apoptosis mechanism

Apoptosis, also called programmed cell death, in biology, a mechanism that allows cells to self-destruct when stimulated by the appropriate trigger. Apoptosis can be triggered by mild cellular injury and by various factors internal or external to the cell; the damaged cells are then disposed of in an orderly fashion.

1. What are the four stages of apoptosis?
2. What are the two pathways of apoptosis?
3. What are the mechanisms of necrosis?
4. What are the causes of apoptosis?
5. What happens after apoptosis?
6. What are some examples of apoptosis?
7. What are the characteristics of apoptosis?
8. What does apoptosis mean?
9. What is the difference between necrosis and apoptosis?
10. What happens if necrotic tissue is not removed?
11. What are the first signs of necrosis?
12. How does necrosis start?

What are the four stages of apoptosis?

To illustrate these apoptosis events and how to detect them, Bio-Rad has created a pathway which divides apoptosis into four stages: induction, early phase, mid phase and late phase (Figure 1).

What are the two pathways of apoptosis?

The two main pathways of apoptosis are extrinsic and intrinsic as well as a perforin/granzyme pathway. Each requires specific triggering signals to begin an energy-dependent cascade of molecular events. Each pathway activates its own initiator caspase (8, 9, 10) which in turn will activate the executioner caspase-3.

What are the mechanisms of necrosis?

The triggers of cell necrosis are multiple (Fig. 1). Tissue ischemia and hypoxia (i.e., lack of supply of cellular energy sources and oxygen) deplete cellular energetic pools (energy starvation), followed by cellular ionic imbalance, mitochondrial alterations, and calcium overload.

What are the causes of apoptosis?

Apoptosis

• Apoptosis can be activated by stimuli coming within the cell, including cell stressors, such as hypoxia or lack of nutrients, and agents that cause damage of DNA or other cell structures. ...
• Other apoptotic pathways. ...
• Regulation of apoptosis. ...
• Elimination of unwanted cells is impaired in some types of tumors.

What happens after apoptosis?

Apoptosis is an orderly process in which the cell's contents break down and are packaged into small packets of membrane for “garbage collection” by immune cells. It contrasts with necrosis (death by injury), in which the dying cell's contents spill out and cause inflammation. Apoptosis removes cells during development.

What are some examples of apoptosis?

Examples of Apoptosis

• From Tadpole to Frog. A spectacular example of this is found in frog tadpoles, which destroy and re-absorb entire body structures as they undergo their transformation into frogs. ...
• Human Nervous System Development. ...
• Mouse Feet. ...
• Extrinsic Pathway. ...
• Intrinsic Pathway.

What are the characteristics of apoptosis?

Apoptosis is characterised by a series of typical morphological features, such as shrinkage of the cell, fragmentation into membrane-bound apoptotic bodies and rapid phagocytosis by neighbouring cells.

What does apoptosis mean?

A type of cell death in which a series of molecular steps in a cell lead to its death. This is one method the body uses to get rid of unneeded or abnormal cells. The process of apoptosis may be blocked in cancer cells. Also called programmed cell death.

What is the difference between necrosis and apoptosis?

Apoptosis and necrosis are two mechanisms involved in the cell death in multicellular organisms. Apoptosis is considered as a naturally occurring physiological process whereas necrosis is a pathological process, which is caused by external agents like toxins, trauma, and infections.

What happens if necrotic tissue is not removed?

While there is significant disagreement on the correct elocution of the word, the literature is clear that proper debridement is critical to propel wounds toward healing. Necrotic tissue, if left unchecked in a wound bed, prolongs the inflammatory phase of wound healing and can lead to wound infection.

What are the first signs of necrosis?

Early symptoms of necrotizing fasciitis can include:

• A red, warm, or swollen area of skin that spreads quickly.
• Severe pain, including pain beyond the area of the skin that is red, warm, or swollen.
• Fever.

How does necrosis start?

Necrosis can be caused by a number of external sources, including injury, infection, cancer, infarction, poisons, and inflammation. Black necrotic tissue is formed when healthy tissue dies and becomes dehydrated, typically as a result of local ischemia.