Micro Lec 6

Question 1

1st line of defense

Answer 1

1) Physical barrier 2) Washing mechanism. 3) Chemical Factors 4) Normal Microbiota

Question 2

2nd line of defense

Answer 2

1) Inflamatory response 2) Fever 3) Antimicrobial substances

Question 3

Antigen

Answer 3

Foreign matter that invokes a specific immune response which is an acquired immunity. Most antigens are proteins or polysaccharides that are on the surface of invading microbes. Examples of nonmicrobial antigens are egg whites, shellfish, and wheat.

Question 4

Antibodies

Answer 4

proteins called immunoglobulins that are made in response to antigen. Binds to antigen help to 1) neutralize (prevent attachment to host cells) or 2) destroy antigen (activating 2nd or 3rd line of defenses). Most antibodies have 2 binding sites

Question 5

Ig G

Answer 5

makes up 80% of all antibodies in serum. Primary antibody found in the secondary immune response. Confers passive immunity to fetus. Can enter tissue.

Question 6

Ig M

Answer 6

Largest anti-body. 1st antibody to appear in response to antigen exposure (primary immune response) Can serve as a B cell receptor.

Question 7

Ig A

Answer 7

Most common antibody found in mucous membranes, saliva, tears, breast milk, and colostrum. Also found in serum.

Question 8

Ig D

Answer 8

Serves as an antigen receptor on B cells but exact function unknown.

Question 9

Ig E

Answer 9

Attached to specialized cells that participate in allergic reactions. Antigen binding leads to release of histamine which attracts Ig G and phagocytes.

Question 10

1) Physical barrier

Answer 10

skin and mucous membranes

Question 11

2) Washing mechanism

Answer 11

tears (eye), mucus (traps microbes), saliva (surface of teeth and mouth), earwax (ears), mucus (coated hair in nose), cilia in lower respiratory tract moves mucus up towards ciliary escalator which is throat and away from lungs, urine (genitourinary tract), and vaginal secretions

Question 12

3) Chemical Factors

Answer 12

sebum (produced by glands in stein which lowers pH in skin), lysozyme ( found in tears, perspiration, saliva, nasal secretions, cleaves glycosidic linkages between NAM and NAG units in murein, which weakens cell wall and leads to lysis) more effective in gram pos bacteria, Gastric Juice (lowers pH of stomach) , Lactoferrins (iron-binding proteins that keep iron away from microbes found in milk, saliva, tears, and mucus)

Question 13

4) Normal Microbiota

Answer 13

In utero all animals are free of microbes. During birth microbes start to colonize various parts of the body such as skin, eyes, nose, throat, mouth, large intestine, and urogenital tract. Normal Microbiota prevents growth of harmful microbes via microbial antagonism. Steps include 1) physically preventing adherence of pathogenic microbes by binding to and hiding host cell receptors. 2) competing for nutrients. 3) Producing substances toxic o invading microbes. 4) Affecting growth conditions such as pH and O2 availability. Sterile parts of the body are lungs, bladder, uterus, deep tissues, blood, brain, and spinal cord.

Question 14

1) Inflammatory response

Answer 14

cellular signals at the site of damage or infection which leads to the migration of phagocytic cells to the injured tissue, then leave the blood/ lymph to enter the infected tissue, then multiple, lastly attach to engulf and finally digest the pathogen. Phagocytic cells consist of macrophages (found in lymph) and neutrophils ( found in white blood cells)

Question 15

2) Fever

Answer 15

Normal body temp is 37 degrees Celcius set by the hypothalamus in the brain. An up in temp caused by cytokines and prostaglandins can intensify effect of antiviral proteins called interferons and increase tissue repair. Does not kill the microbe and after a certain point fever can be dangerous.

Question 16

3) Antimicrobial substances

Answer 16

1) Complement system- protein that initiate the inflammatory response can also form pores in microbial membranes and cellular content leaks out. 2) Interferons- small proteins that interfere with viral multiplication. 3) Transferrins- iron-binding proteins in blood cells to keep iron away from microbes. 4) Antimicrobial peptides- these small peptides can make microbial membranes leaky by either aggregating to form a pore or by interfering with lipid interactions. Also found in all tissues and on nearly all surfaces which is the 1st line of defense.