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BIOCHEM

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winniesmith's version from 2017-01-22 13:29

Section 1

Question Answer
6 things water doesbathes our cells, dissolves and transports compounds in blood, medium for molecular movement, separates charged molecules, dissipates heat, participates in chemical reactions.
percentage of water in adult and child60% adults, 75% child
fluid in the body; % intra/extra cellular60% intracellular, 40% extra cellular
what is the extra cellular fluid made up of66% interstital, 33% blood plasma. Tiny bit transcellular water
What does transcellular water includesmall vol. of extracellular- urine,sweat, gastrointestinal secretions, capillary leakage (eg inflammation)
why is water a good solventhydrogen bonds, strong enough to dissolve polar molecules and separate charges. Weak enough to allow molecular movement of h20 and solutes.
why does water form hydrogen bondsdipolar. covalent bond between O&H cause shared electrons to be O side of molecule. O more -ve. H more +ve. O2 H bonds with 2 other molecules. 4 neighbors in 3D lattice.
What dissolves in water and why?organic molecules and inorganic salts, form H bonds and electrostatic interactions. Organic m- contain high proportion of electro -ve atoms (O,N) are soluble.
Strength of bonds in water (relating to it being a good solvent)covalent bond O-H is 20x stronger than H bond. H bonds continuously break and reform (approx 10 pico seconds).
Speed at which H bonds break and reformapprox every 10 pico seconds.
what does heat of fusion meanenthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid at constant pressure.
Why is water good at thermoregulationhigh heat of fusion (and vaporisation) (large drop/increase in temp to change its state) and high thermal conductivity (heat dispersed quickley).
what happens when you heat water (h bonds)decrease in h bonds
what happens when you cool water (h bonds)increase in h bonds
What are electrolytesinorganic anions, cations and biocarbonates.
electrolytes in ECF Na+ and Cl-
electrolytes in ICFK+ and phosphates.
how is the difference in electrolyte conc. (between ECF & ICF) maintainedpurposely maintained via they ATP requiring pump transporters
what is osmotic pressure force needed to maintain equal volumes of water on each side.
What is osmolarity concentration of solutes.
water moves from low to high osmolarity. OR from high to low water potential
how does water move through semi permeable cell membranesfreely down ion channels.
what is interstitial fluidsolution that bathes and surrounds the tissue cells of multicellular animals
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Section 2

Question Answer
what pH is an AcidpH < 7 (H+)
what pH is a BasepH > 7 (OH-)
pH of water neutral pH 7.
what does pH mean-Log10(c) C= conc. H+ ions. Acidity or alkalinity of a solution on a logarithmic scale
what does water dissociate intoH+ (10^-7 mol/L) and OH- . Can form H30+ hydronium.
A strong acid iscomplete dissociated (H2S04 and HCl)
A weak acid isvery partial dissociation (COOH group)
Weak acids are known asconjugate acid(HA)
what do conjugate acids dissociate intoionic component (CONJUGATE BASE "..ate") and H+ (CONJUGATE ACID "...ic acid")
What is Acetoacetic acid used formetabolism (combustion of fats)
What is Acetoacetate used forenergy, converted to Acetyl-CoA--> NADH/FADH2, via the citric acid cycle.
What is KaTendency of HA to dissociate. Ka= (equilibrium) constant of acid (depending on temp).
What does a high Ka meanhigh tendency to dissociate, high strength of acid. (weaker conjugate base)
what is pKa -log(Ka). Strength of acid.
Relationship between Ka and pKaLarge Ka = Low Pka
What does a low Pka meanhigh acid strength and high stability of conjugate base.
Describe a strong acid in terms of Ka, pKa, pH and conjugate base strengthHigh Ka, Low pKa, low pH, weaker conjugate base/high stability of conjugate base.
Describe a weak acid (or base) in terms of Ka, pKa, pH and conjugate base strengthLow Ka, High pKa, High(er) pH, stronger conjugate base/low stability of conjugate base.
what is the pKa of water16 (-10 (strongest acid) ------16 (water)-------50 (v v v shitty acids))
what is the pKa of metabolic carboxylic acis2-5 pKa
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Section 3

Question Answer
what does a buffer do?Resist changes to pH, due to influx or removal of H+, within 1pH of pKa value.
what does a buffer containWeak concentrated acid and conjugate base.
why is a concentrated buffer better?increases effectiveness, as increased nm of buffer molecules per unit v.
what are the 4 buffer systemsbicarbonate- carbonic acid system (ECF), Hemoglobin system (RBC), Phosphate system (cells), Protein system (cells and plasma)
What amount of acid does metabolic rate produce?22,000(mEq) of acid per day.
What is the pH of blood?7.3-7.4
what is the critical pH of blood?6.8-7.8
What would happen to pH if the metabolic acid was left unbuffered?drop to pH<1
why do we need the Bicarbonate buffer system?As C02 is the major source of metabolic acid in the body and when it dissolves in H20 carbonic acid forms.
What is the major source of metabolic acid in the body?CO2, from oxidation of fuel in TCA cycle.
What happens when CO2 dissolves in watercarbonic acid is produced. (CO2 + H20 ----carbonic anhydrase----> carbonic acid (H2CO3)
What is the enzyme needed for production of carbonic acidcarbonic anhydrase.
In water; What happens to carbonic acid (H2CO3)?It is weak and partially dissociates to H+ and HCO3- (bicarbonate anion). Major acid therefore acts as own buffer (H2CO3+ H20 <----> H3O+ + HCO3-). pKa of 3.8
In blood; What happens to carbonic acid?completely dissociates and pH of 7.4, therefore, unable to generate bicarbonate and unable to buffer.
what is the normal amount of CO2 produced per day?13 mol of CO2 per day (approx 1kg)
How can carbonic acid be replaced?from CO2 in body fluids and CO2 in the air. Dissolved CO2 is in equilibrium with CO2 in alveolar,so adjusting VE can adjust CO2
What is the diffusion path of C02 into RBCs?CO2 produced in TCA diffuses into interstitial fluid and plasma and then into RBC.
Where can you find carbonic anhydrase?In RBC's, not plasma.
What happens to C02 after in enters a RBC?CO2+H2O in presence of H2O forms carbonic acid, Carbonic acid dissociates .H+ then buffered by heamoglobin (hb) side chain of the aa histidine (in hb) has pKa of 6.7 and as such can accept a H+. HCO3- then leaves RBC (into blood). in exchange for chloride anion (Cl-).
what happens when the blood reaches the pulmonary circuit?This whole process is reversed when the blood reaches the chemical environment of the pulmonary circulation.
Where is the brain respiratory centre and what is it sensitive too?The hypothalamus and sensitive to changes in pH.
What happens when pH falls?Breathing rate increases and CO2 expelled.
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