Oxygen - Haemoglobin Dissociation Curve - Physiology

Summary

This video explains lung physiology, focusing on gas exchange and the oxygen dissociation curve. It covers how air travels through the respiratory system to the alveoli, where oxygen is absorbed and carbon dioxide is expelled. The process of oxygen binding to hemoglobin is discussed, highlighting positive cooperativity and the transition from a tense to a relaxed state. The video also explains the oxygen hemoglobin dissociation curve, detailing how oxygen saturation varies with partial pressure and how factors like pH, temperature, and 2,3-DPG influence the curve's shift, ensuring efficient oxygen delivery to tissues.

Takeaways

• 😀 Air enters the respiratory system through the upper airways, conducting airways, and respiratory airways, eventually reaching the alveoli where gas exchange occurs.
• 😀 The heart pumps deoxygenated blood to the lungs where carbon dioxide is expelled and oxygen is absorbed, reoxygenating the blood.
• 😀 Oxygen binds to hemoglobin in red blood cells, forming oxyhemoglobin, which is essential for oxygen transport throughout the body.
• 😀 Hemoglobin undergoes a conformational change from a tense (T) to a relaxed (R) state upon oxygen binding, increasing its affinity for more oxygen.
• 😀 The oxygen-hemoglobin dissociation curve shows how hemoglobin saturation changes with varying partial pressures of oxygen.
• 😀 A high partial pressure of oxygen (in the lungs) causes hemoglobin to become nearly saturated, with minimal change beyond that point.
• 😀 Small changes in partial pressure of oxygen at low levels (in tissues) cause large shifts in oxygen saturation, promoting efficient oxygen release.
• 😀 The dissociation curve is sigmoidal due to positive cooperativity, where binding of oxygen to hemoglobin increases the molecule's affinity for more oxygen.
• 😀 Factors such as decreased pH (increased CO₂), higher temperature, and increased 2,3-DPG cause a rightward shift in the curve, reducing hemoglobin's oxygen affinity.
• 😀 A rightward shift in the curve facilitates oxygen delivery to tissues, such as during exercise or in the placenta for fetal oxygen transfer.
• 😀 A leftward shift in the curve (higher pH, lower temperature, and lower DPG) increases hemoglobin's affinity for oxygen, facilitating oxygen uptake in the lungs.

Q & A

What is the primary function of the alveoli in the lungs?

The alveoli are the building blocks of the lungs where gas exchange occurs. Oxygen is absorbed into the bloodstream, and carbon dioxide is expelled from the body.

How does the heart contribute to oxygen transport in the body?

The heart pumps deoxygenated blood from the right ventricle to the lungs, where it is oxygenated. This oxygenated blood is then pumped to the rest of the body to deliver oxygen to tissues.

What happens to carbon dioxide in the blood during respiration?

Carbon dioxide is expelled from the bloodstream into the alveoli, where it is exhaled out of the body, helping to regulate pH in the blood.

How does hemoglobin bind oxygen in the lungs?

Hemoglobin binds oxygen in a process where the protein's globin chains change shape from a tense to a relaxed configuration. This increases hemoglobin's affinity for oxygen, allowing it to bind more efficiently.

What is the concept of positive cooperativity in hemoglobin?

Positive cooperativity refers to the process where the binding of one oxygen molecule to hemoglobin increases the affinity for additional oxygen molecules, making oxygen uptake more efficient.

What is the oxygen-hemoglobin dissociation curve, and what does it represent?

The oxygen-hemoglobin dissociation curve shows the relationship between the partial pressure of oxygen (pO2) and the saturation of hemoglobin with oxygen. It demonstrates how easily hemoglobin binds and releases oxygen.

What does the plateau of the oxygen-hemoglobin dissociation curve indicate?

The plateau of the curve shows that at high partial pressures of oxygen, the saturation of hemoglobin with oxygen does not change significantly. This indicates that hemoglobin is already nearly fully saturated with oxygen.

How does a shift to the right in the oxygen-hemoglobin dissociation curve affect oxygen delivery?

A shift to the right reduces hemoglobin's affinity for oxygen, making it easier for oxygen to be released to tissues, especially in conditions like high CO2, low pH, higher temperature, and high levels of 2,3-DPG.

What factors can shift the oxygen-hemoglobin dissociation curve to the left?

A shift to the left occurs with lower levels of CO2, higher pH, lower temperature, and lower 2,3-DPG. This increases hemoglobin's affinity for oxygen, facilitating oxygen binding in the lungs.

Why is it important for the oxygen-hemoglobin dissociation curve to shift in response to tissue needs?

The shift in the curve ensures that oxygen is delivered efficiently to tissues where it's needed most. In tissues requiring more oxygen (like muscles during exercise), the curve shifts to the right, facilitating oxygen release.