PRINCIPLES OF CELLULAR FUNCTION - EmergencyPedia



PRINCIPLES OF CELLULAR FUNCTION.

Regarding CSF (page 612)

a. Production 50 – 100ml /day - volume 150ml, production 550ml/day

b. Drained through choroids plexus - 50-70% formed in choroids plexuses, drained in arachnoid villi

c. Greater protein content than blood - no, much less

d. Content essentially same as brain ECF - yes

Regarding body fluid composition, which is approximately 40% of bodyweight

a. ICF - yes

b. ECF - 20% (includes interstitial and plasma volume)

c. TBW - 60%

d. plasma - 5%

Which penetrates CSF fastest

a. H2O, CO2, O2

b. Na, K, Cl - via Na-K-2Cl cotransporter

c. N2O - possibly this

d. HCO3 - slow

The main buffer in the interstitium is

a. protein - blood and intracellular

b. haemaglobin -blood

c. phosphate - intracellular

d. ammonia - urine

e. HCO3 - THIS ONE interstitial and blood

Which of the following is 20% of total body weight

a. ECF - this one

b. ICF - 40%

c. TBW - 60%

d. Blood volume - 5%

Regarding the function of the smooth endoplasmic reticulum; which is incorrect

a. steroid synthesis

b. drug detoxification / cytochrome P450

c. protein synthesis - rough ER

d. role in carbohydrate metabolism -

Regarding ICF; which is incorrect

a. Na+ of 135 - this one, [Na] around 10mmol

b. K+ of 140

c. Mg2+ of 58

d. Ca2+ of 0.0001

e. PO4- of 75

In which component does a solution of 5% dextrose dissolve

a. ECF

b. ICF - mostly this one (2/3)

c. Interstitial fluid

d. Intravascular

e. Transcellular

The concentration of ICF vs ECF

a. lower Mg++ - higher intracellular, also higher K, lower Na, HCO3, Cl

b. higher PO4— - yes

Regarding the composition of CSF

a. production is 50-100 mls per day no, production about 550mL/day

b. has the same composition as cerebral ECF yes

c. higher conc. of K+ with respect to plasma no, about half

d. higher concentration of protein no, almost no protein

Regarding CSF

a. Composition is esentially the same as brain ECF true

b. CSF production is ~150mls per day false

1 litre 5% dextrose given intravenously distrubutes predominantly to: -throughout TBW, 2/3 ICF

a. Intracellular compartment - yes

b. Interstitial compartment

c. Extracellular compartment

d. Intravascular compartment

e. Transcellular fluid

The main buffer in the interstium is

a. Protein

b. Haemoglobin

c. Phosphate

d. Ammonia

e. HCO3 - this one

Total body water ???

a. increases with age - decreases slightly

b. is typically 45% of bodyweight - 60%

c. is typically 63 % of body weight - true

d. is greater in men than women - true

e. is composed largely of interstitial fluid - no intracellular

With the addition of 1 litre of 5% dextrose intravenously to which compartment is it mainly distributed

a. intracellular -disun

b. interstitial

c. extracellular

d. transcellular

e. vascular

Regarding the composition of ECF versus ICF . ECF has

a. decreased magnesium - yes, 2 vs ~25

b. increased phosphate - 2 vs 100

c. increased potassium - 5 vs 140

d. decreased sodium - 140 vs 10

ECF compared to ICF has

a. increased potassium - no

b. decreased phosphate - yes

c. increased phosphate - no

d. decreased sodium - no

A fit healthy 20 y/o male lose 1 litre of blood

a. the haematocrit falls immediately - no it dont

b. this is a 35 % blood loss - 30%

c. plasma protein synthesis is not increased - suspect it is

Anion gap is

a. Sodium + potassium – bicarbonate - Na + K – Cl – HCO3

b. due to organic protein ions and phosphate ions - probably

c. increased in hyperchloremic metabolic alkalosis - probably acidosis in question – normal anion gap

Ratio of HCO3- ions to carbonic acid at pH of 7.1 is

a. 1 - pH 6

b. 10 - this one

c. 0.1 - very very acidic

d. 100 - very very alkalinic

e. 0.01 - uber acidic

With the loss of 1 litre of blood

a. haematocrit falls immediately - no

b. iron resorption is not increased - surely it is

c. this equals 35 % plasma volume loss - 30% (total 3.5litres)

d. baroreceptors increase parasympathetic output - decrease parasympathetic firing, increase sympathetic firing

e. red cell mass normalises within 2 weeks - 4-8weeks

What is the hydrogen ion concentration at a pH of 7.4

a. 0.0001meq/L - 7.0

b. 0.00004 meq/L - this one

c. 0.0004 meq/L - lumen in ascending limb of LoH

d. a high protein diet reduces the ability of the kidney to concentrate urine – increases ability

e. vasopressin has no effect on the movement of urea across tubular epithelium – false according to Wikipedia

Where in the kidney is the tubular fluid isotonic with the renal interstitium

a. PCT

b. DCT

c. Proximal LH – descending LoH

d. Distal LH

What is the osmolality of the interstitium at the tip of the papilla

a. 200

b. 800

c. 1200 – probably this one

d. 2000

What is the osmolality of the interstitium at the tip of the renal papilla

a. 200

b. 800

c. 1200 –this one?

d. 2000

e. 3000

In the kidney, Na is mostly reabsorbed with

a. HCO3

b. Glucose

c. K+

d. Ca2+

e. Cl- – this one

ACID-BASE BALANCE

Regarding blood buffers. What is HCO3:H2CO3 ratio at PH 7.4? (table 39.5)

a. 10 -pH 7.1

b. 16 -pH 7.3

c. 1

d. 20 - this one

e. 0.9 - pH 6.0

Regarding the anion gap

a. Difference between cations including Na and anions including Cl- and HCO3 - not including – that it is

b. Increased in hypochloremic acidosis secondary to NH4 ingestion - ????

c. Decreased with decreased Mg/Ca - no, increased with decreased Ca/Mg

d. Decreased when albumin is increased - decreased with decreased albumin

e. It consists mostly of HPO4, SO4 and organic acids - ??

Which H+ concentrations are compatible with life (Table 39.1 Ganong) - 0.00004 maybe? (range 0.00002 – 0.0001)

a. 0.0004 meq

b. 0.0004 meq

c. meq

d. 0.0002 meq

e. 0.0008 meq

Which agent is most likely to produce the following blood gas result: pH 7.51, HCO3 50, pCO2 45

a. diuretic - lose Na and Cl-. Retain bicarbonate, volume deplete therefore relative [HCO3] increases therefore pH rises.

b. chronic diarrhoea - bicarbonate loss in stool, metabolic acidosis, low bicarb

c. carbonic anhydrase inhibitor - causes Na, Cl, HCO3 loss in urine. acidosis

Regarding the anion gap

a. it is the difference between cations not including Na and K and anions not including HCO3 -no

b. it consists mainly of HPO4, SO4 and organic acids -?? Mainly of albumin acc. To Kumar and Clarke

c. it is increased in hyperchloraemic acidosis due to ingestion of NH4Cl - normal anion gap

d. it is decreased when albumin is increased - decreased with decrease

e. it is decreased when Ca/Mg are decreased - increased

In respiratory acidosis, what would be the first metabolic compensatory response

a. bicarbonate retention / elevation

Which substance does not represent an acid load to the body

a. Fruit - gives alkali

b. DKA

c. CRF

d. Ingestion of acid salts

All of the following represent an acid load to the body EXCEPT

a. DKA

b. CRF

c. Fruit - this

d. Ingestion of acid salts

Which agent is most likely to produce the following blood gas result : pH 7.51 HCO3 50 PCO2 45

a. diuretic - this one

b. chronic diarrhoea

c. carbonic anhydrase inhibitor

Hypokalaemic metabolic acidosis may be associated with

a. Carbonic anhydrase inhibitors - no loss of K+

b. Diuretic use - alkalosis

c. Chronic diarrhoea - bicarb and K+ loss

The ratio of HCO3- ions to carbonic acid at pH 7.1 is

a. 1 - pH 6.0

b. 10 - this one

c. 0.1 - acidic ++++

Regarding the anion gap

a. It is the difference between cations including sodium and anions including Cl and HCO3

b. It is increased in hyperchloraemic acidosis secondary to ingestion of NH4Cl

c. It is decreased when Ca/Mg decreased

d. It consists mostly of HPO4 2- ,SO4 2- and organic acids

e. It is decreased when albumin is increased

In a patient with a plasma pH of 7.1 the HCO3-/H2CO3 ratio is

a. 20 - pH 7.4

b. 10 - this

c. 1 - pH 6.0

d. 0.1

e. 0.2

Which of the following best describes the changes found in uncompensated respiratory alkalosis

a. decreased pH, HCO3- and PaCO2

b. increased pH and lowHCO3- and PaCO2 - this one. Normal HCO3 surely if uncompensated

c. decreased pH and HCO3- and normal PaCO2

d. increased pH low HCO3- and normal PaCO2

e. decreased pH increased HCO3- and normal PaCO2

In chronic acidosis the major adaptive buffering system in the urine is

a. carbamino compounds - red cells only

b. bicarbonate - ??

c. ammonium - ??

d. histidine residues - haemoglobin

e. phosphate - ??

The following blood gases represent pH 7.32, pCO2 31mmHg and HCO3-20mmol/L

a. primary metabolic acidosis - yes, but e more correct

b. primary respiratory alkalosis - would expect high pH

c. a picture consistent with diuretic abuse - water lost, bicarb retained, therefore HCO3 would be high

d. mixed respiratory acidosis, metabolic acidosis - resp acidosis = high CO2

e. partly compensated metabolic acidosis - compensated by low CO2, bicarb not yet caught up

The following gases are associated with PCO2 45 pH 7.57 HCO3- 30

a. acetazolamide treatment - causes NA, Cl, HCO3 loss in urine, therefore acidosis

b. diuretic use

c. diarrhoea - acidosis due to loss of bicarbonate

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