Chapter 9: Water Balance

Question 1

The hormone that conserves body water is

a. vitamin D hormone.
b. antidiuretic hormone.
c. aldosterone.
d. parathyroid hormone.

Answer 1

antidiuretic hormone.

is produced by the pituitary gland and is a water-conserving mechanism that works on the kidneys’ nephrons to induce reabsorption of water.

Question 2

The two minerals that occur in the extracellular fluid and regulate water balance are

a. calcium and potassium.
b. sodium and chloride.
c. phosphorus and magnesium.
d. potassium and magnesium.

Answer 2

sodium and chloride.

Question 3

A person with a high body water content is most likely

a. overweight.
b. underweight.
c. a body builder.
d. sedentary.

Answer 3

a body builder.

An athlete would have a high body water content related to the amount of muscle mass. Muscle mass contains a relatively large amount of water.

Question 4

The term extracellular fluid includes

a. plasma and tissue secretions.
b. plasma and fluid inside cells.
c. fluid surrounding cells and in beverages.
d. fluid surrounding cells and fluid inside cells.

Answer 4

plasma and tissue secretions.

Extracellular fluid is the total body water outside the cells. This water collectively makes up 15% to 20% of the total body weight.

Question 5

A basic mechanism for maintaining body hydration is

a. thirst.
b. electrolyte balance.
c. acid-base balance.
d. activity level.

Answer 5

thirst.

Thirst is the basic mechanism for maintaining hydration. The body’s requirement for water varies with temperature, activity level, functional losses, metabolic needs, age, and other dietary factors.

Question 6

The hormone responsible for promoting conservation of sodium in the kidney is

a. aldosterone.
b. antidiuretic hormone.
c. angiotensin.
d. renin.

Answer 6

aldosterone.

Aldosterone is produced by the adrenal glands, which trigger the kidneys’ nephrons to reabsorb sodium.

Question 7

In the adult, the average daily intake of fluid from all sources is approximately _____ mL.

a. 2000
b. 2200
c. 2400
d. 2800

Answer 7

2400

The approximate daily adult intake from liquids, liquids in foods, and metabolism is approximately 2400 mL/day.

Question 8

Water formed from metabolism comes from

a. what is contained in foods.
b. moving from compartment to compartment.
c. what is absorbed from gastrointestinal secretions.
d. oxidation of nutrients in the cells.

Answer 8

oxidation of nutrients in the cells.

Metabolic water, or water of oxidation, is the product of cell oxidation when nutrients are burned in the body for energy.

Question 9

The approximate volume of digestive secretions produced by the stomach each day is _____ mL.

a. 1000
b. 1500
c. 2000
d. 2500

Answer 9

2500

The approximate total volume of digestive secretions produced by an average-sized adult is 8200 mL per 24 hours. Of this amount, 2500 mL is from gastric secretions.

Question 10

The kidneys must excrete water in the urine because

a. the body needs to get rid of the water ingested.
b. water provides the vehicle for excretion of waste products.
c. they physiologically cannot retain all the water.
d. hormones ensure that a maximal amount of water is retained by the body.

Answer 10

water provides the vehicle for excretion of waste products.

The largest amount of water exits through the kidneys. A certain amount of water must be excreted as urine to carry out the various waste products of metabolism. This is called obligatory water loss because it is compulsory for survival and must occur daily for health. The kidneys may put out an additional amount of water depending on body activities and needs, which is referred to as optional water loss.

Question 11

Plasma proteins and electrolytes are examples of solutes

a. filtered from the plasma by the kidneys.
b. found in body fluids that influence movement of water.
c. released into the plasma by the liver.
d. recycled by the mucosa during digestion.

Answer 11

found in body fluids that influence movement of water.

Plasma proteins, mainly in the form of albumin and globulin, are organic compounds of large molecular size responsible for controlling water movement in the body and guarding blood volume by influencing the shift of water in and out of capillaries in balance with the surrounding water. Electrolytes are particles that are free to move throughout a solution to maintain chemical balance.

Question 12

An example of a substance that can pass through a capillary membrane is

a. glucose.
b. hemoglobin.
c. plasma proteins.
d. antibodies.

Answer 12

glucose

The walls of the capillaries are fairly free membranes because they are thin and porous; therefore water molecules and small particles can move freely across them

Question 13

An acid has a pH

a. greater than 7.0.
b. lower than 7.0.
c. greater than 5.0.
d. lower than 5.0.

Answer 13

lower than 7.0.

A pH less than 7.0 is considered acidic, whereas anything above 7.0 is considered basic. A pH of 7.0 is neutral.

Question 14

An example of a cation is

a. sodium.
b. phosphorus.
c. carbonate.
d. sulfate.

Answer 14

sodium.

Cations are ions carrying positive charges, such as sodium, potassium, calcium, and magnesium.

Question 15

The organic molecule responsible for creating colloidal osmotic pressure is

a. glucose.
b. an electrolyte.
c. protein.
d. sodium.

Answer 15

protein.

Question 16

An example of an electrolyte is

a. glucose.
b. iron.
c. potassium.
d. carbon dioxide.

Answer 16

potassium.

Electrolytes are small, inorganic substances that can dissociate or break apart in a solution and carry an electrical charge. Examples include potassium, sodium, chloride, calcium, magnesium, carbonate, phosphate, and sulfate.

Question 17

Ways in which water and solutes move across membranes include

a. diffusion and filtration.
b. capillary action and circulation.
c. peristalsis and contraction.
d. conduction and pulsation.

Answer 17

diffusion and filtration.

Forces that move water and solutes across membranes include osmosis, diffusion, filtration, active transport, and pinocytosis.

Question 18

Functions of water in the body include

a. providing an energy source.
b. temperature control.
c. nerve impulse transmission.
d. transport of vitamins A, D, E, and K.

Answer 18

temperature control.

The body water supply acts as a solvent, serves as a means of transport, provides form and structure, regulates temperature control, and provides lubrication for the body.

Question 19

The term used to denote concentration of electrolytes in a given volume is

a. valence.
b. colloidal osmotic pressure.
c. pH.
d. milliequivalent.

Answer 19

milliequivalent

Milliequivalent is used to express the number of electrolytes per unit of fluid in a solution.

Question 20

Cations primarily responsible for controlling body water distribution are

a. sodium and chloride.
b. calcium and phosphorus.
c. sodium and potassium.
d. sodium and bicarbonate.

Answer 20

sodium and potassium.

Sodium and potassium are cations that function to control the distribution of water in the body. Sodium is the major extracellular electrolyte and potassium is the major intracellular electrolyte.

Question 21

Body water requirements are increased by

a. age.
b. emotional stress.
c. diarrhea and vomiting.
d. lower environmental temperature.

Answer 21

diarrhea and vomiting.

Diarrhea and vomiting increase the loss of fluid from the body and hence increase body water requirements for replacement to maintain a state of homeostasis.

Question 22

The kidneys “launder” the blood by

a. osmosis.
b. filtration.
c. active transport.
d. diffusion.

Answer 22

filtration.

The kidneys filter the blood and maintain the appropriate levels of all constituents of blood. They also selectively reabsorb water and needed materials to be carried throughout the body.

Question 23

Oral rehydration therapy is preferred over intravenous therapy for fluid replacement caused by diarrhea because it

a. is quicker.
b. tastes better.
c. is just as effective.
d. provides electrolytes as well as fluid.

Answer 23

is just as effective.

Oral hydration is preferred over intravenous therapy if able to be consumed by the patient because it is just as effective as intravenous therapy and uses the gastrointestinal system.

Question 24

The predominant regulator(s) of circulating blood volume is(are)

a. electrolytes.
b. plasma proteins.
c. water intake.
d. hormones.

Answer 24

plasma proteins.

Plasma protein molecules are retained in blood vessels, controlling water movement in the body and guarding blood volume by influencing the shift of water in and out of capillaries in balance with the surrounding water.

Question 25

The action of antidiuretic hormone on the kidney causes

a. sodium excretion.
b. sodium retention.
c. water excretion.
d. water retention.

Answer 25

water retention.

Antidiuretic hormone is a water-conserving mechanism that works on the kidneys’ nephrons to induce reabsorption of water. In any stressful situation with threatened or real loss of body water, this hormone is released to conserve vital body water.

Question 26

Thirst tends to be an unreliable index of fluid needs in

a. infants.
b. pregnant women.
c. breastfeeding women.
d. older adults.

Answer 26

older adults.

Thirst is an unreliable index of fluid needs in the elderly because the thirst mechanism usually diminishes with age and dehydration can easily occur.

Question 27

Plasma proteins maintain colloidal osmotic pressure because

a. they are large molecules.
b. proteins are not found in the cells.
c. proteins are positively charged.
d. they contain water as part of their structure.

Answer 27

they are large molecules.

Plasma proteins maintain colloidal osmotic pressure because they are large molecules, mainly in the form of albumin and globulin. Plasma protein molecules are retained in the blood vessels, controlling water movement in the body and guarding blood volume by influencing the shift of water in and out of capillaries in balance with the surrounding water, which in this form is referred to as colloids.

Question 28

Treatment for diarrhea in children is to

a. withhold oral intake until diarrhea stops.
b. sponge with an electrolyte solution.
c. give age-appropriate diet along with oral fluids that contain sodium, potassium, sugar, and sodium bicarbonate.
d. administer the BRAT (bananas, rice, applesauce, and tea) diet.

Answer 28

give age-appropriate diet along with oral fluids that contain sodium, potassium, sugar, and sodium bicarbonate.

Question 29

The electrolyte present in the most abundance in gastric digestive fluids
 is
a.	chloride.
b.	potassium.
c.	sodium.
d.	bicarbonate.

Answer 29

chloride.

The approximate concentration of certain electrolytes in gastric secretions of the digestive fluids is mostly composed of chloride followed by sodium and potassium.

Question 30

The principle of osmosis is best exemplified by

a. water.
b. plasma protein.
c. fat.
d. glycerol.

Answer 30

water.

Osmosis is used to describe the process or force that impels water molecules to move throughout the body.