Chapter 14 Water Part 1 Flashcards
How much water in body
50% to 75% body weight. 55% of body weight for adults.
Who has the most water in body
Infants have the most water in body, and the water decrease as the age increase. Lean people have greater percent of water in body than obese people.
Why lean people contain more water?
Because lean tissue contains 73% of water, but adipose tissue contains only 20% water.
Two compartments of water in body
Intracellular and extracellular. Almost 2/3 of water is in intracellular compartment, and rest of the water is found in extracellular
Two additional compartments of extracellular
interstitial fluid(between cells) and intravascular fluid(in blood and lymph).
The fluid in compartment is not _____
pure water. It also contains dissolved substances known as solutes.
What is the most abundant solute
Electrolytes.
Electrolytes
It will form when salt, such as NaCl, potassium phosphate, dissociate in solution and form ions.
Intracellular contains primarily
potassium and magnesium cations and negative charged phosphate anions.
Extracellular contains
Sodium cations and chloride anions along with bicarbonate, predominate.
How do body control the amount of water in body
By controlling the concentration of electrolytes in compartment.
The sophisticated gatekeeping system
Involves transmembrane pumps keeps intra and extra water and electrolytes concentration in a narrow range.
Osmosis
It is the passive diffusion of water across a semipermeable membrane — in the body, these are cell membrane. When the concentration of solutes (mainly electrolytes) differs on the 2 sides of a cell membrane, water will move from the side with a low solute concentration to the side with the higher solute concentration.
Adding water
will make the absorbed water move through the osmosis from high concentration side to low concentration side. This happens when we drink water.
Functions of water
Maintenance of blood volume, transport of nutrients and oxygen. Water is the basis synthesis for the fluid synthesized in body, such as bile and saliva. It also forms lubricants in knees and joints. It also participate in many metabolic processes and reactions as a solvent. It also regulate the temperature of body and remove waste product.
Two ways of water regulate body temperature
First, water has high heat capacity, so the temperature rises slowly when it is heated. Another way is sweat. 99% of sweat is water, the heat energy is taken out the body with perspiration.
Body waste removal
Most unwanted substances in body are water soluble, so that they can be excreted through urine.
What happens if the urea is low frequent
its heavy ion concentration may increase the risk of kidney stone formation in susceptible people, especially men.
Water beverage
Contains high calorie and sugar which cause obesity and cardiovascular disease. Also should consider the micronutrients in the beverage.
If beverage take place of juice
decrease Vitamin C, Vitamin A, and folate intake.
Dehydrate of caffeine
Will not cause dehydrate up to 500 mg per day.
How do ethanol increase the urine output?
By inhibiting the action of antidiuretic hormone which helps to control the amount of fluid lost in the urine.
Bottle water
Is no safer than tap water since it comes from various of resources. Pay attention to the label. Consider if the water contains fluoride which can prevent dental carries.
Water in vegetables
75% to 95%.
Water in potato, chicken, and steak
50% to 75%
Food less than 35%
Jam, honey, crackers, butter, and margarine.
Water in vegetable oil
no water.
Water needs
Adequate water in 15 cups (3.7 L) per day for adult men, 11 cups (2.7 L) for adult women.
Plain water we need
13 cups for men, and 9 cups for women.
Water produced from metabolism
1 to 1.5 cups. 250 to 350 ml.
Sensible water loss
Urine and heavy perspiration.
Insensible water loss
Loss from the skin, lungs and feces that we do not notice.
How much water enter the intestinal tract?
32 cups from the secretion of mouth, stomach, intestine, pancreas, and other organs. And diet supplies an additional 8 to 13 cups.
How much water loss in the feces
0.5 to 0.75 cups.
Water reabsorption of kidney
Kidney can conserve water. It is the primary means to regulate the balance of water in body. And kidney can reabsorb 97% water from the waste.
Water regulation
Kidney is the main regulator, but the brain, lungs, and liver also have important roles. And this regulation is very precise.
When water intake is too low
Blood will be more concentrated(the osmotic pressure of the extracellular increase) and blood pressure falls. And pituitary secretes ADH to let kidney retain water and decrease urine. And low down the blood pressure initiate the another sequence of events in body.
Symptoms of dehydration
Solute concentration in the blood rise, blood pressure decrease, and heart rate increases due to low blood volume. If fluid loss continue, will cause kidney failure, seizures, delirium, and coma.
