Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MD3001 Respiratory > Gas Transport > Flashcards

Gas Transport Flashcards

1
Q

What are the ways that oxygen can be transported in the blood?

A
  • physically dissolved in the plasma (2%)

- combined with haemoglobin (98%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the structure of haemoglobin/foetal haemoglobin

A
  • normal: 2a and 2B chains

- foetal: 2a and 2-gamma chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What change in haemoglobin constitutes to sickle cell anaemia (HbS)?

A

glutamate at position 6 in the B-globin is replaced with a valine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe binding of oxygen to haemoglobin

A

O2 can only bind to haemoglobin in ferrous state (Fe2+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the change in haemoglobin structure with oxygenation

A
  • deoxygenated Hb exists in a tensed state with strong ionic bonds formed between the 4 polypeptide chains
  • immobile and apart
  • oxygenated Hb exists in a relaxed staate
  • as O2 binds, the bonds break and Fe moves to the plane of prophyrin rings forming the relaxed state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the consequence of 2,3 DPG binding to B-globin?

A

Fe of Hb lies deeper in the pocket and cannot bind O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is O2 capacity?

A
  • amount of O2/L of blood attached to Hb at full saturation

- depends on Hb concentration in blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain the physiological significance of the haemoglobin O2 dissociation curve

A
  • binding of one O2 molecule makes it easier for the subsequent ones to attach
  • haem-haem interaction cooperatively which is what causes the shape of the O2-Hb dissociation curve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can you calculate how much oxygen is in the blood?

A

max O2 bound Hb = O2 capacity * [Hb]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does myoglobin and foetal haemoglobin affect the O2 dissociation curve?

A
  • MyHb and HbF shifts the curve to the left
  • HbF has a higher O2 affinity than HbA due to special properties of gamma chains
  • MyHb has the highest affinity for O2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does left and right shift mean?

A
  • left shift: high affinity

- right shift: low affinity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Factors that shift O2 curve to the left

A
  • increase in pH
  • decrease in PCO2
  • decrease in temperature
  • decrease in 2,3 DPG
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Affinity for O2 in systemic capillaries

A
  • higher CO2
  • higher temperature
  • lower in pH
  • causes rightward shift
  • Hb in low affinity tensed state
  • more O2 released
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Affinity for O2 in pulmonary capillaries

A
  • lower temperature
  • lower PCO2
  • higher pH
  • Hb in higher affinity relaxed state
  • more O2 taken up by Hb
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 components of acidosis?

A
  • decrease in pH

- increase in PCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is Hb a good buffer?

A

H+ increases conformational change in Hb structure and O2 affinity reduces

17
Q

What is the effect of hypercapnia on O2-Hb dissociation curve?

A
  • small changes in affinity to the the right

- CO2 binds with unprotonated amino groups on Hb - carbamino haemoglobin

18
Q

How does 2,3 DPG increase in the blood?

A
  • decreasing PO2 of RBC stimulates glycolysis
  • increased levels of 2,3 DPG
  • interacts with B-chains destabilising interaction of O2 with Hb
19
Q

Describe the effect of CO on Hb affinity for O2

A
  • CO (as well as NO and H2S) can bind to Hb and snap it into relaxed state
  • CO has greater affinity for Hb than O2
  • causes maximal O2 capacity falls to extent that CO binds
  • also increases O2 affinity of Hb and shifts O2 dissociation curve to left
  • does not release O2 when it gets to tissue
    (decreases Hb O2-carrying capacity and O2 unloading)
20
Q

How can CO2 be transported?

A
  • in plasma: physically dissolved (10%), combined with plasma proteins and as bicarbonate ions
  • in RBC: in physical solution, combined with Hb (20%) and as bicarbonate ions (70%)
21
Q

Describe CO2 release from blood into the lungs

A
  • partial pressure gradients for O2 and CO2 reverse
  • high PO2 causes H+ to dissociate from Hb
  • H+ and CO3- combine to form CO2 and H20
  • HCO3- re-enters RBC and combines with H+ to form H2CO3 which dissociates to release CO2 and H20
22
Q

What does transport of CO2 in the blood depend on?

A
  • PCO2
  • plasma pH
  • PO2
23
Q

Describe the haldane effect

A
  • as blood enters systemic capillaries and release O2, CO2 carrying capacity rises
  • as blood enters pulmonary capillaries and binds O2, CO2 carrying capacity falls and blood dumps CO2

MD3001 Respiratory (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions