BSI 2 Lecture 4: Immunology 1 Flashcards
Why does the skin provide an excellent barrier?
The outer epidermis, which is composed of dead keratinized skin cells with plenty of tight junctions to limit access between them, is hard to penetrate unless broken or cut.
Where do skin secretions come from?
Mainly hair follicles (sebaceous glands)
How do skin secretions protect us?
The secretions have a low pH and contain lactic and fatty acids which inhibit bacterial growth
True or False? Non-hairy skin is more susceptible to bacteria.
True
What enzyme does sweat, tears, saliva, and some nasal secretions contain?
Lysozyme
What does the enzyme lysozyme do?
It is capable of destroying the cell walls of certain bacteria
What else in sweat may help with destroying the cell wall of certain bacteria?
Saline
What secretes ear wax in the external auditory canal?
modified sweat and sebaceous glands
What does ear wax do?
It traps dust particles and repels insects
How does mucus work?
It’s viscosity allows it to trap organisms and expel them through coughing or sneezing before they adhere in the body. It also contains antimicrobial peptides.
How does urine and vaginal secretions aid in protecting our bodies?
They tend to wash potential pathogens away
What happens to the vaginal secretions once menstruation begins?
They become slightly acidic which inhibits bacterial growth
When the vaginal secretions turn slightly acidic, what is the negative aspect?
It favors fungi/yeast growth which leads to infection
What does semen contain that is lethal to some pathogens?
Spermine and zinc
What is the main defense for the GI tract?
Stomach acid which has a pH of about 1.5 due to HCl secretion plus pepsin. This kills virtually all pathogens entering the GI tract
