Parts of the Nervous System.

The nervous system is made us of three different system sections. First is the Central Nervous System, or CNS. The CNS is central to the bodys systems and workings, and is composed of the brain and its chrif nerve, the spinal cord which runs along the inside of the backbone (vertibral or spinal column). Fron the CNS branches off 43 different nerve pairs 12 of which run form the brain and 31 from the spinal cord. As the pairs divide, they snake along among tissue and organs. Form here they part and form the PNS or peripheral nervous system. In the nervous system the CNS is the coordinator and decision maker. The PNS sends niformation as sensatory input and recieves instructions as output to glands and muscles. The third and last component that makes up the nervous systen is the ANS or autonomic nervous system which has some elements located in the CNS and also shares some nerves with hte PNS. The autonomic nervous system aslo has its own seperate nerve chains which run alongside the spinal cord. Is work is mosty 'automatic' meaning it deals with activities such as blood pressure and heart rate adjustment which are things we are rarely aware of.

Nerves and Neurons.

A typical neuron has a amin cell body that includes a nucleus, but a aneuron also has a wire like process that reache sout to transmit messages th other neurons which happens at junctions called Synapses. This process has two main kinds, Dendrites, which recieve messages from other neurons or nerve like cells in sense organs and conduct towards the cell body of a neuron. The other types are called Axons which convey messages away form the cell body of a neuron. Axons are longer and usually branch less than Dendrites which are shorter and branch out more aklong their length. To conclude, Neurons that are in the brain and spinal cord are protecetd and nurtured or fed by supporting cells called Glail Cells.

Neurotransmitters.

In addition, the most important part in understanding the nervous systems workings is the Neurotransmitters. When electrical impulses arrive at the body's synapses, they trigger the release of different chemicals. The Neurotransmitters cross the Synaptic Cleft which is an incredibly thin gap, between Presynaptic membranes which send the chemicals , and Postsynaptic or recieving neurons. With the chemicals there now is either a new impulse in the neuron that recieves (postsynaptic) or the chemicals will inhibit the neuron form firing more chemicals.

Acquired Immunity.

With the human immune system, Innate Immunity is only the body's first defense. There are always cases where bacterial pathogens get past our first blocking immune defenses. When the pathogens do get past our first defenses, internally, we still do have other defenses. With acquired immunity, the pathogens have already entered the system and have started to affect the system, thus creating sickness. What the body now does starts with the blood cells. When the pathogens are identifided with the antigens, our white blood cells start to produce antibodies. Our antibodies climg onto the pathogens, grouping them togeter until they can safely be dissolved or eaten by other cells.

Immunity.

When the immune system is fighting bacteria, the first defense put up is called Innate Immunity. The first step to innate immunity is the prevention of bacteria entering the system. When preventing the entry of bacteria your skin is dead, so when there is bacteria on your skin, it prevents anything from passing through. Another way of preventing the entry of bacteria is mucus. All of the openings on our bodies have mucus. For example, at the opening in your ear. In your ear, the mucus you have is called wax. Just like the other mucus in your body, it is kind of gooey and sticky, which is how it helps with defense. When pathogens gets near or have contact with your ear wax or other mucus, it traps the pathogens. The last way our body prevents he entry of disease or sickness is with bacteria. Inside our tracts, we have bacteria that destroy different pathogens. For example, in the digestive tract, we have a bacteria called salmionilla. When pathogens go through or enter the digestive tract, the salmionilla helps by destroying them, while on the other hand, if we ingest salmionilla and it enters the stomach, it can be very dangerous, and sometimes can even be fatal. The second half of Innate immunity is destroying pathogens if they get into our tissue or blood. The first thing our system uses to destroy the infecting pathogens are Neutrophilis, or white blood cells. When the pathogen enters the body, they sense it, and so they rush to the location of the pathogen then surrounding, engulfing (eating) and destroying them. The second part of the elimination are Macrophages, which enter the site of the pathogen and Neutophilis and start destroying hte pathogens. In addition, when there is infection, inflimation or swelling can occur. When this happens it is the trapped pathogens and the ones who are killing them.

Cells In The Human Immune System.

The human immune system is not made up of different major organs, instead, it is made up of different kinds of immune cells. First, in the body there are many white blood cells, called Lymphocytes. When a perticular pathogen enters your system the immune system is notified by its antigens. This is where the Lymphocytes come in. When the immune system is aware of an intruder, the white blood cells react by releasing antibiodies, which are "Y" shaped tolls designed to immobilize the intruding pathogen until other cells can break them down.

The Immune System

When bacteria enters the human body, the immune system is what helps with the elimination of germs. First, for example, if there is a small cut on the surface of your skin, bacteria enters it. Every cell in the body and every pathogen that invades the body has special makers on its sufcae called Antigens. Antigens are markers that tell the immune system if it is part of the body. The first time a pirticular pathogen enters the body, it Antigen marker alerts the immune system that it does not belong. It is the first time that a certain bacteria enters the body that might cause sickness. The reason for this, is since it has never been identified before, it might take a bit londer for the white blood cells to produce enought to quickly eliminate the bacteria before it has a chance to affect the body. After the bacteria has been identified for the first time, there are extra antibodies that were released by the white blood cells so when it enters your system the next time, there is defense ready to help eliminate it much more quickly. The white blood cells that release the antibodies are called Lymphocite cells. Antibodies are 'Y' shaped tools that are designed so that its ends fit on the antigen marker of a cretain bacteria.
http://http://videos.howstuffworks.com/hsw/6074-disease-defense-the-immune-system-video.htm

The Human Digestive System

The human Digestive System is one of 11 systems in the body. When it comes to the digestive system, there are differents steps apart from digestion in the stomach. First, digestion of food, starts in the mouth. Your teeth are the first step to your digestion of food; they start with chewing your food into small bits that are easier to be moved through your asophagus. Also in the mouth saliva helps digest you food because it contains ensymes that slowly help break down your food while is traveling toward the stomach. From the moth, when you swallow your food, it slowly travels down your esophagus and into your stomach. In the stomach, you have an acid that breaks down the protein in your food. From the stomach, food travels through the intestines and eventually is ro\emoved form the body.