3/25/99

Microbiology II

 

Non-specific Defense Mechanism

1.      Anatomical

2.      Chemical nature

3.      Cellular Function

4.      Specific organs

·        Information from ch 17

·        Skin—needs to be intact; things cannot penetrate the skin to infect it except for the few worms that we have discussed

·        Fig 17.1 (p450)

·        Has antimicrobial substances that it produces

·        Sebaceous glands—sebum which is an acid oil; start producing at puberty; leads to acne

·        Sweat glands found in the dermis; watery from pores

·        Lactic acid from lactobacillus—acid pH of 3-5; pathogenic organisms are not likely to survive

·        First line of defense

·        Skin diseases and the skin is continuously broken the rate of infection is much higher ex:  psorhisis, exzema

·        Mucous Membranes

·        Found at various locations in our bodies

·        Delicate membranes

·        Penetratable by some microorganism (Syphillus and Treponoma pallidum)

·        Produce mucus that is a thick but watery secretion of glycoproteins and electrolytes

·        Removed from the body by the replacement of the mucous membranes every so often

·        Histological fig 17.2

·        Important in respiratory tract b/c of the ease that microbes can enter the system

·        PH (esp. in urinary tract) is important role; acidic at 5-5.5

·        Vit C is the pH lowering chemical

·        Fixed macrophages—trapping organisms the come across into the system

·        Table17.1

·        Neutrophils—phagocytosis, macrophages

·        Monocytes—phagocytosis, macrophages

·        Eye

·        Open and exposed to air that can carry many microorganisms

·        Anatomically, eye is made that they are kept free of infection w/o a low pH

·        Most important component is the lysozyme (enzyme) produced by normal cells, lacrimal gland, tears contain this

·        Eyelids moving

·        Always wet

·        Protected against physical damage

·        Eyes close at a rapid rate

·        Read p464-5

·        Ear

·        P 465

·        Anatomical organization protects it

·        Fig 17.12—Micrococcus luteus is lyzed by lysozyme

·        Inner ear infection is rare

·        Outer and middle ear infection is common in children (auditory tubes are shorter and wider)

·        As get older, wax formation traps microbes and the microbes do not make it to infect

·        Physical damage to ear can lead to infections further inside the head

·        Respiratory system

·        P465-6

·        Lowered infections by virtue of anatomical arrangement, chemicals,

·        Upper respiratory tract has many microbes

·        Lower respiratory tract is mainly sterile

·        Alcoholics and Pneumonia—applications block

·        GI tract

·        Better equipped than the respiratory tract

·