Relationship Between Respiration & Metabolism

How do plants respire?
••• Plant image by Platinum Pictures from Fotolia.com

Respiration is the process that gets oxygen from the air to the tissues of the body and removes carbon dioxide from the body. Metabolism refers to all the chemical reactions in the body, including those that use oxygen and create carbon dioxide. Oxygen and carbon dioxide, therefore, are involved in both respiration and metabolism. Metabolic reactions are sometimes referred to as cellular respiration, which can cause confusion.

Respiration Occurs in the Lungs

Air enters the nose, where it is warmed and humidified before entering the lungs. When the air reaches the alveoli, small air sacs in the lungs, the oxygen diffuses into the blood in the capillaries around the alveoli while carbon dioxide (the product of metabolism) leaves the blood and enters the air. During exhalation the carbon dioxide is released into the atmosphere.

Metabolism Occurs in All Tissues

The oxygenated blood leaves the lungs and is pumped throughout the body by the heart. When the blood enters the capillaries in the tissues, oxygen diffuses out of the blood and into the tissue. Cells use this oxygen in metabolic reactions. Metabolic reactions produce carbon dioxide. The carbon dioxide enters the blood as it leaves the tissues to be returned to the lungs and eventually the atmosphere.

What is Metabolism?

All the chemical reactions that occur in the body are metabolic reactions. Some reactions break down molecules to make energy while other reactions build up molecules (and use energy). Reactions that use energy include making new membrane, making proteins that determine the shape of the cell, and making molecules that are secreted from the cell. Every cell also has to store energy from nutrients so there is enough energy to make needed molecules.

ATP is the Metabolic Currency

Adenosine triphosphate—ATP—is the intermediate for metabolic reactions because there is a lot of energy stored in the phosphate bond of ATP. ATP is broken down to adenosine diphosphate (ADP) and the released energy is used to make other molecules. Reactions that make more ATP use the energy of food molecules to add a phosphate bond to ADP to regenerate ATP.

Food Provides Raw Materials

Food is digested into small molecules that can enter the blood stream. Sugars and fiber are broken down to small sugar molecules. Protein is broken down to amino acids. Special molecules in the intestines transport these small molecules to the blood. Fats are broken down to fatty acids which can diffuse across the intestines to enter the blood. All cells have special molecules that help them absorb nutrients from the blood stream so they can be used in metabolic reactions.

Related Articles

10 Facts on Photosynthesis
Why Do We Need Enzymes for Digestion?
Six Main Cell Functions
Five Major Organ Systems of the Body
The Definition of Body Systems
Functions of Human Organs
Where Does Respiration Occur?
How Are Photosynthesis & Cellular Respiration Related?
What Kind of Energy Makes Muscle Cells Contract?
What Is the Respiratory System's Role in Homeostasis?
How Is Oxygen Important to the Release of Energy in...
How Do the Liver & Kidney Communicate & What Hormones...
Cellular Respiration in Plants
What Are the 10 Major Body Systems?
What Is the Role of Pigments in Photosynthesis?
How are Chemical Bonds Important in Metabolism
How Cell Organelles Work Together
How Do the Respiratory & Cardiovascular System Work...
Where are Lipids Located in the Body?
How Do Plant Cells Obtain Energy?