Physioreview26D(Gas Exchange)

Front 1

What is the hemoglobinoxygen(Hb-O) dissociation curve?

Back 1

The curve relating percentage saturation of the o2 carrying capacity of hemoglobin to the Po2.

Front 2

How does the hemoglobin structure affect its o2 capacity?

Back 2

Hemoglobin has a quarternary structure that varies in its affinty for o2 depending on the number of o2 bound to it.

Front 3

how does the Hb-O dissociation curve affect the hemoglobin subunits in deoxygenated state?

Back 3

hemoglobin subunits are in a tense configuration where they have a reduced affinity for O2.

Front 4

How does the Hb-O dissociation curve affect the hemoglobin subunits when O2 is bound to it?

Back 4

With each progressive O2 molecule, hemogllobin takes on a relaxed configuration where subsequent binding of o2 is facilitated as each O2 binding site is exposed(allosterism).

Front 5

How does the sigmoid curve affect oxygen delivery at the:
Plateau
Steep section

Back 5

Plateau- High Po2 gives a large reserve during O2 loading.
Steep section- Small change in Po2 results in large changes in O2 saturation. This facilitates unloading of O2 at tissues.

Front 6

Where is the plateau and the steep section of the sigmoid curve found in the human body?

Back 6

Plateau- pulmonary capillaries
Steep section- Tissue capillaries.

Front 7

What does decreased O2 affinity mean?

Back 7

A higher Po2 is required for hemoglobin to bind a given amount of Oxygen.

Front 8

What factors decrease the affinity of O2?

Back 8

1. Low pH
2. Increased PCo2
3. Increased temperature
4. Increased 2, 3 diphosphoglycerate concentration.

Front 9

What factors decrease the affinity of O2?

Back 9

1. Low pH
2. Increased PCo2
3. Increased temperature
4. Increased 2, 3 diphosphoglycerate concentration.

Front 10

What factors cause an increase in 2, 3-DPG concentration?

Back 10

1. High pH
2. Thyroid hormone
3. Growth hormone
4. Androgens
5. High altitudes

Front 11

What are the functions of Hemoglobin?

Back 11

1. Facilitates oxygen transport
2. " Co2 transport
3. Acts as a buffer in the blood
4. Facilitates NO transport

Front 12

What happens to the Hb-O dissociation curve with decreased affinity for o2 by hemoglobin?

Back 12

Curve shifts to the right.

Front 13

What does decreased oxygen affinity favor?

Back 13

O2 delivery to tissue.

Front 14

What is the Bohr effect?

Back 14

Decrease in affinity of Hb for o2 due to lowered pH. This relates to the fact that deoxygenated Hb binds H+ ions more avidly than does oxygenated Hb.

Front 15

Where is the Bohr effect used physiologically/

Back 15

In the peripheral tissue(helps unload oxygen).

Front 16

How does fetal Hb(Hbf) differ from adult hemoglobin(Hb-A)

Back 16

HbF contains gamma polypeptide chains instead of beta chains.

Front 17

What is the significance of the gamma chains versus the beta chains HbF?

Back 17

There is a poor binding of 2, 3 DPG by the gamma chains causing HbF to have greater affinty for o2 than HbA.

Front 18

How does anemia affect 2, 3 DPG concentration in RBCs?

Back 18

Increases it.

Front 19

How is myoglobin different from hemoglobin?

Back 19

Myoglobin binds one rather than 4 molecules of o2 per molecule, resulting in a rectangular hyperbolar dissociation curve, typical of Michelis-mentin kinetics.

Front 20

How does the dissociation curve of myoglobin affect its O2 uptake relative to hemoglobin?

Back 20

because its curve is to the left of the Hb curve, it takes up o2 from hemoglobin in the blood and releases O2 only at low Po2 values.

Front 21

Much of the myoglobin is found in the skeletal muscles. TRUE/FALSE

Back 21

TRUE.

Front 22

What does decreased arterial O2 content cause?

Back 22

Decreased Hb concentration and reduced arterial O2 tension.

Front 23

Which does Hb have more affinity for CO or O2?

Back 23

CO(app 200 X greater affinity)

Front 24

What is formed as a result of CO reacting with Hb?

Back 24

Carboxyhemoglobin

Front 25

How does carboxyHb formation affect o2 content?

Back 25

1. decreases the functional Hb concentration
2. Reduces o2 carrying capacity of blood
3. Lowers tissue O2 tension.

Front 26

How is Co2 transported in the blood?

Back 26

H= buffered as HCO3- in plasma
2. Dissolved in plasma or in RBCs
3. Formation of carbamino-Hb in RBCs.
4. Formation of carbamino compounds with plasma protein.

Front 27

Where does hydration of Co2 into HCO3- occur?

Back 27

RBCs

Front 28

What enzyme catalyzes the conversion of Co2 into HCO3-?

Back 28

Carbonic anhydrase catalyzes formation of H2CO3 from H2O and Co2, which dissociates into H+ and HCO3.

Front 29

How does HCO3 enter the plasma?

Back 29

Exchanged with Cl-(chloride shift)

Front 30

Which two factors determine arterial or alveolar CO2 tensions?

Back 30

Rate of Co2 production and alveolar ventilation.

Front 31

Whatis the haldane effect?

Back 31

Binding of O2 to Hb reduces its affinity for CO2.

Front 32

Where is the haldane effect used physologically?

Back 32

Lungs

Front 33

What is methmoglobin?

Back 33

Hb that contains ferric(Fe3+) iron. It has a very high affinity for o2, resulting in decreased ability of Hb to unload O2.

Front 34

How do obstructive diseases affect gas exchange?

Back 34

Increases the time constant and results in a slower rate of acinar filling and emptying.

Front 35

How do restrictive diseases affect gas exchange?

Back 35

Reduce the time constant?