Exchange and Transport in Animals (O2/CO2 Transport) Flashcards

1
Q

How are erythrocytes adapted for their function? - 3

A

Biconcave- large SA:V for diffusion of gases

No nucleus when mature- more space for more molecules of haemoglobin so more oxygen can be carried

Haemoglobin- pigment with four polypeptide chains to carry four oxygen molecules

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2
Q

Where are red blood cells made?

A

In bone marrow

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3
Q

Describe the structure of haemoglobin

A

Quaternary protein- globular conjugated
Four iron molecules at centre/ Prosthetic group is iron containing haem group
2 alpha and 2 beta subunits

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4
Q

What is the symbol equation for the relationship between haemoglobin and oxyhaemoglobin?

A

Hb + 4O2 ⇆ HbO8 / Hb(O2)4

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5
Q

What is partial pressure?

A

A measure of the concentration of a chemical when in a mixture of gases.

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6
Q

What is the term for the ability of something to bind?

A

Affinity

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7
Q

What happens to haemoglobin as each O2 molecule binds and what effect does this have?

A

Alters conformation, making subsequent binding easier. - cooperative binding

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8
Q

What controls loading and unloading of oxygen?

A

Concentration gradient for diffusion

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9
Q

What do oxygen dissociation curves show?

A

Relationship between oxygen levels (as partial pressure) and haemoglobin saturation, therefore affinity of Hb for O2.

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10
Q

Why is the saturation of Hb not linear?

A

Binding potential changes with each additional O2 molecule.

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11
Q

What word can be used to describe the shape of the oxygen dissociation curve for adult haemoglobin?

A

Sigmoidal

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12
Q

How does oxygen affinity affect loading/unloading?

A

High affinity for O2 found in areas with higher O2 partial pressure. It is therefore loaded more readily.

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13
Q

What is myoglobin?

A

O2 binding tissue in skeletal muscle tissue. Single polypeptide with only one haem group.

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14
Q

How does the oxygen dissociation curve for fetal haemoglobin differ from that of adult haemoglobin?

A

Fetal disscoation curve is shifted to the left.

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15
Q

Why does a fetus need a different type of haemoglobin from adults?

A

Fetus gains O2 across placenta as mother releases it. Partial pressure in placenta is low. Fetal haemoglobin has a higher affinity so loads the oxygen as the mother unloads it. This maintains the concentration gradient. Fetal haemoglobin can pick up O2 at the same/low pO2.

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16
Q

Why is the change from fetal to adult haemoglobin essential?

A

O2 would not be released readily enough because affinity of fetal would be too high.
Adult females will need difference with any fetus in future.

17
Q

What shape is the curve for myoglobin?

A

Logarithmic

18
Q

When does myoglobin release O2?

A

When levels in muscles are very low. Delayed release of O2 helps to slow onset of anaerobic respiration and lactic acid formation during exercise.

19
Q

In what ways is CO2 transported? (% for each mechanism)

A

5% dissolved in blood plasma

95% red blood cells:
10-20% bound to amino acid groups in haemoglobin to form carbaminohaemoglobin
about 75% diffuses into cytoplasm of erythrocytes

20
Q

Equation for CO2 dissociation

A

CO2 + H20 ⇆ H2CO3 ⇆H+ + HCO3-

21
Q

What does a buffer do?

A

Keeps pH within a certain range

22
Q

What is the chloride shift?

A

HCO3- (bicarbonate) pumped out of cell in exchange with Cl- ions to ensure erythrocyte remains unchanged/ stops build up of electric charge.

23
Q

What is formed when CO2 combines with water? and what enzyme catalyses reaction?

A

Carbonic acid

Carbonic anhydrase

24
Q

What does carbonic acid dissociate into?

A

Hydrogen ions and hydrogen carbonate ions. (H+ and HCO3-)

25
What does bicarbonate bind with before travelling to lungs?
Sodium to form sodium bicarbonate
26
What is effect of H+ and what happens to them?
Make environment less alkaline causing Hb to release O2. | Hb absorbs H+ and acts as a buffer to maintain intracellular pH.
27
What is produced when H+ binds with haemoglobin?
Haemoglobinic acid
28
What effect does haemoglobin's role as a buffer have on oxygen?
Causes haemoglobin to release oxygen, unloading it to respiring tissues.
29
Equation for haemoglobin as a buffer
H+ + HbO2 → HHb +O2
30
What relationship does the Bohr effect show and how does the oxygen dissociation curve change?
Describes the effect of CO2 on the oxygen dissociation curve for haemoglobin. The curve moves to the right.
31
What causes the Bohr shift/ effect?
AsnCO2 partial pressure increases, haemoglobin gives up oxygen more easily.
32
What would happen if remaining tissue fluid that was not reabsorbed did not drain into the lymphatic system?
Fluid would accumulate, leading to oedema/swelling of tissue.