Gas Transport: Effect of Temperature, pH & Metabolism

Lesson Transcript
Instructor: John Simmons

John has taught college science courses face-to-face and online since 1994 and has a doctorate in physiology.

Hemoglobin transports most of the oxygen in the lungs to the metabolizing tissues; however, various factors like increased temperature, acid, pH, 2,3-BPG, or carbon dioxide can decrease the oxygen hemoglobin is capable of transporting. Learn about gas transport, metabolism, the Bohr Effect, the role of hemoglobin in oxygen transport, and the effect of temperature on hemoglobin. Updated: 08/26/2021

Hemoglobin and Oxygen Transport

Hemoglobin loaded with oxygen becomes oxyhemoglobin.
Oxyhemoglobin Diagram

As you know, we breathe to get oxygen into our body. Specifically, our cells need the oxygen to make ATP, which then provides energy for work: for example, muscular contraction. Our red blood cells contain hemoglobin, which is a complex protein that carries the oxygen from our lungs to the metabolizing tissues.

As blood flows through the lungs, oxygen is loaded onto hemoglobin, and that forms what we call oxyhemoglobin. Oxyhemoglobin is like a delivery truck that will transport the oxygen to the tissues. As blood flows through the metabolizing tissues, oxygen is unloaded from the oxyhemoglobin, forming what we call deoxyhemoglobin.

Have you ever wondered what causes the oxygen to be unloaded? In this lesson, we will discuss the physiological factors that help hemoglobin unload oxygen as it goes through our metabolizing tissues.

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  • 0:05 Hemoglobin and Oxygen…
  • 1:11 Effect of Temperature…
  • 2:11 Bohr Effect
  • 3:19 Metabolism
  • 4:22 Lesson Summary
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Effect of Temperature on Hemoglobin

Most people consider normal body temperature to be 37 degrees Celsius. While this may be accurate, body temperature is not the same everywhere in our body. For example, temperature can increase a few degrees in our metabolizing tissues as heat is released from the cells when they work.

Okay, so temperature increases in our tissues, but what does this have to do with oxygen transport? As it turns out, temperature affects the affinity, or binding strength, of hemoglobin for oxygen. Specifically, increased temperature decreases the affinity of hemoglobin for oxygen. As oxyhemoglobin is exposed to higher temperatures in the metabolizing tissues, affinity decreases and hemoglobin unloads oxygen. This is very important, as only free oxygen can enter the cells. In other words, it has to be released from the hemoglobin before it can get into our cells.

Bohr Effect

Here's a question for you: does increased temperature alone release enough oxygen to meet our metabolic needs? As it turns out, other factors are needed to unload oxygen from hemoglobin in our metabolizing tissues.

Carbon dioxide produced in cellular metabolism lowers pH.
Tissue Lung pH Scale

Let's take a look at how carbon dioxide and acid help us out. Cellular metabolism produces carbon dioxide and lactic acid, which lowers pH to about 7.2 - now that's compared with a pH of 7.4 in the lungs. While this may seem like a small decrease, it represents a relatively large increase in acidity.

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