Lecture 41

Question 1

What physical aspects of skin enable it to act as a barrier against pathogens?

Answer 1

• tightly packed epidermis —-> pathogens can’t slip through
• exterior layer of dead cells —> dead skin cells are constantly shed and replaced
• high cell turnover —> pathogens on skin are removed when def skin is replaced
• dendritic cells —-> survey for pathogens and alert adaptive immune system

Question 2

What chemical aspects of skin enable it to act as a barrier against pathogens?

Answer 2

• sebaceous glands secrete sebum
• –> low pH - hostile environment for pathogens
• sweat glands secrete sweat - Salt
• –> hypertonic environment - dehydrates microbes
• Lysozymes - enzymes that breaks sown bacterial cell walls
• Antimicrobial peptides - forms porse in microbial membrane

Question 3

How do the bodies mucous membranes protect the body ?

Answer 3

• layers of mucus from goblet cell secretion trap microbes

- MUSCOCILARY escalator

Question 4

Where are mucous membranes found?

-what are mucus membranes?

Answer 4

Location = line all interior body surfaces of the body
e.g GI tract, Urogenital tract, respiratory tract
1-2 layers of epithelium –> tightly packed live, mucus producing goblet cells

Question 5

How does the respiratory tract act as a barrier?

- Mucocillary escalator

Answer 5

• sweeps mucous to mouth where it can be coughed up or swallowed so trapped microbes are degrade in the stomach

Question 6

How does the gastrointestinal tract protects us from pathogens?

Answer 6

• Low pH = hostile environment for pathogens
• Gall bladder produces bile
• digestive enzymes

Question 7

How does the urogenital tracts protect us from pathogens?

Answer 7

Urine flow = flushes out pathogens
High osmolarity = dehydrates bacteria
Lysozymes = breaks down cell wall

Question 8

How do tears protect us from pathogens?

Answer 8

Flushing action = washes away microbes
Lysozyme - breaks down bacterial cell walls
Drainage = swallowed

Question 9

What are the main characteristics of inflammation?

Answer 9

• Heat
• Redness
• Swelling
• Pain
• Loss of function

Question 10

What are granulocytes?
myeloid —– granulocytes
= innate immune system cells that phagocytose

Answer 10

• Neutrophils
• Basophills
• Eosinophils
• Mast cells
• Monocytes, macrophages & dendritic cells in periphery

Question 11

Damage to tissue by pathogens causes mast cells to release:

Answer 11

Histamines - vasodilaiton —->diapedesis

Prostaglandins & leukotriens —> vascular permeability

Question 12

How do neutrophils get from the blood stream to infected tissue?

Answer 12

• DIAPEDESIS
• increased blood flow
• blood capillaries bcm sticky, neutrophils still to capillary wall and moves from wall and into infected tissue
• phagocytose microbes and die forming puss cells