Fluid, Electrolytes, and Acid-Base Balance (Concepts) Flashcards
The average healthy adult’s weight is ______ and what is its percentage?
Water; 60 %
T/F: In good health this volume remain relatively constant, and a person’s weight varies by less than 0.2 kg (0.5 lb) in 24 hours, regardless of the amount of fluid ingested.
T
What are the cellular functions of water?
- A medium for metabolic reactions within cells
- A transporter for nutrients, waste products, and other substances
- A lubricant
- An insulator and shock absorber
- A means of regulating and maintaining body temperature
Who has the highest proportion of water? Accounting 70-80 % of their body weight?
Infants
T/F: The proportion of water decreases as we age.
T
T/F: Women generally have lower percentage of body water than men.
T
This is due because of lower levels of ______ and great percentage of ______.
muscle mass; fat tissue
T/F: Fat tissue is essentially free of water, whereas lean tissue contains a significant amount of water. Therefore, water makes up a greater percentage of a lean individual’s body weight than of an individual who is obese.
T
The body’s fluid is divided into two major compartments, what are them?
Intracellular Fluid (ICF) and Extracellular Fluid (ECF)
It is found within the cells of the body. It constitutes approximately two thirds of the total body fluid in adults.
Intracellular Fluid (ICF)
It is found outside the cells and accounts for about one third of total body fluid.
Extracellular Fluid (ECF)
T/F: ECF is not further subdivided into compartments.
F
It accounts for approximately 20% of ECF and is found within the vascular system.
Intravascular fluid or Plasma
It is accounting for approximately 75% of ECF, surrounds the cells.
Interstitial Fluid
The other compartments of ECF include the:
lymph and transcellular fluids
Transcellular fluids include:
- cerebrospinal
- pericardial
- pancreatic
- pleural
- intraocular
- biliary
- peritoneal
- synovial fluids
It is vital to normal cell functioning. It contains solutes such as oxygen, electrolytes, and glucose, and it provides a medium in which metabolic processes of the cell take place.
Intracellular fluids
T/F: Although ECF is in the smaller of the two compartments, it is the transport system that carries oxygen and nutrients to, and waste products from, body cells.
T
Extracellular and intracellular fluids contain:
- oxygen from the lungs
- dissolved nutrients from the gastrointestinal tract
- excretory products of metabolism such as carbon dioxide
- charged particles called ions.
Many salts dissociate in water; that is, they break up into electrically charged ions. The salt called _________ breaks up into one ion of sodium (Na+) and one ion of chloride (Cl−).
Sodium chloride
These charged particles are called _______ because they are capable of conducting electricity.
Electrolytes
T/F: The number of ions that carry a positive charge, called cations, and ions that carry a negative charge, called anions, should be equal.
T
What are the following: sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+).
Cations
What are the following: chloride (Cl−), bicarbonate (HCO3−), phosphate (PO34–), and sulfate (SO24–).
Anions
Electrolytes generally are measured in _________ or _______. The first term refers to the chemical combining power of the ion, or the capacity of cations to combine with anions to form molecules, whereas the second term refers to the weight of the ion.
Milliequivalent per liter (mEq/L); milligrams per 100 milliliters (mg/100 mL)
T/F: 1 mEq of any anion equals 1 mEq of any cation in terms of their capacity to combine into molecules. Therefore, sodium and chloride combine equally, so 1 mEq of Na+ equals 1 mEq of Cl−.
T
T/F: A molecule of sodium is equal in weight to a molecule of chloride.
F
_________ levels frequently are reported in milligrams per deciliter (1 dL = 100 mL) instead of milliequivalents per liter.
Calcium
It also is important to remember that laboratory tests are usually performed using ________, an extracellular fluid. These results reflect what is happening in ECF, more specifically within intravascular fluid, but generally it is not possible to directly measure electrolyte concentrations within body cells.
Blood plasma
T/F: The composition of fluids varies from one body compartment to another
T
T/F: In ECF, the principal electrolytes are sodium, chloride, and bicarbonate. Other electrolytes such as potassium, calcium, and magnesium are present, but in much smaller quantities.
T
Plasma and interstitial fluid, the two primary components of ECF, contain essentially the same electrolytes and solutes, with the exception of _______. Plasma is a protein-rich fluid, containing large amounts of________, but interstitial fluid contains little or no protein
protein; albumin
T/F: The composition of ICF differs significantly from that of ECF.
T
Potassium and magnesium are the _________ present in ICF, and phosphate and sulfate are the _________. As in ECF, other electrolytes are present within the cell, but in much smaller concentrations.
primary cations; major anions
Other body fluids such as gastric and intestinal secretions also contain electrolytes. This is of particular concern when these fluids are lost from the body (for example, in severe vomiting or diarrhea, or when gastric suction removes gastric secretions). ___________ can result from excessive losses through these routes.
Fluid and electrolyte imbalances
The body fluid compartments are separated from one another by __________ and the _______. Although these are completely permeable to water, they are considered to be selectively permeable to solutes, because substances other than water move across them with varying degrees of ease.
cell membranes; capillary membrane
___________ are substances dissolved in a liquid. They may be crystalloids (salts that dissolve readily into true solutions) or colloids (substances such as large protein molecules that do not readily dissolve into true solutions).
Solutes
A _________ is the component of a solution that can dissolve a solute. In the body, ________ is the solvent; the solutes include electrolytes, gases such as oxygen and carbon dioxide, glucose, urea, amino acids, and proteins.
Solvent; water
The concentration of solutes in body fluids is usually expressed as the ___________. It is determined by the total solute concentration within a fluid compartment and is measured as parts of solute per kilogram of water.
Osmolality
Osmolality is reported as:
milliosmoles per kilogram (mOsm/kg).
Sodium is by far the greatest determinant of the osmolality of _________, or serum osmolality, although glucose and urea also contribute.
plasma
Potassium, glucose, and urea are the primary determinants of the osmolality of ___________.
intracellular fluid.
The term _____________ may also be used to refer to the osmolality of one solution in relation to another solution.
tonicity
In relation to body fluids, an _____________ has the same osmolality as ECF. Normal saline, 0.9% sodium chloride, is an example of an isotonic solution.
isotonic solution
____________, such as 3% sodium chloride, have a higher osmolality than ECF.
Hypertonic solutions
______________, such as 0.45% sodium chloride, have a lower osmolality than ECF.
Hypotonic solutions
____________ is the power of a solution to pull water across a semipermeable membrane.
Osmotic pressure
When two solutions of different concentrations are separated by a semipermeable membrane, the solution with the ________ solute concentration exerts a higher osmotic pressure, pulling water across the membrane to equalize the concentrations of the solutions.
higher
Infusing a hypertonic IV solution such as 3% sodium chloride will pull fluid out of red blood cells (RBCs) and into plasma, causing the cells to ________.
shrink
On the other hand, a hypotonic solution administered intravenously will cause the RBCs to ________ as water is pulled into the cells by their higher osmotic pressure.
swell
In the body, plasma proteins also exert osmotic pressure called ___________ , holding water in plasma, and when necessary pulling water from the interstitial space into the vascular compartment. This is an important mechanism for maintaining vascular volume.
colloid osmotic pressure or oncotic pressure
Diffusion occurs when two solutes of different concentrations are separated by a _______.
semipermeable membrane
The__________ of diffusion of a solute varies according to the size of the molecules, the concentration of the solution, and the temperature of the solution.
rate
Which of the following are true?
- Larger molecules move less quickly than smaller ones - molecules move from a solution of higher concentration to a solution of lower concentration
- increases in temperature increase the rate of motion of molecules and therefore the rate of diffusion.
All of the above
_________ is a specific kind of diffusion in which water moves across cell membranes, from the less concentrated solution (the solution with less solute and more water) to the more concentrated solution (the solution with more solute and less water).
Osmosis
In other words, water moves toward the higher concentration of solute in an attempt to________ the concentrations of both water and solute.
equalize
Osmosis occurs in the body when the concentration of solutes is _________ on one side of a selectively permeable membrane, such as the capillary membrane, than on the other side.
higher
______ is a process whereby fluid and solutes move together across a membrane from an area of higher pressure to an area of lower pressure. An example of filtration is the movement of fluid and nutrients from the capillaries of the arterioles to the interstitial fluid around the cells.
Filtration
The pressure that results in the movement of the fluid and solutes out of a compartment is called __________.
filtration pressure
__________ is the pressure exerted by a fluid within a closed system on the walls of the container in which it is contained.
Hydrostatic Pressure
Which of the following are true?
- The hydrostatic pressure of blood is the force exerted by blood against blood vessel walls.
- The plasma proteins and other solutes in the blood exert osmotic pressure.
- Osmotic pressure opposes and balances the force of hydrostatic pressure, and holds fluid in the vascular compartment to maintain the vascular volume.
- When hydrostatic pressure is greater than osmotic pressure, fluid filters out of the blood vessels.
All of the above
_________ is the difference between the hydrostatic pressure and the osmotic pressure.
Filtration pressure
It is the movement of solutes across cell membranes from a less concentrated solution to a more concentrated one. This process differs from diffusion and osmosis, which are passive processes, in that metabolic energy is expended.
Active transport
It is the movement of solutes across cell membranes from a less concentrated solution to a more concentrated one. This process differs from diffusion and osmosis, which are passive processes, in that metabolic energy is expended.
Active transport
T/F: The process of active transport is of particular importance in maintaining the differences in sodium and potassium ion concentrations of ECF and ICF.
T
Which of the following are true?
- Under normal conditions, sodium concentrations are lower in ECF, and potassium concentrations are higher in ICF.
- To maintain these proportions, an active transport mechanism (the sodium-potassium pump) is activated, moving sodium from cells into plasma and potassium from plasma into cells.
- Active transport moves and holds sodium and potassium against their diffusion gradients.
2nd and 3rd only - Under normal conditions, sodium concentrations are higher in ECF, and potassium concentrations are higher in ICF.
T/F: In a healthy person, the volumes and chemical composition of the fluid compartments stay within specific and narrow limits. Normally, fluid intake and fluid loss are balanced. Illness can upset this balance so that the body has too little or too much fluid.
T
During periods of normal activity at moderate temperature, the average adult drinks about _______, despite the fact that they need ________ for normal functioning.
1,500 mL/day; 2,500 mL/day
The additional 1,000-mL volume is acquired from _______ and from the oxidation of these foods during metabolic processes.
foods
The water content of food is relatively large, contributing about ________.
750 mL/day
Water as a by-product of food metabolism accounts for most of the remaining fluid volume required. This quantity is approximately _______ for the average adult
200 mL/day
The thirst mechanism is the primary regulator of fluid intake. The thirst center is located in the __________ of the brain.
hypothalamus
A number of stimuli trigger the thirst center causing the sensation of thirst and the desire to drink fluids, including:
- the osmotic pressure of body fluids
- vascular volume
- angiotensin (a hormone released in response to decreased blood flow to the kidneys),
Thirst is normally relieved immediately after drinking a small amount of fluid, when the ingested fluid distends the _________, but before the fluid is actually absorbed from the gastrointestinal tract.
upper gastrointestinal tract
However, this relief is only temporary, and thirst returns in about 15 minutes. The thirst is again temporarily relieved by drinking a small amount of fluid. This mechanism protects the individual from drinking too much, because it takes between ___________ for fluid to be absorbed and distributed throughout the body.
30 minutes and 1 hour
________ is formed by the kidneys and excreted from the urinary bladder, and is the major route of fluid output.
Urine
Normal urine output for an adult is __________ per 24 hours, or at least 0.5 mL per kilogram per hour.
1,400 to 1,500 mL
Which of the following is/are true:
- In healthy people, urine output may vary noticeably from day to day.
- Urine volume should automatically decrease as fluid intake increases.
- If fluid losses through other routes are large, however, urine volume should increase to maintain fluid balance.
1st one only - Urine volume should automatically increase as fluid intake increases; If fluid losses through other routes are large, however, urine volume should decrease to maintain fluid balance.
The ___________ that passes from the small intestine into the large intestine contains both water and electrolytes.
chyme
The volume of chyme entering the large intestine in an adult is normally about _________. Of this amount, all but about _______ is reabsorbed in the proximal half of the large intestine. The reabsorbed volume contains primarily water and electrolytes.
1,500 mL/day; 100 mL
Insensible fluid losses occur through the _________. They are called insensible because it is usually not noticeable and cannot be measured.
skin and the lungs
Insensible fluid loss through the skin occurs in two ways; ____________.
diffusion and perspiration
Water loss through diffusion is not noticeable but normally accounts for _________. This loss can be significantly increased if the protective layer of the skin is damaged, as with burns or large abrasions.
300 to 400 mL/day
________, which may be noticeable but is not measurable, varies depending on factors such as environmental temperature, body temperature, and metabolic activity.
Perspiration
Fever and exercise increase __________, thereby increasing fluid losses through the skin.
metabolic activity and heat production
Another type of insensible loss is the water in_________. In an adult, this is normally 300 to 400 mL/day. When respiratory rate accelerates, for example, due to exercise or an elevated body temperature, this loss can increase.
exhaled air
Certain fluid losses are required to maintain normal body function. These are known as_________.
obligatory losses
Approximately__________ of fluid must be excreted through the kidneys of an adult each day to eliminate metabolic waste products.
500 mL
Water lost through respirations, the skin, and in feces also are obligatory losses, necessary for temperature regulation and elimination of waste products. The total of all these losses is approximately ___________.
1,300 mL/day
The volume and composition of body fluids are regulated through ___________.
several homeostatic mechanisms
A number of organs and systems contribute to this regulation, including the:
kidneys, lungs, and the cardiovascular and gastrointestinal systems
The_______ are the primary regulator of body fluids and electrolyte balance.
kidneys
The kidneys help maintain homeostasis by:
- They regulate the volume and osmolality of ECF by regulating water and electrolyte excretion.
- The kidneys control the reabsorption of water from plasma filtrate and ultimately the amount excreted as urine.
- Electrolyte balance is maintained by selective retention and excretion by the kidneys.
- The kidneys also play a significant role in acid–base regulation, excreting hydrogen ion (H+) and retaining bicarbonate.
All of the above
Although 135 to 180 L of plasma per day is normally filtered in an adult, only about ______ of urine is excreted.
1.5 L