CO2 Transport | Carbon-di-oxide Transport | Respiratory Gas Exchange | Respiratory Physiology
Summary
TLDRThis Bite Size Med video explains carbon dioxide transport in the blood. Carbon dioxide, a byproduct of tissue metabolism, is transported in three forms: dissolved (5%), bound to hemoglobin as carbaminohemoglobin (20%), and chemically modified as bicarbonate (70%). The video highlights the Bohr and Haldane effects, which regulate oxygen and carbon dioxide exchange. It also details the role of carbonic anhydrase in forming carbonic acid, the chloride shift, and how oxygenation of hemoglobin promotes carbon dioxide release for expiration.
Takeaways
- π The purpose of respiration is gas exchange, where oxygen enters the bloodstream and carbon dioxide is expelled.
- π Carbon dioxide in the pulmonary capillaries originates from mixed venous blood, which carries waste from body tissues.
- πββοΈ Tissue metabolism produces carbon dioxide as a byproduct when using oxygen.
- π§ Dissolved carbon dioxide constitutes about 5% of its transport in the blood, being more soluble than oxygen.
- π©Έ The bound form of carbon dioxide is carbaminohemoglobin, accounting for approximately 20%, and it affects oxygen binding.
- π The Bohr effect describes how carbon dioxide binding to hemoglobin reduces its oxygen affinity, shifting the oxygen dissociation curve rightward.
- π The Haldane effect explains how the removal of oxygen from hemoglobin increases its affinity for carbon dioxide.
- π§ͺ The most significant form of carbon dioxide transport is chemically modified as bicarbonate ions, about 70%.
- π Carbon dioxide reacts with water in the presence of carbonic anhydrase to form carbonic acid, which then dissociates.
- π The chloride-bicarbonate exchange, or chloride shift, maintains ionic balance as bicarbonate leaves red blood cells for chloride.
- π‘ Hemoglobin buffers hydrogen ions to prevent an acidic environment and maintains blood pH.
Q & A
What is the primary purpose of respiration?
-The primary purpose of respiration is gas exchange, where oxygen enters the capillary from the alveolus and carbon dioxide leaves the capillary to enter the alveolus and is then breathed out.
Where does the carbon dioxide in the pulmonary capillaries come from?
-The carbon dioxide in the pulmonary capillaries comes from mixed venous blood that arrives via the pulmonary artery, which in turn receives blood from all the body tissues.
How is carbon dioxide produced in the body?
-Carbon dioxide is produced during tissue metabolism, where tissues use oxygen and form carbon dioxide as a byproduct.
In what three forms is carbon dioxide transported in the blood?
-Carbon dioxide is transported in the blood in three forms: dissolved carbon dioxide, bound form as carbaminohemoglobin, and chemically modified form as bicarbonate.
What percentage of carbon dioxide is transported as dissolved carbon dioxide?
-About five percent of carbon dioxide is transported as dissolved carbon dioxide, which is more soluble than oxygen.
How does carbon dioxide bind to hemoglobin and what is the effect on oxygen affinity?
-Carbon dioxide binds to hemoglobin at the n-terminus of the globin chain, forming carbaminohemoglobin. This binding reduces hemoglobin's affinity for oxygen, which is known as the Bohr effect.
What is the Haldane effect and how does it relate to oxygen and carbon dioxide binding to hemoglobin?
-The Haldane effect is the phenomenon where the binding of oxygen to hemoglobin lowers its affinity for carbon dioxide. Conversely, if less oxygen is bound, there's a higher affinity for carbon dioxide.
What is the most important form in which carbon dioxide is transported in the blood and what percentage does it represent?
-The most important form in which carbon dioxide is transported is as bicarbonate, accounting for around 70 percent of its transport in the blood.
How does the chloride shift or anion exchange protein Band 3 contribute to carbon dioxide transport?
-The chloride shift, facilitated by the anion exchange protein Band 3, allows bicarbonate to leave the red blood cell to maintain ionic balance, and chloride enters in exchange, which is crucial for the transport of carbon dioxide.
How does hemoglobin buffer hydrogen ions to maintain blood pH?
-Hemoglobin buffers hydrogen ions to prevent an acidic environment, thus maintaining the pH of the red blood cells and blood. This is important for the proper functioning of the blood's transport mechanisms.
What happens to carbon dioxide in the pulmonary capillaries during oxygenation of hemoglobin?
-During oxygenation of hemoglobin in the pulmonary capillaries, hydrogen ions dissociate from hemoglobin, and bicarbonate enters the red blood cell in exchange for chloride. This leads to the formation of carbonic acid, which then dissociates into carbon dioxide and water, with carbon dioxide being exhaled.
How does the concentration of carbon dioxide in the blood depend on tissue metabolism and alveolar ventilation rate?
-The concentration of carbon dioxide in the blood depends on the rate of its production through tissue metabolism and the rate at which it is expired through alveolar ventilation.
Outlines
π¬οΈ Carbon Dioxide Transport in Blood
This paragraph discusses the process of carbon dioxide transport in the blood. It begins by explaining the purpose of respiration, which is gas exchange. Oxygen enters the bloodstream from the alveolus, while carbon dioxide exits the bloodstream into the alveolus to be exhaled. The script then traces the origin of carbon dioxide to tissue metabolism, where it is produced as a byproduct of oxygen use. The transport of carbon dioxide is detailed in three forms: dissolved in the plasma (5%), bound to hemoglobin as carbaminohemoglobin (20%), and chemically modified as bicarbonate (70%). The binding of carbon dioxide to hemoglobin is explained, along with the Bohr and Haldane effects, which describe the interplay between oxygen and carbon dioxide binding to hemoglobin. The paragraph concludes with a description of how carbon dioxide is converted to bicarbonate in red blood cells through the action of carbonic anhydrase, and how this bicarbonate is exchanged for chloride ions to maintain ionic balance, a process known as the chloride shift.
Mindmap
Keywords
π‘Respiration
π‘Carbon Dioxide
π‘Capillary
π‘Alveolus
π‘Tissue Metabolism
π‘Hemoglobin
π‘Bohr Effect
π‘Haldane Effect
π‘Bicarbonate
π‘Chloride Shift
π‘Carbonic Anhydrase
Highlights
Respiration's purpose is gas exchange, with oxygen entering the capillaries from the alveolus and carbon dioxide leaving to be exhaled.
Carbon dioxide in the pulmonary capillaries originates from mixed venous blood, which comes from the pulmonary artery.
Carbon dioxide is a byproduct of tissue metabolism where tissues use oxygen and produce carbon dioxide.
Transport of carbon dioxide occurs in three forms: dissolved, bound to hemoglobin, and chemically modified.
Dissolved carbon dioxide makes up about 5% of the total carbon dioxide in the blood.
Carbon dioxide is more soluble than oxygen, hence its higher percentage in dissolved form.
Bound carbon dioxide forms carbaminohemoglobin, accounting for about 20% of carbon dioxide transport.
Carbon dioxide binds to hemoglobin at a different site than oxygen, at the n-terminus of the globin chain.
Binding of carbon dioxide to hemoglobin reduces its affinity for oxygen, causing a rightward shift in the oxygen dissociation curve (Bohr effect).
The Haldane effect describes how the removal of oxygen from hemoglobin increases its affinity for carbon dioxide.
The most significant form of carbon dioxide transport is as bicarbonate, accounting for approximately 70%.
Carbon dioxide from tissues diffuses into capillaries, binds to water, and forms carbonic acid through carbonic anhydrase in red blood cells.
Bicarbonate ions leave red blood cells to maintain ionic balance, and chloride ions enter in a process known as the chloride shift.
Hemoglobin buffers hydrogen ions to prevent an acidic environment and maintain blood pH.
In the lungs, oxygenation of hemoglobin promotes the dissociation of hydrogen ions, allowing bicarbonate to re-enter red blood cells.
The formation of carbonic acid from bicarbonate and hydrogen ions leads to the production of carbon dioxide and water, which is then exhaled.
The concentration of carbon dioxide in the blood is determined by tissue metabolism rate and alveolar ventilation rate.
The video provides a comprehensive journey of how carbon dioxide moves from tissues to the lungs.
Transcripts
hi everyone welcome to bite size med
where we talk about quick
bite-sized concepts in basic medical
sciences for study and rapid review
this video is on carbon dioxide
transport in blood
the purpose of respiration is gas
exchange
oxygen enters the capillary from the
alveolus
and carbon dioxide leaves the capillary
to enter the alveolus
and then get breathed out the oxygen
comes from the atmosphere
but where does the carbon dioxide come
from
if we backtrack it carbon dioxide in the
pulmonary capillaries
is from mixed venous blood that comes
from the pulmonary artery
which came off the right heart receiving
blood from all the body tissues
so carbon dioxide is formed during
tissue metabolism
the tissues use oxygen and form carbon
dioxide
the transport of carbon dioxide from the
tissues
through systemic circulation and then
pulmonary circulation
happens in three forms as dissolved
carbon dioxide
a bound form and a chemically modified
form
dissolved carbon dioxide is around five
percent
carbon dioxide is more soluble than
oxygen
so it dissolves more and that's why it's
five versus oxygen which was at just two
percent
the bound form is with hemoglobin as
carb amino hemoglobin
this is around 20 percent carbon dioxide
binds to hemoglobin
at a different site than oxygen the
n-terminus of the globin chain
the binding of carbon dioxide to
hemoglobin reduces
its affinity for oxygen shifting the
oxygen dissociation curve to the right
this is the bohr effect the binding of
oxygen to hemoglobin
lowers the affinity for carbon dioxide
so if less oxygen is bound that means
there's a higher affinity for carbon
dioxide
and this is the haldane effect
so let's see how these work together
the tissue produces carbon dioxide that
binds to hemoglobin
reducing the affinity for oxygen and
shifting the oxygen dissociation curve
to the right
so more oxygen is released to the
tissues
that was the bohr effect
now the removal of oxygen from
hemoglobin
increases hemoglobin's affinity for
carbon dioxide
for the carbon dioxide that the tissues
have produced
and that's the haldane effect
that was the bound form the most
important form in which carbon dioxide
gets transported is chemically modified
as bicarbonate
around 70 percent
the carbon dioxide from the tissues
diffuses into the capillaries
it binds to water and by carbonic
anhydrase in the rbcs
it forms carbonic acid that then
dissociates into a hydrogen ion and a
bicarb ion
now these reactions are reversible
the bicarbonate leaves the rbc to
maintain ionic balance
a negative ion enters that's chloride
this is by the anion exchange protein
that's the band
3 protein and this is the chloride
bicarbonate exchange
also called a chloride shift
if the hydrogen ions were to remain as
such
it would create an acidic environment so
it gets buffered by hemoglobin
that maintains the ph of the rbc and the
blood
now the bicarbonate is in the plasma and
the hydrogen ions have been buffered by
hemoglobin
they travel to the lung and reach the
pulmonary capillaries
here oxygen is diffusing from the
alveolus into the capillary
the oxygenation of hemoglobin promotes
dissociation of the hydrogen ions from
hemoglobin
because hemoglobin wants to take up
oxygen
the bicarbonate enters the rbc in
exchange for chloride
so now hydrogen ions bind to bicarb ions
and by carbonic anhydrase they form
carbonic acid
which then dissociates into carbon
dioxide and water
and the carbon dioxide gets breathed out
so the oxygenation of hemoglobin shifts
this reaction
towards the formation of carbon dioxide
for expiration
so the carbon dioxide concentration in
blood
depends upon how much is produced that's
the tissue metabolism rate
and how much is expired that's the
alveolar ventilation rate
and that is the journey that carbon
dioxide takes from the tissues to the
lungs
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