Immune System

Question 1

What are non specific defence mechanisms?

Answer 1

.Protect us from a variety of microbes and foreign substances by providing a general response to destroy pathogens

.They do not provide exact recognition of the pathogens and they do not produce the specific antibodies

Question 2

What are specific defence mechanisms?

Answer 2

.Used against specific pathogens, they involve the formation of antibodies.

.Usually referred to as the immune response

Question 3

What are the 4 different types of non specific defence mechanisms?

Answer 3

.Defence at body surfaces
.Phagocytosis
.Natural anti microbial substances
.The inflammatory response

Question 4

What is phagocytosis?

Answer 4

.The process of cell eating

.Phagocytes such as neutrophils are attracted to sites of infection

.Adherence is the attachment of the phagocytes to pathogens

Question 5

What are the natural antimicrobial substances?

Answer 5

.Hydrochloric acid: kills ingested microbes

.Lysozyme: protein with antibiotic properties, found in tears and other body secretions

.Interferlns: prevent viral replication within the cells

.Complement: a system of about 20 proteins, their function is to stimulate phagocytosis

Question 6

What is the inflammatory response?

Answer 6

.Purpose is protective: to isolate, inactivate, and remove both the causative agent and damaged tissue so that healing can take place.

Question 7

What are specific defence mechanisms?

Answer 7

.Known as immunity
.The cell involved is the lymphocyte.
.Lymphocytes are further processed to make two functionally distinct types:
-T-Lymphocytes
-B-Lymphocytes

Question 8

What are T lymphocytes

Answer 8

.Processed by the thymus gland
.Thymosin promotes the production of T-lymphocytes
.A mature T cell will only recognise 1 type of antigen and will regale directly to that antigen and ignore any others
.This is known as cell mediated immunity

Question 9

What are B lymphocytes?

Answer 9

.Processed by bone marrow
.Produces antibodies
.Also target one specific antigen
.The released antibody reacts with one type of antigen only
.Known as antibody-mediated immunity

Question 10

Stages of cell mediated immunity

Answer 10

1. T-lymphocytes activate in thymus gland and release in the blood stream.
2. Encounter antigen and become sensitive to it
   3.If antigen is from outside the body, it needs to be presented to the TCytes by an antigen presenting cell.
3. Microphages are antigen-presenting cells(they engulf antigens)
4. When the antigen comes in contact with the TCytes, it stimulates their division and expansion.
5. Three different types of Tcytes are produced

Question 11

What are the three different types of T lymphocytes produced in cell mediated immunity?

Answer 11

.Memory T-Lymphocytes: Remembers the antigen so response is quicker.

.Cytotoxic T-Lymphocytes: Attach themselves to target and kill the antigen

.Helper T-Lymphocytes: most common and most important type. They produce substances that promotes cytotoxic T cells and macrophages. They also alter B-Lymphocytes to make antibodies

Question 12

Stages of antibody-mediated immunity (B Lymphocytes)

Answer 12

.B-Lymphocytes are fixed in lymph tissues
.Can perform their function without antigen presenting cell; they detect and attack the antigen directly
.After attaching to the antigen (with the help from helper Tcytes) they become bigger and start to split.
.As a result, plasma and memory B cells are produced

Question 13

What are Memory B cells

Answer 13

.Remain in the body after the initial attack and rapidly respond to another encounter with the same antigen by stimulating the production of antibody-secreting plasma cells.

Question 14

What are Plasma Cells

Answer 14

.Without leaving the lymphoid tissue, plasma cells produce antibodies and release them into the bloodstream to attack antigens.
.They only produce one type of antibody to attack only one type of antigen.

Question 15

What is acquired immunity?

Answer 15

.Antibodies can be detected in the blood about 2 weeks after encountering antigens.
.This response can be enough to kill antigens.
.The more encounters with an antigen the higher amount of antibodies.

Question 16

What is active immunity

Answer 16

.When an individual responds to an antigen and produces their own antibodies, lymphocytes are activated and memory cells have been formed to provide long lasting resistance.

Question 17

What is passive immunity

Answer 17

.Means the individual is given antibodies produced by someone else. The antibodies are then destroyed unless the lymphocytes are stimulated.
.Passive immunity is short lasting

Question 18

What are the 4 different types of acquired immunity?

Answer 18

1- Naturally acquired active immunity: the use of B cells and T cells, plasma and cytotoxic cells.

2.Naturally acquired passive immunity: Transfer of antibodies from the mother to the foetus through placenta or breastfeeding

3. Artificially acquired active immunity: introduced during a vaccination, stimulate cell mediated and antibody mediated immune response.
4. Artificially acquired passive immunity: IV injection of antibodies.