biochemistry Flashcards
what is the energy storage form of lipids
triglycerides
where are triglycerides stored
as fat droplets in adipose tissue
what happens to triglycerides when blood glucose is low
triglycerides are hydrolysed
what happens to triglycerides when fat is in excess
metabolised in the mitochondria to produce acetyl-CoA in TCA cycle
are triglycerides high or low energy per yield
high
what does cis mean
hydrogens are on the same side
what does trans mean
hydrogen are on opposite sides
what is budding
they recruit coat proteins and then can shed their coat leaving their receptor/ligand behind
what is targeting and trafficking meditated by
Rab proteins of GTPase
what is exocytosis
move out
what is endocytosis
move in
what is pinocytosis an example of
endocytosis
what is phagocytosis an example of
endocytosis
examples of energy
ATP
NADPH
what produces most energy in human diet
- lipids
- polysaccharides
where does glycolysis occur
in cytosol
what does glycolysis produce
pyruvate
what is the product of anaerobic conditions
lactic acid
what happens to lactate
metabolised by the lier back into glucose by gluconeogensis
what is the regeneration of lactate called
cori cycle
what cycle does pyruvate enter under aerobic condition
TCA cycle
in TCA cycle what happens to pyruvate
- decarboxylated to acetyl-CoA
what happens to acetyl-CoA in TCA cycle
joins with oxaloacetate to form citrate
how many reactions is TCA cycle
8
what is oxidative phosphorylation
movement of NADh and FADH2 through membranes to oxygen to produce water
energy released is used to efflux H+ set tun up a electrochemical gradient
what happens to the H+ electrochemical gradient
used for ATP synthesis through F0F1ATPase
what can failure to remove dysfunctional or misfiled proteins result in
- alzhemiers
- dementia
what is a free radical
any atom or molecule that contains one or more unpaired electrons
making it more reactive
what are the major free radical species in the human body
- hydroxy radical (OH)
- superoxide radical (02-)
- nitric oxide (NO)
what makes up total body water
- intracellular fluid
- extracellular
- plasma
what is osmotic pressure
ability to hold water in the compartment
what does the intracellular fluid contain mainly
potassium
what does the extracellular compartment contain
- sodium salt
- proteins
what is the capillary wall impermeable to
plasma proteins
what is the cell membrane impermeable to
sodium and potassium
what is the extracellular volume determine by
sodium concentration
what does a decreased extracellular volume do to cardiac output
decrease it
what filters most sodium
proximal tubule
what is responsible for day to day variation in sodium
aldosterone and ANP
what conditions cause sodium and water retention
- cardiac failure
- hepatic cirrhosis
- hypoalbuminaemia
what does a high dose of mineralocoroitcoid initially increase
renal sodium retention so that extracellular volume is increased
what does spironolactone do
block mineralocorticoid
what does the release of cardiac ANP require
optimum sodium concentration at the site of its action
what are changes in plasma sodium and osmolarity sensed by
osmoreceptors
what do osmoreceptors influence
thirst and release of ADH (vasopressin)
what does ADH play a role in
urinary concentration by increasing the water permeability
what does the absence of ADH do to water
means little water is reabsorbed in the collecting ducts
what are principal cells
have sodium and potassium channel in the apical membrane
what are intercalated cells
they do not transport sodium but have a role in hydrogen and bicarbonate handling
what is the name of water channels
aquaporins
what direction does water move in aquaporins
down an osmotic gradient
what happens to water channels when ADH has worn off
water channels are removed from the luminal membrane by endocytosis
what does ingestion of water cause
decreased release of ADH
what does a decrease in water reabsorption allow the water to go
excreted in dilute urine
what does water loss via sweat cause a rise in
both plasma osmolarity and ADH secretion
what disease can cause patients to become very thirsty
central diabetes insipidus
what are patients with central diabetes insipidus have a decrease in
ADH
when is a water load rapidly excreted
by inhibition of ADH release
what is another occasion where ADH is released
stress e.g. surgery or trauma
what does increased extracellular volume a result of
whole body salt retention
what is peripheral oedema caused by
expansion of the extracellular volume by at least 2L
where is peripheral oedema normal seen first
the ankles
what is lipodermatosclerosis
the skin is tethered and cannot expand to accommodate the oedema
when can oedema be noted in the face
in the morning
where does oedema accumulate in a patient in bed
in the sacral area
what other diseases does expansion of interstitial volume cause
- pulmonary oedema
- pleural effusion
- pericardial effusion
- ascites
what does expansion of the blood volume do
- raise JVP
- cardiomegaly
- added heart sounds
- basal crackles
- raised blood pressure
what is extracellular volume expansion due to
sodium chloride retention
what does reduction in cardiac output and a fail in effective circulatory volume to do RAAS
activates it
why is there peripheral vasodilatation in hepatic cirrhosis
due to increased NO generation
what is interstitial oedema a common clinical finding with
hypoalbuminaemia
what do oestrogen cause for sodium
mild sodium retention due to weak aldosterone like effect
reason for weight gain in premenstrual phase
what do mineralocorticoids and liquorice have
aldosterone like actions
what do NSAIDs cause
sodium retention in the presence of activation of RAAS
why may oedema result
from increased capillary pressure owing to relaxation of pre-capillary arterioles
what drug has a side effect of peripheral oedema
dihydropiridine calcium channel blocker
what drug can cure oedema
diuretics
but returns when they are stopped
where does loop diuretics act
in ascending limb of loop of Henle
examples of loop diuretics
- furosemide
- bumetanide
where does thiazide diuretic act
early distal convoluted tubule
examples of thiazide diuretic
- bendroflumethiazide
- metolazone
what do loop diuretics stimulate excretion of
both sodium chloride and water by blocking the sodium-potassium-2-chloride (NKCC2)
side effects of loop diuretics
- urate retention
- hypokalaemia
- decreased glucose tolerance
are thiazide diuretics more or less potent than loop diuretics
less potent
how do thiazide diuretics act
by blocking a sodium chloride channel in the distal convoluted tubule
example of aldosterone antagonist
spironolactone
when is spironolactone used
in patients with heart failure
do you need to administer lots of loop diuretic to work
yes
what causes decreased extracellular volume
loss of salt and water in a variety of ways
examples of how a patient may lose salt and water
- blood loss in haemorrhage
- vomiting
- diarrhoea
- fluid shift in sepsis
what can decrease extracellular fluid lead to
postural hypotension
symptoms of decreased extracellular water
- thirst
- muscle cramps
- nausea
- vomiting
- postural dizziness
- confusion
- coma
what does loss of interstitial fluid lead to
loss of skin elasticity
what does loss of circulating volume lead to
decreased pressure in the venous and arterial compartments
where is the fluid volume of the body controlled
kidneys
what does water follow
salt by osmosis
what is salt retention controlled by
RAAS
what happens if too much salt and water is retained
oedema
what is the best way to monitor volume status
measure their weight over a period of days
what is the osmolarity of the blood controlled by
kidneys
what does ADH react to
retain free water which dilutes the blood
what is the bodys sodium concentration determined by
the amount of free water
what is a decrease in conc of H+ termed
rise in blood pH
alkalaemia
what is an increase in the conc of H+ termed
decrease in pH
acidaemia
where is excess sulphate excreted
in the urine
what 3 cell types does the collecting duct have
- principal cell
- alpha-intercalated cell
- beta-intercalate cell
what do principle cells do under the influence of aldosterone
reabsorb Na+ and water and secrete K+
what is the primary source of ammonia
glutamine
what is deamination of ammonia catalysed by
glutaminase
what does deamination result in
alpha-ketogluutaric acid and ammonia
what is abnormal CO2 removal in the lungs termed
respiratory acidosis and alkalosis
what is the abnormality in the regulation of bicarbonate termed
metabolic acidosis and alkalosis
what does metabolic acidosis cause
hyperventilation leading to increased removal of CO2 in the lungs and partial compensation for the acidosis
what is respiratory acidosis accompanied by
renal bicarbonate retention
what are the ABG results in respiratory acidosis
pH = decreased PaCO2 = increased HCO3 = increased for compensated
opposite direction to pH
ABG results for respiratory alkalosis
pH = increased PaCO2 = decreased HCO3 = decreased
opposite direction to pH
ABG results for metabolic acidosis
pH = decreased PaCO2 = decreased HCO3 = decreased
same direction to pH
ABG results for metabolic alkalosis
pH = increased PaCO2 = increased HCO3 = increased
same direction to pH
what is respiratory acidosis caused by
retention of CO2
example of respiratory acidosis
COPD
what is respiratory alkalosis
increased removal of CO2
what causes respiratory alkalosis
hyperventilation
what is metabolic acidosis due to
accumulation of any acid other than carbonic acid
what disorders can lead to metabolic acidosis
- lactic acidosis during shock
- impaired acid excretion
what is chronic acidosis a risk factor for
muscle wasting in renal failure
where is ammonia and H+ excreted
in the urine
what can tubular disease cause
bicarbonate wasting
when does ketoacidosis occur
in starvation and after alcohol overdose
