Chapter 14

Hydrogen Ions (H+)

Ions generated during normal metabolism; crucial for acid/base balance and maintaining life.

Isohydric Buffering

A mechanism that allows carbonic acid to buffer changes in blood pH through the interaction of CO2 and H2O.

Carbonic Acid (H2CO3)

The only volatile acid of physiological importance in the body.

Buffer Solution Characteristics

Solutions that resist changes in pH upon addition of acid or base, typically composed of a weak acid and its conjugate base.

Henderson-Hasselbalch Equation

An equation to describe the pH of a buffer system in relation to the concentration of bicarbonate and carbonic acid.

Acidosis

A condition where blood pH drops below 7.35, often due to an accumulation of fixed acids or a decrease in bicarbonate.

Alkalosis

A condition where blood pH rises above 7.45, typically due to excess bicarbonate or loss of fixed acids.

Compensation Mechanisms

Physiological responses initiated to restore normal pH; includes respiratory compensation (alveolar ventilation) and renal compensation (H+ and HCO3- excretion/reabsorption).

Anion Gap

A calculation used to diagnose the cause of metabolic acidosis, defined as the difference between the primary measured cations and anions.

Respiratory Disturbances

Primary changes in pH caused by alterations in carbon dioxide (CO2) levels due to respiratory function.

Metabolic Disturbances

Changes in blood pH caused by gains or losses of fixed acids or bicarbonate in the body.

Bicarbonate Buffer System

The primary buffering system in the blood that utilizes bicarbonate (HCO3-) to neutralize acids.

Ventilation

The process by which carbon dioxide is exhaled from the lungs, assisting in the regulation of blood pH.

Hypoventilation

A respiratory condition leading to elevated levels of carbon dioxide in the blood, resulting in respiratory acidosis.

Hyperventilation

A respiratory condition resulting in low levels of carbon dioxide in the blood, which can lead to respiratory alkalosis.

hydrogen is a

acid

normal metabolism continually generates

H+

REGULATION OF H+ IS IMPORTANT DUE TO

its role in maintaining acid-base balance in the body AND SUPPORTS LIFE.

HYDROGEN IONS FORMED IN THE BODY COME FROM EITHER

FIXED (NON-VOLATILE) OR VOLATILE ACIDS

TISSUE METABOLISM PRODUCES LARGE AMOUNTS OF

Carbon dioxide and hydrogen ions during energy production processes.

THE CARBON DIOXIDE PRODUCED FROM TISSUE METABOLISM IS THEN

HYDOLYZED INTO A HYDROLYZED ACID (CARBONIC ACID)

ISOHYDRIC BUFFERING

A process that helps maintain pH stability in the body by utilizing the bicarbonate buffer system, preventing excessive changes in hydrogen ion concentration.

CARBONIC ACID IS THE ONLY

VOLATILE ACID OF PHYSIOLOGIC IMPORTANCE

WHAT IS THE EQUATION OF AEROBIC METABOLISM

CO2 + H20 = H2CO3 = HCO3- + H+

WHAT HAPPENS TO CARBON DIOXIDE IN THE BLOOD

IT DIFFUSES AT THE TISSUE LEVEL

A REACTION OCCURS MOSTLY IN THE RBC WHERE CARBONIC ANHYDRASE CONVERTS CO2 INTO CARBONIC ACID.

CARBONIC ANHYDRASE

An enzyme that catalyzes the conversion of carbon dioxide and water into carbonic acid, facilitating CO2 transport in the blood.

AN ENZYME WHICH ASSISTS IN THE RAPID COVERSION OF CO2 AND WATER INTO CARBONIC ACID

HOW IS MOST H+ PRODUCED

THROUGH ISOHYDRIC BUFFERING

ISOHYDRIC BUFFERING DOES IT CAUSE A CHANGE IN PH

No, it maintains pH stable.

WHY DOES ISOHYDRIC BUFFERING NOT CAUSE A CHANGE IN PH

BECause hemoglobin in the RBC IMMEDIEALETLY BUFFERS THE H+

WHEN BLOOD REACHES THE LUNGS HEMOGLOBIN RELEASES WHAT

H+ TO FORM CO2 and H2O.

THE CO2 IS EXHALED BY THE LUNGS

2 MAJOR WAYS THE BODY KEEPS THE BLOODS PH CONSTANT OF HOW MUCH CO2 IS PRODUCED IS

ISOHYDRIC BUFFERING AND VENITILATION

BUFFER SOLUTION CHARACTERISTICS

A SOLUTION THAT RESISTS CHANGE IN PH WHEN AN ACID OR BASE IS ADDED

BICARBONATE IS COMPOSED OF

HC03- AND H2CO3

AN OPEN SYSTEM (H2CO3) WHICH IS HYDOLYZED TO CO2

VENTILATION REMOVES WHAT

CO2 from the bloodstream AND ACIDS that can affect blood pH levels.

CARBONIC ACID AND BOCARB EXIST

IN REVERSIBILE COMBINATION AS NAHC03 + H2CO3 in the bicarbonate buffer system, helping to maintain pH balance in biological systems.

NON-BICARBONATE IS COMPOSED OF

PHOSPHATE AND PROTIENS

CLOSED SYSTEM = NO GAS TO REMOVE ACID BY VENTILATION

WHAT IS THE DIFFERENCE BETWEEN OPEN AND CLOSED SYSTEMS

An open system allows gas exchange with the environment, enabling waste removal, while a closed system does not permit gas to enter or exit, restricting acid removal through ventilation.

WHAT IS AN EXAMPLE OF AN OPEN SYSTEM

BICARBONATE BUFFERS

FIXED (VOLATILE) ACIDS

like carbonic acid that can be converted to gas and expelled.

CO2 CAN BE REMOVED ONLY IF WHAT CAN KEEP UP

VENILATION

CLOSED SYTEM WHAT IS THE BUFFER

CARBINIC ACID

NON-BICARBONATE BUFFERS

HEMOGLOBIN

ORGANIC PHOSPHATES

INORGANIC PROTIENS

PLASMA PROTIENS

WHAT ARE THE ONLY BUFFERS TO BUFFER H2CO3

HEMOGLOBIN

ORGANIC PHOSPHATES

INORGANIC PHOSPHATES

PLASMA PROTIENS

WHAT IS THE HENDERSON-HASSELBALCH EQUATION

SECRIBES H+ AS A RATIO OF H2CO3/HCO3-

PH=6.1 +LOG [HC03-]/PACO2X0.03

PH IN THE H-H EQUATION IS

LOG EXPRESSION OF H+

6.1 IS THE

LOG IF H2CO3

EQUILLIBRIUM CONSTANT

PACO2 X 0.03 =

IS AN EQUILLBRIUM WITH AND DIRECTLY PROPORTIONAL TO BLOOD

BLOOD GAS ANALYZER MEASURE

PH AND PACO2

THEN H-H EQUATION CALCULATES THE HCO3

HCO3- CAN CONTINUE TO BUFFER FIXED ACID H+ IF

VENTILATION IS ADEQUATE, HELPING TO MAINTAIN ACID-BASE BALANCE.

VENTILATION EQUATION

H+ + HC03- =====H2C03======H20. + CO2

IN HYPOVENTILATION WHAT ACCUMULATES

H2CO3

ONLY NON-BICARBINATE SYSTEM SERVE AS BUFFER

WHAT IS THE MOST ABUNDANT BUFFER IN THE CLOSED SYSTEM (NON-BICARBOINATE)

HEMOGLOBIN in red blood cells.

IN A CLOSED SYSTEM, WHAT CAN BUFFER A VOLATILE ACID

HEMOGLOBIN

AS A CLOSED SYTEM, PRODUCTS OF BUFFERING ACCUNULATES AND BUFFERING MAY

SLOW OR STOP

WHAT ARE THE IMMEDIATE DEFENSE AGAINST THE ACCUMULATION OF H=

BICARBONATE AND NON-BICARBONATE SYSTEM

IF ACIDS ARE NOT EXCRETED WHAT COULD HAPPEN

ACIDOSIS

LUNG PRODUCE LARGE AMOUNTS OF WHAT DURING AEROBIC METABOLISM

CARBON DIOXIDE

EXCRETING CO2 DOES WHAT

Helps regulate blood pH levels.

HOW ,MUCH CO2 IS EXCRETED OR REMOVED DAILY

APPROX 24,000 MMOL/L

ACID EXCRETION DOES WHAT

PHYSICALLY REMOVES H+ FROM THE BODY

THE PROCESS OF ACID EXCRETION CONTROLS EXCRETION OR RETENTION OF

bicarbonate (HCO3-) in the kidneys.

HOW MUCH FIXED ACID IS EXCRETED DAILY

LESS THAN 100 MEQ

IF BLOOD IS ACIDIC THE KIDNEYS WILL EXCRETE

MORE H+ AND RETAIN BICARBONATE

IF THE BLOOD IS ALKALOTIC, WHAT HAPPEN WITH H+ AND BICARB

EXCRETE LESS H+ AND RETAIN BICARBONATE

THE LUNG SCAN ALTER CO2 WITHIN

SECONDS

THE KIDNEYS REQUIRE HOW MUCH TIME TO CHANGE HC03- AND AFFECT PH

DAYS

RENAL GLOMERULUS FILTERS WHAT

BLOOD BY PASSING WATER, ELECTROLYTES, AND NON-PROTEINS THROUGH SEMI PERMEABLE MEMBRANE TO FORM FILTRATE.

WHAT HAPPENS TO BICARB IN THE KIDNEYS ONCE IT REACHES THE SEMI PERMEABLE MEMBRANE

FILTERED

WHAT HAPPENS TO CO2 IN THE KIDNEYS

DIFFUSES INTO TUBULE CELL

HYROLYZED INTO H+ WHICH IS SECRETED INTO RENAL TUBULE

H+ SECRETION INCREASES

IN RESPONSE TO ACIDOSIS

WHAT ELSE INCREASES THE SECRETION OF H+

HYPOVENTILATION

KETOACIDOSIS

REABSORPTION OF BICARB

FOR EVERY H+ SECRETED AN equal amount of bicarbonate (HCO3-) is reabsorbed into the bloodstream.

DURING THE REABSORPTION PROCESS, WHAT DOES BICARB DISSOACIATE INTO

CARBON DIOXIDE (CO2) AND WATER (H2O)

CARBON DIOXIDE IMMEDIATELY DIFFUSES INTO THE CELL WHERE IT IS HYROLYZED TO FORM BICARBONATE (H2CO3)

IF THERE IS AN EXCESS HCO3- THAT DOES NOT REACT WITH H+, WHAT HAPPENS WITH IT

IT GETS EXCRETED IN THE URINE.

WHAT IS THE ROLE OF URINARY BUFFER

IS IN EXCRETION OF EXCESS OF H+

ONCE H+ HAS REACTED WITH ALL AVAILABLE BICARB EXCESS REACTS WITH PHOSPHATE AND AMMONIA

WHAT DO PHOSPHATE AND AMMONIA CREATE

A NEGATIVE ION

THAT CAN BE EXCRETED IN URINE

ELECTRONEUTRAILITY

The principle that states the total positive charge in a solution must equal the total negative charge, maintaining electrical balance.

IF ALL URINARY BUFFERS ARE CINSUMED FURTHER H+ WHAT MUST OCCUR

FILTRATION ENDS WHEN PH FALLS TO 4.5

ACTIVATION OF AMMONIA BUFFER SYSTEM ENHANCES CL- LOSS AND BICARB GAIN

KIDNEY MUST MAINATAIN

ELECTRONEUTRALITY

AND MAINTAIN BICARB OF 22-26

LUNGS MUST MAINTAIN CO2 OF

35-45 mmHg

A RATIO OF 20:1 WILL PROVIDE A NORMAL PH OF

7.4

WHAT HAPPENS TO THE RATIO INCREASES

IF INCREASED RATION WILL BE SEEN IN ALKALOSIS

A higher ratio of bicarbonate to carbonic acid will be observed in alkalosis, indicating a more alkaline state.

A DECREASED RATIO SHOWS

ACIDOSIS, INDICATING A MORE ACIDIC STATE.

PACO2 IS CONTROLLED BY THE

LUNGS

CHANGES IN PACO2 ARE CONSIDERED

a primary respiratory disturbance that impacts acid-base balance.

HYPERVENTILATION

LOWERS PACO2 WHICH RAISES PHand leads to respiratory alkalosis.

HYPOVENTILATION

increases PACO2, which lowers pH and leads to respiratory acidosis.

SYSTEMATIC CLASSIFICATION

INSPECT PH

IS IT ACIDOC

OR ALKALOSIS OR NOMAL

IF NORMAL BUT NOT 7.40 WHICH SIDE IS IT TOWARDS

INSPECT PACO2, IS IT A

CAN IT EXPLAIN THE PH

RESPIRATORY COMPONENT

INSPECT THE BICARB

IS IT A METABOLIC COMPONENT

CAN IT EXPLAIN THE PH

METABOLIC DISTURBANCES INVOLVE

GAIN OR LOSS OF FIXED ACIDS OF BICARB

BOTH APPEAR AS CHANGES IN BICARB BECAUSE CHANGES IN FIXED ACIDS WILL ALTER THE BICARB USED IN BUFFERING

A DECREASE IN BICARB RESULTS IN

METABOLIC ACIDOSIS

AN INCREASE IN BICARB RESULTS IN

RESULTS IN METABOLIC ALKALOSIS

COMPENSATION ALLOWS FOR WHAT

RESTORING PH TO NORMAL

IN RESPIRATORY ACIDOSIS (HYPOVENTILATION) THERE IS TOO MUCH WHAT PRESENT

CARBON DIOXIDE

IF TEHRE IS TOO MUCH CO2, WHAT DO THE KIDNEYS DO

RETENTION OF BICARBONATE (BASE) TO INCREAE PH TOWARD NORMAL

RESPIRATORY ALKALOSIS (HYPERVENTILATION)

TOO LITTLE CO2

RENAL ELIMINATION OF BICARB LOWERS PH TOWARD NORMAL

METABOLIC ACIDOSIS (HYPERVENTILATION)

LOWERS CO2 LEVELS RAISING PH TOWARD NIORMAL

METABOLIC ALKALOSIS (HYPOVENTILATION)

RAISES CO2 LEVELS LOWERING pH TOWARD NORMAL

THE CO2 HYDRATION REACTION EFFORT ON B ICARB

A LARGE PORTION OF CO2 IS TRANSPORTED AS BICARB

AS CO2 RISES IT ALSO RAISES BICARB

IN GENERAL THE EFFECT INCREASES OF APPROX 1 MEQ/L FOR EVERY 10 MMHG ON PACO2

RESPIRATORY ACIDOSIS (ALVEOLAR HYPBENTILATION)

ANY PROCESS THAT RAISES PACO2 OF GREATER 45 MMHG AND LOWERS PH BELOW 7.35