Difference between sum of measured cations and sum of measured anions.
Properties of solutions that depend on number of solute particles present but not on chemical properties of solute; four colligative properties are osmosis, freezing point, boilng point, and vapor pressure.
Secretion and passage of large quantities of urine; often occurs in diabetes mellitus.
Major ions of body fluids; constitute majority of osmotically active particles; cation electrolytes include sodium and potassium; anion electrolytes include chloride and bicarbonate.
Extracellular water (ECW)
Water external to cell membranes.
Abnormally high plasma potassium concentration.
Abnormally high plasma sodium concetration.
Diminished blood volume.
Fluid that lies between and bathes tissue cells and constitutes portion of physiological extracellular water; includes extravascular and extracellular water into which ions and small molecules diffuse freely from plasma.
Latin for potassium.
Latin for sodium.
Excretion of large quantities of sodium in the urine.
Includes family of proteins that function to regulate water and sodium metabolism; examples include atrial natriuretic peptide and brain-type natriuretic peptide.
Calculated parameter derived by subtracting calculated osmolality from measured osmolality.
Measurement of number of moles of particles per kilogram of water.
Osmotic concentration expressed as osmoles or milliosmolesof solute per liter of solvent.
Liquid component of blood in which cells are suspended; deffers from serum in containing fibrinogen and related compounds that are removed from serum when blood clots.
Clear liquid that separates from blood on clotting.
Syndrome of Inappropriate ADH secretion (SIADH)
Condition in which inappropriate antidiuretic hormone secretion produces hyponatremia, hypovolemia, and elevated urine osmolality.
Total Body Water (TBW)
All water within body; both inside and outside cells; including that contained in gastrointestinal and genitourinary systems
Condition of decreased pH of blood.
Pathological condition characterized by increased acidity of blood because of accumulation of acids or excessive loss of bicarbonate; fluid hydrogen in concentration increases, lowering pH.
Condition of increased pH of blood.
Condition resulting in increased blood alkalinity because of accumulation of alkalies or reduction of acids.
Difference between titratable acids and bases of blood sample and normal blood sample at pH of 7.4, pCO2 of 40mmHg, and temperature of 37 C.
Compound with structure R-NH-COO-; also form in which CO2 is carried in blood.
Mechanism in humans that maximizes gas exchange by continuously supplying atmospheric air to external surface of of gas-exchange barrier (e.g., alveoli), thereby maintaining high external PO2 and low external PCO2; average human inspires about 4.0 liters of fresh air per minute with alveolar PO2 of about 100mmHg and alveolar PCO2 of about 40 mmHg.
Equation that defines relationships among pH, bicarbonate, and partial pressure of dissolved carbon dioxide gas.
Increased amount of carbon dioxide in blood.
Specialized mechanism in circulatory system that maximizes flow of O2 and CO2 across gas-exchange barriers by delivering blood that has low PO2 and high PCO2 to barrier's inner surface; perfusion is process of delivering blood to lungs.
Pathological condition that leads to accumulation of acid, which lowers bicarbonate concentration and decreases pH.
Pathological conditions that leads to accumulation of base, which raises bicarbonate concentration and increases pH.
Oxygen saturation (O2 sat or sO2)
Fraction of total hemoglobin in form of HbO2 at defined PO2.
Partial pressure (P or p)
Pressure exerted by gas, whether alone or mixed with other gases.
Pathological condition that leads to accumulation of carbon dioxide, which raises PCO2 and decreases pH.
Pathological condition that leads to excessive elimination of carbon dioxide, which lowers PCO2 and increases pH.
Systems used to transport oxygen and carbon dioxide throughout the body.
Acid-base balance can be described as the maintenance of homeostasis of the hydrogen-ion concentration of body fluids. It is defined by the degree of acidity or alkalinity of a body fluid.
-Determines acid-base balance
-Range is between 1, which is highly acidic, and 14, which is strongly alkaline. A value of 7 represents a neutral pH
-Solution w/ pH below 7 = acid(ic)
-Solution w/ pH greater than 7 = base(ic)
Concentration of Hydrogen Ions (cH+)
-An acid is a hydrogen donor e.g. carbonic acid
-A base is a substance that can yield hydroxyl ions (OH-) e.g. bicarbonate (H+ or proton acceptor)
A buffer is defined as a solution containing a weak acid and its conjugate base that resists changes in pH when a strong acid or base is added. The human body has several buffer systems.
What are the four important blood buffers in the human body?
What is the most important blood buffer?
-Accounts for majority of buffering capacity in the extracellular space.
Carbon dioxide (CO2)
-Large amounts produced within the body as a whole (tissues)
-Potential for large amounts of acid (H2CO3) is the greatest
Buffering system in the blood (CA = carbonic anhydrase)
CO2 + H2O <--ca--> H2CO3 <--ca--> H+ + HCO3
***The #1 method for maintaining optimal blood pH at 7.4***
-For every 20 bicarbonate there should be 1 carbonic acid
-This ratio represents normal kidney and lung function
-Directly proportional to pCO2 level in blood
-Controlled by the lungs
-Immediately influenced by the presence or absence of CO2
-Any change in cH2CO3- is RESPIRATORY in nature
-Primarily under the control of the kidneys
-If there is a change in HCO3-, it is caused by a metabolic process associated with the kidneys
-Metabolic or nonrespiratory control
-Abnormal bicarbonate due to kidney malfunction (primary) and disease or condition affecting the kidney (secondary)
-Hyperventilation: will decrease CO2 levels in the blood and increase blood pH (e.g., Asthma, COPD)
-Hypoventilation: will increase CO2 levels in the blood and decrease blood pH as well as decrease pO2 level in the blood (e.g., drugs, mechanical obstruction, asphyxiation) Note O2 is considered an acid in the blood
Why is the bicarbonate buffer system signigicant?
1.) H+ is eliminated as CO2 by the lungs
2.) A change in PCO2 modifies the ventilation rate
3.) The kidneys can alter the concentration of bicarbonate
Hemoglobin Buffer System
-Binds oxygen in the lungs and releases to tissues
-Accounts for 30% buffering capacity of whole blood
-In lungs, oxygen is loaded; CO2 is released
-In tissues, CO2 is loaded; oxygen is released
-Participates in the chloride shift and isodydric shift which allows large amounts or CO2 produced by metabolism to be carried in the blood with little or no change in pH
-Oxygen-Hgb dissociation curve
------shift to the right: acid; high CO2; decrease affinity of oxygen by hgb
------shift to the left: alkaline; low CO2; increase affinity of oxygen by hgb
(Note 2, 3 DPG levels maintain Hgb structure)
Phosphate Buffer System
-Essential withing erythrocytes
-Phosphate buffers enable the kidney to excrete H+
-Low phosphate levels in the blood
-Minor buffering action
Protein Buffer System
-Cellular buffers, only minor role in blood
-The ionizable side chains allow them to pick up or release H+
-Some amino acids are basic (e.g., histidine and lysine), and others are acidic (e.g., glutamic acid and asparagine)
-Example: the protein albumin, with 16 histidine residues withing its structure, contributes to a significant percentage of buffering capability
-The movement of uncharged, hydrophobic solute through a lipid bilayer
-Important fundamental mechanism of O2 and CO2
-Random movements of molecules in gaseous phase or dissolved in water, result in net movement of the substance from regions of high concentration to region of low concentration
-No expenditure of energy is involved
-Driving force for diffusion
-gradient, change in value or quantity, represents the difference in concentration on either side of a membrane, which allows for diffusion of solutes or gases from one side to another
-The process of moving air into and out of the lungs
-In larger organisms and mammals, simple diffusion of gases is not adequate
-In humans, facilitates movement of gases
-Consists of the lungs, the airway, and respiration muscles
-Serves to maximize gas exchange by continuously supplying atmospheric air to external surface of gas-exchange barrier (e.g., alveoli)
-Maintains high external PO2 and low external PCO2
-Average human inspires 4.0 liters of fresh air per minute
-Alveolar PO2 of approximately 100 mmHg
-Alveolar PCO2 of about 40 mmHg
-Maximizes flow of O2 and CO2 across gas-exchange barriers by delivering blood that has low PO2 and a high PCO2 to the inner surface of the barrier
-The process of delivering blood to the lungs
-Ventilatory and circulatory
-Long-distance transport of oxygen and carbon dioxide
-Diffusion used primarily for short-distance movements of oxygen and carbon dioxide
Important Components of the Respiratory Apparatus
-Inspiration: a means of moving outside air to the alveolar air spaces
-Carries oxygen and carbon dioxide in the blood; erythrocytes transport oxygen from the lungs to the peripheral tissues and transport carbon dioxide in the oppisite direction
-Provides surface for gas exchange (e.g., alveoli)
-Contains internal convection system and a circulatory system that consists of a four-chamber heart; separate systemic and pulmonary circulation system
-Provides a mechanism for locally regulated ventilation and perfusion; inspiration and exhalation, uses feedback-control to regulate this ratio
-Respiratory control center (in CNS) that consists of neurons withing the medulla called respiratory-related neurons, rhythmically stimulate the muscles of inspiration
Transport of oxygen in the blood
The mechanism by which O2 and CO2 are transported throughout the body which contributes to the maintenance of normal body pH through the elimination or retention of CO2.
-Stoichiometry [a(heme)]2 [B(heme)]2
-Binds as many as 4 O2 molecules
-Only binds O2 in ferrous (Fe2+) state
-Globin portion very important to physiology of the O2-heme interaction
-Reversible allowing repetative capture and release of O2
-Interacts w/ about 20 amino acids which cradle the heme in the globin so that O2 loosely and reversibly bind to Fe2+
-Histidine, which binds Fe2+ is most important aa
-Each histidine donates a negative charge that serves to stabiliaze the Fe2+-O2 complex
Hemoglobin-Oxygen Dissociation Curve
-Shows relationship between percent hemoglobin saturation with oxygen and PO2
-PO2 at which the hemoglobin is half-saturated is known as P50
-Normal P50 = 26.5 mmHg
-Decreased P50 = Shift to the left (elevated % hgb sat. and decrease in available O2 to tissues)
-Increased P50 = Shift to the right (reduced % hgb sat. and increase in available O2 to the tissue
Characteristics of metaboliclly active tissues
1.) Having a high demand for O2
2.) Being warm
3.) Producing large amounts of CO2
4.) Being acidic
Factors affecting Hgb
-Sensitive to high temps.
-These factors tend to decrease oxygen affinity of hgb
-Decreased oxygen concentration in inspired air (high altitude where low PO2 exists).
-Increase temp. causes the Hb-O2 dissociation curve to shift to the right
-Decrease temp. = shift to the left
-Decreases O2 affinity of hgb and O2 is released
-Excess H+ in the blood = lower pH = shift to the right
-Occurs in conditions associated with respiratory acidosis and increased amounts of acid metabolites
-Decrease O2 affinity for hgb (due to high cH+ allowing for the more efficient unloading of O2 at tissue sites)
-Decrease in blood pH = increase in extracellular PCO2
-CO2 enters the erythrocytes = decrease in intracellular pH
-Hypercapnia (increased blood CO2)
-Shift to the right
-Increase causes hgb to release O2 in the tissues and conversely, increase in PO2 causes hgb to unload CO2 in the lungs
Transport of CO2 in the Blood
-Carbon dioxide is transported in the blood primarily as HCO3- (Bicarbonate)
-Transport dependent on carbonic anhydrase, the Cl- -HCO3- exchanger (chloride or Hamburger shift)
-At any PCO2, total CO2 contents rises as PO2 falls
-Blood enters systemic capillaries and releases O2, the CO2-carrying capacity rises so that blood picks up extra CO2. The oppisite occurs as blood enters the pulmonary capillaries.
Control of Ventilation
1.) Must be automatic rhythm in the conctractions of the respiratory muscles
2.) The rhythm of contraction must accommodate changing metabolic demands--for example, changes in blood pH, PO2, or PCO2
Role of the Kidneys in Acid-Base Balance
-Kidneys excrete nonvolatile acids that are produced by metabolic processes
-In acidosis, renal excretion of acid is increased and base is conserved; just the oppisite occurs in alkalosis
-Their ability to excrete variable amounts of acid or base makes them significant organs that compensate for changes in body pH
3 mechanisms that facilitate renal excretion of acid and conservation of HCO3- are:
1.) The Na+ -H+ exchange
2.) The production of ammonia and excretion of NH4+
3.) The reclamation of HCO3-
Na+ -H+ Exchange
-Kidney cells contain a plasma-membrane, ATP-hydrolyzing protein that is capable of exchanging sodium ions for protons
-Occurs in renal tubule
-Na+-H+ exchanger extrudes H+ ions into tubular fluid in exchange for Na+ ions
-Na+-H+ exchange is enhanced in states of acidosis and inhibited in conditions alkalosis
-Important in renal responses to acid-base imbalance
-K+ compete with H+ in the renal tubular Na+ -H+ exchanger mechanism
-Elevated K+ concentration in renal tubular cells = more K+ and fewer H+ are exchanged for Na+
-Results in less-acidic urine and increased acidity in body fluids
-Conversely, a decrease in K+ concentration results in more H+ ions exchanged for Na+
-Urine pH becomes more acidic and body fluids become more alkaline
Hyperkalemia (increase in serum K+)
-Contributes to acidosis
Hypokalemia (decrease in serum K+)
-Contributes to alkalosis
Regulation of Bicarbonate
-Kidney (within tubules)
-Reabsorption of Na & Bicarb
-Loss of CO2, H2O, Na, KCl, H2PO4, (NH4)2SO4
-If bicarb level is >30mmol/L bicarb will be excreted in the urine
-If bicarb level is <30mmol/L bicarb will be reclaimed by the kidneys