RAHSI revised 3 September 2010

Name Period Date

It’s Electrifying! Electrical Signals in the Human Body

Homeostasis, which is a state of balance or equilibrium, is essential for optimal body function. A body at equilibrium will maintain a

balanced pH, temperature, and solute concentration among the intracellular and extracellular body fluids. Body fluids are comprised

of water (solvent) and electrolytes or nonelectrolytes (solute). Electrolytes, also known as ions, are atoms that have gained electrons (negative charge) or lost

electrons (positive charge). The combination of positive and negative charges in solution allows electricity to be conducted. This characteristic is significant

since the body relies on electrical signals for functions, such as muscle contraction, digestion and nerve impulses. On the other hand, non-electrolytes are also

essential in the human body but do not conduct electricity.

Vocabulary:

Anion Cation Covalent bond Electrolytes Equilibrium Homeostasis

Ion Ionic bond Metal Nonelectrolytes Nonmetal Solute

Solution Solvent Valence electron

Materials:

8-250 mL Beakers Conductivity tester per station Distilled water (for rinsing)

Stations (250 mL solution): 1% calcium salt solution, distilled water, 1% ethanol solution, 1% glucose solution, 1% lipid solution, 1% potassium salt solution, 1%

protein solution,1% sodium chloride solution

Procedure:

1) Each lab station contains one solution, one conductivity tester, and one beaker of distilled water for rinsing.

2) To begin each station, complete the information for Data Table I.

3) Then, pick up the beaker of solution and submerge the conductivity tester into the solution.

4) Observe the light bulb. If it turns on, the solution conducts electricity. If it does not, the solution does not

conduct electricity.

5) Fill in Data Table II with the information that is missing for each lab station.

RAHSI revised 3 September 2010

Name Period Date

Data Table I: Before Testing

Station

Dissolved solute

in solution

Chemical Formula of the

solute

Elements which make up solute

Metal or

Nonmetal

Group number for each element

Valence electrons for each element

Draw dots around element symbol representing valence

electrons (Lewis Dot)

Example

Sucrose

C11H22O11

Carbon Nonmetal 4A 4

Hydrogen Nonmetal 1A 1

Oxygen Nonmetal 6A 6

1

2

3

4

5

6

7

8

RAHSI revised 3 September 2010

Name Period Date

Data Table II: After Testing

Station

Dissolved solute

in solution

Conduct Electricity

Electrolyte or Nonelectrolyte

Ionic or Covalent

Example

Sucrose

No

Nonelectrolyte

Covalent

1

2

3

4

5

6

7

8

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In solution, electrolytes tend to disperse evenly

throughout the solvent until a state of equilibrium is

reached. The bonding patterns of electrolyte

compounds are that of an ionic bond and separate in

solution to produce cations (positively-charged ions)

and anions (negatively-charged ions). These positive

and negative charges form an electrical pathway along

which electricity can be conducted. Nonelectrolyte

compounds share electrons and, therefore, form

covalent bonds and do not conduct electricity.

Dissolving salt crystal in solution

RAHSI revised 3 September 2010

Name Period Date

Post-Lab Questions and Analysis:

Directions: Complete the question on the left with the correct answer on the right.

Question Answer 1. Refer to your data table above. Which type(s) of elements bonded

to form the solute that would be considered ionic and which type bonded to form the solute that would be considered covalent? (i.e. metal with nonmetal, metal with metal, nonmetal with nonmetal)

Ionic

Covalent

2. How does the group number for each element relate to its number of valence electrons?

3. Refer to the Lewis dot structures that you made in the last column of Data Table I. The atoms of ionic compounds prefer to gain or lose electrons in order to reach a noble gas configuration (full outer shell). Pick one ionic compound that you tested in this lab and show how the atoms become ions by transferring electrons.

4. Describe electrolytes and nonelectrolytes in terms of ionic compounds and covalent compounds. Which is ionic? Which is covalent?

5. Which type of solution conducted electricity and describe how this can happen?

6. Explain why electrolytes are essential to the human body.

RAHSI revised 3 September 2010

Name Period Date

Calcium (Ca2+)

Calcium ions are known as the building components for bones and teeth. A lack of calcium can lead to cavities or osteoporosis. However, calcium is also essential for muscle control and function, blood clotting, nerve

signaling, hormone balance and normal heart beat.

Water (H2O)

Approximately 70% of the human body mass is made up of water. Water is essential for several reasons. It is needed for dehydration synthesis and hydrolysis of ATP (molecular energy) and macromolecules. It creates a

medium for electrolytes to maintain proper functioning and homeostasis. Water aids in digestion and provides protective intracellular and extracellular fluids.

Ethanol (C2H5OH)

Ethanol is highly soluble in water and, therefore, can penetrate the cell membrane of any organ in the human body. Ethanol acts as a nervous system depressant. Its concentration in the blood is measured as BAC (blood

alcohol content) and can be detected using a redox reaction in a breathalyzer test. Ethanol breaks down into fatty acids in the liver, eventually resulting in the cirrhosis of the liver.

Glucose (C6H12O6)

Glucose is a monosaccharide monomer and is the basic component that makes up starch, glycogen and cellulose. Glucose is utilized by cells as the basic molecular source of energy which is a necessary reactant in cellular

respiration, leading to the production of ATP. If glucose levels are too high, then insulin is released to convert glucose into glycogen during dehydration synthesis. If glucose levels are too low, glycogen polymers break

down into glucose monomers during hydrolysis.

Lipid—Cholesterol (C27H46O)

Although cholesterol gets a bad rap for causing heart disease, atherosclerosis and gall stones, it has many important roles in keeping the body healthy. Cholesterol is an important component in cell membranes and is

synthesized in the liver to manufacture vitamin D, bile, hormones, and nerve tissue. The liver makes all the cholesterol that the body needs. So, eating foods high in saturated fat will increase the level of LDL’s (bad

cholesterol) in the blood. On the other hand, HDL (good cholesterol) acts to clear arteries of fatty build-up. Smoking and lack of physical activity will lower HDL’s which can also be an indicator of heart disease.

Potassium (K+)

Potassium has several important roles in the human body. It helps to regulate body fluids, blood pressure and heart rate, muscle function, nervous system function including escorting oxygen to the brain, and waste

removal in the kidneys. Lack of potassium ions leads to muscle cramping, twitching, weakness, brittle bones, irregular heartbeat, slowing of thinking processes, kidney disorder and lung disease.

Protein (C2H4O2N-R group)

Proteins have several functions in the body. They act as enzymes/catalysts to speed up chemical reactions, help maintain and repair tissues, help transport particles across the cell membrane, fight disease, and cell

signaling.

Sodium (Na+)

Sodium helps to regulate body fluids, acid-base balance in your body, and is important in nerve conduction. It also helps maintain blood pressure, bone density, and homeostasis by assisting in nutrient transport across cell

membranes. Sodium is regulated in the body by the digestive system and by the kidneys.

RAHSI revised 3 September 2010

Name Period Date

Electrolyte Infusion: Power-Aid for that Deep Down Body Thirst In the human body, electrolytes may be found in intracellular (inside the cell) body fluids or in extracellular (outside the cell)

body fluids. Electrolytes are frequently transported across a membrane in order to reach the part of the body that need ions for

proper functioning, such as skeletal muscle cells, cardiac muscle cells, axon of the nerve cell, epithelial lining of the digestive

system, and so on.

When the body is active, a relatively high level of electrolytes are used and excreted through sweat and urination. Electrolytes,

in the form of salts, must be replaced by the food we eat and liquids we drink. Some drinks claim optimal replacement of

electrolytes. Gatorade® is a thirst quencher for that deep down body thirst. Powerade® has an advanced electrolyte system. Glaceau Vitamin Water hydrates

responsibly. Pedialyte® is specially-formulated to replace lost fluid and electrolytes when illness strikes. All-Sport® is not just a thirst quencher…it is a body

quencher. However, which one is most effective and how can you test effectiveness of this type of product? One way is to test the efficiency by which the

electrolytes in each drink transport across a membrane allowing them to be utilized by the cells in the body.

Materials:

8-250 mL beakers distilled water 8 conductivity probes 8 computer stations 8 plastic baggies (or dialysis tubing)

100 mL Gatorade in baggie 100 mL Powerade in baggie 100 mL Glaceau Vitamin Water in baggie

100 mL Pedialyte in baggie 100 mL All-Sport in baggie 100 mL distilled water in baggie

100 mL salt (NaCl) solution in baggie 100 mL 1% sucrose solution in baggie String or ties (optional)

Procedure:

1. Each station contains one 250 mL beaker of distilled water, one conductivity probe connected to a computer, one plastic baggie or dialysis tubing,

and 100 mL of one solution that will be tested.

2. Pour approximately 100 mL of your station’s solution into the plastic baggie or dialysis tubing. Depending on the size of the baggie or tubing, we

may need to add more but each group will be adding the same amount.

3. Tie a tight knot to close the opening of the baggie or dialysis tubing.

4. Place the conductivity probes in the 150 mL of distilled water and check to make sure the program is running.

5. Rinse the outside of the baggie or dialysis tubing with distilled water to reduce contamination.

6. When ready, place the baggie with your solution in the beaker of distilled water and observe the change in conductivity by watching the change in

the graph for 20 minutes or until conductivity returns to zero.

Beforetheyhatch.com

RAHSI revised 3 September 2010

Name Period Date

Data and Analysis:

1. Identify the solution that your group tested. ___________________________________________________

2. Below is sample data of a variety of solutions: electrolyte and nonelectrolyte.

Draw or print and paste a representation of your graph in the space below. Include a title for your graph and label your axes.

3. Explain what happened to the conductivity of your solution over time and prepare to present your findings.

4. Based on class data, which solution would you recommend to an athlete who is looking for the most effective post-workout electrolyte

replacement?

RAHSI revised 3 September 2010

Name Period Date

Case Study: Acute Hyponatremia—This Is Far From “Ecstasy!”

Hyponatremia is an electrolyte disturbance when the sodium (Na+)

concentration in blood is too low and water concentration is too

high. If water cannot be excreted in order to reach homeostasis,

then hyponatremia will result.

Sodium is the dominant cation in extracellular fluid and must be

able to cross the membrane into the cells. Normal sodium

concentration is no lower than 135 mEq/L while 125 mEq/L is

considered severely low. Since water surpasses sodium in concentration in hyponatremia, water

will enter the cells through osmosis, preventing the presence of essential sodium concentration in

the cells and, therefore, proper functioning.

Among other cells, brain cells can become overpowered by a high water concentration which may

help to explain Riley’s lack of concentration, severe headache, seizure and resulting coma. If ER

physicians and staff do not act quickly, then Riley will die. What should the ER do to stabilize Riley

and how did anorexia nervosa play a role in amplifying Riley’s symptoms?

Riley, age 19, suffers from anorexia nervosa

and other body-image issues which are

typical in teenagers. Some acquaintances

invited her to a “rave” party and, wanting to

fit-in, she decided to go. Succumbing to peer

pressure, Riley agreed to try the drug

“Ectasy.” She followed the advice of her peers

who told her to drink several gallons of

water to avoid “dehydration” from excessive

sweating. So, she drank water—a lot of

water.

As time passed, Riley began to feel nauseous

and unable to concentrate. Soon after, she

began to vomit uncontrollably coupled with

an excruciating headache. Worried, her new

“friends” called for an ambulance. When

Riley arrived in the emergency room, she

experienced a grand mal seizure

(convulsions and unconsciousness) and

slipped into a coma.

Riley’s blood was drawn immediately and

her lab results showed that her PNa (blood

plasma sodium) was 120 mEq/L.

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