Blood physiology with MCQs

October 13, 2021

Ferenc Domoki

Warm-up: normal values

The osmotic concentration of blood plasma: (1)

a) 400 mosm /l

b) 340 mosm /l

c) 200-300 mosm /l

d) 390 mosm /l

e) 290 mosm /l

The calcium concentration of the blood plasma is (1)

a) 25 mmol/l

b) 2.5 mmol/l

c) 25 mol/l

d) 0.25 mol/l

e) 2.5 nmol/l

The potassium concentration of the blood plasma is (1)

a) 4 mmol/l

b) 0.4 mol/l

c) 40 umol/l

d) 143 mmol/l

e) 14 mmol/l

Concentration of plasma proteins: (1)

a) 40-60 g/dl

b) 60-80 g/l

c) 20-40 g/l

d) 20-40 g/dl

Protein fractions in human plasma: (3)

a) fibronectin

b) globulin

c) fibrin

d) albumin

e) fibrinogen

Which of the following nitrogen-containing metabolite has the largest concentration in the blood plasma? (1)

a) creatinine

b) creatine

c) urea

d) ammonium ion

e) uric acid

Urea cc. is ~2.5-6 mM, the others are smaller at least one order of magnitude!

Calculation of fluid compartments

To determine blood volume, 1 ml Evans blue (concentration: 18 g/liter) has been injected. After 10 min, the concentration of Evans blue in the blood plasma is 5 mg/liter. The hematocrit is 40 %. The calculated blood volume is (1)

a) 5 l

b) 4 l

c) 9 l

d) 6 l

e) 3 l

(18 mg / 5mg/l) / (1-0.4) =

3.6 / 0.6 = 36 / 6= 6 l

Hematocrit: the volume ratio of blood cells to total blood!

To determine the blood volume, a rat is injected iv. with 0.1 ml dye; the concentration of the dye is 12 mg/ml; the concentration of the dye is 0.4 mg/ml in the plasma. The hematocrit is 40% . The blood volume is as follows: (1)

a) 5 ml

b) 10 ml

c) 15 ml

d) 12 ml

(1.2 mg / 0.4 mg/ml) / (1-0.4) =

3 / 0.6 = 30 / 6 = 5 ml

True statements concerning blood plasma proteins: (3)

a) hemoglobin belongs to them

b) albumin occurs in the largest concentration

c) the complement factors belong to them

d) their total concentration is 30-40 g/l

e) the majority is produced in the liver

Which of the following hemoglobin concentration is in the normal range in humans? (1)

a) 15-17 mg/100 ml

b) 13-15 ng/100 ml

c) 12-14 mmol/100 ml

d) 15-16 g/100 ml

e) 29-31 mg/100 ml

The measurement unit of blood sedimentation rate (1)

a) mN / mm2

b) 1 / hour

c) mm / cm3

d) mm / hour

e) 1 / cm

The most important factor determining blood sedimentation rate is (1)

a) the plasma potassium level

b) the leucocyte count

c) the plasma albumine-globulin ratio

d) specific gravity of the plasma

Albumin/Globulin ≈ 2DECREASES, if

Albumin cc decreases: -decreased synthesis (liver damage, malnutrition)

-increased loss (renal diseases)

Globulin cc. Increases: - acute phase proteins- immunglobulins

RBC aggregates ≠ clots! – money roll formation

In the anticoagulated resting blood column, the RBCs form aggregates „money rolls”. This aggregation is inhivited by albumin, promoted by globulins.

This phenomenon couples plasma dysproteinemia to altered sedimentation rate (rate increases when albumin/globulin ratio decreases). The larger aggregates sink faster!

What can be the „use” of determining blood sedimentation rate?

Indicates plasma DYSPROTEINEMIA

Sensitive, non-specific, low-cost, SO

Easy to detect that „something is out of order”, but cannot be used to diagnose a specific illness. (Mandates further testing)

If the the diagnosis is known, however, one can FOLLOW the course of the derangement.

Which of the following statements are NOT correct (3)

a) Na-citrate is used as anticoagulant for erythrocyte sedimentation test

b) in order to avoid changes in plasma volume, heparin is used as anticoagulant in the sedimentation test

c) increased sedimentation rate indicates a decreased albumin-globulin ratio

d) to determine erythrocyte sedimentation, the blood sample is centrifuged for 10 min

e) increases in albumin concentration enhances eryhtrocyte sedimentation rate

What kinds of information can be gained from the microscopic study of May-Grünwald-Giemsa stained blood smear? (2)

a) reticulocyte count

b) absolute white blood cell count

c) determination of red blood cell morphology

d) differential leucocyte count (% contribution of different white blood cell types)

Red blood cell alterations observed in blood smear

stomatocyte

Target cellsSickle cells

elliptocytesphaerocyte

malaria

True statements concerning erythroid development: (2)

a) mature erythrocytes do not have a nucleus, and their membrane MHC antigens are specific for the individual.

b) The maturation of the erythroid progenitors takes place on the surface of granulocytes in the red bone marrow.

c) In the normoblast stage, the cells have already lost their nuclei.

d) The reticulocytes do not possess MHC antigens.

e) The maturation of the erythroid progenitors takes place on the surface of macrophages in the red bone marrow.

Eryithroblastic-islands: central macrophage maintaining physical and humoral contact with the developing erythroid cells

Production of RBC (2)

a) is mainly the function of the marrow of the flat bones in healthy adults

b) is greatly stimulated at low altitudes

c) is mainly the function of the marrow of the long bones in healthy adults

d) is stimulated by CO2

e) is regulated by erythropoietin

The most important stimulus for RBC production is (S)

a) low concentration of RBC in the blood

b) exercise

c) hypercapnia

d) folic acid

e) hypoxia

f) vitamin B12

Endocrinology: the science of hormones. Basic points

What is the chemical structure of the hormone (peptide, amino acid, amine)?

Where is it produced? What factors control its production and release?

How is it transported in the blood?

What kind of receptors are expressed by target organs? Signal transduction mechanisms?

What are the effects of the hormone?

Gene expression controlled by hypoxia: HIF

Hypoxia inducible factor PHD: proline hydroxilase

domain enzymes: in normoxia steer HIFa to be degraded

FIH: factor inhibitor HIF (inactivates HIF by hydroxylation)

In hipoxia, these enzymes are rendered inactive, thus HIF can bind to the beta subunit and exert its effect on response elements.

The erythropoetin gene is under HIF control.

Physiology October 2008 vol. 23 no. 5 263-274

Renal EPO synthesis

is HIF-2a depend.!

HIF-2a

HIF-2a

HIF-1a

HIF-1a

EPOmRNA

EPOmRNA

EPOmRNA

EPOmRNA

The HIF-2a induction in renal cortical fibroblasts appears to be responsible for EPO induction.

Source: Paliege A. et al.: Hypoxia-inducible factor-2α-expressing interstitial fibroblasts are the only renal cells that express erythropoietin under hypoxia-inducible factor stabilization. Kidney International77, 312-318 ,2010 |

Reticulocytes (1)

a) can be found in high number in the blood of patients with pernicious anemia

b) are young RBCs present in small quantities into the blood (~1 %)

c) are abnormal RBCs lacking Hb

d) are hemopoietic stem cells in the bone marrow

What can be the „use” of reticulocyte count?

The ratio of 1-day old RBCs is determined (relative reticulocyte count)

Depends on the ACTUAL erythropoesis (TODAY how much the marrow produces)

In anemia diagnosis: too few is produced (low), too many die early (high)?

To check therapy: did the marrow respond??

Absolute reticulocyte count: more informative, can be calculated, but apps exist too

Vitamine B12 deficiency causes anemia because (1)

a) synthesis of globin is impaired

b) iron incorporation in hemoglobin is impaired

c) it is a co-factor for erythropoietin

d) nuclear division of erythroblasts is impaired

B12 vitamin biochemistry(in part)

In B12 deficiency the regeneration of THF is being impaired, there is relative folate deficiency and impaired DNA synthesis

The impaired synthesis of methionine likely contributes to the impaired myelin synthesis causing the neurological symptoms of the disease

Folic acid

dTMP

B12 absorption:topics: 18, 71, 74, 77,

IF: intrinsic factor

R: R-factor

Tcl: transcobalamine

Which of the following statements is NOT true? (1)

a) cobalamine is combined with an R-protein in the stomach

b) the R-protein - vitamin B12 complex is digested by the pancreas proteases

c) the cobalamnine released from the complex is combined with the intrinsic factor (IF)

d) the IF - B12 complex is also digested by the proteases

e) cobalamine enters the enterocytes via endocytosis

Which of the following statements is correct? (1)

a) obstruction of bile flow seriously impairs absorption of vitamin B12

b) the role of vitamin B12 is to stimulate hemoglobin synthesis

c) iron is a co-factor for vitamin B12 d) vitamin B12 deficiency results in reticulocytosis e) daily requirement of vitamin B12 is 1 mg f) the cause of pernicious anemia is usually not a low

vitamin B12 content of the diet g) folic acid deficiency impairs production of the

intrinsic factor

Haptoglobin is the plasma carrier of (1)

a) bilirubin

b) iron

c) copper

d) vitamin B12

e) hemoglobin

Haptoglobin-physiology

Alpha-2 globulin

Can bind myoglobin or hemoglobin

Enters macrophage with receptor-mediated endocytosis (CD163 scavenger-receptor)

Vitally important mechanism to protect the kidney

When haptoglobin gains significance…

From crushed muscles (rhabdomyolysis) myoglobin/hemoglobin is released that after saturating haptoglobin binding capacity get filtrated resulting in occlusion of renal tubuli leading to ACUTE RENAP FAILURE!

The casualty can be saved with dialysis, since the renal injury is often reversible.

Free bilirubin* is released from (2)

a) transferrin

b) urobilinogen

c) Kupffer cells

d) hepatocytes

e) macrophages in the red pulp of the spleen

f) erythrocytes

*Aka: indirect bilirubin, unconjugated bilirubin, UCB

Which of the following statements are correct (3) ?

a) urobilinogen is produced by liver cells b) conjugated (direct) bilirubin is secreted by

Kupffer cells in the liver c) free bilirubin (indirect bilirubin) is secreted by

liver cells d) normal plasma bilirubin concentration is less

than 20 mmol/l e) "jaundice" means a yellowish tint to the body

tissues, including yellowness of the skin and the sclera

f) conjugated (direct) bilirubin is produced by liver cells

Bilirubin metabolism at a glance

The bilirubin-diglucuronide (3)

a) is digested by the enzymes of the pancreatic juice

b) is a synonym for free bilirubin

c) can be found in the bile

d) can be detected by direct diazo-reaction

e) is a synonym for conjugated bilirubin

Bilirubin uptake, conjugation and excretion in the liver cell

UGT1a1

ABCC2

(ABC pump)

The definition of icterus (jaundice) >20 mM bilirubin

Icterus galbulaBaltimore Oriole

The mechanism of iron uptake in erythroblasts (2):

a) active transport

b) simple diffusion

c) facilitated diffusion

d) endocytosis

e) Na+-cotransport

Iron handling in red blood cells and macrophages

TF: transferrin, TFR: transferrin receptor, CP: ceruloplasmin, DMT1 divalent metal transporter

Select the answer that is most closely associated with ceruloplasmin (1)

a) carrier molecule for vitamin B12

b) carrier molecule for hemoglobin

c) carrier molecule for fatty acids, bilirubin

d) carrier molecule for iron

e) carrier molecule for copper

Also serves as a ferrooxidase involved in transferrin iron loading

Iron homeostasis: 1-2 mg daily uptake/loss, app 10x larger internal turnover

Fpn: ferroportin

Hepcidin: a novel hormone Produced by the liver (peptide, 25 AA)

Induced by both elevated plasma and store iron levels (homeostasis!), although stimulated by inflammatory cytokines (acute phase response).

Its receptor is the ferroportin iron tranporter itself – that it inhibits, thus inhibiting both iron absorption and release of stores

Key to the mcqs:

3 e, 4 b, 5 a, 6 b, 7 bde, 8 c, 10 d, 11 a, 13 d, 14 d, 18 bde, 19 cd, 21 de, 23 ae, 24 e, 28 b, 30 d, 33 d, 34 f, 35 e, 38 ce, 39 def, 41 cde, 44 ad, 46 e,