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UA / food and nutrition / NHM 361 / Is water intracellular or extracellular?

Is water intracellular or extracellular?

Is water intracellular or extracellular?


School: University of Alabama - Tuscaloosa
Department: food and nutrition
Course: Nutritional Biochemistry
Professor: Amy ellis
Term: Fall 2016
Tags: acids and bases, Blood, bodyfluid, and pH
Cost: 25
Name: NHM 361-921 Module 2 Notes
Description: These notes cover Module 2 (Chapter 15), and give answers to the self study guide, as well as the quiz, and go over our powerpoint and briefly outline our chapter this week. Includes helpful pictures/diagrams and bright pink text to indicate key terms for smart studying! Hope it helps.
Uploaded: 09/02/2016
8 Pages 169 Views 1 Unlocks

Friday, September 2, 2016

S water intracellular or extracellular?

NHM 361-921: Module 2 Notes (CH. 15)

“Body Fluids”  


• water is the most abundant molecule in the human body - accounting for 2/3 of total  body weight Don't forget about the age old question of Why does time go by so fast when you get older?

• body water can be categorized as intracellular or extracellular fluid INTRACELLULAR FLUID- body fluid located within the cells

EXTRACELLULAR FLUID- body fluid located outside the cells

Does water provide lubrication for organs?

• can be divided further into interstitial fluid and plasma

INTERSTITIAL FLUID- fluid surrounding individual cells and fluid in the lymph vessels PLASMA- the liquid portion of whole blood


Friday, September 2, 2016

Unique Properties of Water: If you want to learn more check out What are the similarities of comparison?

• water cushions and lubricates the body’s tissues and organs

• water is a great solvent due to its polarity

• water is an excellent transport medium of nutrients to cells and tissues

HYDROPHILIC- water loving molecules that have a sufficient number of polarized  bonds or ionized groups in order for it to dissolve in water

HYDROPHOBIC- molecules that are electrically neutral and are not attracted to the (+)  and (-) charges of H2O

What happens when polar and nonpolar molecules are combined?

AMPHIPATHIC MOLECULES- are those that consist of both hydrophilic and  hydrophobic parts (think fatty acids)

• in aqueous environments. these molecule types will typically cluster together so  their polar ends will face the water & the non polar ends will be oriented away from  the water  

HYDROLYSIS- breaking of chemical bonds

DEHYDRATION SYNTHESIS- formation of chemical bonds

• note reaction 7.7 on p. 204 & reaction 8.2 on p. 225

• gas exchange is a critical functions of the blood  

• oxygen is carried from lungs to tissues Don't forget about the age old question of What is american culture?

• because oxygen is insoluble in plasma, most oxygen is carried in RBCs bound to  hemoglobin

• carbon dioxide is a common byproduct of cellular metabolism

• CO2 must be transported from tissues to the lungs to be exhaled

• CO2 is more soluble in plasma than oxygen, so about 5% can be transported  unchanged in plasma We also discuss several other topics like What is an expansion upon freezing?

• another 10-25% of CO2 binds to plasma proteins or proteins portion of hemoglobin for  transports

• most CO2 in plasma (about 75%) is in the form of bicarbonate ions (HCO3-) • can diffuse back and forth between plasma and RBC If you want to learn more check out What is the puritan concept of community?


Friday, September 2, 2016

• HCO3- and Cl- ions move in and vice versa in order to maintain charge neutrality  and osmotic balance between plasma and RBC… this is called the CHLORIDE  SHIFT

• HCO3- ions entering RBCs can combine with the H+ ions to form carbonic acid  (H2CO3) If you want to learn more check out What are the major parts of the digestive system?

• an enzyme inside RBCs, carbonic anhydrase, promotes the breakdown of H2CO3  to CO2 & H2O

• this action is reversible

• when blood reaches the lungs, the low pressure of CO2 in the lungs favors this  reaction so that H2CO3 is broken down to CO2 & H2O

• CO2 diffuses from RBCs to alveoli (air sacs) of the lungs where it is expelled as  exhaled air

Fluid & Electrolyte Balance: 

Key Electrolytes:

Sodium (Na+) : principle extracellular cation

Potassium (K+) : principle intracellular cation

Chloride (Cl-) : principle extracellular anion

Phosphate ( mainly as HPO4 2-) : principle intracellular anion

• these are called “electrolytes” because they can generate charge across plasma  membranes

Principle Cation

Principle Anion

Protein Content

Intracellular Fluid




Interstitial Fluid







Relatively High

• fluid & electrolyte balance is very important to human health

HYPERKALEMIA- serum potassium is too high

HYPOKALEMIA- serum potassium is too low

• these may result in dangerous cardiac arrhythmias


Friday, September 2, 2016

HYPERNATREMIA- high serum sodium

• sign of dehydration

HYPONATREMIA- low serum sodium

• may result from diuretic medications or rarely, from excessive water intake during  exercise

HYPERPHOSPHATEMIA- high serum phosphate

HYPPHOSPHATEMIA- low serum phosphate

• concentrations of Na+ & Cl- are regulated in the blood to maintain osmotic  pressure (also known as osmolality) of blood plasma  

• edema is an example of osmotic imbalance

Homeostatic regulation of fluid balance in the body: 

• the hypothalamus regulates the sensation of thirst

• fluid is lost through urine, air exhaled from the lungs, through the skin, & through feces

• the kidneys also play a role in fluid and electrolyte balance as well as acid-base  balance

ANTIDIURETIC HORMONE (ADH)- reduces the excretion of water in urine by  increasing reabsorption of water by kidney tubules, resulting in concentrated urine; it is  also known as “vasopressin”


Friday, September 2, 2016

• urine is ordinarily about 96% water and 4% hate products

• pH of urine is tightly maintained between 7.35-7.45

• veggies & fruits will make the urine more alkaline while high-protein foods will make  the urine more acidic

• acids and bases dissociate in water & conduct an electric current • acids release H+ & therefore are proton donors  

HCl —> H(+) + Cl(-)

• bases accept H+ & are proton acceptors

NaOH —> Na(+) + OH(-)

• water is an acid & a base

• it dissociates to form a hydroxide ion & proton, which bonds to another r water  molecule

H2O <—> HO(-) + H(+)

• the concentration of H+ in solution is expressed by pH

pH = -log[H+]

• so solutions with a high [H+] have a low pH, & solutions with a low [H+]  have a high pH

• pH runs on a scale from 0-14 with 7 being neutral

• compounds that contain a carboxyl group (R-COOH) are acids, specifically  carboxylic acids

• normal blood pH is maintained tightly at 7.35-7.45

ALKALOSIS- high blood pH

ACIDOSIS- low blood pH

• both conditions are very serious as either could result in death

• buffers work in the blood, the respiratory system, and the urinary system & they all  work together to maintain the acid-base balance in the blood


Friday, September 2, 2016

Buffer Control of Blood pH: 

• bicarbonate, phosphate, & plasma proteins in the blood all function as buffer systems

• these buffers prevent major swings in pH of the blood when acids or bases are  introduced

• the bicarbonate buffer system consists of a mix of bicarbonate ions (HCO3-) &  carbonic acid (H2CO3)

• acids and bases tend to dissociate, releasing H+ or OH- ions in the blood

Respiratory Control of Blood in pH: 

• respiratory system helps maintain acid-base balance in the blood by regulating how  much CO2 & H2O are exhaled

• the more CO2 & H2O that are exhaled, the more carbonic acid is removed from the  blood, which raises the blood pH to a more alkaline level

• increases in CO2 induces faster and deeper breathing (hyperventilation), so that more  CO2 will be expelled & blood pH normalizes

• likewise, decreases in CO2 causes slower respiration rates (hypoventilation), so that  more CO2 will be retained. Less CO2 exhaled = more carbonic acid = decrease in pH

Urinary Control of Blood pH: 

• the kidneys respond to increases and decreases in blood pH by excretion of ions by  urine

• the distal tubes of kidney nephrons are sensitive to blood pH

• if blood is too acidic, the renal tubules excrete excess H+ ions & conserve bicarbonate  ions (HCO3-)

• if blood is too basic, renal tubules excrete HCO3- & conserve H+

RESPIRATORY ALKALOSIS- occurs when a person is hyperventilating and is expelling  too much CO2

RESPIRATORY ACIDOSIS- results from slow, shallow breathing and retention of CO2;  example is pneumonia  


Friday, September 2, 2016

METABOLIC ALKALOSIS- occurs when the body has lost too much acid; example is  vomiting

METABOLIC ACIDOSIS- occurs with the loss of too much bicarbonate or buildup of acid  in the blood for a reason other than hypoventilation; examples are alcholism, kidney  disease, or severe dehydration

• oxygen binds to the iron (Fe2+) portion of hemoglobin for transport from the lungs  (alveoli) to the cells

• CO2 can be transported in 3 different ways

1. unchanged in the plasma (5%)

2. bound to the hemoglobin or plasma proteins (10-25%)

- doesn’t compete with oxygen to bind to hemoglobin since CO2 is  binding to protein portions

 3. most transports as bicarbonate ions (HCO3-)

Quiz 2: Questions & Answers 

1. A fatty acid is an example of a (n) ______ molecule?


2. A decrease in blood pH below normal will stimulate:


3. The normal pH of extracellular fluid and blood is:


4. High serum potassium is called:


5. Carbon dioxide is transported in the bloodstream chiefly in the form of: HCO3-

6. Bicarbonate ions which diffuse into and out of red blood cells are replaced by ____  ions:



Friday, September 2, 2016

7. Which of the following is the major cation of plasma and extracellular fluid? Na+

8. An increase in vasopressin secretion will result in ____ water excreted in urine More

9. Which of the following is NOT one of the properties of water?

Atoms of adjacent water molecules repel one another

10. A condition of high blood pH for a reason other than respiratory dysfunction would  be called?

Metabolic alkalosis


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