Ch 27

What percent of the fluids outside the cell is water?

Water makes up 99% if the volume of the fluid outside the cell. Essential ingredient to the cytoplasm.

Define extracellular fluid

All body fluids other than that contained within cells; includes plasma and interstitial fluid

Define Intercellular fluid

The fluid in the tissues that fills spaces between cells

Explain how fluid balance, electrolyte balance, and acid balance are interrelated and essential to homeostasis

Fluid Balance is when the amount of water you gain each day is equal to the amount you lose to the environment. Maintenance of norm. fluid balance involves regulating the content and distribution of body water in the ECF & ICF. Digestive system is main so

What are three interrelated processes that stabilize the volume, solute concentration, and pH of ECF and ICF

Diffusion, osmosis, and carrier-mediated transport.

List the components of ECF and ICF

Largest subdivision of the ECF are the interstitial fluid of the peripheral tissues and the plasma of circulating blood. Minor components of the ECF include lymph, cerebrospinal fluid (CSF), synovial fluid, serous fluids (pleural pericardial, and peritone

Compare the body composition of the adult male and the adult female.

Adult Male: Water 60%
Intracellular Fluid 33%
Interstitial Fluid 21.5%
Plasma 4.5%
Other body fluids <1%
Solids 40% organic and inorganic
Adulte Female: Water 50%
Intracellular Fluid 27%
Interstitial Fluid 18%
Plasma 4.5 %
Other body fluids <1%
Solids 50%

What are the most important cations and anions in the ECF and ICF ?

The principle ions in the ECF are sodium(cation), clhloride(anion), bicarbonate(anion).
The ICF contains an abundance of potassium(cation), magnesium(cation), and phosphate ions, plus large amounts of negatively charged proteins.

List the largest components of the ECF

Interstitial fluid of peripheral tissues and the plasma of circulating blood.

List the minor components of the ECF

Lymph, cerebrospinal fluid (CSF), synovial flui, serous fluid(pleural, pericardial, and peritoneal fluids), aqueous humor, perilymph, and endolymph.

Explain how the components of the ECF interact

Exchange between fluid volumes and the rest of the ECF takes place more slowly than does the exchange between plasma and other interstitial fluids.
Exchange among the subdivisions of the ECF occurs primarily across the enotheliual lining of capillaries. F

Explain characteristics of plasma membrane

Plasma membranes are selectively permeable: Ions can enter or leave cell only by specific membrane channels. Also, carrier mechanisms move specific ions into or out of the cell. Most plasma membranes are freely permeable to water. The regulations of fluid

Name the mechanism of fluid and electrolyte across the cell membrane.


Name and explain the 4 basic principles that regulate fluids and electrolyte balance

1. All the homeostatic mechanisms that monitor and adjust the composition of body fluids respond to changes in the ECF, not in the ICF: Receptor monitoring the composition of two key components of the ECF- plasma and cerebrospinal fluid- detect significan

How does ADH (Antidiuretic hormone) control physiological adjustments of fluid and electrolyte balance.

Hypothalamus contains a special cell known as osmoreceptor, which montior the osmotic concentration of the ECF. They are sensitive to change. The population of osmoreceptors includes neurons the secrete ADH. Neurons in the hypothalamus have axons that rel

How Aldosterone control physiological adjustments of fluid and electrolyte balance.

Secreated by adrenal cortex in response to rising K+ or falling Na levels in blood and activiation of renin-agiotensin system kidney conserve salt ans stimulate water rentention.

Natriuetic peptid and adjustments of fluid and electrolyte balance

Reducing thirst. Blocking secretion of ADH and aldosterone salt and water loss increase ECF volume decrease if plasma volume is to high.

Hydrostatic pressure

Pushes water out of plasma and into interstitial fluid osmotic pressures draws water out of interstitial fluid and into plasma.

Explain fluid movement within the ECF

Fluid volume is redistributed (lymphatic --> venous system) interaction between opposing forces (continous filtration of fluid) ECF vol. is 80% in ICF and minor fluid compartments and 20% plasma

Explain water loss

body loses 2500 mLof water each day through urine and insensible perpiration, fever can also include water loss, and sensible perspiration (sweat) varies and can cause signifcant water loss (4L/hr)

Explain water gain

About 2500 mL/day, required to balance water loss - through eating (1000 mL), drinking (1,200 mL), and metabolic generation (30 mL)

Explain water generation (metabolic generation)

Produced within cells, result from oxidative phosphorlaytion in mitchondria.

What is fluid shift

Rapid shifts between ECF and ICF (response to osmotic gradient). If ECF osmotic concentration increases, fluid becomes hypertonic to ICF and water moves from cells to ECF. If osmotic pressure in ECF decreases fluid becomes hypotonic to ICF moves water fro


(Water depletion) develops when water loss is greater than gain. If water is lost, but electrolytes retained- ECF osmotic concentrations rises. Water moves ICF to ECF and net change in ECF is small.

Causes of dehydration



Body content water rises

Major cation contributors to osmotic concentration in ECF and ICF

Na+ (sodium) and K+ (potassium)

What is equivalent (Eq)

Electrolytes in body fluids are measured in terms of equivalents. Which is the amount of a positive or negative ion that supplies one mole of electrical charge and 1 equivalent= 1000 milliequivalents (mEq).

What is sodium uptake

Sodium Ion Uptake across the digestive system
Sodium ions enter the ECF by crossing the digestive epithelium through diffusion and carrier-mediated transport. The rate of absorption varies directly with the amount of sodium in diet.

What is sodium secreation

Sodium Ion Excretion by the Kidneys and other sites
Sodium losses take place primarily by excrection in urine and through perspiration. The kidneys are the most important sites of Na+ (sodium) regulation.

What is hypernatremia

When body water content decreases, the Na+ (sodium) concentration increases. When that concentration exceeds 145 mEq/L, hypernatremia exist.

What are the factors the promote hypernatemia


What is hyponatremia

When body's water content increases enough to decrease the Na+ concentration of the ECF below 135 mEq/L, a state of hyponatremia (natrium, sodium) exist.

What factors promote hyponatremia


Explain the sodium balance and ECF volume

It changes the ECF volume but keeps the Na+ concentration stable. When you eat something salty without drinking, the plasma Na+ concentration increases temporarily. A change in the ECF volume follows soon. Fluid wil exit the ICFm increasing ECF volume and

Explain potassium balance.

98% of potassium is in the ICF
Potassium loss in urine is regulated by controling the activities of ion pumps along the distal protions of the nephron and collecting system. Whenever a sodium ion is reabsorbed from the tubular fluid, it generally exchange

What factor promotes hypokalemia

A deficiency of potassium in the bloodstream.
Factors are :
Chronic kidney disease.
Diabetic ketoacidosis.
Excessive alcohol use.
Excessive laxative use.
Excessive sweating.
Folic acid deficiency.
Prescription water or fluid pills (diuretics) us

What factors promote Hyperkalemia

an elevated level of potassium in the bloodstream.
Factors are:
kidney dysfunction
diseases of the adrenal gland
potassium sifting out of cells into the blood circulation and medications.

Explain the calcium balance

Calcium is the most abundant mineral in the body. Play key roles in controlling muscular and neural activities, in blood clotting, as cofactors for enzymatic reactions, and as second messengers. The hormones parathyriod (PTH), calcitriol, and calcitonin m

What factors promote Hypercalcemia

Exist when the Ca2+ concentration of the ECF exceeds 5.3 mEq/L. Primary cause in adults is hyperparathyroidism, a condition resulting from PTH oversecretion. Less common causes are malignant cancers of the breast, lung, kidney, and bone marrow, and extrem

What factor promote Hypocalcemia

a Ca2+ concentration under 4.3 mEq/L is much less common than hypercalcemia. Hypoparathyroidism, vitamin D deficency, or chronic renal failure are responsible for hypocalcemia.

Explain the Magnesium balance

The body contains 29 g of magnesium, 60% in skeleton. Found mainly in the ICF. Magnesium is required as a cofactor for imp. enzymatic reations like the phodphorylation of glucose within cells and the use of ATP by contracting muscle fibers. Typical range

What factors promote

A Ca@+ concentration under 4.3 mEq/L is much less common than hypercalcemia. Hypoparathyroidism, vitamin D defincey, or chronic renal failure are respnsible for hypocalcemia

Magneisum Balance

An important structural component of bone, the adult body contains about 29 g of magneisum. 60% deposisted in skeleton. Is a cofactor for important enzymatic reactions affectively reabosbed by PCT, daily requirement to balance urinary loss ( about 24 - 32


Overdose of magneisum supplements or antiacids (rare)


Poor diet, alcholism, severe diaherra , kidney disease, malabosption sysdrome, hyperparathyriodism, vitamin D defiency.

Phosphate balance

Required for bone mineralization about 740 g PO3- 4 is bound in mineral salts of the skeleton, daily urinary and fecal loss about 30-45 mEg ( 0.8 - 1.2 g). In ICF phosphate is required for formation of high energy compounds. Activation of enzymes and synt


High dietary phosphate intake. Hypoparathyriodism


Poor diet, kidney diease, malabosorption sysdrome, hyperparthyriodism, vitamin D defincy.

Chloride Ions

Are the most abundant in ECF, plasma concentration is 100-108 mEg/L. ICF concentrations are usually low, are absorded across digestive tract with sodium by carrier protiens along renal tubules, daily loss is small 48-146 mEg/L (1.7-5.1 g)


Dietary excess including chloride retention


Vomiting and hypokalmia

Concept of pH

The negative exponent of the hydrogen ion concentrations, expressed in moles per liter

Importance of pH

Determines acids, bases, and salts

Nutral pH


pH of human blood



physiological state resulting from abnormally low plasma pH acidemia plasma pH <7.35

Respiratory Acidosis

Develops when the repiratory system cannot elimante all co2 generated by peripheral tissue . Primary signs low plasma pH do hypercapnia primary cause of hyperventilatiion

Metabolic Acidosis

Production of large numbers of fixed organic acids (lactic acidosis and ketoacidosis) Imparied H+ excretion at kidneys and severe bicarbonate loss


Physiological state resulting from abnormally high pH alkelemia plassma pH >7.45

Repiratory Alkalosis

Primary sign, high plasma pH due to hypocapnia, primary cause hyperventilation


An abnormally low blood pCo2 ; commonly form hyperventilation

Metabolic Alkalosis

Caused by elevated HCO3 concentrations, bicarbonate ions interact with H+ in solution forming H2CO3 reduced H+ cause alkalosis

Lactic Acidosis

Produced by an aerobic cellular respiration

Keto Acidosis

Produced by excess ketone bodys


Are dissloved compounds that stabalize pH ( by providing or removing H+) weak acids (donate) weak bases (absorb)

Buffer System

Consists of combinations of weak acid and the anion relased by its dissociation. The anions function as a weak base, in solution, molecules of the weak acid exist in equalisbrium with its dissociation products ( protien, carbonic acid bicarbonate, and pho

Classes of Acids

Fixed, organic, volatile

Relationship between PC02 and Plasma pH

When CO2 levels include more carbonic acid forms addition hydrogen ions and bicarbonate ions are release and pH decreases

Hemoglobin Buffer System

CO2 diffuses across RBC mebrane as carbonic acid dissociates bicarbnate ions diffuse into plasma , in exhange for chloride ions ( chloride shift ) hydorgen iions are buffered by hemoglobin molecules that only intracellulalr buffer system with an immediate

Carbonin- Acid buffer System

Carbon cloride formed by bicarbonic acid and its dissociation products, prevent changes in pH caused by organic acids and fixed acids in ECF.Cannot protect ECF changes in ECF resulting from rising or falling levels of CO2 functions only when repiratory sy

Phostphate buffer system

Consists of anion H2O PO4 (weak acid ) works like the carbonic acid - bicarbonate buffer system and is important in buffering pH of ICF.

Repiratory Compensation of pH

A change in repiratory rate that helps stabalize pH of ECF, occurs when body pH moves outside normal limits

Renal Compensation of pH

Change in rates of H+ and HCO3 sectreion or reabsorbtion by kidneys and response to changes in pH

Blood pH

HCO3 21-28 mEg/L and
PCO2 35-45 mmHg PO2

Changes in blood with acid / base disorders

Repiration aidosis ph decreases less than 7.35 HCO3 acute - comp. inc PCO2 inc. <45
Metabolic Acidosis- pH decrease less than 7.35 HCO3 dcerease less than 24 PCO2 Acute - comp < 35
Repiratory Alkalosis- pH increases >7.45 HCO3 acute comp. <24 PCO2 decreas

Aging and fluid Blance

Body water content 40-60 males55% females 47%
after 60 males have 50% females 45% decrease body water content reduceses dilution of waste products toxins and drugs, reduction in glomular filtration rate and number of functional nephrons reduces pH an rena