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Physiology > Circulating Body Fluids ( 5% ) > Flashcards

Circulating Body Fluids ( 5% ) Flashcards

1
Q

Immunoglobulins

  • Are produced in greatest quantities by activated memory B cells
  • There are 5 types of heavy chain
  • Fc portion mediates reactions initiate by antibodies
  • J chains are found in IgA and IgE
  • Variable segments are only found on the heavy chain
A

Fc portion mediates reactions initiate by antibodies

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2
Q

Haemoglobin F

  • α chains are replaced with delta chains
  • has a higher oxygen content at the same pO2 as adults
  • has a higher affinity for 2,3, DPG
  • is replaced by adult Hb during adolescence
  • is able to displace oxygen from myoglobin
A
  • beta chains are replaced with delta chains
  • has a higher oxygen content at the same pO2 as adults
  • has a lower affinity for 2,3, DPG
    • 2, 3 DPG binds deoxy Hb, stabilising it and making it more likely to release O2 (lower affinity for O2)
  • is replaced by adult Hb shortly after birth
  • ??is able to displace oxygen from myoglobin
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3
Q

Given an Hb of 140g/L how many mLs of O2 is carried in 1L of 100%

  • 5mL
  • 100mL
  • 200mL
  • 500mL
  • 1L
A

200mL

Each gram of Hb can carry 1.39ml of O2 at 100% saturation

140g x 1.39ml = 194.6

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4
Q

In a healthy person in standard conditions with a pO2 of 60mmHg which is the correct Hb saturation

  • 75%
  • 90%
  • 95%
  • 57%
  • 85%
A

90%

pO2 of 60mmHg is where the curve starts to fall off

pO2 100 = 97.5%

90 = 96.5%

80 = 94.5%

70 = 92.7%

60 = 89%

50 = 83.5%

40 = 75 %

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5
Q

Which is true of Hb

  • Abnormalities can lead to haemolysis in conditions such as spherocytosis and sickle cell anaemia because of increased RBC fragility
  • HbF has a lower affinity for 2,3 DPG and thus oxygen compared to HbA
  • Is the major oxygen and CO2 carrier.
  • Colours the blood: oxygenated (red) methaemoglobin (blue)
  • In normal venous blood carries 6 atoms of oxygen per molecule and so is saturated 75% with oxygen
A
  • Spherocytosis is caused by abnormalities in the proteins making up the erythrocyte skeleton, leading to fragility and haemolysis. Sickle cell anameia is caused by defective beta chains that reduce the oxygen carrying capacity of Hb and cause it to polymerise at low O2 tensions, become sickle-shaped, and haemolyse.
    • ​ie spherocytosis is not a problem with haemoglobin, which is why this answer is wrong
  • HbF has a lower affinity for 2,3 DPG and thus higher affinity for oxygen compared to HbA
  • Is the major oxygen carrier and bicarbonate is the major CO2 carrier.
  • Colours the blood: oxygenated (red) methaemoglobin (blue)
    • ​Methaemoglobin has Fe3+ rather than Fe2+, and this cannot carry O2 and turns the skin dusky
    • ??Methaemoglobinaemia turns the blood chocolate brown in colour
  • In normal venous blood Hb is 75% saturated, but carries ?3 molecules of O2 per molecule
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6
Q

Which is true of CD4+ cells

  • Are derived from the bone marrow
  • Do not have Fc receptors
  • Have class MHC II receptors
  • Can be inactivated by cyclosporin
  • Are unaffected by cytokines
A

Do not have Fc receptors

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7
Q

Which is true of the blood types

  • Are determined by RBC surface agglutinogens
  • When incompatible between recipient and donor at transfusion usually results in recipient heamoagglutination
  • Can help determine parenthood, eg the child of a parent who are both type B must be type B
  • Are determined by plasma agglutinins
  • Rh incompatibility between mother and foetus may necessitate intrauterine transfusion of the foetus with maternal compatible blood
A
  • Are determined by RBC surface agglutinogens
  • When incompatible between recipient and donor at transfusion usually results in donor heamoagglutination
    • Concentrations of agglutinins are very low in the donated plasma that accompanies the RBC so the recipients RBC are not agglutinated, however the reverse can occur and the donated blood may agglutinate
  • Can help determine parenthood, eg the child of a parent who are both type B must be type B
    • Mendelian inheritence, and A + B are both dominent. Both parents could be BO, and thus have an OO child.
  • Are determined by plasma agglutinins - no, see above for correct answer
  • Rh incompatibility between mother and foetus may necessitate intrauterine transfusion of the foetus with maternal compatible blood
    • Prevention seems to be the only treatment, with Anti-D
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8
Q

Which of the following has the greatest effect on the ability of the blood to transport oxygen

  • The capacity of the blood to dissolve oxygen
  • The amount of Hb in the blood
  • The pH of plasma
  • The CO2 content of RBC
  • The temperature of the blood
A

The amount of Hb in the blood

pH, 2,3 DPG, temperature all affect Hb affinity for O2, but not to the same extent as changing the amount of O2.

Higher temps and lower pH shift the curve to the right - ie reduced Hb affinity for O2

Dissolved blood makes up a very small portion of O2 delivery.

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9
Q

The Haldane effect describes

  • The shift to the right of the HbO2 dissociation curve caused by increased CO2 in the blood
  • The enhanced loading of CO2 in the presence of deoxygenated Hb
  • The shift of chloride ions into RBC to balance HCO3 shift from those cells
  • The action of carbonic anhydrase on carbonic acid
  • None of the above
A

The enhanced loading of CO2 in the presence of deoxygenated Hb

Deoxygenated Hb has more capacity for CO2 (and vice versa). This means venous blood can carry more CO2, there is more CO2 release in the lungs, and more CO2 uptake in the tissues (once the Hb has delivered O2)

Bohr effect describes the decreased Hb affinity for O2 with low pH

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10
Q

With regard to CO2 carriage in the blood

  • Dissolved CO2 has an insignificant role in the carriage of CO2 in the blood
  • HCO3 production is fast in plasma
  • Ionic dissociation of carbonic acid in the RBC is fast without an enzyme
  • The CO2 concentration in blood is independent of the saturation of Hb with oxygen
  • The majority of CO2 is carried in the blood in the forms of dissolved CO2 and carbamino compounds
A

Ionic dissociation of carbonic acid in the RBC is fast without an enzyme

  • This would be H2CO3 -> HCO3 + H+*
  • H2O + CO2 <-> H2CO3 is only fast with an enzyme*
  • Dissolved CO2 has a significant role in the carriage of CO2 in the blood (20x more soluble than O2)
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11
Q

With regard to the normal HbO2 dissociation curve, which is true

  • PaO2 = 60mmHg, SaO2 = 80%
  • PaO2 = 40mmHg, SaO2 = 75%
  • PaO2 = 30mmHg, SaO2 = 40%
  • Acidosis shifts curve to the left
  • Decreased CO2 shifts curve to the right
A

40mmHg = 75%

PaO2 60mmHg = 90%

30 = 57%

Acidosis shifts the curve to the right (less affinity for O2)

Reduced CO2 shifts the curve to the left (more affinity for O2)

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12
Q

regarding the Rh antigen system

  • Rh + individuals have C,D, E antigens
  • 50% caucasions are D+
  • do not develop anti D antibodies without exposure of D– individuals to D+ RBC
A

do not develop anti D antibodies without exposure of D– individuals to D+ RBC

85% Whites are D+

Rh+ people have the D antigen (this is all that is tested for)

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13
Q

Regarding granulocytes

  • All have cytoplasmic granules
  • Basophils are identical to mast cells
  • Eosinophils phagocytose viruses
  • Neutrophils have a half life of 4 days
A
  • All have cytoplasmic granules
    • ​hence the name
  • platelets have a half life of 4 days
    • Neutrophils have a half-life of 8 hours
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14
Q

Regarding HbF

  • Fe3+ binds O2
  • HbF has no β chain
  • Globin is synthesised from porphyrin
A
  • Fe3+ is the cause of methmoglobinaemia and cannot carry O2
  • HbF has no β chain - replaced with gamma chains
  • Heme is synthesised from porphyrin, globin is a polypeptide
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15
Q

increased 2,3 DPG occurs in all of the following except

  • chronic hypoxia
  • acidosis
  • androgens
  • thyroid hormones
  • none of the above
A

Acidosis causes a fall in 2,3 DPG

Thyroid hormones, growth hormones, and androgens all increase the concentration of 2,3 DPG

Altitude (and thus hypoxia) causes an increase in 2,3 DPG

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16
Q

All of the following are characteristics of haemoglobin EXCEPT:

  • It contains four haem moieties
  • It has a lower affinity for oxygen in its relaxed state.
  • It contains 38 histidine residues
  • When fully saturated it carries 1.39mL of O2 per gram haemoglobin
  • Each molecule of adult haemoglobin contains 2 α and 2 β polypeptide chains
A

It has a higher affinity for oxygen in its relaxed state.

‘Relaxed state’ refers to oxy-Hb, whereas Hb with a vacant O2 site is called the “tense state”. Relaxed state has a higher affinity for oxygen, tense state has a higher affinity for CO2, H+, and 2,3 DPG

17
Q

platelets

  • contain α and β granules.
  • are biconcave discs.
  • contain a nucleus.
  • are found in the plasma at levels of 200-500 per microlitre
  • are the main source of thrombin
A
  • contain α and delta granules
  • RBCs are biconcave discs
  • Do not contain a nucleus
  • are found in the plasma at levels of 200-500 per microlitre
  • are the main source of thrombin
    • Prothrombin is the main source of thrombin. This is produced in the liver in a Vit. K dependent reaction (and I assume is found in the plasma rather than specific cells)
18
Q

A man with type B blood

  • Has the commonest blood type.
  • Cannot have a child with type O blood.
  • Cannot have a child with AB blood
  • Cannot have a child with type A blood
  • None of the above
A
  • Has the commonest blood type - no, Group O is
  • Cannot have a child with type O blood. Can if he is BO and partner has an O gene
  • Cannot have a child with AB blood - can if his wife is A
  • Cannot have a child with type A blood - can if he is BO and partner has an A gene
  • None of the above
19
Q

Platelets

  • Have a normal concentration range of 80 – 100 x 10^3/mm3
  • Are important in haemostasis only
  • Remain viable in stored blood for 24 hours only
  • Normally are removed from the circulation almost entirely by the spleen
  • Have an average lifespan of 20 days
A
  • Have a normal concentration range of 300 x 10^3/mm3 (=uL)
  • Are important in haemostasis only - also play a role in inflammation due to histamine and serotonin release
  • Remain viable in stored blood for 24 hours only
  • Normally are removed from the circulation almost entirely by the spleen and liver
  • Have an average lifespan of 4 days
20
Q

With regard to blood types

  • Group A is most common
  • Anti A and anti B agglutinins increase into the 6th decade
  • There are 6 possible ABO genotypes.
  • Group AB persons have both anti A and anti B agglutinins.
  • Group O + is the universal recipient.
A
  • AB is the most common type
  • Anti A+B agglutinins are steady-ish throughout life I think
  • 6 ABO phenotypes: AA, AO, AB, BO, BB, OO
    • ​But at least 500 billion to >1 trillion overall phenotypes
  • AB people have no agglutinins
  • AB is universal recipient, O- is universal donor
21
Q

Of the heritable hypercoagulable states

  • ATIII deficiency results in reduced destruction of Va and VIIIa
  • Factor V gene mutations are the most common
  • Antiphospholipid antibody syndrome results in reduced platelet activation
  • The Leiden mutation renders thrombin resistant to deactivation.
  • All of the above
A

Antiphospholipid antibody syndrome results in reduced platelet activation

Leiden mutation leads to factor V that is resistant to degradation

ATIII inhibits II, IX, X, XI, XII

22
Q

The blood group of the universal recipient is

  • AB+
  • O+
  • A-
  • B+
  • O-
A

AB+

23
Q

An infectious complication of transfusion

  • Is most commonly hepatitis C
  • Is most commonly hepatitis B
  • Is rarely transmission of HIV since screening was instituted
  • Never includes gonorrhoea or malaria
  • Can be clinically apparent mononucleosis in about 7 % of cases
A

Is most commonly hepatitis C

24
Q
  1. Red blood cell destruction occurs mainly in the
  • a. Liver
  • b. Spleen
  • c. Lymph nodes
A

b. Spleen

25
Q
  1. Regarding the rhesus blood group system
  • a. Rh negative people are D and E negative
  • b. Has very few spontaneous agglutinins within this system
  • c. 50% Caucasians are Rh positive
  • d. cannot get reactions if Rh negative people are given antigen
A

a) D negative, as this is the antigen tested for

b) Has very few spontaneous agglutinins within this system

c) 85% whites are Rh+
d) Anti-D reduces rates of reaction but unlikely to completley eliminate it (as with everything in medicine, can never be absolute)

Physiology (9 decks)

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