The importance of Apoptosis

This is a term that I heard before, and that now after reading more about it, I decided to write of the term Apoptosis, what it means, and how this process develops.
Apoptosis is a program mechanism of cell death, every cell has a time to live and die, and there are two ways in which they die, by injury or suicide.
If a cell is damage by injury or a toxic substance, the its call necrosis. If this is the case they undergo a seeries of changes, like, they swell becasue of the ability of the plasma membrane to control the passage of ions and water is disrupted. Also, the cell contents can leak out, causing inflammation of the surrounding tissues.



If a cell is induced to commits suicide then it is call apoptosis. When this happens cells shrink, have their DNA and protein in their nucleus degraded, have their mitochondria break down with the reales of cytochrome c. In mammalians cells release ATP and UTP.
These nucleotides bind to receptors on wandering phagocytic cells like macrophages and dendritic cells and attract them to the dying cells.
The phospholipid phosphatidylserine, which is normally hidden within the plasma membrane, is exposed on the surface.
This "eat me" signal is bound by other receptors on the phagocytes which then engulf the cell fragments.
The phagocytic cells secrete cytokines that inhibit inflammation.
There are two reasons why cells commit suicide. One is that there is a need to destroy cells that represent a threat to the organism. And second, is needed for proper development as mitosis is.
Some examples of cell that represent a threat to the integrity of the organism are:

• Cells of the inmune system
• Cells infected with viruses
• Cells with DNA damage
• Cancer cells

For cells to survive they will need stimulation from other cells, and continued adhesion to the surface to which they are growing. Here is a video that will help explain more the concept of apoptosis as well as necrosis.

Neurotransmitters

Neurotransmitters are chemicals that a neuron releases and allow the transmition of signals to another neuron across synapses. There are many neurotransmitters, but here we will mention just some of those.

Acetylcholine it is a chemical similar to an amino acid, it was the first one discovered in 1921 by Otto Loewi, who won a Nobel Prize for his work.Acetylcholine is responsible for the stimulation of muscles. there are some poison in plants that cause paralysis by blocking the acetylcholine receptor sites of muscles cells.

Norepinephrine is associated with bringing the nervous system in high alert, increased the heart rate and blood pressure. With stress our levels of adrenaline goes down, while exercise increase it. Some amphetamines like speed, cause the release of norepinephrine, as well as dopamine and seratonin.

Purines are chemicals that include adenosine and its derivatives.

Nitric oxid is a gas released by small local neurons, which in large quantities can be poisonous. Although it is difficult to make in laboratories, many neurons have the enzyme to make it efficiently, and they can released nitric oxide when are stimulated.

Here is a small video aboout neurotransmitters that I found to be very easy to understand their functions.

The Structure of a Neuron

In the past it was believed that neurons were somehow connected to one another, but after the 1900's this concept changed and it was possible to see that the  brain was composed of individual cells.
It is very difficult to know the amount of nervous cells or neurons that are in humans because of their difference in size and density. Neurons are in charge of recieve and give information to other cells in the body, their specialty is carry messages through an electrochemical process across the body.
Neurons like other cells are surrounded by a membrane, have a nucleus, as well as mitochondria and other organelles.

Neurons are different from other cells because they have extensions called dendrites and axons. Dendrites specialized in recieved incoming information. Axons take information away from the cell body.
One curious note that I found is that neurons are the longest and oldest cells in our bodies. We have many cells in our bodies that die and are replaced during our lifetime, but many neurons are never replaced when they die.

Comparison on brain size between men and women

In the book they talk about the differences in brain size between men and women. Not sure if I got this correctly, what I undestand is that men have bigger brain size than women, but they both have equal IQs. Men have more white matter (axons) and both sexes have about the same number of neurons (gray matter) even though men's brain is bigger than of women.
Another interesting point is that men think they are better at certain things, when in fact, women are just not interested in some of the activities that men think are better than us... That was a great point!

I decided to read a little further because it is an interesting topic for me. I found a great article on this subject and I will give you all the link to this page. One thing that I learned is that brain size decreased with age in men over the age span of 25 to 80 years, but age hardly affected brain size in women.... That explain some things :)
I found a very good video that helped a lot with this concept of brain size between male and female, it talked about testosterone and many other things, it is very interesting. I hope it will help you as well as it did to me .