CBL - The Physiology of Cellular Metabolism Lesson

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The Physiology of Cellular Metabolism

The human cell is in a constant state of a chemical reaction. Not simply a single chemical reaction, but thousands of chemical reactions required to maintain homeostasis of the cell and vital to the maintenance of human life. The many chemical reactions occurring inside the cell membrane are described as metabolic processes.  

Let's take a look at metabolic reactions and pathways:

The cycle of catabolism and anabolism requires an efficient control system for proper function. If the catabolism process fails to yield the proper energy-releasing reactions and does not meet the needs (or exceeds the needs) of the building-up reactions, the risk of cellular damage exists.  

Human cells have a continuous need for water and various nutrients for cellular growth and repair. Cell differentiation allows for specialized metabolic processes in different cells. But all cells perform the basic reactions including the buildup and breakdown of carbohydrates, lipids, proteins, and nucleic acids. Cellular function depends on energy production and transportation of substances within the individual cell and among cells in general.

Food functions as the primary source of energy to the body. Food energy or calories cannot be used directly by the cell. Calories must be converted to ATP to power cellular processes. This is accomplished through cellular respiration.

Watch the video below to learn more about cellular respiration.

 

 

The conversion cycle of ATP to ADP is explained. 
1. Rupture: ATP to ADP conversion occurs when the terminal high-energy phosphate bond ruptures.
2. Release: The third phosphate is liberated energy stored in the chemical bond is therefore released.
3. Recycle: Mitochondrial enzymes then reconvert ADP and the liberated phosphate to ATP. To obtain the energy needed for the reattachment, mitochondria oxidize food nutrients. This makes recycled ATP available for energy production.

In the previous chapter, we explored the structure and function of the cell membrane, including the regulation of substances allowed to enter and leave the cell. The mechanisms by which substances cross the cell membrane include:

  • Diffusion - the tendency of atoms, molecules, and ions to move from areas of higher concentration to areas of lower concentration. Eventually, an equal distribution of solutes will occur.  This is a passive activity.  
  • Osmosis - the passive movement of fluid from a region of higher water concentration to a region of lower water concentration across a selectively permeable membrane. Osmosis stops when the fluid level equalizes the solute concentration on both sides of a selectively permeable membrane.

The process of osmosis.

 

  • Active Transport - Movement of atoms, molecules, and ions across a selectively permeable membrane in the opposite direction from lower concentration to an area of higher concentration.  

Active transport functions as a pump, moving substances to the desired location. This action is equivalent to pushing a load up a steep hill and requires substantial energy for successful completion.

Sodium Potassium Pump

One function of the sodium-potassium pump is to maintain homeostasis by maintaining an acid-base balance and healthy kidney function. The image below shows the process.

The sodium potassium pump process

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