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Physiology Exam 3 > Respiration 3 > Flashcards

Respiration 3 Flashcards

1
Q

how much O2 is dissolved in the blood

A

less than 2 %

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2
Q

how do we get a sufficient amount of oxygen to support basal metabolism

A

98% of our oxygen comes from oxygen that is bound to hemoglobin (Hb)

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3
Q

what form must oxygen be in to be used by tissues of the body

A

dissolved oxygen

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4
Q

is the dissolved oxygen component alone sufficient to support basal metabolism

A

no

need Hb bound oxygen

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5
Q

what is Hb

A

a respiratory pigment

protein carrier for oxygen

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6
Q

what is the structure of Hb

A

tetrameric molecule: 4 subunits each with a heme group that includes 1 iron atom that reversible binds O2

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7
Q

maximum amount of O2 that can bind to one Hb molecule

A

4 O2 molecules

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8
Q

what are the possible oxygen states for each Hb

A

can carry 0-4 O2 molecules

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9
Q

what cell contains Hb predominantly

A

erythrocytes

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10
Q

when is oxygen carrying capacity of Hb full

A

when all 4 O2 molecules are bound

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11
Q

what influences total O2 available in the blood

A

amount of hemoglobin

partial pressure of O2

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12
Q

what is cooperative binding

A

this is how O2 binds to Hb

as each O2 molecule binds to Hb it increases Hb affinity for more O2 until reaches saturation

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13
Q

how does the binding of O2 increase the affinity of more O2 to Hb

A

the binding of O2 causes a conformational change

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14
Q

what type of curve represents the cooperative binding of Hb

A

sigmoid curve

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15
Q

what are the other substances that can affect the Hb’s affinity for O2

A

H+, CO2, CO, DPG

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16
Q

how does PO2 affect Hb saturation if it is increase

A

increases saturation of Hb

more O2 available to bind to Hb

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17
Q

loading phase

A

above 60 mmHg PO2

Hb will pick up O2 but not as readily give it up (plateau region)

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18
Q

unloading phase

A

less than 60 mmHg PO2

rapid decrease in Hb saturation as PO2 decreases (steep region)

no enough dissolved O2 so Hb will want to give off O2 so it can be used by tissues

19
Q

what is P50 on the sigmoid curve

A

the partial pressure of O2 at which half of the hemoglobin are saturated

20
Q

why is dissolved O2 never over 2 %

A

because of poor solubility of O2

21
Q

what happens to PO2 as if flows from the air to the mitochondria of the cells

A

PO2 will decrease

22
Q

what happens to O2 on Hb when PO2 is decreased

A

more O2 will be released as “dissolve oxygen” to be taken up by the tissues

23
Q

what measure ONLY dissolved O2

A

PO2

24
Q

what is the main purpose of Hb

A

increases the total oxygen at any PO2 but must be released in order to diffuse

also storage of O2

25
Q

pathway of O2 from alveoli to pulmonary blood

A

diffuse across respiratory surface into plasma–>diffuse across plasma membrane of erythrocyte to bind to Hb

26
Q

how is the PO2 gradient conserved in transport of O2 from alveoli to pulmonary blood

A

uptake of oxygen by Hb

27
Q

what happens when PO2 drops

in terms of Hb and bound oxygen

A

Hb will release O2 and O2 will diffuse out of the erythrocyte

28
Q

what is the pathway of O2 from the diffusing out of erythrocyte to the mitochondria of tissue cells

A

diffuses out of erythrocyte–>interstitial fluid–>tissue cells–>mitochondria

29
Q

what maintains the pressure gradient for O2 from the erythrocyte to the mitochondria

A

the oxygen is consumed in the mitochondria so O2 stays at a very low pressure in the mitochondria keeping the pressure gradient

30
Q

how much free oxygen is delivered to the tissues in tissue capillaries (from when the pressure is 100-40 mmHg)

A

about 20% of oxygen

31
Q

what factors decrease Hb affinity

A
  1. increase temperature
  2. increased CO2
  3. increased H+
  4. increased 2,3 diphosphoglycerate (DPG)
32
Q

explain role of temperature on Hb affinity

A

increased temperature decreases affinity of oxygen to Hb

ex: drowing in cold water is better because increases affinity of oxygen to Hb and have more stored; can be released when tissues need it

33
Q

explain role of CO2 on Hb affinity

A

CO2 binds to a non competitive site on Hb which decreases affinity for O2 (allosteric modulation)

34
Q

explain role of H+ on Hb affinity

A

H+ binds to histamine residues on Hb which decreases affinity to O2 (allosteric modulation)

35
Q

explain role of 2,3 DPG on Hb affinity

A

RBC produce DPG when PO2 drops

decreases affinity of O2 to Hb so more dissolved O2 is readily available for tissues

36
Q

what happens during exercise to increase free O2 for tissues

A

increase temperature
increase DPG
increase acidity

37
Q

What are the normal arterial values for Hb and oxygen in the blood

A

15 gm if Hb and 20 ml of oxygen in 100 ml of blood

38
Q

What happens to the amount of Hb in the blood in anemia

A

Fewer erythrocytes so less Hb per ml of blood

39
Q

In anemia what is not changed and what is reduced in terms of Hb saturation po2 and total oxygen content

A

Po2=same
Hb saturation= same
Total oxygen content= reduced

40
Q

Is the relationship between CO and O2 competitive or non competitive

A

Competitive; fight to bind to the same Fe site on hemoglobin

41
Q

What is the product called when CO binds to Hb

A

Carboxyhemoglobin

42
Q

If o2 and CO are floating around, which one will more likely bind to the Fe site on Hb

A

CO; Hb has 200 fold more affinity to CO than O2; can displace O2

43
Q

In CO poisoning what happens to pO2 or Hb concentration and total oxygen content

A

Po2 does not Change
Hb concentration does not change
Total oxygen content is reduced

44
Q

Three ways to treat CO poisoning

A
  1. Remove source of CO
  2. Ventilate with pure O2
  3. Increase atmospheric pressure so PO2 will increase in the lung (breathe in)

Physiology Exam 3 (7 decks)

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