WHAT IS CYTOLYSIS? - BIOLOGY - 2026

The cytolysis refers to cell death due to disruption of the cell membrane. This is caused when osmosis generates an excessive movement of water into the cell, which ends up causing the membrane to rupture.

When the amount of water increases, the pressure that the liquid exerts against the membrane becomes greater. That is why when the cell receives more than it can process, its membrane breaks down, the cell contents are released, and the cell dies.

Blood cells in solutions with different osmotic pressures. Cytolysis would result in the image on the far right.

Cytolysis does not occur in plant cells, however, in animal cells it occurs very frequently. This phenomenon can occur naturally, but it can also be the cause or consequence of sensitive medical conditions.

Osmosis

Osmosis is the movement of a liquid substance, mainly water, that enters a cell through a semi-permeable cell membrane. In this process, the water moves from a hypertonic medium (with a higher concentration of solutes, to a hypotonic medium (with a lower concentration of solutes).

This phenomenon allows cells to receive the water they require from the environment to carry out their vital processes.

Osmotic pressure

Osmotic pressure, or turgor pressure, refers to the pressure created by water when it enters the cell and generates tension against the cell membranes. The greater the amount of water that enters, the greater the osmotic pressure.

The turgor of a cell depends on the substances that the cell houses, on the existence of a semi-permeable membrane that allows osmosis and on the supply of water it receives from the outside through said membrane.

The turgor pressure is very important in the development of cells and therefore also of living beings.

In animal cells, osmotic pressure is responsible for the growth of organs and the elasticity of the skin. For this reason, the dehydration of an organism can be visible in the lack of turgor of the skin.

In the case of plant cells, turgor is responsible for the plants to grow and remain firm. When a plant does not receive enough water, the cells lose turgidity, thus wilting.

The process of cytolysis

Osmotic lysis occurs when water enters the cell in large quantities. As the water enters, the cell grows larger and larger until the cell membrane yields to osmotic pressure and eventually ruptures, releasing the contents of the cell and leading to cell death.

This process can occur when the interior of the cell is hypotonic, that is, when it has little water in its interior in relation to the water present in the surrounding environment. In these cases, the fluid enters the cell and the cell swells until it breaks.

In the human body, this phenomenon occurs due to the existence of some medical conditions that affect cell metabolism.

On the other hand, it is also possible that bacterial cytolysis is generated. In this case, the cell fills with bacteria or pathogenic parasites that saturate it until causing the breakdown of the cell membrane.

Cytolysis only occurs in animal cells. This is because plant cells do not have a semi-permeable membrane but rather a strong cell wall that controls osmotic pressure and prevents cell breakdown.

Some cells and organisms have generated different ways to prevent cytolysis. For example, paramecium has a contractile vacuole that performs the function of rapidly pumping excess water to prevent its accumulation and subsequent cytolysis.

Related diseases

Cell death is part of the natural process of life. However, on some occasions this phenomenon can be caused abnormally by diseases that can endanger human life.

Cytolytic hepatitis

Cytolytic hepatitis is a liver disease caused by cell destruction. This condition causes massive damage to liver cells, endangering the life of those who suffer from it.

This disease, also known as "brutal hepatitis" can have different causes. It can be caused by alcoholic or viral cirrhosis, but it can also be caused by an overdose or an allergic reaction to a drug.

The main symptoms of liver damage are abdominal pain, nausea, vomiting, jaundice (yellowing of the skin), bleeding and even some neurological signs when the damage is very advanced.

The destruction of liver cells can be stopped if detected early. However, in some very serious cases it is necessary to resort to liver transplantation to avoid fatal consequences.

Cytolytic vaginosis

Cytolytic vaginosis is a condition that consists of the destruction of the cells of the vaginal walls. This disease is caused by an overgrowth of bacteria that are naturally found in the vagina.

Lactobacilli are bacteria that are found in low quantities in the vaginal flora of women of reproductive age. In fact, these microorganisms are considered essential for the maintenance of the normal pH of the vagina.

However, faced with certain hormonal or external conditions, an excessive growth of lactobacilli may occur. In these cases, this overpopulation of bacteria can cause cytolysis of the epithelial cells of the vaginal mucosa.

Therefore, the treatment of this disease consists of reducing the amount of lactobacilli present in the mucosa through medications. Usually, this procedure is enough for the cells to develop normally and the tissue to recover.

Strokes

Cytolysis has been shown to also occur as a consequence of a stroke. This occurs because the damage resulting from the accident results in a poor distribution of nutrients.

This distribution ends up affecting cell metabolism and generating too much fluids, which eventually degenerates into the destruction of some brain cells.

References

1. Health CCM. (SF). Cytolytic hepatitis. Recovered from: health.ccm.net
2. Med Friendly. (SF). Cytolysis. Recovered from: medfriendly.com
3. Study.com. (SF). Osmotic Pressure: Definition & Formula. Recovered from: study.com
4. Suresh, A. (2009). Cytolytic vaginosis: A review. Recovered from: ncbi.nlm.nih.gov
5. University of Bridgeport. (SF). Cytolysis. Recovered from: generativemedicine.org.