NR 412 PATHOPHYSIOLOGY EXAM 1
- What is the total body water (TBW) per body weight in infants?
75-80% - What is the total body water (TBW) per body weight in adult males?
60% - What is the total body water (TBW) per body weight in adult females?
50% - What is the total body water (TBW) per body weight in obese adults? Why?
30-40% because of the increase in adipose tissue, and decrease in muscle mass in
obese people - What is the total body water (TBW) per body weight in elderly adults? Why?
45% because they have a decrease in muscle mass and decreased thirst mechanism in
hypothalamus - List some functions of body fluids
-Maintain blood volume
-Regulate body temperature
-Transport material to and from cells
-Serves as an aqueous medium for cellular metabolism
-Assists with food digestion
-Serves as a medium for excreting waste
- Intracellular fluid (ICF)
-Fluid within the cells
-2/3 of body fluid is found within the cells - Extracellular fluid (ECF)
-Interstitial – fluid between the cells
-Intravascular – vessels, blood
-Transcellular – specialized fluids such as synovial fluid, cerebrospinal fluid, digestive
juices, peritoneal fluid, pleural fluid… - The 2 types of movement of fluids/electrolytes
-Passive transport
-Active transport - Passive transport
No energy is expended to move substances. There are 3 different types of passive
transport; diffusion, osmosis, and filtration. - Active transport
ATP is required to move substances from a low concentration to a high concentration. - Diffusion
The passive movement of solute molecules through a permeable membrane from [high]
to [low] - Solute
The particles dissolved in the solution - Solvent
The liquid substance that contains the solute - Osmosis
The movement of water across a permeable membrane from low concentration of
solute to high concentration of solute - Osmolarity
The total concentration of all solute particles in a solution. Osmolarity is classified as;
-Hypotonic
-Hypertonic
-Isotonic - Hypertonic solution
A solution in which the concentration of solutes is greater than that of the cell that
resides in the solution. Meaning there is more “salt” in the solution than in the RBC so
water will leave RBC and they will crenate. - Hypotonic solution
A solution in which the concentration of solutes is less than that of the cell that resides
in the solution. Meaning there is more “salt” inside the RBC so water will enter the RBC
and they will lyse. - Filtration
Movement of both water and small molecules through a semi-permeable membrane
from an area of high pressure to low pressure.
Filtration occurs due to hydrostatic pressure balanced with osmotic pressure. - Hydrostatic Pressure
-Pressure exerted by a fluid within a closed system
-Force of the weight of water molecules pressing against confining walls
-Moves from high pressure to low pressure - Osmotic Pressure
-The power of a solution to draw water
-A highly concentrated solution draws water
-For example an artery has high pressure that travels by cells and “bathes” them, then
at the venous side fluid is drawn back into the artery via osmotic pressure. - What structure regulates thirst in the body?
Hypothalamus – it tests the tonicity of the blood and decides if we need more water or
not - Fluid output come from what 4 main organs?
-Kidneys: urination
-GI tract: BM
-Skin: perspiration (insensible loss)
-Lungs: exhalation (insensible loss)