Acid-Base Flashcards
pH
potential of the H+ ion
- concentration of H+ in a solution
As H+ increase, so does…
acidity (pH decreases)
What can acids do?
Donate H+
Bases properties
- fewer H+
- accept H+ and give up OH-
How do strong and weak acids act in solution?
- dissociate fully in solution (give up all H+)
- weak acids dissociate partially
Hydrogen ion properties
- maintain cell wall
- part of H2O
- help with enzyme activity
- help with enzyme production
- part of sugar, starch, fats, and protein–energy production
normal pH
7.35-7.45
How is pH measured?
in blood serum
Most acidic part of the body
stomach; HCl–damaging outside of the stomach
Which other body parts help control gastric acid?
LES protects eso
Duodenum neutralizes it
What does pH affect?
hormones, oxygen transport and delivery, electrolytes (esp K, and Na, Cl) enzymes fxn (work w/i a narrow pH range)
oxyhemoglobin dissociation curve
Curve for basing O2 partial pressure on Hgb O2 saturation (O2 sat with pulse ox)
- more basic, hgb holds on to oxygen more tightly and does not give it to the tissue
- more acidic, hgb gives up oxygen more readily (we prefer this if had to choose)
pH that is incompatible with life
Under 6.8 or over 7.8
Volatile acids
- can be converted to gas
- excrete/elim by lungs
- carbonic acid and CO2
What does carbonic acid help with?
Helps the lungs to expel CO2
Non-volatile (fixed) acids
- can’t be converted to a gas
- lactic, phosphoric, sulfuric, acetoacetic, beta-hydroxybutyric
- elim by kidneys (except lactic)
How is lactic acid excreted
Met by the body esp liver and kidney
- can be reconverted if oxygen is given back to tissue
- byproduct of anaerobic metabolism
Phosphoric acid fxn
Works with Ca to to form strong bones
Sulfuric acid fxn
Produced by pro met
Acetoacetic acid
made by the liver
beta-hydroxybutyric acid
- inc with exercise, calorie restriction, fasting
- diagnostic of DKA
What things change pH
MANY
- ingested food and drink
- metab of lipids and pros
- cell metab waste products (CO2)
Survivable range of pH
7.2-7.5/6
- want to avoid alkalosis bc harder to fix
How is acid-base balance maintained?
With buffers, respiratory system, renal system
Buffers
- chems in the body that combine with acid or base to change pH
- accept or release H
- almost instant
- short lived
3 main buffer systems
Bicarbonate, phosphate, protein buffers (hgb)
Bicarbonate (carbonic acid) buffer
- main ECF buffer
- Co2 produced in cell metab combines with H20 to form carbonic acid
- carbonic anhydrase in lungs, kidneys, etc b/d carbonic acid
What does carbonic acid break into in the lungs?
H20 and CO2
What does carbonic acid break down into in the kidneys?
H and HCO3
Inc CO2 pushes the equation…
towards bicarb (more acid, more H+)
Phosphate buffer
- ICF buffer (main)
- can’t measure what is there
- picks up a H+ to balance
Excess H+ pushes the equation towards…
H20 and CO2
Protein buffers
- most pros are buffers
- carboxyl group (COOH) is a weak acid that gives up H (AAs and acetic acid)
- amino group accepts H+ (both carboxyl and amino group, ammonia NH3)
- Hgb included (picks up CO2 cellularly)
Cellular compensation
Cells like a neutral charge
- H+ and potassium (K+) in the cell
- When person is acidic, H+ moves into the cell and K moves out (neutrality restored)
- process reverses when pH is corrected but if kidneys are working, they will excrete excess K so you can have a depletion of K
Respiratory buffer mechanisms
- body makes CO2 which helps make carbonic acid in the lungs primarily
- exhalation excretes carbonic acid
- chx rate/depth of breath which affects amount of CO2 exhaled
- rate/depth dec if more alkalotic to retain CO2
- does not affect fixed acids like lactic
Kidneys buffer system mech
- elim large amt of bases and acid except carbonic
- can conserve and make bicarb ions to balance pH
- most effective regulator of pH
- if kidneys fail, pH balance fails
- need normal fxn of kidneys to work; if not, need daily bicarb
Main controller of carbonic acid
Lungs
How quick does resp compensation occur?
minutes to hours
How quick does renal compensation occur?
hours to days
If acidotic, kidneys will respond how?
by inc reabs or bicarb (and making new) and inc secretion of H+ into the urine to raise the pH
If alkalosis, kidneys will respond how?
by dec bicarb reabs and dec H+ into urine which lower pH
What is compensation?
Attempt by body to return to homeostasis
Compensation with a metabolic problem
Respiratory compensation: hypovent or hypervent (conserve or excrete CO2)
Compensation with a resp problem
met compensation with renal sys by reabs HCO3 or excreting HCO3
Patho of acid-base homeostasis with acidois
acidosis
stim brain and arterial receptors
RR inc
blood CO2 dec
carbonic acid dec
pH inc
