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Cardioresp > 10 > Flashcards

10 Flashcards

1
Q

what are the three functions of the CV system

A
  1. supply o2 and nutrients to tissues
  2. take away metabolic products like CO2
  3. Defense against microorganisms
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2
Q

what kind of dangerous chemical reaction is oxygen involved with

A

oxidazing agent (electron thief)

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3
Q

what is oxidation in terms of electron gain or loss

A

electron LOSS

but oxidising agents gain an electron

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4
Q

does oxidation release or require energy

A

release energy in the form of heat

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5
Q

what is reduction in terms of electron gain or loss

A

electron gain

but reducing agents lose an electron

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6
Q

what dictates whether an oxidation reaction is reversible or irreversible

A

the amount of energy released as a result.

if large energy, irreversible

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7
Q

is the oxidation of NAD reversible or irreversible=

A

reversible

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8
Q

the reaction from NADplus to NADH is an example of…

A

reduction reaction

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9
Q

the reaction from NADH to NADplus is an example of…

A

oxidation reaction

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10
Q

how do Anaerobic bacteria live in oxygen-poor environments

A

Use other oxidising agents such as sulphate, nitrate (NO3−), sulphur (S), etc

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11
Q

what is one unique feature of haemoglobin

A

can combine rapidly and reversibly with oxygen without becoming oxidised

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12
Q

what is the shape of RBC

A 
biconcave disks
 7 µm in diameter
 2 µm thick. 
Volume of about 90 cu mm (1 cu mm = 1 femtolitre)
270 million hemoglobin molecules
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13
Q

pathology where RBC is smaller than usual

A

microcytic anemia

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14
Q

pathology where RBC is larger than usual

A

macrocytic anemia

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15
Q

what do RBC lack that most other cells have

A

nucleus and mitochondria bc maybe o2 would damage mitocondraia

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16
Q

where are RBC made

A

bone marrow

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17
Q

what are reticulocytes

A

immature RBC that are about to leave BM or have just left it

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18
Q

what percentage of circulating RBCs are reitculocytes

A

1-2%

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19
Q

how long after entering circulation to reticulocytes become RBC

A

a day

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20
Q

why are reticulocytes called that way

A

bc of reticualar mesh like network of rRNA that is visible under microscope.

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21
Q

why cant RBC live long

A

bc they lack mitochondria and nucleus so they cant divide

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22
Q

can reticulocytes carry O2

A

yes but not as well.

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23
Q

what would a high reticulocyte count indicate

A

lots of hemolysis going on or there a haemorrhage.

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24
Q

why do RBCs need to generate energy (ATP=

A

they require ATP to maintain their ion pumps

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25
Q

where do RBCs get their energy from

A

not mitochondria cause they don’t have one.

RBCs make ATP by glycolysis (glucose to pyruvate to lactic acid.

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26
Q

what’s better at generating energy, glycolysis made by RBCs or aerobic respiration made by all other cells

A

aerobic respiration

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27
Q

what’s the natural pH of RBCs and why

A

acidic because they get their energy by glycolysis which converts glucose to pyruvate to LACTIC ACID

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28
Q

how to RBCs uptake glucose

A

via Glut1 receptor: facilitated diffusion

NOT regulated by insulin

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29
Q

how to RBCs get NADPH and why do they need it

A

pentose phosphate pathway

NADPH helps counteract the oxidative stress

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30
Q

what three things are necessary for RBCs to survive

A

ATP (energy)
glucose
NADPH
antioxidants

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31
Q

what is the name of haemoglobin when its oxidised too much and therefore damaged

A

methaemoglobin

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32
Q

typical lifetime of a RBC

A

120 days

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33
Q

how are RBC degraded

A

ageing erythrocytes have high levels of methaemoglobin so this causes changes to their PM markers and so are recognised by phagocytes

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34
Q

can methaemoglobin carry oxygen

A

no

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35
Q

where does erythrocytes phagocytosis occur

A

bone marrow liver or spleen

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36
Q

The ability to transport oxygen without being oxidised depends on

A

the ability of the iron atom to be hexavalent (form six bonds with surrounding atoms).​

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37
Q

what’s a ferrous ion

A

Fe plus plus

38
Q

how many unpaired electrons in ferrous ion

A

6 electrons (4 on a plane and one above and one below)

39
Q

what’s a heam group

A

porphyrin ring AND ferrous iron centre

40
Q

what’s a porphyrin ring

A

The four iron electrons in the plane are held by four covalent bonds to nitrogen atoms

41
Q

what do the four planar iron electrons bind to

A

nitrogen in porphyrin ring

42
Q

what does the bottom electron pari up with

A

histidine

43
Q

where does oxygen bind

A

weakly binds to top electron

44
Q

why is the interaction between oxygen and the top electron only weak

A

because of steric hinderance caused by 3D structure (cannot get close enough to fully remove electron)

45
Q

what is the structure of haemoglobin

A

four polypeptide units each with a HEAM group attached

46
Q

what bonds link the four polypeptide chains in Hb

A

salt bridges
hydrogen bonds
hydrophobic interaction

47
Q

what does oxygen bonding depend on

A
  1. interlocking of the heat subunits

2. partial pressur iof oxygen in solution

48
Q

what happens to oxygen binding when the oxygen partial pressure is high

A

oxygen binds and you get oxyhemoglobin

in tehe lungs

49
Q

what happens to oxygen binding when the oxygen partial pressure is low

A

oxygen DISSOCIATES and you get deoxyhemoglobin

in tissue

50
Q

what’s haemoglobin with ferric ion called

A

methaemoglobin

51
Q

why cant methaemoglobin carry oxygen

A

bc out of its 6 electrons, four are int he plane the one on the bottom is attached to histidine and the last one which would binds O2 binds the Ferric ion like the four int he middle

52
Q

what enzyme may repair the damaged of methaemoglobin

A

methaemoglobin reductase but we don’t know how many times it can fix it

53
Q

what substance does methaemoglobin reductase depend on

A

NADH

54
Q

as the cell ages what happens to the level of methaemoglobin

A

increases

55
Q

what percentage of our haemoglobin is methaemoglobin

A

1-2%

56
Q

what would cause a high percentage of methaemoglobin in the blood indicate

A

genetic or exposure to some chemicals (Methaemoglobinemia)

57
Q

what condition do alaskan inuits have a lot and how do they compensate

A

congenital deficiency of methaemoglobin reductase
They compensate for the defect by making more red blood cells than normal individuals (polycythemia). Thus the total oxygen carrying capacity of the blood is increased. ​

58
Q

what subunits make up normal adult Hb

A

2 alpha 2 beta (alpha2beta2)

59
Q

how do different forms of Hb differ

A

Diff amino acid sequence and so diff steric hinderance

60
Q

what subunits make up normal fetus Hb

A

2 alpha 2 gamma (alpha2gamma2)

61
Q

how does maternal oxygen go to fetus across placenta

A

fetal hb has higher affinity for O2 than maternal Hb. so leaves moms oxyhemoglobin to come to babysit deoxyhemoglobin

62
Q

what molecule enhances the ability of RBCs to release oxygen in hypoxic tissues.

A

2,3 DPG (2-3 diphosphoglycerate)
Small separate molecule bound loosely to Hb
When beta subunits start to deoxygenate, it binds to them more tightly, moves into the centre of the haemoglobin and increases the rate of oxygen release.

63
Q

What is percent saturation

A

The proportion of haemoglobin that is bound to oxygen

written as % Hb saturation or often for arterial blood as SaO2

64
Q

how can percent saturation be measured

A

pulse oximeter

65
Q

normal oxygen saturation values

A

between 96% and 99%, and should be above 94%.

66
Q

how is hypoxemia defined

A

​An SaO2 (arterial oxygen saturation) value below 90% is

67
Q

is oxygen saturation the same as tissue oygenation=

A

no bc that depends on ability to unload oxygen

68
Q

oxygen unloading is described by what curve

A

Oxygen-haemoglobin dissociation curve.​

69
Q

whats the shape of O2 dissociation curve

A

‘s’shaped, flat at high pO2 and steep at medium and low pO2

70
Q

whats the temperature like of heavily metabolising tissue vs slowly metabolising tissue

A

Heavily metabolising tissue heats up;

slowly metabolising tissue is colder than normal.

71
Q

whats the effect of heat on Hb curve

A

heat moves it to the right (unloading MORE O2 at any given time

72
Q

whats the effect of pH on Hb curve

A

heavily metabolising tissue make a lot of CO2 so it becomes more acidic and moves it to the right (unloading MORE O2 at any given time

73
Q

whats the Bohr shift

A

shift of oxygen dissociation curve caused by pH changes

74
Q

which of myoglobin or hemoglobin has a higher affinity for oxygen

A

myoglobin

75
Q

whats myoglobin

A

form of hb found in muscle

76
Q

Whats rhabdomyolysis.

A

When myoglobin is released from damaged muscle tissue. The released myoglobin is filtered by the kidneys but is toxic to the renal tubular epithelium and so may cause acute renal failure.

77
Q

what makes muscles look red

A

myoglobin

78
Q

whats the myoglobin dissociation curve shape

A

exponential

79
Q

how do muscles get o2

A

As oxygenated blood goes through muscle capillaries you get transfer of o2 from hemoglobin to myoglobin.

80
Q

what does the amount of blood carried depend on

A

hematocrits (percentage of blood which is red blood cells)

81
Q

what a normal hematocrits percentage

A

45%

82
Q

how is hematocrits controlled

A

via erythropoietin
which is continually released from interstitial cells in the kidney; when the kidney is hypoxic, erythropoetin secretion is increased. Thus this is a negative feedback loop. There is some evidence that erythropoetin secretion is inhibited by a rise in pulmonary arterial pressure

83
Q

when can synthetic EPO be useful

A

in treating anaemia resulting from chronic kidney disease, from the treatment of cancer (chemotherapy & radiation), and from other critical illnesses (heart failure).

84
Q

what kind of feedback is EPO

A

negative

85
Q

what enzyme converts carbon dioxide to bicarbonate in red blood cells

A

carbonic anhydrase

86
Q

whats the chloride shift

A

when cl enters RBCs to maintain cellular neutrality because bicarbonate just left the cell.

87
Q

why does CO2 leave as bicarbonate not as CO2

A

bc co2 is not dissolvable in water and bicarbonate is

88
Q

how does released bicarbonate make it to the lugs

A

via veins

89
Q

does bicarbonate get released as is from the alveoli

A

no it gets converted to CO2 by CA in the lungs

90
Q

what percentage of CO2 from tissues is carried to lungs as carbaminohaemoglobin​

A

23%

91
Q

what are the two forms that CO2 can be carried to the lungs as

A

bicarbonate

carbaminohaemoglobin

92
Q

whats the most important mechanism by cwhich CO2 leaves the lungs

A

via bicarbonate

Cardioresp (23 decks)

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