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Kine 3012 - Physiology II > Unit 1 Lecture 7: Gas Transport > Flashcards

Unit 1 Lecture 7: Gas Transport Flashcards

1
Q

What percent of oxygen is dissolved in blood? What percent is bound to Hb

A
  • 1.5% dissolved in blood
  • 98.5% bound to Hb
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2
Q

What is Haemeglobin bound to oxygen called?

A

Oxyhaemoglobin; reversible process

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3
Q

Where does the dissociation of oxyhaemeglobin into haemoglobin and free oxygen occur?

A

At the level of the tissues

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4
Q

If a total of 15mL of O2 is carried & dissolved in blood/min and we need 250mL of O2/min for basal functions, where does the rest of O2 go?

A

The rest binds to Haemoglobin to get transported

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5
Q

Explain the structure of Hb and how oxygen binding works? Does the Hb binding oxygen increase or decrease partial pressure?

A

Hb is made of 4 heme groups & 4 globin subunits & 1 oxygen per heme group so 4 oxygens total per haemoglobin

  • Hb-O2 has no pressure because it isn’t dissolving rather it being bound to the Hb

Note: Oxygen binds to the iron in Hb

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6
Q

For 100mL of blood how many grams of Hb are there? How many mL of O2 per gram bind to Hb (carrying capacity of Hb for O2)?

A
  • 15g of Hb for 100mL of blood
  • 1.34mL of O2/g

Heart pumps 5000mL blood/min

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7
Q

If the body needs 250ml blood/min why is there an excess amount?

A

In case the tissues require more but it also explains why venous oxygen is never 0 because of that excess amount

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8
Q

Explain how Hb acts as a method of transport?

A
  1. Since there is no Hb, the level of oxygen in both the pulmonary capillary & alveoli are equal and not much diffusion of oxygen into the pulmonary capillary occurs
  2. When Hb is introduced, the Hb acts as a way to decrease the amount of Arterial O2 in the pulmonary capillaries to create a pressure gradient for oxygen to keep moving into the pulmonary capillaries
  3. When the Hb molecules are filled they go to their destination and drop off the oxygen
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9
Q

What two factors determine O2 carrying capacity?

A
  1. Total amount of Hb
  2. Alveolar and Arterial O2 partial pressure
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10
Q

What is meant by saturation?

A

How much oxygen is bound to Hb

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11
Q

What is the key takeaway when it comes to partial pressures of O2 and percent saturation?

A
  • High percent saturation is where partial pressure of oxygen is high
  • Low percent saturation is where partial pressure of oxygen is low
Relationship between percent saturation and partial pressure of O2
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12
Q

What happens when PO2 that dissolved in the blood starts to diffuse into the tissues?

A

Signals are sent to the Hb to start dissociating with oxygen

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13
Q

What factors help promote the unloading of oyxgen from Hb

A
  1. Increase in PCo2
  2. Increased acidity and temperature
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14
Q

What is the Bohr Effect?

A

An increase in PCo2 will cause the blood pH to drop which in turn promotes the unloading of oxygen from Hb to balance out with the sudden PCo2 increase

Dissociation curve shifts to the right

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15
Q

The production of 2,3-Bisphosphoglyceric acid (BPG) does what to the dissociation curve?

A

Shifts the curve to the right

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16
Q

What is the main factor that determines percentage of Hb saturation?

A

Partial Pressure of Oxygen (PO2)

17
Q

What is the significance of the plateau and steep portion of the O2-Hb curve?

A

Plateau = PO2 is high
Steep = Exists at systemic capillaries, where Hb unloads oxygen to the tissue

18
Q

If you were an elite athlete that is using artificial oxygen in between a game, what does this do to your arterial O2 and saturation of O2?

A
  • Since we’re at sea level the partial pressure of oxygen should be normal and the saturation of O2 will not change given that it is already at 99%.
  • Arterial O2 increases since the athlete is increasing the amount of oxygen they intake in that time but more so the partial pressure of oxygen increases because more oxygen is coming in

Saturation does not change mainly because if the Hb takes on a certain number of units increasing the amount of oxygen does not change that number

19
Q

What does this show in terms of oxygen saturation?

A

Amount of oxygen being saturated is the same for a normal and anaemic person, but the amount of oxygen in the blood is far less for anaemic people as there is not enough Hb to transport the oxygen

KEY TAKEAWAY: Reduction of oxygen means reduction of Hb transporting oxygen

20
Q

What are the three things that change the shape of the oxygen dissociation curve?

A
  • Increase in PCo2, Increased acidity, Increased temperature will promote the unloading of oxygen from Hb, at the level of the tissue when the level of PO2 in the blood is low.
  • This is a good thing because there is an increase in oxygen participating in internal respiration

All three lead to Bohr Effect - increase in Co2 which shifts curve to the right and offloads Po2 into tissue to counteract the Pco2 increase or metabolic production increase

21
Q

What are the ways Co2 can be transported?

A
  1. 10% dissolved in Plasma
  2. 30% bound to Hb
  3. 60% converted to Bicarbonate

Co2 has a higher solubility than O2 allowing it to be dissolved in Plasma and it can be converted to bicarbonate by reacting with H2O

22
Q

When carbonic acid is broken into HCO3- (bicarbonate) and H+ what happens to the H+

A
  • Since having too much hydrogen makes the blood acidic by lowering pH it binds to Hb to become HbH and this is done after O2 has been unloaded from Hb at the level of the tissue
  • When O2 starts to load onto the Hb that is when H+ gets kicked off and goes to HCO3- to form carbonic acid
23
Q

Explain how CO2 transport works from tissue to systemic (venous) circulation?

A
  • From the tissue 10% jumps off and dissolves in mainly plasma but some in the blood
  • 1/3 binds to the free seats on Hb which makes HbCO2
  • Mainly binds with water to form carbonic acid (H2CO3-) and then it dissociates to form H+ ions and bicarbonate ions
24
Q

What is chloride shift?

A

Chlorine diffuses into the RBC because it replaces the bicarbonate due to bicarbonate being to basic that it would denature the cell

KEY TAKEAWAY: Plasma membrane of erythrocyte passively diffuses bicarbonate ions out and chloride ions in

25
Q

Explain CO2 transport from the systemic to the pulmonary circulation?

A
  1. Chloride and bicarbonate switch places and hydrogen dissociates with Hb
  2. Bicarbonate and H bind to form carbonic acid
  3. Carbonic acid dissociates to form H2O and Co2
  • Also CO2 diffuses out of the plasma and into the alveoli along with it being released from Hb

At the same time that Co2 and H+ is being released, oxygen is binding to Hb
Note: Dissolving of Co2 happens first to let the body know Co2 is low and promote Hb to unload Co2 then.

Kine 3012 - Physiology II (30 decks)

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