Chapter 21 Bio 202 Anatomy & Physiology Part 2 Tim Pimperl A & P Instructor Copyright © The...
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Transcript of Chapter 21 Bio 202 Anatomy & Physiology Part 2 Tim Pimperl A & P Instructor Copyright © The...
Chapter 21
Bio 202
Anatomy & Physiology Part 2
Tim Pimperl
A & P Instructor
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
2
Important Points in Chapter 21:Outcomes to be Assessed
21.1: Introduction
Explain the balance concept.
Explain the importance of water and electrolyte balance.
21.2: Distribution of Body Fluids
Describe how body fluids are distributed in compartments.
Explain how fluid composition varies among compartments and how fluids move from one compartment to another.
21.3: Water Balance
List the routes by which water enters and leaves the body.
Explain the regulation of water input and water output.
3
Important Points in Chapter 21:Outcomes to be Assessed
21.4: Electrolyte Balance
List the routes by which electrolytes enter and leave the body.
Explain the regulation of the input and the output of electrolytes.
21.5: Acid-Base Balance
Explain acid-base balance.
Identify how pH number describes the acidity and alkalinity of a body fluid.
List the major sources of hydrogen ions in the body.
Distinguish between strong acids and weak acids.
Explain how chemical buffer systems, the respiratory center, and the kidneys keep the pH of body fluids relatively constant.
4
Important Points in Chapter 21:Outcomes to be Assessed
21.6: Acid-Base Imbalances
Describe the causes and consequences of increase or decrease in body fluid pH.
5
21.1: Introduction
• The term balance suggests a state of constancy• For water and electrolytes that means equal amounts enter and leave the body• Mechanisms that replace lost water and electrolytes and excrete excesses maintain this balance• This results in stability of the body at all times• Keep in mind water and electrolyte balance are interdependent.
6
21.2: Distribution of Body Fluids
• Body fluids are not uniformly distributed• They occupy compartments of different volumes that contain varying compositions• Water and electrolyte movement between these compartments is regulated to stabilize their distribution and the composition of body fluids
7
Fluid Compartments• An average adult female is about 52% water by
weight, and an average male about 63% water by weight
• There are about 40 liters of water (with its dissolved electrolytes) in the body, distributed into two major compartments:• Intracellular fluid – 63% - fluid inside cells• Extracellular fluid – 37% - fluid outside
cells• Interstitial fluid• Blood plasma• Lymph• Transcellular fluid – separated from
other extracellular fluids by epithelial layers
• Cerebrospinal fluid• Aqueous and vitreous humors• Synovial fluid• Serous fluid
Extracellularfluid(37%)
Intracellularfluid(63%)
40
3836
34
323028262422
201816
14121086420
Lit
ers
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Total Body Water40 liters (10.6 gallons)
8
63% Intracellular Fluid d37% Extracellular FluidInterstitial Fluid
PlasmaLymph
Transcellular Fluid
Female – 52%Male – 63%
9
Total body water
Interstitial fluidPlasma
Lymph
Transcellular fluid
Extracellular fluid(37%)
Membranes ofbody cells
Intracellular fluid(63%)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Transcellular:CSF, aqueous & vitreoushumors, joints, body cavitiesexocrine gland secretions etc.
10
Body Fluid Composition
• Extracellular fluids are generally similar in composition including high concentrations of sodium, calcium, chloride and bicarbonate ions
• Blood plasma has more proteins than interstitial fluid or lymph
• Intracellular fluids have high concentrations of potassium, magnesium, phosphate, and sulfate ions
Ion
co
nce
ntr
ati
on
(m
Eq
/L)
20
30
50
60
70
80
90
100
110
120
130
140
Relative concentrations and ratios of ions in extracellular and intracellular fluids
150
40
10
0
14:1Ratio(Extracellular: intracellular)
Na+
1:28K+
5:1Ca+2
1:19Mg+2
26:1Cl
3:1HCO3
1:19PO4
3
1:2SO4
2
Extracellular fluid
Intracellular fluid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
11
Movement of Fluid Between Compartments
• Two major factors regulate the movement of water and electrolytes from one fluid compartment to another
• Hydrostatic pressure• Osmotic pressure
Interstitial fluid
Capillary wall
Transcellularfluid
Lymph
Plasma
Serousmembrane
Intracellularfluid
Cellmembrane
Lymphvessel
Fluid leaves plasmaat arteriolar end ofcapillaries becauseoutward force ofhydrostatic pressurepredominates
Fluid returns toplasma at venularends of capillariesbecause inward forceof colloid osmoticpressure predominates
Hydrostatic pressurewithin interstitialspaces forces fluidinto lymph capillaries
Interstitial fluid isin equilibrium withtranscellular andintracellular fluids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
12
21.3: Water Balance
• Water balance exists when water intake equals water output• Homeostasis requires control of both water intake and water output
13
Water Intake• The volume of water gained each day varies among individuals averaging about 2,500 milliliters daily for an adult:
• 60% from drinking• 30% from moist foods• 10% as a bi-product ofoxidative metabolism ofnutrients called water ofmetabolism
Water inbeverages(1,500 mL or 60%)
Average daily intake of waterWater lost in sweat(150 mL or 6%)
Total output(2,500 mL)
Average daily output of water
(a) (b)
Total intake(2,500 mL)
Water inmoist food(750 mL or 30%)
Water ofmetobolism(250 mL or 10%)
Water lost in feces(150 mL or 6%)Water lost throughskin and lungs(700 mL or 28%)
Water lost in urine(1,500 mL or 60%)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
15
Water Output
• Water normally enters the body only through the mouth, but it can be lost by a variety of routes including:
• Urine (60% loss)• Feces (6% loss)• Sweat (sensible perspiration) (6% loss)• Evaporation from the skin (insensible perspiration)• The lungs during breathing(Evaporation from the skin and the lungs is a 28% loss)
16
Regulation of Water Output
The osmoreceptor-ADH mechanism in the hypothalamus regulates the concentration of urine produced in the kidney.
17
21.1 Clinical Application
Water Balance Disorders
(Read all of this Clin. App. Carefully pg. 816 12e & 808-809 13e)
Water intox./hyponatremia Dehydrationheadacheweakness dry mouth & mucous membranesdizziness confusionnausea profuse sweating progressingmuscle cramps to no sweatingslurred speech increased temperatureconfusion loss of consciousness seizures in severe cases
18
21.4: Electrolyte Balance• An electrolyte balance exists when the quantities of electrolytes the body gains equals those lost
Foods Fluids Metabolicreactions
Electrolyte intake
Electrolyte output
UrinePerspiration Feces
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19
Electrolyte Intake• The electrolytes of greatest importance to cellular functions release sodium, potassium, calcium, magnesium, chloride, sulfate, phosphate, bicarbonate, and hydrogen ions• These ions are primarily obtained from foods, but some are from water and other beverages, and some are by-products of metabolism
20
Regulation of Electrolyte Intake
• Ordinarily, a person obtains sufficient electrolytes by responding to hunger and thirst• A severe electrolyte deficiency may cause salt craving
21
Electrolyte Output
• The body loses some electrolytes by perspiring (more on warmer days and during strenuous exercise)• Some are lost in the feces• The greatest output is as a result of kidney function and urine output
Regulation of Electrolyte Output
• The concentrations of positively charged ions, such as sodium (Na+), potassium (K+) and calcium (Ca+2) are of particular importance
• These ions are vital for nerve impulse conduction, muscle fiber contraction, and maintenance of cell membrane permeability
• Sodium ions account for nearly 90% of the positively charged ions in extracellular fluids
22
Regulation of Electrolyte Output
23
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Potassium ionconcentration increases
Adrenal cortex is signaled
Aldosterone is secreted
Renal tubulesincrease reabsorption ofsodium ions and increasesecretion of potassium ions
Sodium ions areconserved and potassiumions are excreted
Calcium ionConcentration decreases
Parathyroid glandsare stimulated
Parathyroid hormoneis secreted
Intestinal absorptionof calcium increases
Renal tubules conservecalcium and increasesecretion of phosphate
Calcium ion concentrationreturns toward normal
Normal phosphateconcentration is maintained
Activity of bone-resorbingosteoclasts increases
Increased phosphateexcretion in urine
Addition of phosphateto bloodstream
24
21.2 Clinical Application
Sodium and Potassium Imbalances
Read through these imbalances carefully
Pg. 820 12 e & pg. 811 13e
Hyponatremia - PubMed Health
25
21.5: Acid-Base Balance• Acids are electrolytes that ionize in water and release hydrogen ions• Bases are substances that combine with hydrogen ions • Acid-base balance entails regulation of the hydrogen ion concentrations of body fluids• This is important because slight changes in hydrogen ion concentrations can alter the rates of enzyme-controlled metabolic reactions, shift the distribution of other ions, or modify hormone actions• pH number indicates the degree to which a solution is acidic or basic (alkaline). • The more acid the solution, the lower its pH• The more alkaline the solution, the higher its pH
26
Sources of Hydrogen Ions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H+
Hydrolysis ofphosphoproteinsand nucleic acids
Internal environment
Oxidation ofsulfur-containingamino acids
Incompleteoxidation offatty acids
Anaerobicrespirationof glucose
Aerobicrespirationof glucose
Phosphoricacid
Sulfuricacid
Acidic ketonebodies
Carbonicacid
Lacticacid
27
Strengths of Acids and Bases
• Acids:• Strong acids ionize more completely and release more H+
• Ex: HCl• Weak acids ionize less completely and release fewer H+
• Ex: H2CO3
• Bases:• Strong bases ionize more completely and release more OH-
or other negative ions• Weak bases ionize less completely and release fewer OH-
or other negative ions
28
Regulation of Hydrogen Ion Concentration
• Either an acid shift or an alkaline (basic) shift in the body fluids could threaten the internal environment• Normal metabolic reactions generally produce more acid than base• The reactions include cellular metabolism of glucose, fatty acids, and amino acids• Maintenance of acid-base balance usually eliminates acids in one of three ways:
• Acid-base buffer systems• Respiratory excretion of carbon dioxide• Renal excretion of hydrogen ions
29
Chemical buffer systems are in all body fluids and are based on chemicals that combine with excess acids or bases. •Bicarbonate buffer system
• The bicarbonate ion converts a strong acid to a weak acid• Carbonic acid converts a strong base to a weak base H+ + HCO3
- H2CO3 H+ + HCO3-
• Phosphate buffer system• The monohydrogen phosphate ion converts a strong acid to a weak acid• The dihydrogen phosphate ion converts a strong base to a weak base H+ + HPO4
-2 H2PO4- H+ + HPO4
-2
• Protein buffer system• NH3
+ group releases a hydrogen ion in the presence of excess base• COO- group accepts a hydrogen ion in the presence of excess acid
Chemical Buffer Systems
31
• The respiratory center in the brainstem helps regulate hydrogen ion concentrations in the body fluids by controlling the rate and depth of breathing• If body cells increase their production of CO2…
Respiratory Excretion of Carbon Dioxide
Cells increase production of CO2
CO2 reacts with H2O to produce H2CO3
H2CO3 releases H+
Respiratory center is stimulated
Rate and depth of breathing increase
More CO2 is eliminated through lungs
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
33
• Nephrons help regulate the hydrogen ion concentration of body fluids by excreting hydrogen ions in the urine
Renal Excretion of Hydrogen Ions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
High intake of proteins
Increased metabolismof amino acids
Increased formationof sulfuric acid andphosphoric acid
Increased concentrationof H+ in body fluids
Increased secretionof H+ into fluid ofrenal tubules
Concentration of H+
in body fluids returnstoward normal
Increased concentrationof H+ in urine
35
• Various regulators of hydrogen ion concentration operate at different rates• Acid-base (chemical) buffers function rapidly• Respiratory and renal (physiological buffers) mechanisms function more slowly(Resp.-takes several minutes.Renal- up to 1 to 3 days.)
Phosphatebuffer system
Proteinbuffer system
First line of defenseagainst pH shift
Second line ofdefense againstpH shift
Chemicalbuffer system
Physiologicalbuffers
Bicarbonatebuffer system
Respiratorymechanism(CO2 excretion)
Renalmechanism(H+ excretion)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Time Course of pH Regulation
36
• Various regulators of hydrogen ion concentration operate at different rates• Acid-base (chemical) buffers function rapidly• Respiratory and renal (physiological buffers) mechanisms function more slowly(Resp.-takes several minutes.Renal- up to 1 to 3 days.)
Phosphatebuffer system
Proteinbuffer system
First line of defenseagainst pH shift
Second line ofdefense againstpH shift
Chemicalbuffer system
Physiologicalbuffers
Bicarbonatebuffer system
Respiratorymechanism(CO2 excretion)
Renalmechanism(H+ excretion)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Time Course of pH Regulation
37
21.6: Acid-Base Imbalances
• Chemical and physiological buffer systems ordinarily maintain the hydrogen ion concentration of body fluids within very narrow pH ranges• Abnormal conditions may disturb the acid-base balance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Acidosis Alkalosis
pH scale
6.8 7.0 8.07.87.35 7.45
Normal pH range
Survival range
38
Acidosis
• Acidosis results from the accumulation of acids or loss of bases, both of which cause abnormal increases in the hydrogen ion concentrations of body fluids• Alkalosis results from a loss of acids or an accumulation of bases accompanied by a decrease in hydrogen ion concentrations
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Loss ofbases
Accumulationof acids
Acidosis
Increased concentration of H+
pH scale
pH drops
pH rises Alkalosis
Decreased concentration of H+
Accumulationof bases
Loss ofacids
7.4
39
• Two major types of acidosis are respiratory acidosis and metabolic acidosis
Acidosis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Decreasedgas exchange
Decreased rateand depth ofbreathing
Obstruction ofair passages
Accumulation of CO2
Respiratoryacidosis
Excessive production of acidicketones as in diabetes mellitus
Kidney failureto excrete acids
Accumulation of nonrespiratory acids
Metabolic acidosis
Excessive loss of bases
Prolonged diarrheawith loss of alkalineintestinal secretions
Prolonged vomitingwith loss of intestinalsecretions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
40
Alkalosis• Respiratory alkalosis develops as a result of hyperventilation• Metabolic alkalosis results from a great loss of hydrogen ions or from a gain in bases, both accompanied by a rise in the pH of blood
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Anxiety
• Fever
• Poisoning
• High altitude
Hyperventilation
Excessive loss of CO2
Decrease in concentration of H2CO3
Decrease in concentration of H+
Respiratory alkalosis
Gastricdrainage
Vomiting with lossof gastric secretions
Loss of acids
Net increase in alkaline substances
Metabolic alkalosis
• Normal Arterial Blood Gas Values
• pH 7.35-7.45
• PaCO2 35-45 mm HgPa
• O2 80-95 mm Hg
• HCO3 22-26 mEq/LO2
• Saturation 95-99%
• BE +/- 1
Four-Step Guide to ABG Analysis
• Is the pH normal, acidotic or alkalotic? • Are the pCO2 or HCO3 abnormal? Which
one appears to influence the pH? • If both the pCO2 and HCO3 are abnormal,
the one which deviates most from the norm is most likely causing an abnormal pH.
• Check the pO2. Is the patient hypoxic? \• manuelsweb.com
• http://orlandohealth.com/pdf%20folder/Inter%20of%20Arterial%20Blood%20Gas.pdf
• ABG interpreter – calculator
• http://manuelsweb.com/abg.htm
pH control and ABG’s (Arterial Blood Gases)
• Interp. of Arterial Blood Gases.pdf
• ABG interpreter - calculator.mht
pH control and ABG’s (Arterial Blood Gases)
pH control and ABG’s Practice
• Analyze the following:
• pH 7.35
• pCO2 33
• HCO3 15
• ABG interpreter - calculator.mht• (Must allow blocked content for interpreter to work.)
pH control and ABG’s Practice
• Analyze the following:
• pH 7.35
• pCO2 49
• HCO3 28
• ABG interpreter - calculator.mht
pH control and ABG’s Practice
• Analyze the following:
• pH 7.48
• pCO2 40
• HCO3 30
• ABG interpreter - calculator.mht