Week 1- Infections and Immunity

Question 1

what is the difference between gram positive and gram negative bacteria?

Answer 1

Positive- singles cell membrane

Negative- two cell membranes and more resistant to antibiotics

Question 2

What are some of the RNA viruses?

Answer 2

Hepititis, Flu and HIV

Question 3

What are some examples of DNA viruses?

Answer 3

Varicella

Hepatitis b

Question 4

What is virulence?

Answer 4

the degree of pathogenicity- how fast it makes people sick and how sick and how large the infectious dose is.

Question 5

What are the stages of infection that a pathogen must go through?

Answer 5

• Infectious dose of pathogen penetrate the hosts defensive barrier
  -Micro-organisms enter sterol environment of hosts tissue
  Target tissue and cause disease
• Leave the host through exit portal to infect another host

Question 6

What is the first line non-specific defence?

Answer 6

Skin, mucous membranes, chemicals

Question 7

What is the non-specific second line of impunity defence?

Answer 7

Phagocytes, complement interferon, inflammation and fever

Question 8

what are the third line specific immune defences that the body has?

Answer 8

Lymphocytes and antibodies

Question 9

What steps must a pathogen undergo to infect a host?

Answer 9

Enter body- evade external barriers
Multiplication- Use body to increase numbers
Local or general speed in body- avoid phagocytes
Damage body- Evade immune and other defences to cause tissue damage
-Shed/exit- leave body in sufficient numbers to new hosts

Question 10

What are Exotoxins?

Answer 10

Proteins that are produced in pathogenic bacteria, most commonly in gram-positive that are then related after lysis and cause chemical damage to cells and tissues.

Question 11

What are Endotoxins?

Answer 11

Lipid portions of outer membranes of mainly gram-negative bacterial that are liberated when the cells are lysed and cell wall breaks apart. These then cause chemical damage to cells and tissue

Question 12

What changes can viruses cause in infected cells?

Answer 12

Cell swelling and bursting
cell fusion
carcinogenic changes

Question 13

What is the chain of infection?

Answer 13

Infectious agent
resivour
portal of exit
mode of transmission
portal of entry
susceptible host

Question 14

What are the phases of progression of disease?

Answer 14

Incubation period- pathogen reproduces to sufficient numbers
Prodromal period- onset of some symptoms
Period of illness- most severe signs and symptoms
Period of recovery- deciding of sings and symptoms
Period of convalescence- disease is gone

Question 15

What is a latent infection?

Answer 15

Where there is an initial infection and the virus move subsequently into the dorsal root ganglion and remain indefinitely. Later if there is immune depression there can be a reactivation of the virus

Question 16

What is a chronic infection?

Answer 16

After initial infection, with or without symptoms the virus may remain in the body which can become deadly later.

Question 17

What are the two internal defences agains infection?

Answer 17

Innate internal defences- Inflammatory response carried out by phagocytes within hours
Adaptive internal defences- immune response by lymphocytes carried out over a few days

Question 18

What is an antigen?

Answer 18

Large fringe chemical that is precent on the outside of virus/bacteria/microbes stimulates an immune response

Question 19

What are antibodies

Answer 19

Immunoglobulin proteins made by B-lymphocytes after contact with a specific (lock and key) antigen to inactive them through clumping them together and signal them for destruction

Question 20

What are the three types of cells that T-lymphoctes can transform into?

Answer 20

T-helper cells- help to produce antibodies with the B-cells
Cytotoxic T cells- able to destroy pathogen cells
T-memory cells remain in circulation in case of future infection

Question 21

What is active immunity?

Answer 21

Antibodies proceeded by a persons body

• Natural- pathogens enter the body in a natural manner
• Artificial- vaccines

Question 22

What is passive immunity?

Answer 22

Antibodies from another organism enter a persons body
Natural- cross from mother to baby
Artificial- injected into another person

Question 23

What is heard immunity?

Answer 23

Group immunity at a population level. Where the proportion of the population are immune to the disease so the disease is less likely to spread and come into contact with susceptible individuals.

Question 24

What are some common side effects of vaccines?

Answer 24

Local heat, swelling, pain, fever, chills, headache

Rarely anaphylaxis