There are two major pathways that mediate apoptosis: intrinsic and extrinsic pathways. During extrinsic apoptosis, members of the TNF (tumor necrosis factor) superfamily (TNFSF) can induce cell death by binding to their cell surface receptors and activating a deathly signaling cascade causing extrinsic apoptosis.
How does apoptosis occur in neurons?
Neuronal apoptosis represents an intrinsic suicide program by which a neuron orchestrates its own destruction. During normal nervous system development, physiologically appropriate neuronal loss contributes to a sculpting process that removes approximately one-half of all neurons born during neurogenesis.
What causes neuronal cell death?
Later in life, inappropriate neuronal cell death may result from pathological causes such as traumatic injury, environmental toxins, cardiovascular disorders, infectious agents, or genetic diseases. In some cases, the death occurs through apoptosis.
Why is neuron death important?
Neuronal cell death (apoptosis) plays an important role in normal neural development. When a muscle is first innervated, far more than the normal adult number of neurons supply it. Some axons fail to reach their normal target, and cell death is a way of eliminating them.
What happens to a neuron when it dies?
When these neurons die, people lose their capacity to remember and their ability to do everyday tasks. Physical damage to the brain and other parts of the central nervous system can also kill or disable neurons. These neurons may still live, but they lose their ability to communicate.
Why do neurons die?
After decades of the molecular dissection of the mechanism, it is now acknowledged that, in most cases, neuronal cell death is the outcome after a neuron activates well-orchestrated programs in order to terminate its existence, a process that can be triggered by internal or external signals throughout the cell’s lifetime.
What kills neurons in the central nervous system?
Physical damage to the brain and other parts of the central nervous system can also kill or disable neurons. – Blows to the brain, or the damage caused by a stroke, can kill neurons outright or slowly starve them of the oxygen and nutrients they need to survive.
What happens to a new neuron in the adult brain?
These freshly born cells establish neural circuits – or information pathways connecting neuron to neuron – that will be in place throughout adulthood. But in the adult brain, neural circuits are already developed and neurons must find a way to fit in. As a new neuron settles in, it starts to look like surrounding cells.
What are the two types of cells in the nervous system?
The central nervous system (which includes the brain and spinal cord) is made up of two basic types of cells: neurons (1) and glia (4) & (6). Glia outnumber neurons in some parts of the brain, but neurons are the key players in the brain. Neurons are information messengers.
