12.4.4 Carbon Dioxide Transport Flashcards Preview

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Flashcards in 12.4.4 Carbon Dioxide Transport Deck (12)
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1
Q

Carbon Dioxide Transport

A
  • Carbon dioxide produced from respiring cells must be transported in the blood to the lungs where it will be expelled.
  • While some of the carbon dioxide produced by respiring cells is captured and transported by hemoglobin, most of it is converted to carbonic acid, which travels through the blood.
  • Hemoglobin helps maintain a constant pH in the blood by binding with H+ ions released from carbonic acid. When it reaches the lungs, hemoglobin releases the H+ ions which then combine with bicarbonate ions to reform carbonic acid. The carbonic acid then breaks down to make CO2 and water.
2
Q

carbonic acid

A
  • Carbon dioxide is produced in the mitochondria of every cell during respiration. Carbon dioxide diffuses from cells into the blood plasma and then enters red blood cells. In an enzyme-catalyzed reaction, CO2
    combines with water to form carbonic acid (H2CO3). As an acid, H2CO3 is able to ionize and release protons into its environment; thus lowering the pH. This change spells trouble for the body because a steady pH must be maintained to prevent the denaturation of proteins
    and other molecules.
3
Q

bicarbonate ions

A
  • A relatively small percentage of CO2 is taken up and
    transported by hemoglobin. An even smaller amount of CO2 is dissolved in the blood plasma. The majority of CO2 is converted to carbonic acid. Hemoglobin acts as a buffer and maintains a stable pH in the cell by accepting protons (H+) released from carbonic acid. Most of the bicarbonate ions that result from the dissociation of carbonic acid then diffuse into the plasma, where they act as a buffer.
4
Q

note

A
  • Once a bicarbonate ion reaches the lungs, it will enter red blood cells and recombine with the protons released from hemoglobin to form carbon dioxide and water. The carbon dioxide then diffuses out of the red blood cells and is expelled from the lungs.
5
Q

Carbon dioxide moves from cells into blood plasma by the process of

A
  • diffusion
6
Q

Carbon dioxide (CO2 ) combines with water (H2O) in the blood to

A
  • produce H2CO3 and lower the pH.
7
Q

What does blood plasma consists mainly of?

A
  • water
8
Q

Carbon dioxide enters the blood stream through __________ as a by-product of __________.

A
  • diffusion, respiration
9
Q

Most CO2 produced by respiration is

A
  • converted directly to carbonic acid.
10
Q

How is the pH maintained in the blood despite the presence of CO2?

A
  • Hemoglobin releases O2 and combines with H +
11
Q

What will happen to CO2 if it is left to dissolve in blood plasma?

A
  • It will become carbonic acid and lower the pH of plasma.
12
Q

What is the origin of the carbon dioxide produced by the body?

A
  • Mitochondria

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