Immune System The immune system is the body’s defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade body systems and cause disease The main way that your skin protects you against disease is through acting much as armor does to knight. The skin creates an impermeable layer that separates your body’s internals from the disease causing bacteria and viruses outside of you.
Of course, a break in the skin barrier can allow disease to make its way into the body, but as long as the skin is free of cuts or open sores, foreign invaders are unable to get in. The skin also protects you from diseases by shedding on a regular basis. Although disease causing bacteria and viruses are unable to get through the skin to infect you without help from an opening or sore, they can attach themselves to the skin. Your skin is constantly making new cells and shedding old ones.
When the dead skin cells are shed off your body to make room for the new cells, the bacteria and other disease causing agents fall of with the skin cells as well, removing them from the body Nonspecific like the skin, it designed with and acidic surface that, for the most part, repels bacteria. Specific immunity has to do with how our lymphocytes (specialized white blood cells) can remember a specific virus or bacteria, and the next time it shows up. There are two types of specific immune system responses: cellular and humoral immune responses.
T cells destroy body cells that are infected with pathogens. B cells produce proteins that inactivate pathogens that have not yet infected a body cell A vaccination cause your body to become immune to whatever the vaccination is for. A vaccination is a shot that helps you fight off an infection or viruses, while immunity is your body fighting off your own body. During an allergic reaction the immune system turns its defense against a substance that does not normally cause disease, one that is ignored by the immune system of people without allergies, resulting in the symptoms of allergies.
Autoimmune disease is a group of more than 100 diseases where the body’s own immune system gets confused and starts to attack your good body cells. Respiratory System The lungs are paired organs that lie on either side of the heart and fill up the thoracic (chest) cavity. Inferior to (below) the lungs is the diaphragm, a broad thin muscle that separates the thoracic cavity from the abdominal (gut) cavity. On the medial (inner) surface of each lung is the hilus, where blood vessels, nerves, and bronchi (air passages) enter the lungs. The lungs differ in size and shape.
Because the heart is slightly larger on the left side, the left lung has a cardiac notch (indented border). The left lung is also slightly smaller than the right. Each lung is divided into lobes (partitions) by fissures. The right lung has three lobes: lower, middle, and upper. These horizontal and oblique fissures create these lobes. The left lung has upper and lower lobes that are divided by the oblique fissure. Air enters the body through the mouth or nose. In the nose, thick hairs lining the nostrils prevent small objects from entering the nasal cavity.
This cavity is lined with cells that produce mucus. Small foreign matter that enters the nasal cavities is trapped in the mucus, while tiny cilia (small hair-like projections) push the mucus to the pharynx (throat), where it is swallowed and digested in the stomach or expectorated. From the pharynx, the air passes to the larynx, which is called the voice box because it contains the vocal cords. To prevent food or liquid from entering the larynx, the epiglottis (a small flap of tissue) closes over the opening of the larynx during deglutition (swallowing).
If this process works improperly, a cough reflex expels the foreign material. When air travels past the larynx, it enters the trachea (windpipe). The trachea is a strong tube containing rings of cartilage that prevents it from collapsing. The mucosa that lines the airway warms and moistens the air before it reaches the trachea. Within the lungs, the trachea branches into a left and right bronchus, which divide into increasingly smaller branches called bronchioles. The smallest bronchioles end in a cluster of air sacs, collectively called an acinus.
The acinus comprises individual air sacs called alveoli. Alveoli are like small balloons that inflate and deflate with air during respiration. When you inhale, the muscles of the rib cage contract, causing the rib cage to expand. The diaphragm then flattens and moves downward. The volume of your lungs increases, and the air pressure decreases, falling below the air pressure outside your body. When you exhale, the rib cage muscles relax, and the rib cage becomes smaller. The diaphragm also relaxes, causing it to rise and regain its domelike shape.
Now the air pressure inside your lungs is greater than the air pressure outside your body, so air flows out. Breathing rate is controlled by certain nerves in the brain stem. These nerves automatically send impulses to the diaphragm, to speed up breathing, when your carbon dioxide levels increase in the blood. When you inhale, air fills the alveoli and oxygen passes from the alveoli through a semipermeable membrane and into the capillaries, leading into the bloodstream. During the same process, carbon dioxide is outgassed from the blood to the alveoli, and exhaled