Internal

1
InternalExternal Respiration

• Done by Azima Ihsan, Amanpreet Thind Mario

2
Four Phases of
Respiration

• Breathing
• act of inhaling and exhaling gases
• External Respiration exchange of gases between
  air in the alveoli and blood in the pulmonary
  capillaries
• Internal Respiration exchange of gases in the
  systemic capillaries and tissue fluid
• Cellular Respiration
• process of oxidizing food molecules

3
Site of Internal and External Respiration
4
Transport of Oxygen By Blood

• Oxygen is transported in two forms in the
  blood
• 1. Physically dissolved in plasma (2 )
• Compared to carbon dioxide, oxygen is relatively
  insoluble in plasma
•  
• 2. Bound to the haemoglobin molecule (Hb) (98 )
• Hb can combine rapidly and reversibly with
  oxygen.
• The reversibility of this reaction allows oxygen
  to be released to the tissues.
• Hb O2 in
  lungs HbO2
• Deoxyhaemoglobin in tissue
  Oxyhaemoglobin
• (a.k.a reduced Hb)

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The Oxyhaemoglobin Dissociation Curve

• a. Loading oxygen in the lungs
• Venous blood entering the pulmonary capillaries
  has a PO2 of 40 mm Hg
• As the blood passes through the pulmonary
  capillaries, it equilibrates with the alveolar
  PO2 of about 100 mmHg
•  
• b. Unloading oxygen at the tissues
• As blood passes from the systemic arteries into
  the capillaries, it is exposed to lower PO2,
  oxygen is released from Hb

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Factors that enhance the unloading of the oxygen

• Factors that enhance the unloading of the oxygen
  at the tissues and shift the curve to the right
• H, pH
• 2) PCO2 (Bohr Shift)
• 3) temperature

pH Temperature
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Other Factors That Affect Oxygen Transport in The
Blood

• 1) Anaemia
• The Hb saturation is not affected
• The reduced amount of haemoglobin per 100 ml
  blood decreases the oxygen carrying
• capacity of the blood

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• 2) Carbon Monoxide (CO)
• The affinity of Hb for carbon monoxide is 240
  times that for O2
• CO competitively blocks the combination of
  oxygen with Hb
• CO bound Hb is called carboxyhaemoglobin (HbCO)
• Together these characteristics of CO can lead to
  severe tissue hypoxia

9
How is Co2 carried in the blood?

• 1. Physically dissolved in plasma (5)
• Carbon dioxide is much more soluble in blood
  than oxygen
• 2. Bound to haemoglobin and plasma proteins (5)
• Carbon dioxide combines reversibly with
  hemoglobin to form carbaminohaemoglobin.
• Carbon dioxide binds to amino groups on the
  polypeptide chains of haemoglobin
• Carbon dioxide also binds to amino groups on
  the polypeptide chains of plasma proteins
•  

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• 3. BICARBONATE IONS (HCO3- ) (90)
• Carbon dioxide enters red blood cells in the
  tissue capillaries, combines with water to form
  carbonic acid (H2CO3)
• This reaction is catalyzed by the enzyme
  carbonic anhydrase (C.A.), which is found in the
  red blood cells.
• Carbonic acid then dissociates to form
  bicarbonate ions (HCO3- ) and hydrogen ions (H).
• CO2H20 H2CO3 HCO3-H

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(HCO3- ) IN TISSUE AND
LUNGS

• The hydrogen ions combine with haemoglobin in
  the red blood cell.
• Bicarbonate ions diffuse out into the plasma
  whilst chloride ions (Cl-) to diffuse in
  (chloride shift).

• The reversal of the reactions which occurs at the
  lungs.
• Bicarbonate ions enter the red blood cells and
  combine with hydrogen ions to form carbonic acid.
  
• This is broken down into carbon dioxide and
  water.
• Carbon dioxide diffuses out of the red blood
  cells into the alveoli.

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The Carbon Dioxide Dissociation Curve

• Transport of CO2 is dependent on O2 release.
• The CO2 dissociation curve is influence by the
  state of oxygenation of the Hb
• High PO2 tends to displace CO2 from haemoglobin
  (Haldane effect)
• It takes place in lungs causing release of CO2
  from the blood.

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External Respiration

• As O2 passes from the alveoli into the red blood
  cells, Hb becomes saturated with O2
• Hb releases H that binds to more HCO3- to form
  carbonic acid
• The carbonic acid dissociates into CO2 and water
• The CO2 diffuses from the blood into the alveoli.

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Internal Respiration

• CO2 leaves the tissue cells and enters the red
  blood cell
• It causes more O2 to dissociate from Hb (Bohr
  shift)
• Thus more CO2 combines with Hb and
• More HCO3 is produced

15
Quiz

• Where does External and Internal Respiration
  takes place?
• External in lungs and internal at tissues
• 2 ways by which O2 travels in blood
• As dissolved in plasma and oxyhaemoglobin.
• Does this reaction occur at the lungs
• or at the tissue?
• Hb O2 HbO2
• In lungs or pulmonary capillaries.
• 3 ways by which CO2 travels in blood
• As dissolved in plasma, carbaminohaemoglobin,
  and
• bicarbonate ions.

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What are these curves called?
Oxyhaemoglobin dissociation curves.
17


Bibliography

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  McGraw-Hill, 1997.
• Osborne, Sally. Transport of Oxygen by Blood.
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• Respiration. Internal and External
  respiration. 10 November 2007.
  www.coolschool.ca/lor/BI12/unit11/U11L05.
• Gas transport in blood. Gas exchange. 10
  November 2007. www.healthsystem.virginia.edu/Inter
  net/AnesthesiologyElective/airway/gastransport.cfm
  
• Binding of Ligands. Haemoglobin. 12 November
  2007. www.en.wikipedia.org/wiki/UserSaravask/Hemo
  globin.
• Haemoglobin saturation. Human Physiology. 12
  November 2007. www.people.eku.edu/ritchisong/301no
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