late august viva Flashcards
addisons
deficinet aldosterone secretion from adrenal
stewarts theory
CORE
Stewart stated that H+ and HCO3‐ ion concentration were
dependent variables, and thus acknowledged the
importance of other factors controlling the pH
ACID/BASE Balance should = (OH‐) / (H+)
The H+ and HCO3‐ ion concentrations in the body were
determined by 3 INDEPENDENT VARIABLES
1) SID = Na+, K+,Ca2+,Mg2+ minus
Cl‐, and all (Other Strong Anions)
2) A (total) –Weak non‐volatile acids – Inorganic
Phosphate, Plasma Proteins and Albumin
3) pCO2 – really CO2 concentration – however
solubility varies only slightly in the human temp
range and pCO2 is easily measured
stewart negative
COMPLEX Computer Algorithms
Lack of Clinical Correlation
SID reflects only Plasma, whereas SBE reflects Hb
influence and the Whole Body Status
– ISOHYDRIC PRINCIPLE
SBE –Well Validated clinically over a long period of
Time.
SID
Sum of Routinely Measured Strong Cations – MSC ‐ (Na+K)
MINUS Routinely Measured Strong Anions ‐ MSA ‐ (Cl)
= 42meq L.
SID and Plasma HCO3 have a direct relationship
↑ SID = ↑ Plasma HCO3 (Metabolic Alkalosis)
‐ Filling up SID Space caused by ⇓ Cl.
↓ SID = ↓ Plasma HCO3 (Metabolic Acidosis)
‐ SID Space occupied by Cl or Strong Acids (LTKR) not
routinely measured.
SID and IVF
In order to maintain Acid – Base Homeostasis with the
administration of NON Albumin containing fluids, the SID
of the infused 1L of fluid needed to decrease from
42 to 27 = NEUTRALITY
BENEFIT OF PLASMALYTE
Plasmalyte
–>SID of 50
high SID–>high HCO3–>alkalaemia
CSL
–>SID of 27–>neutral
SID of blood if 42 but vol explansion causes decreased albumin–>increased SID–>alkalaemia so less SID of 27–>neutral
buffer
BUFFER – is a mixture of a Weak Acid and its
Conjugate Base
Attenuates the change in H+ ion concentration when a
Strong Acid or Base is added
pka
pKa = the negative Log 10 of the Ionization constant
IONIZATION CONSTANT is the pH at which EQUAL
values of the Conjugate Base and the Weak Acid are
present.
Anion gap explained
Lethal Acids CONSUME HCO3, but do nothing to Cland
thus cause an ↑ in the AG
Buffer systems
ISF: H2CO3 Blood: Hb, Pr, H2CO3 ICF: HPO4, H2CO3 kidneys: NH4, HPO4 (titratable) Bone: CaCO3
law of mass action
Total Concentration‐‐ must equal the sum of all the dissociated components
Plus the sum of All the Undissociated Components
isohydric principle
The isohydric principle is the phenomenon whereby multiple acid/base pairs in solution will be in equilibrium with one another, tied together by their common reagent: the hydrogen ion and hence, the pH of solution.
mass action
Law of Mass Action states that the multiplication of the concentration of the Individual
constituents of a chemical reaction, divided by the concentration of the product of the
chemical reaction at equilibrium =a constant Ka
Ka = (H+) (HCO3‐)/H2CO3
Hb as buffer
Buffering is by the imidazole group of the histidine residues
– Pk = 6.8
imidazole is basic and a part of the AA histidine
Hb is 6x more important than plasma proteins as a buffer due to
1) Double the plasma concentration of Hb
2) Hb has 3x the amount of histidine residues per molecule
De –Oxy Hb has greater buffering power –Weak Acid
Pr buffer
Consists of Amino Acids that have Free Acidic Radicles
that can Dissociate into Base plus H+ ions.
PK ‐‐ 7.40
Most Important Buffer in ICF (large Protein conc in
ICF) – Thus contributes the MOST of all buffer
systems to Acid‐Base AbN
Contributes only 5% of Acute ECF Buffering due to the
Relative Impermeability of Cell Membranes to H+ and
HCO3‐ (delays buffering ability of Plasma Acid‐Base
AbN for several hours)
can be weak acids or weak bases
PO4 pka and site
Phos buffer pair very important in ICF
Phosphate conc much higher in ICF than ECF = 100x
pH of ICF is closer to the pK of the Phosphate Buffer
system, than is Ph of ECF
boen buffer
IONIC EXCHANGE
Bone can take up H+ in exchange for Ca+
Involved in buffering of Acute Metabolic Acidoses
without bone breakdown
OSTEOCLASTIC REABSORPTION of BONE
Release of CaCO3 which leads to HCO3‐ formation
Involved in Chronic Metabolic Acidoses – ESKD, RTA
meq/kg
A certain amount of univalent ions provides the same amount of equivalents while the same amount of divalent ions provides twice the amount of equivalents
Strong acids prod
1meq/kg/day
glutamine glutamate
glutamate punches you and it hurts T=transmitter
glutamine is an AMINoacide
NH4
glutamine (AMINOACID)–NH4 + HCO3
info on ABG for acid base
pH ‐ Measured directly
pCO2 – Measured directly
Actual HCO3 – Measures pH and pCO2 from blood sample and then
calculates HCO3 from the H‐H Equation
Standard HCO3 – Calculated parameter when the blood sample is
equilibrated with a gas mixture with PCO2 level of 40mmHg – attempt
to represent the True metabolic component in patients with dual Acid –
Base AbN.
BASE EXCESS = Amt of Acid or Base that must be added to the blood
sample to restore the pH back to 7.40 if the pCO2 is N (40mm)
STANDARD BASE EXCESS = As for BE but equilibrated with a
specimen of anaemic blood – Hb = 5,0
osmolar gap
10
uncharged particles that contribute to osmolarity but not measured
osmol define
an osmole is the amount of a substance that yields the number of particles that would depress the freezing point of the solvent by 1.86K
Avogadro’s number of particles in an ideal solution
NH4 system
The capacity of this system to excrete hydrogen ions in the urine exceeds that of phosphate
make urinary ph depression
The minimum urinary pH is 4.4, because the
mechanism of active transport of hydrogen
secretion is inhibited at higher hydrogen ion
concentrations.
minimum urine
maximally concentrating still needs to remove waste. –>0.3ml/kg/hr=430ml/day
nodes of ronvier mech
In some large-diameter nerves, the process of
action potential conduction is not continuous
along the length of the bre. Instead, action potentials jump along from point to point in a ‘saltatory’
manner (Figure 1.15a). is occurs in myelinated
nerves where a fatty layer composed of overlapping Schwann cells covers the axon apart from at
the regularly spaced nodes of Ranvier.
RMP of different tissues
SA -55
Vent-90
Nerve 70
m. -90
hyperpolarization cause
If all the sodium channels are open, however, then the neuron becomes ten times more permeable to sodium than potassium, quickly depolarizing the cell to a peak of +40 mV.[2] At this level the sodium channels begin to close and voltage gated potassium channels begin to open. This combination of closed sodium channels and open potassium channels leads to the neuron re-polarizing and becoming negative again. The neuron continues to re-polarize until the cell reaches ~ –75 mV,[2] which is the equilibrium potential of potassium ions. This is the point at which the neuron is hyperpolarized, between –70 mV and –75 mV. After hyperpolarization the potassium channels close and the natural permeability of the neuron to sodium and potassium allows the neuron to return to its resting potential of –70 mV.
RMP and Na
Hypernatremia:-generally change of sodium doesn’t affect RMP, The permeability of it is
low , so Na will accumulate(more distribution) extracellulary,
RMP and K
INCREASED (Hyperkalemia):-hyperpolarized because of more incurrent K+, SO the RMP will
be at new level further from the Threshold, so the probability to have an Action potential is
less. This will affect the heart and muscles in general, weakness, ascending paralysis, and If
untreated cardiac arrhythmias.
DECREASED (hypokalemia):-Weakness, fatigue, motor paralysis, Myopathies
(Myotonia:delay relaxation or continuous spasm after voluntary contraction).
RMP and Ca
Ca++ competes with Na so if there is more Ca+2 this means more blocked channels so less
Na influx and less depolarization , but when Ca++ is low so the competition is less and Na
influx increased and so the depolarization.
Ester link
COO
NOOT CCO
CVS and CNS LA ratio
CC/CNS ratio
PEEP effect
R and L
And Starling
Interdependence
USS depth and vision
High freq–> better resolution as smaller wave length but more absorption (attenuation) –> shallow pentration
Freq wave eqn
V=wave.freq
V is constant
Daba vs rivarox
Evernote
Oxycodone met
Oxymorphone is active met weakly
Hm met
HM3g and HM6G
NEUROTOXIC and accumulate in renal
Buprenorphine met
Hep then bilary excretion with only a touch of renal so good in shitty kidneys
This class
Barbiturate
Barbiturate moa
Augment cl flow indep of GABA
Decrease NT release and response
Thiopentone structure function
Thio is sulfur analog of oxybarbituatuate
Pentone is substition at 5–>hypnotic
Thio and ketamine isomers
Ketamine has S and R enantiomers
Thio has enol tautomerism to keto in acidity of blood!
Play ketamine and thio
7.5 and 7.6
Theory of alb
Oncotic
Antioxidant
Acid buffer
Won’t work in leaky
Non essential
Allergy