(22.7) Transport of Respiratory Gasses by Blood

Describe how oxygen is transported in blood

1. 1.5% is dissolved in plasma 

2. 98.5% is loosely bound to each Fe of hemoglobin (Hb) in RBCs

T/F: O₂ is highly soluble in the blood

→ FASLE

O2 is POORLY SOLUBLE in the blood → only 1.5% is dissolved in plasma, remaining 98.5% must be carried on hemoglobin

How many O2 molecules can be reversibly bound to a molecule of hemoglobin?

Each Hb molecule is composed of 4 polypeptide chains, each with an iron-containing heme group → so each Hb can transport 4 oxygen molecules

Distinguish between Oxyhemoglobin & Deoxyhemoglobin 

1. Oxyhemoglobin (HbO₂) 

   • Hemoglobin-O₂ combination 

2. Deoxyhemoglobin (HHb)

   • Hemoglobin that has released O₂ 

   • Reduced hemoglobin   

Explain Influence of O₂ on Hemoglobin Shape

Loading and unloading of O2 is facilitated by change in shape of Hb 

1. O₂ binds, Hb changes shape → INCREASING its affinity for O₂ increases

2. O₂ is released, Hb shape change → causes a DECREASE in affinity of O₂

Explain Influence of O₂ on Hemoglobin Saturation

• FULLY saturated (100%)

  • ALL 4 heme groups carry O2 

• PARTIALLY saturated 

  • ONLY 1 to 3 hemes carry O2

Factors regulating oxygen loading and unloading from hemoglobin 

Rate of loading and unloading of O2 is regulated to ensure adequate oxygen delivery to cells 

1. P_O2

2. Temperature 

3. pH 

4. BPG 

5. P_CO2

Explain Influence of P_O2 on Hemoglobin Saturation 

• HIGH plasma partial pressure of O2 → hemoglobin unloads little oxygen 

• DROP plasma partial pressure of O2 → more oxygen can be unloaded to the tissues  

T/F: Increased temperature results in decreased O₂ unloading from hemoglobin.

→ FALSE 

• Increased temperature results in INCREASED O₂ unloading from hemoglobin

  • Decrease the affinity (binding strength) of hemoglobin for oxygen.

T/F: If your core temperature becomes colder, it is more difficult for oxygen to dissociate from hemoglobin at any

→ TRUE

Decrease in temperature increases hemoglobin's binding affinity for O_2, making it more difficult to dissociate (unload) O₂from hemoglobin

Which of the following would induce the loss of oxygen from hemoglobin and the blood?

• A.) a decrease in plasma carbon dioxide

• B.) an increase in hemoglobin that already has one or more oxygen molecules bound to it

• C.) a drop in blood pH

• D.) a decrease in blood temperature

→ C.) a drop in blood pH

• Lower pH (more acidic) → Bohr effect → reduced hemoglobin affinity for O₂ → more O₂ released.

• Less CO₂ → fewer H⁺ ions → higher pH, which increases hemoglobin’s affinity for O₂

• Hemoglobin the more O₂ it carries, the higher its affinity becomes

• Lower temperature shifts the dissociation curve left, increasing O₂ affinity

T/F: As carbon dioxide enters systemic blood, it causes more oxygen to dissociate from hemoglobin (the Haldane effect), which in turn allows more CO₂ to combine with hemoglobin and more bicarbonate ions to be generated (the Bohr effect).

→ FALSE

• CO₂ (and H⁺) → O₂ unloading

  • Bohr effect 

  • As carbon dioxide enters systemic blood, it forms carbonic acid → H⁺.

  • These H⁺ ions decrease hemoglobin’s affinity for O₂, causing more oxygen to dissociate from hemoglobin

• Deoxygenated Hb → increased CO₂ uptake and bicarbonate formation

  • Haldane effect

Explain Cause and Effect of Hypoxia 

• CAUSE 

  • Inadequate O₂ delivery to tissues  

• EFFECT 

  • Cyanosis

List and explain causes of Hypoxia

1. Anemic hypoxia 

   • Too few RBCs or abnormal or too little Hb

2. Ischemic hypoxia 

   • Impaired or blocked circulation 

3. Histotoxic hypoxia 

   • Cells unable to use O₂, as in metabolic poisons

SUMMARY  how P_O2, temperature, pH, BPG, and P_CO2 affect oxygen loading and unloading from hemoglobin 

ALL of these factors influence Hb saturation by modifying hemoglobin’s three-dimensional structure, thereby changing its affinity for O2

• Increase in temperature, PCO2, H+, or BPG levels in blood lowers Hb’s affinity for O₂, enhancing oxygen unloading from the blood

• Decrease in any of these factors increases hemoglobin’s affinity for oxygen, decreasing oxygen unloading

Carbon Monoxide Poisoning Affect in Hb

Hb has 200x greater affinity for carbon monoxide than oxygen 

Describe carbon dioxide transport in the blood 

1. 7-10% is dissolved in plasma as P_CO2 

2. 20% of CO₂ is bound to the globin part of hemoglobin (carbaminohemoglobin) 

3. 70% is transported as bicarbonate ions (HCO₃^-) in plasma 

T/F: The largest amount of carbon dioxide is transported in the bloodstream in the form of carbonic anhydrase.

→ FALSE

1. 7-10% is dissolved in plasma as P_CO2 

2. 20% of CO₂ is bound to the globin part of hemoglobin (carbaminohemoglobin) 

3. 70% is transported as bicarbonate ions (HCO₃^-) in plasma 

Role of Bicarbonate

Important buffer of blood pH

Explain Formation of Bicarbonate 

• Occurs primarily in RBCs, where enzyme carbonic anhydrase reversibly and rapidly catalyzes this reaction

• Involves CO2 combining with water to form carbonic acid (H₂CO₃) → which quickly dissociates into bicarbonate and H+ 

• In capillaries, after HCO₃^- is created → it quickly diffuses from RBCs into plasma

Which of the following best describes the chloride shift as seen in the figure?

Chloride ions rush into RBCs to counterbalance the outflow of bicarbonate ions (HCO₃^-)

• The outflow of negatively charged bicarbonate ions from RBCs is balanced by the inflow of negatively charged chloride ions

Explain Influence of CO₂ on Blood pH

Carbonic acid-bicarbonate buffer system → helps blood resist changes in pH

• If H+ concentration in blood rises → excess H+ is removed by combining with HCO₃^- to form H₂CO₃ which dissociates into CO₂ and H₂O

• If H+ concentration drops→ H₂CO₃ dissociates, releasing H+ 

• CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

List Factors the Affect Blood pH

Rapid, deep breathing causes a DECREASE in CO₂ in blood → resulting in a RISE in pH

1. Respiratory rate

2. Depth

T/F: Breathing plays a major role in acid-base balance of body

→ TRUE

Your patient has several cracked ribs from a car accident, which of these would you expect from his or her blood gases?

• A.) Decreased P_CO2 and decreased pH

• B.) Elevated P_CO2 and decreased pH

• C.) Decreased P_CO2 and increased pH

• D.) Elevated P_CO2 and increased pH

→ B.) Elevated P_CO2 and decreased pH

• Cannot take a deep breath, their P_CO2 will elevate leading to respiratory acidosis.

Effect and Cause of Hyperventilation

• EFFECT

  • Increased depth and rate of breathing that exceeds body’s need to remove CO₂

  • DECREASE in CO₂ in the blood → HYPOCAPNIA 

• CAUSE

  • Anxiety attacks

Effect, Cause, and Treatment of Hypocapnia 

• EFFECT 

  • DECREASE in CO₂ in the blood

  • SYMPTOMS → tingling and involuntary muscle spasms in hands and face

• CAUSE

  • Cerebral vasoconstriction and cerebral ischemia → resulting in dizziness and fainting

• TREATMENT

  • Breathing into paper bag increases CO2 levels being inspired

SUMMARY of Transport & Exchange of CO₂ and O₂

At the tissues:

1. O₂ leaves the blood → goes into tissues (where it’s needed)

2. CO₂ leaves tissues → enters the blood (to be carried away)

In the lungs:

1. INSPIRATION: O₂ enters from alveoli to blood (to be delivered to the body)

2. EXPIRATION:CO₂ leaves the blood goes into alveoli (to be exhaled)

Summary of O₂ and CO₂ Transport

O2

1. Air enters through the nose or mouth

2. Air travels down the trachea and then enters the bronchi 

3. Air travels down smaller and smaller bronchioles

4. Air reaches small sacs (alveoli)  

CO2

1. CO₂ is released from the mitochondria 

2. CO₂ diffuses into a capillary

3. CO₂ is carried to the lungs

4. CO₂ diffuses into an alveolus

5. Air exits through nose or mouth

Summary of O₂ Loading & Unloading

• Increased Loading

  1. Increased P_O2 in the alveoli 

  2. Increased surface area of respiratory membrane

• Decreased Loading

  1. Decreased ventilation alveoli 

  2. Increased thickness of the respiratory membrane

  3. Decreased atm

• Increased Unloading

  1. Increased P_CO2 in the tissues

  2. Decreased pH in the tissues

  3. Decreased P_O2 in the tissues

• Decreasing Unloading

  1. Decreased temperature in the tissues 

  2. Decreased concentration of BPG 

Effect and Cause of COPD

Chronic Obstructive Pulmonary Diseases

• EFFECT

  • Emphysema

  • Chronic bronchitis

• CAUSE

  • Seen in patients that have history of smoking → result in progressive dyspnea, coughing, and frequent pulmonary infections

Distinguish between Emphysema & Chronic bronchitis

Chronic Obstructive Pulmonary Diseases

• Emphysema 

  • Permanently enlarged alveoli and deterioration of alveolar walls  

• Chronic bronchitis

  • Results in excessive mucus production, inflammation and fibrosis of the lover respiratory mucosa 

Effect and Cause of Asthma

• EFFECT

  • Coughing

  • Dyspnea

  • Wheezing

  • Chest tightness

• CAUSE

  • Active inflammation of the airways

Cause and Effect of Tuberculosis (TB) 

• CAUSE

  • Infectious disease caused by the bacterium Mycobacterium tuberculosis  

• EFFECT 

  • Spread by coughing and inhalation 

Effect and Cause of Lung Cancer

• EFFECT 

  • In both sexes, long cancer is the most common type of malignancy 

• CAUSE

  • Strongly correlated with smoking 

SUMMARY of Lung Diseases