Ion Balance — Regulation & Homeostasis

How Does the Body Regulate Ion Levels?

An important part of homeostasis is ion regulation. The concentrations of certain ions designate pH in the extracellular fluid, including things like blood and bile.

Let's review:

The pH scale runs from $0$ to $14$ and tells us if something is acidic or basic, and to what degree.

Maintaining a stable internal pH is crucial. If the pH inside the body changes drastically, our enzymes will stop working, cells will likely be damaged, and proteins will degrade.

To make things more confusing, different parts of the body can have a different pH. The body has several mechanisms in place to maintain the pH in each part.

How Does the Body Maintain Ion Balance?

Buffers

When certain chemicals are mixed together, they can create a buffer solution. Buffers can resist or minimize pH changes to a solution, even when ion concentrations change quickly.

Urinary System

The urinary system, or excretory system, plays a pretty big role in pH balance. The star player is the kidney. Our kidneys filter out excess ions from our blood so that they can be excreted through urine.

If the concentration of ions is too high, the kidneys make sure to filter as much of them as they can out of the body. If there are not enough ions, the kidneys will filter them back into the system.

Respiratory System

We know that cellular respiration releases carbon dioxide into the blood.

It turns out that carbon dioxide often exists in our blood as carbonic acid. It makes our blood more acidic. When you breathe out, you are expelling carbon dioxide from your body and actually lowering the pH of your blood. The rate of your breathing controls this mechanism of ion regulation.

The combination of all of the above mechanisms keeps ion concentrations in check. Without them, our cells would not be able to function.

Acid-Base Homeostasis

Ion regulation, also known as acid–base homeostasis, is the maintenance of the pH levels in body fluids.

Maintaining the pH levels in extracellular fluids, such as blood, stomach acid, and bile, is extremely important in ensuring that cells do not get damaged. Many of the cells in the human body are sensitive to high or low pH levels. The proteins that reside on the surface of cells are sensitive to pH and can become damaged and useless if the ion concentration is too high or too low in the fluid. Damaged surface proteins can stop cell to cell communication and can affect a cell's ability to respond to stimuli.

Regulation in the Digestive Tract

Cells in the digestive tract, such as the stomach and intestine, are adapted to deal with more extreme pH levels. They need a very big change in pH to really be affected. When the pH does get out of hand, certain cells release natural buffers to counteract these abrupt pH levels. The buffers counteract the effects of both strong acids and strong bases to return the stomach acid or bile to a relatively normal acid level.

Buffers can also be released into the blood to help counteract pH levels there. Ammonia and red blood cells are examples of these kinds of buffers. They both have a pH very close to 7 and are capable of raising or lowering the pH of the blood.

Regulating the Urinary System

The second form of pH maintenance is the urinary system. Blood flows into the kidneys and swirls around a complex system of tubes. These tubes remove ions from the blood and concentrate them in the bladder. They are eventually excreted in the form of uric acid.

Respiratory Regulation

The third form of pH maintenance is respiratory regulation. When you breathe out, carbon dioxide leaves your body, lowering the number of hydrogen ions in the blood. This makes the blood more basic by raising the pH.

What Is Ion Regulation?

Ion regulation, sometimes called acid-base regulation, is how organisms control their extracellular pH. Just in case you didn't already know, extracellular means outside of the cell, or the exterior of the cell. This type of regulation is how your blood, stomach, and other vital parts of your body maintain their pH.

Ion pumps like the sodium-potassium pump help with regulation. They keep the balance between the interior ion concentration and the exterior concentration.

If the extracellular pH is too acidic, the cell may release basic ions to counteract it and vice versa. Cells can also release buffers to prevent any drastic changes in pH from occurring.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Homeostasis}}$ : The ability of living things to keep a balance between things entering and leaving the cell. In other words, the organism controls its internal environment

$\color{#8925AE}{\text{Thermoregulation}}$ : Thermoregulation is the process that allows organisms to maintain their internal temperature

$\color{#8925AE}{\text{Ion Regulation}}$ : The process of balancing the ion content inside the body. It is how organisms control the pH outside their cells

$\color{#8925AE}{\text{Osmoregulation}}$ : The process of balancing the water content inside the body

$\color{#8925AE}{\text{Equilibrium}}$ : All things in a system are perfectly balanced

(Video) Ionic Regulation Across Cell Membranes

by geneedinc

Watch this video to see a quick example of how the body balances ion concentrations by controlling the amount of sodium inside and outside of cells.