Transcript
infection: The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body. An infection may cause no symptoms and be subclinical, or it may cause symptoms and be clinically apparent. An infection may remain localized, or it may spread through the blood or lymphatic vessels to become systemic (bodywide). Microorganisms that live naturally in the body are not considered infections. For example, bacteria that normally live within the mouth and intestine are not infections.
Bacteria are microscopic living organisms, usually
one-celled, that can be found everywhere. They
can be dangerous, such as when they cause
infection, or beneficial, as in the process of
fermentation (such as in wine) and that of
decomposition.
White blood cells (WBCs), also
called leukocytes or leucocytes, are the cells of
the immune system that are involved in protecting
the body against both infectious disease and foreign
invaders. All white blood cells are produced and
derived from multipotent cells in the bone
marrow known as hematopoietic stem cells.
Leukocytes are found throughout the body,
including the blood and lymphatic system
How many white blood cells are in the human body?
In normal adult bodies there are 4,000 to 10,000 (average 7,000)
white blood cells per microliter of blood. If the number of white
blood cells in your blood increases, it is a sign of an infection
somewhere in the body.
Neutrophils are active in phagocytosing bacteria and are present in large amount in the pus of wounds. These cells are not able to renew their lysosomes (used in digesting microbes) and die after having phagocytosed a few pathogens. Neutrophils are the most common cell type seen in the early stages of acute inflammation. The life span of a circulating human neutrophil is about 5.4 days.
Let B(t) denote the number of bacteria in a wound
and N(t) the number of neuthrophiles. The bacterial
growth factor is a [bacteria/hour] and the killing
factor of the neuthrophiles b [bacteria/hour] and
assume that the entry rate of new neuthrophiles is u(t)
[neuthrophiles/hour].
We Simulated the system in Simulink with a = 3,b = 1.1,g = 1.5, and
with initial conditions B(0) = 100, N(0) = 0 and let u(t) be a step
with magnitude 10. What happens if a becomes large (> 8)?
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