vesicle (membrane-bound sac) transports large molecules or whole cells across the plasma membrane

passive transport mechanisms (requires no energy)

• diffusion

• osmosis

• filtration

active transport

• transport that uses energy and requires assistance

• used when molecules are too large or too specialized to pass through membranes without assistance

diffusion

• the random movement of molecules from an area of higher concentration to an area of lower concentration

osmosis

the diffusion of water (or other liquid) across a semipermeable membrane

passive transport processes

both diffusion and osmosis are __________

salt

water follows ____

filtration

transport of water and dissolved materials through a membrane from an area of higher pressure to an area of lower pressure

passive

if a transfer does not need energy, it is _______ transport

active

if a transfer requires energy, it is _______ transport

sensible water loss

visible, able to be sensed

insensible water loss

not perceptible to the senses

diaphoresis

profuse sweating

acid

one type of compound that contains the hydrogen ion

base

a compound that contains the hydroxyl ion

lower

pH is _____ than 7, the solution is an acid

greater

pH is _____ than 7, the solution is basic (alkaline)

acids include

vinegar, lemon juice, wine, black coffee, tomato juice

bases include

baking soda, toothpaste, detergents, oven cleaner

lungs, kidneys

____ and ____ are the organs of the body that are the most involved in H+ regulation

kidney

bicarbonate - base

lungs

carbon dioxide - acid

metabolic acidosis

decreased pH; decreased bicarb

respiratory alkalosis

increased pH; decreased CO2

respiratory acidosis

decreased pH; increased CO2

metabolic alkalosis

increased pH; increased bicarb