Acid Base Balance Revision Notes Flashcards by Sally Awad

Total body volume
Total blood volume

60%* body wieght’
42L
Blood 5.6 L (RBCS + plasma )

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Fluid losses from our body occurs in 4 routes mention them with the amount of loss

Lungs 400ml/day
Skin 1L / day
Feces 100ml / day
Urine output 1.5L / day

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Daily urine output min volume

400m; / day

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Maintenance fluid requirement daily

30 ml / kg /day

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Amount of Floyd fluid loss depends on

Humidity temp , intake

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Direct hormone regulate ECF

ADH

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Hormones that indirectly regulate ECF

ANP
Renin angiotensin system directly regulate plasma osmolarity
Indirectly blood volume via aldosterone

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Minor regulators

Glucocorticoids
Catecholamines

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Osmosis definition

Movement of water from low solute concentration to higher solute concentration.
Type of simple diffusion
Movement of water from the higher water content to the lower water content .

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Intracellueler fluid

28 L

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ECF

14 L
Plasma 1/4 = 3.5 L
Interstitial fluid 10.5 L

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What power oppose osmotic pressure

The water passes from a high concentration outside of the vessels to a low concentration inside of the vessels, but equilibrium is never reached because the constant blood flow. Osmotic pressure works opposite to hydrostatic pressure to hold water and substances in the capillaries
Hydrostatic pressure

the pressure that is exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.

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1osmol/ L depresses freezing point by how much

By 1.86 C’

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Define osmolality
Define osmolarity
Which one is measure for solute concentration

OsmolaLity Osm/ kg
Number of osmoles of solution per kg of solution
OsmolaRity
Number of osmoles of solute per Liter of solution . Osm/l

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Total plasma osmolarity

300mosm/ L

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Consist of , concentration of
Na
Cl
Anion
K
Glu
Urea

Na 140
Cl 104 / 140
K 4
Anion 4
Glu 5
Urea 5
mOsm/L

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Define starling law of the capillaries

Fluid movement across capillary membrane as a result for filtration .
Hydrostatic pressure vs on optic pressure

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Starling low of forces define relationship between

Hydrostatic pressure and on optic pressure

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Net filtration pressure

Pressure promotiong filtration - pressure promoting reabsorption
Arterial Nfp = 35 +1 - 26+0 = 10 mmhg. ( blood hydrostatic pressure+ interstitial hydrostatic pressure - interstitial on optic + blood on oncotic pressure )
Venous NFP = 16+1 - 26 + 0 =-9 mmhg

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O edema definition

Increased fluid in the interstitial space

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Anasarca

Generak]lized edema with subcutaneous tissue swelling .

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Pathophysiology of the edema

1 increased hydrostatic pressure
2 decreased oncotic pressure
3 lymphatic obstruction
4 na retention
5 inflammation .

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Causes of edema

Lymphatic obstruction : inflammation . Post surgical , postradiation , neoplasia .
Na retention : renin angiotensin system activation increased activity.

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Plasma content

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Blood content

Main organs in regulation acid base balance

Kidneys Lungs ‘blood Bone liver

How does liver regulate acid base balance

By producing HCO3- and NH4+ thru glutamine metabolism

Anion gap definition

Difference between body cations and anions

Nl value for anion gap

8-16meq/l 12+4

Causes of high anion gap , mostly it’s metabolic acidosis

Lactic acidosis methanol , salicylate , paraldehyde . Ketoacidosis Hyopalbuminemia

Decreased anion gap

Myeloma Bromide

Co2 -> <- H+ + hco3- What causes shift to the left What causes shift to the right

Increase h+ leads to shift to the left consuming hco3- it will decrease and generating co2 Decrease in hco3- will lead to shift to the right , generating H+ , consumes CO2

Always a net gain in H+ = net gain in HCO3-

PH definition

It’s a logarithmic relationship o]with H concentration Ph = - log (H+) Ph = pk+ log10 ( hco3-/co2)

Normal values on maternal blood O2 sat Hb Po2 Pco2 Hco3- Ph base excess

Hb 12 Po2 100 mmhg Pco2 40 mmhg , 4 kpa Hco3- 24 mEQ/l Base excess -2 to +2 Nl ph 7.34 to 7. 44 toward alkalosis .

What happens in pregnancy for each h+ co 2 , hco3- , respiratory rate , min ventilation tidal volume

In pregnancy due to the effect of progesterone min ventilation increase leading to washing of CO2 mild hyopcapnia; which result in decrease H+ ; so it’s a state of respiratory alkalosis , with matabolic compensation by the kidneys Respiratory rate spent change in pregnancy . Tidal volume increase .

Percentage of o2 seats in fetus

Venous 75% Arterial 25%

Ph of the fetus Venous Arterial

Venous 7.17- 7.48 alkalitic Arterial 7.o7 - 7. 38 acidic

Hi of the fetus

Po2

Venous 35 At]rterial25

Co2 pressure in the fetus

80-100 mmhg 8-10 kpa

Base excess In the fetus vein and artrey

Vein -1 to 9 Artrey -2.5 to10

Which is slow , respiratory or metabolic compensation

Respiratory very fast Metabolic slow

When does respiratory compensation occurs

It only occurs in case of metabolic disorders It can’t compensate for primary respiratory disorders at all.

How does metabolic compensation occur And what does compensate for

Via kidneys It compensate for metabolic disorders caused by non kidney cause and for respiratory disorders

HCO3- m]is manufactured in ?

DCT Collecting duct

Which tubule of the kidney that doesn’t have a role in acid - base balance

PCT

How does DCT cells produce HCO3 - and why

The me[anifacture it since they have carbonic anhydrase Co2 + h2o= h2co3 = h+. +. Hco3- . H2co3 is unstable organ rapidly catalyzed to h=+ & hco3- Then HCO3- goes to the circulation and H+ secreted in the urine to buffer it by NH4+ and HPO4-2

What buffers H+ in the urine

Nh4+ HPO4-2

Increased NH4+ production by the kidneys does it increase in acidosis or m]alkalosis

Nh4+ is increased in acidosis

What happen at the cellular level when long term acidosis occur H+ K+

H+ is in excess amount at the ECF so it starts to enter into the cell Then to replace it the k+ will be shifted out of the cell leading to hyperkalemia

Hypokalemia occurs with acidosis or alkalosis

It occurs with alkalosis Acidosis - hyperkalemia

Define base deficit /excess

Is the amount of acid or alkali needed for 1 L of blood to retain Nl pH At a pco2 5.3 kpa ant temp 37 C*

What we use to calculate acid base deficit Normal range

We use bicarbonate concentration (hco3-) and ph values Base excess = 0.93 * ( hco3 - _ 24.4) + 14.8* (ph-7.4 ) . Normal range -2 to +2 .

Negative base excess means