BIOL 100 Chapter 40-48: Module 4 Abstracts
40. Innate Immune System
• Immune system: innate and adaptive immune response of white blood cells
• First defense mechanism consisting of physical and chemical barriers of the surface
• Secondary defense mechanism through a process called inflammation
• Macrophages fight against microbial infection, are responsible for harmful particles and
You ever wondered what your life would be if you could not touch your breast or go play
with your friends. This was the story of David Vetter, the "boy in a bubble". He had no
immune system and died when I was 12 but never left his bubble until the day of his death.
To understand this we must remember that our body not only nourishes but we must also
be protected through a system of active defense. This system uses a mechanism of
regulation and recognition to distinguish between self cells and foreign agents. White cells
of the innate immune system are phagocytes and NK cells
We have three lines of defense: the first two are associated with the innate system and the
adaptive third. The first line is nonspecific and involves surface defenses are physical
barriers. The second occurs within the fabric and refers to inflammation.
The third line of defense consists of the human flora, consisting of fungi and bacteria that
established a symbiotic relationship with our body.
The skin is the largest organ in vertebrates, form 15% of the total weight in humans and its
primary function is to keep the water inside and outside microbes.
Additional input port of microbes and bacteria is by inhalation into the respiratory tracts,
secreting airway mucus to trap the microbes before they reach the warm, moist areas deep
in the lungs. The cilia of the respiratory mucosa drag these microbes to facilitate its
removal sneezing, coughing or swallowing into the gastrointestinal tract where the
stomach acid kills them.
Lysozyme is abundant in secretions such as tears; saliva and mucus will destroy the
bacterial cell wall polysaccharides and thus provides protection against infection.
Inflammation occurs as a consequence of infection accelerates the death of the microbes,
and changes in the walls of blood vessels that allow local additional molecules to pass from
the blood into the infected tissue, and dilate the capillaries and increase the blood flow.
This is very important because without inflammation the body could not heal wounds and
Have you ever wondered why we have a fever?
Although it is hard to believe fever is another defense mechanism of the body to treat
infections. Fever helps the body creating a less favorable environment for the growth of
microbes. Fever also stimulates phagocytosis and reduces levels of iron that bacteria need
What are phagocytes?
They are a type of cells kill microbes by ingestion, this process is called phagocytosis.
One of the most important phagocytes in our body is the macrophage to engulf anything
that looks abnormal including dust and infected cells.
41. Adaptive Immune System
• Key elements of successful immune defense are recognition, activation, and response
• Immune system organs lymphoid organs are divided into primary and secondary
• The cell mediated immunity using mediating T cells (activated macrophages)
• Humoral immunity works through the natural activation of B cells (antibodies) and
activation by vaccines
This system is more specialized than the innate, has the ability to recognize specific
bacteria. The adaptive system responds quickly after encountering a microbe like
remember previous encounters with microbes (chickenpox suffer through it alone once in
The adaptive immune system is closely related to the circulatory system, the immune
system cells that circulate blood throughout the body. This movement ensures that the B
and T cells are exposed to foreign antigens. Part lymphocytes 20-40% of the white cells of
the body and its total mass is equivalent to the brain or liver.
The most important processes are the adaptive immune system recognize, activate, and
quickly respond to unknown organisms.
What are the organs of the immune system?
Primary lymphoid organs were bone marrow and thymus where they mature B and T
lymphocytes, and where is the identification of antigens. When these lymphocytes have
matured migration occurs from the primary organs to the blood and secondary organs
(lymph nodes, spleen, etc.). In these secondary organs the lymphocytes keep dividing and
differentiate. The adaptive immune system operates primarily through secondary organs.
Microbes enter the blood stimulates an immune response in the spleen. All immune cells
originally derived from the bone marrow through a process called hematopoiesis. In bone
marrow B cells mature in the thymus and T cells.
Two fundamental adaptive mechanisms:
● Cellular immunity refers to surrounding macrophage antigens, and displays the
processed internally of them on its surface. This allows T cell recognition.
● Humoral immunity refers to an immature B cell is stimulated and mature when an
antigen binds to the surface of the receptor, a T cell cytokine release to help.
T cells are most important because without them we could not live. In the absence of B
cells, T cells are responsible. When a baby is born without T cells, the first weeks showed
no abnormalities, but later acquired infectious diseases and died in his childhood because B
cells cannot function without the help of T cells.
42. Infectious Diseases
• Microbial pathogens are bacteria, viruses, protozoa, and prions
• Host-microbe interaction depends on virulence factors and host immunity
• Sexually transmitted diseases, HIV / HPV
• Treatment and prevention of the disease by vaccination and antibiotic
Have you ever wondered why cold or flu sick when the weather changes? Well, the cause is
usually opportunistic pathogens are microbes that are in contact with the host or the
person is infected. Infectious diseases are diseases caused by the presence of a microbial
pathogen such as a bacterium, fungus, protozoan, virus, multicellular parasites and
modified proteins as prions.
What happens when a pathogen is in contact with the host? The pathogen can enter and
multiply or die if the host has a strong immune system.
Infectious diseases can be transmitted by various means such as fluids, body fluids,
contaminated objects and inhalation air. Some examples are: respiratory diseases
transmitted by sneezing or kissing, gastrointestinal disease caused by ingesting
contaminated food and sexual diseases by body fluids.
There are two vectors in the transmission of infectious diseases: biological and mechanical.
- The biological vector if the pathogen is located within it, (eg mosquito) and introduced
into the host.
- The vector is mechanical if only carries the parasite to the host (eg fly).
Virulence factors are molecules expressed and secreted by pathogens that help you adhere
to the host, evade the immune response of the same and feed him.
Other things you'll learn in this module are:
- H.Pylori bacteria, which causes gastritis and ulcers and it is considered that half of the
population in the world has.
- Sexually transmitted diseases, the virus HPV (human papilloma virus) disease is the most
common sexually transmitted.
- The prevention of these diseases, the role of antibiotics.
- And the recent emergence of swine flu which quickly became infected and was the cause
of approximately 17,000 deaths.