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Flashcards in Acid base balance Deck (24)
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1
Q

what artery is usually used for a blood test

A

radial artery

2
Q

Why is acid base important

A

Physiologically threat

  • Enzyme function eg coagulation
  • Electrolyte regulation - hydrogen and potassium ions
  • Drug ionization eg local anaesthetics

Diagnotic guide
- Establish diagnosis and to monitor during therapy

Acid base balance composed of acid production and acid elimination

3
Q

what are the 2 ways acid is produced

A

respiratory - carbonic from CO2

metabolic - organic such as lactate or amino and inrognaic like sulphuric and phosphorus

4
Q

acidic and alkaline secretions are produced in normal GI physiology from where

A

gastric - hydrogen ion

pancreatic - bicarbonate

5
Q

how is acid removed from the body

A

respiratory - ventilation removes CO2

metabolic - inorganic excreted via the kidneys unchanged

organic undergo liver metabolism before being excreted

6
Q

formular for pH

A

-log to the base 10 multiplied by the hydrogen conc

7
Q

what is plasma pH

A

7.4

8
Q

what is stomach pH

A

2

9
Q

the acid base homeostasis aims to keep pH constant - what are the 3 main systems for regulation of this

how quick are all these processes

A
  1. Buffers - immediate seconds to minutes
  2. Respiratory - rapid minutes to hours
  3. Renal ( metabolic) - slow hours to days - plus minor from liver contribution

Respiratory and/or metabolic dominant under normal conditions - other systems provide compensation

10
Q

what is the most important extracellular buffer for maintaing acid-base balance in the blood

A

carbonic acid-bicarbonate buffer - dissolved Co2 and bicarbonate ion are at eq

other mentions are protein albumin ( histidine - donor of positive charges in case of alkalosis and and negative charges in acidosis) and phosphates

11
Q

the Henderson hasselbalch equation can be written as

A

pH = pKa + Log [HCO3-] / [H2CO3]

because or rapid reaction resulting from carbonic anhydrase, PCO2 can be substituted for [H2CO3]

12
Q

how does the respiratory system regulate acid-base homeostasis

A

central chemoreceptors detect rise or fall in Pco2 which is kept between 5.1-5.5 kPa
acts on medulla via the CSF pH to stimulate ventilation to increase to get rid of CO2

13
Q

what is hyperventilation

A

Hyperventilation is rapid or deep breathing, usually caused by anxiety or panic. This overbreathing, as it is sometimes called, may actually leave you feeling breathless. When you breathe, you inhale oxygen and exhale carbon dioxide.

high volume but low PaCO2

14
Q

how does the renal system monitor acid base homeostasis

A

The kidneys have two main ways to maintain acid-base balance - their cells reabsorb bicarbonate HCO3− from the urine back to the blood and they secrete hydrogen H+ ions into the urine. By adjusting the amounts reabsorbed and secreted, they balance the bloodstream’s pH.

15
Q

what is respiratory acidosis indicated by

A

raised carbon dioxide

16
Q

what is metabolic acidosis indicated by

A

dropped bicarbonate

17
Q

what is respiratory alkalosis indicated by

A

dropped carbon dioxide due to hyperventilation

18
Q

what is metabolic alkalosis indicated by

A

raised bicarbonate and severe vomiting

compensation and respiratory failure should be looked for with all

19
Q

final urien acidity is determined by what cells in the DCT

A

intercalated cells

20
Q

what other ion via contransport - transports bicarbonate into the blood in PCT

A

sodium

Bicarbonate is the marker of metabolic disturbance but not the cause
So if excess acid is made - conc of bicarbonate is going to full to restore eq
Fall is marker not cause

21
Q

what is the anion gap

A

A measure to help identify the cause of metabolic acidosis as benign a disturbance of
Organic acid raised anion gap
Or inorganic acid which is normal anion gap

AG = [Na + K] - [Cl + HCO3 ]

total cations must equal anions
the anion gap is usually albumin

this gap increased with metabolic acidosis due to ketoacids

22
Q

how does the body compensate during acidosis

A

respiratory compensation : primary metabolic acidosis increase hydrogen concentration this acts on peripheral chemoreceptors (aortic and carotid bodies) conducted to the medulla to increase Vmin

opposite changes are seen in compensation fro alkalosis

metabolic compensation : primary respiratory acidosis ( increase CO2) leads to kidney retaining additional bicarbonate and excreting more protons

23
Q

3 rules fro determine acid-base anylsis

A

Acidosis or alkalosis - pH value
Respiratory or metabolic - biacroabte- metabolic or co2- repsiroatyr
Compensated or not

Compensation attempts to return Ph to normal with change in the box opposite to primary abnormality
Egh primary problem of respiratory acidosis - so CO2 high - compensation comes from increasing bicarbonate

24
Q

How does acetazolamide help

A

Acetazolamide belongs to a class of drugs known as carbonic anhydrase inhibitors. It works by decreasing the production of fluid inside the eye. It is also used to decrease a buildup of body fluids (edema) caused by heart failure or certain medications.

hydrogen ion retention so less bicarbonate produced