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medical science xy1110 > haematology 2 > Flashcards

haematology 2 Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

what are globular proteins

A
  • spherical compact proteins
  • most water soluble forming colloids (suspension)
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2
Q

what are the different between fibrous and globular proteins

A

fibrous - long and narrow, structure support, most insoluble, repetitive amino acid sequence, less sensitive to change in heat and pH

globular - round/ spherical, catalysts and transport, most soluble, irregular amino acid sequence, more sensitive to changes in heat and pH

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3
Q

what is the structure of haemoglobin

A
  • tetrametric proteins each with a haem group
  • subunits interact through hydrogen and ionic bonds
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4
Q

what is the function of haemoglobin

A
  • transports oxygen in red blood cells by nitrogenous, iron containing pigments - haem groups
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5
Q

what is the 3 groups of haemoglobin

A
  • HbA
    -HbA2
  • HbF
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6
Q

where is HbA found and what is its formation

A
  • major in adult
  • > 97%
  • 2 x alpha chains
  • 2 x beta chains
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7
Q

where is HbA2 found and what is its formation

A
  • minor in adults
  • 1-3%
  • 2x alpha chains
  • 2 x delta chains
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8
Q

where is HbF found and what is its formation

A
  • fetal
  • 2 x alpha chains
  • 2 x gamma chains
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9
Q

where is myoglobin only found

A
  • muscle tissue
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10
Q

what is the function of myoglobin

A
  • short term storage of oxygen for muscular contractions
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11
Q

what is the structure of myoglobin

A
  • monomeric protein with high affinity for oxygen
  • 153 amino acids with highly bound haem groups
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12
Q

what is the content, capacity and saturation of oxygen

A

content - quality of oxygen sample
capacity - maximum quantity of oxygen that can combine with haemoglobin in given sample
saturation - ratio of oxygen content: capacity in a given sample

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13
Q

what is the equation for working out percentage saturation

A

[O2Hb]/ [O2HB] [HHb]

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14
Q

what is oxyhaemoglobins struture

A
  • combining 4 O2 with haem groups
  • produce blood red colour
  • reversible binding of O2
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15
Q

what happens to oxyhaemoglobin at low oxygen concentration

A

dissociates to deoxyhaemoglobin and releases oxygen
- darker deep purple

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16
Q

what is partial pressure measured by

A
  • kPa or mmHg
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17
Q

what happens at high and low partial pressure

A

high - in alveolar capillaries of the lungs, O2 and Hb combine to form O2Hb

low - O2 dissociates from Hb and diffuses down concentration gradient into cells via interstitial space

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18
Q

what is the conformational changes of haemoglobin

A
  • O2 binding breaks ionic bonds and forms new hydrogen bonds relaxing the quaternary protein structure
  • increases O2 affinity of remaining hem groups
  • positive co-operativity
19
Q

why is myoglobin not positive co-operativie

A
  • only 1 globular chain
20
Q

describe the Hb standard curve

A
  • sigmoidal
  • tissue with high partial pressure, O2 readily associates with Hb due to positive co-operativity
  • lower partial pressure than alveolar blood, rapid dissociation of O2 from Hb
21
Q

why is positive co-operativity efficient

A
  • allows rapid delivery of 02 to tissue
  • without an 81-fold increase in partial pressure would raise O2 saturation from 10 to 90%
22
Q

what is the 02 binding affinity of Hb affected by

A
  • temperature
  • pH
  • partial pressure of carbon dioxide
  • metabolites
23
Q

what is the definition of le chateliers Principe

A
  • a system in dynamic equilibrium responds to stress by restoring the equilibrium
24
Q

what is the chloride shift

A

HCO3- diffuses out of RBC; Cl- diffuses in to balance charge

25
Q

what is formed when CO2 reacts with H2O in RBC

A

carbonic acid

26
Q

when does the bohr shift occur in the blood

A
  • when CO2 in the blood helps release O2 from O2Hb
27
Q

how does pH buffering in the blood help

A

allows large quantities of HCO3- to be transported in the blood without major changes in pH.

28
Q

what is carbaminohaemoglobin

A

when a small amount of CO2 is transported by Hb

29
Q

what does the Bohr shift do to the saturation curve of O2

A

right shift

30
Q

what does an increase in partial pressure of venous capillaries cause

A
  • decreases the affinity of Hb for O2
  • right shift in ligand saturation curve
31
Q

where does carbon monied bind

A
  • ferrous iron group in Hb and myoglobin with a 200x affinity compared to oxygen
  • competitive antagonism
32
Q

what are the symptoms of carbon monoxide poisoning

A
  • headache, dizziness, nausea, confusing, fainting
33
Q

when is glycerine Hb formed

A
  • when glucose binds to HbA1
  • irreversible glycosilation of beta chain n terminal of proline
34
Q

what are the levels of HbA1C

A

<42 - non diabetic
42-47 - prediabeties
>48 type 2 diabetes

35
Q

what causes cyanide poising

A
  • smoke inhalation from burning house materials
  • fruit stones
  • inhalation of hydrocyanic acid
36
Q

what are the symptoms of cyanide poising and what causes them

A
  • inhibitor of cytochrome C oxidase, impairing oxidative phosphorylation
  • coma, seizure, cardiac arrest, weakness, paralysis, nerve lesions
37
Q

what is the treatment for cyanide poising and how does it work

A
  • amyl nitride
  • promotes formation of methemoglobin which CN has a high affinity for
  • forms cyanomethemoglobin which slowly releases CN from RBC which can be metabolised by hepatic enzymes
38
Q

what is methemoglobin

A
  • has a ferric haem group - Fe3+
39
Q

when is methemoglobin formed

A
  • exposure to environmental agents that oxidise Hb
  • germline mutations causing oxidation of Hb
  • reduces O2 carrying capacity because Fe3+ cannot reversibly bind to oxygen
40
Q

when is 2,3BPG made

A
  • by red blood cells during glycolysis
41
Q

what does 2,3-BPG do

A
  • facilitates efficient transport of oxygen without it Hb would only release 8% to tissue
42
Q

where is 2,3-BPG found in Hb

A
  • 1 molecule binds to centre pocket of Hb only when in T form
43
Q

what are the differences between fetal Hb and adult Hb

A
  • 72% similarity in amino acid sequence
  • reduced affinity for 2,3-BPG in fetal so affinity for O2 is higher
  • difference between affinity between fetal and maternal allows efficient transfer from maternal to verbal RBC via the placenta
44
Q

what happens to the Hb curve when an allosteric effector is added

A
  • shifts right due to a decrease O2 affinity of Hb

medical science xy1110 (40 decks)

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