NSC 170 Exam #3 Questions &
Answers New Version 2026!!
About what percent of the human body is made up of water? - CORRECT ANSWER-
babies: 70%
adult males: 60%
adult females: 55%
How is water distributed in the body? - CORRECT ANSWER-66% Intracellular,
33% Extracellular (25% Interstitial, 8% blood plasma)
What are electrolytes? - CORRECT ANSWER-Electrolytes are substances that, when
dissolved in water, dissociate into charged ions. Positively charged electrolytes are
called cations and negatively charged electrolytes are called anions.
How do cells maintain fluid balance? - CORRECT ANSWER-Osmoregulation. The
movement of water between fluid compartments happens by osmosis, which is simply
the movement of water through a selectively permeable membrane from an area where
it is highly concentrated to an area where it is not so concentrated
Explain what happens when a cell is placed in a hypotonic and hypertonic solution. -
CORRECT ANSWER-hypotonic: if a cell is placed in a solution that contains fewer
dissolved particles than the cell itself, water moves into the more concentrated cell,
causing it to swell.
hypertonic: if a cell is placed in a solution that is more concentrated water moves from
inside the cell to the outside, causing it to shrink
,Describe the importance of water as a: Transportation vehicle - CORRECT ANSWER-
more substances dissolve in it than any other fluid, the solvent action of water allows for
substances to be more readily transported.
Describe the importance of water as a: Medium for chemical reactions - CORRECT
ANSWER-Water is required for even the most basic chemical reactions. Proteins fold
into their functional shape based on how their amino-acid sequences react with water.
These newly formed enzymes must conduct their specific chemical reactions in a
medium, which in all organisms is water. Water is an ideal medium for chemical
reactions as it can store a large amount of heat, is electrically neutral, and is not acidic
or basic
Describe the importance of water as a: Lubricant/shock absorber - CORRECT
ANSWER-It protects tissues from irritants, entraps pathogens, and contains immune-
system cells that destroy pathogens. Water is the main component of the lubricating
fluid between joints and eases the movement of articulated bones.
Describe the importance of water as a: Temperature regulator - CORRECT ANSWER-
Water is good at storing heat, an attribute referred to as heat capacity and thus helps
maintain the temperature set point of the body despite changes in the surrounding
environment.
How is water gained and lost in the body? - CORRECT ANSWER-Our tissues produce
around 300 milliliters of water per day through metabolic processes. The remainder of
water output must be balanced by drinking fluids and eating solid foods. There are two
types of outputs. The first type is insensible water loss, meaning we are unaware of it.
The body loses about 400 milliliters of its daily water output through exhalation. Another
500 milliliters is lost through our skin. The second type of output is sensible water loss,
meaning we are aware of it. Urine accounts for about 1,500 milliliters of water output,
and feces account for roughly 100 milliliters of water output.
What does the scientific evidence say about the amount of water a person should drink
per day? - CORRECT ANSWER-The amount of water/fluids a person should consume
every day is actually variable and should be based on the climate a person lives in, as
, well as their age, physical activity level, and kidney function. No maximum for water
intake has been set.
- there is no consistent scientific evidence proving that drinking a particular amount of
water improves health or reduces the risk of disease
Describe the physiological events that increase the thirst mechanism. - CORRECT
ANSWER-The thirst mechanism is activated in response to changes in water volume in
the blood, but is even more sensitive to changes in blood osmolality. Blood osmolality is
primarily driven by the concentration of sodium cations. The urge to drink results from a
complex interplay of hormones and neuronal responses that coordinate to increase
water input and contribute toward fluid balance and composition in the body.
How is the output of water regulated? - CORRECT ANSWER-Regulating urine output is
a primary function of the kidneys, and involves communication with the brain and
endocrine system.
What is the kidney's role in maintaining fluid and electrolyte balance? - CORRECT
ANSWER-The kidneys filter about 190 liters of blood and produce (on average) 1.5
liters of urine per day. Urine is mostly water, but it also contains electrolytes and waste
products, such as urea. The amount of water filtered from the blood and excreted as
urine is dependent on the amount of water in, and the electrolyte composition in the
blood.
What is osmotic pressure? - CORRECT ANSWER-The force driving the water
movement through the selectively permeable membrane is the higher solute
concentration on the one side. Solutes at different concentrations on either side of a
selectively permeable membrane exert a force, called osmotic pressure.
How is a concentration gradient used to maintain electrolyte balance in the extracellular
and intracellular fluid of a cell? - CORRECT ANSWER-when an electrolyte at higher
concentration in the extracellular fluid is transported into a cell, the potential energy is
harnessed and used to perform work
Answers New Version 2026!!
About what percent of the human body is made up of water? - CORRECT ANSWER-
babies: 70%
adult males: 60%
adult females: 55%
How is water distributed in the body? - CORRECT ANSWER-66% Intracellular,
33% Extracellular (25% Interstitial, 8% blood plasma)
What are electrolytes? - CORRECT ANSWER-Electrolytes are substances that, when
dissolved in water, dissociate into charged ions. Positively charged electrolytes are
called cations and negatively charged electrolytes are called anions.
How do cells maintain fluid balance? - CORRECT ANSWER-Osmoregulation. The
movement of water between fluid compartments happens by osmosis, which is simply
the movement of water through a selectively permeable membrane from an area where
it is highly concentrated to an area where it is not so concentrated
Explain what happens when a cell is placed in a hypotonic and hypertonic solution. -
CORRECT ANSWER-hypotonic: if a cell is placed in a solution that contains fewer
dissolved particles than the cell itself, water moves into the more concentrated cell,
causing it to swell.
hypertonic: if a cell is placed in a solution that is more concentrated water moves from
inside the cell to the outside, causing it to shrink
,Describe the importance of water as a: Transportation vehicle - CORRECT ANSWER-
more substances dissolve in it than any other fluid, the solvent action of water allows for
substances to be more readily transported.
Describe the importance of water as a: Medium for chemical reactions - CORRECT
ANSWER-Water is required for even the most basic chemical reactions. Proteins fold
into their functional shape based on how their amino-acid sequences react with water.
These newly formed enzymes must conduct their specific chemical reactions in a
medium, which in all organisms is water. Water is an ideal medium for chemical
reactions as it can store a large amount of heat, is electrically neutral, and is not acidic
or basic
Describe the importance of water as a: Lubricant/shock absorber - CORRECT
ANSWER-It protects tissues from irritants, entraps pathogens, and contains immune-
system cells that destroy pathogens. Water is the main component of the lubricating
fluid between joints and eases the movement of articulated bones.
Describe the importance of water as a: Temperature regulator - CORRECT ANSWER-
Water is good at storing heat, an attribute referred to as heat capacity and thus helps
maintain the temperature set point of the body despite changes in the surrounding
environment.
How is water gained and lost in the body? - CORRECT ANSWER-Our tissues produce
around 300 milliliters of water per day through metabolic processes. The remainder of
water output must be balanced by drinking fluids and eating solid foods. There are two
types of outputs. The first type is insensible water loss, meaning we are unaware of it.
The body loses about 400 milliliters of its daily water output through exhalation. Another
500 milliliters is lost through our skin. The second type of output is sensible water loss,
meaning we are aware of it. Urine accounts for about 1,500 milliliters of water output,
and feces account for roughly 100 milliliters of water output.
What does the scientific evidence say about the amount of water a person should drink
per day? - CORRECT ANSWER-The amount of water/fluids a person should consume
every day is actually variable and should be based on the climate a person lives in, as
, well as their age, physical activity level, and kidney function. No maximum for water
intake has been set.
- there is no consistent scientific evidence proving that drinking a particular amount of
water improves health or reduces the risk of disease
Describe the physiological events that increase the thirst mechanism. - CORRECT
ANSWER-The thirst mechanism is activated in response to changes in water volume in
the blood, but is even more sensitive to changes in blood osmolality. Blood osmolality is
primarily driven by the concentration of sodium cations. The urge to drink results from a
complex interplay of hormones and neuronal responses that coordinate to increase
water input and contribute toward fluid balance and composition in the body.
How is the output of water regulated? - CORRECT ANSWER-Regulating urine output is
a primary function of the kidneys, and involves communication with the brain and
endocrine system.
What is the kidney's role in maintaining fluid and electrolyte balance? - CORRECT
ANSWER-The kidneys filter about 190 liters of blood and produce (on average) 1.5
liters of urine per day. Urine is mostly water, but it also contains electrolytes and waste
products, such as urea. The amount of water filtered from the blood and excreted as
urine is dependent on the amount of water in, and the electrolyte composition in the
blood.
What is osmotic pressure? - CORRECT ANSWER-The force driving the water
movement through the selectively permeable membrane is the higher solute
concentration on the one side. Solutes at different concentrations on either side of a
selectively permeable membrane exert a force, called osmotic pressure.
How is a concentration gradient used to maintain electrolyte balance in the extracellular
and intracellular fluid of a cell? - CORRECT ANSWER-when an electrolyte at higher
concentration in the extracellular fluid is transported into a cell, the potential energy is
harnessed and used to perform work
