THE IMMUNE SYSTEM

Question 1

The immune system

Answer 1

The immune system is a collection of molecules, cells, tissues and organs that work together to defend the
body. The immune system defends the body against non-self elements (pathogens, foreign objects, tumor
cells and such).

Question 2

major histocompatibility complex (𝑀𝐻𝐶)

Answer 2

Every cell in the body contains an 𝐻𝐿𝐴-gene which codes for a protein marker called major histocompatibility complex (𝑀𝐻𝐶).
The 𝑀𝐻𝐶 marks the cell as a “self” cell, and prevents an immune response against it. Non-self cells contain different surface marker called antigens. Cells containing antigens trigger an immune response.

Question 3

Disease

Answer 3

Any disruption to the normal physiological function of the body (disruption of homeostasis).

Question 4

Pathogen

Answer 4

Infectious agents that trigger an immune response.

Question 5

Inflammation

Answer 5

The body’s response to any harmful stimulus. This response includes:

• Vasodilation.
• Increased permeability.
• 𝑊𝐵𝐶 mobilization.

Question 6

Signs and symptoms of Inflammation

Answer 6

• Heat.
• Swelling.
• Redness.
• Loss of functions.
• Pain.

Question 7

Infection

Answer 7

The invasion and proliferation of pathogens in the body.

Question 8

White blood cell (𝑊𝐵𝐶)

Answer 8

Cells of the immune system involved in defending the body.

Question 9

Antibodies (immunoglobulins)

Answer 9

Proteins that adhere to pathogens and neutralize them. 𝑌 shaped proteins; neutralize or mark for destruction.

Question 10

complement

Answer 10

A group of proteins activated by series of reactions and promotes inflammation, phagocytosis and cell lysis.

Question 11

An immune response can be dived into two types

Answer 11

• Cellular immunity – an immune response by cells.

* Humoral immunity – an immune response by circulating compounds.

Question 12

An immune response can be dived into two systems

Answer 12

• Innate immunity system – triggers and immune response in a general manner (non-specific
  immune response).
• Adaptive immunity system – triggers and immune response against a specific pathogen (specific
  immune response).

Question 13

White Blood Cells (𝑾𝑩𝑪)

Answer 13

White blood cells (leukocytes) – the cells of the immune system. These cells divide into two kinds:

1. Granulocytes – these are white blood cells (leukocytes) containing large granule in their cytoplasm.
2. Agranulocytes – these are white blood cells (leukocytes) that do not contain granule.

Question 14

Granulocytes WBC

Answer 14

Granulocytes are divided into 3 classes. These classes are determined by the hue of the cells after an
absorption of an inserted type of paint (very similar process to gram negative/positive in pathogens):
*Neutrophils
*Eosinophils
*Basophils

Question 15

Neutrophils

Answer 15

these are phagocytes cells, meaning they are fighting pathogens by engulfing them in order to neutralize the foreign object. Afterwards, they remove the remains of the foreign object outside of their membrane. These cell are part of the innate immune system. Neutrophils are 65% from all of the 𝑊𝐵𝐶, and they are having no paint. They are the first line of defense and have a
short life span.

Question 16

Eosinophils

Answer 16

They are characterized by a large, bi-lobed nucleus that resembles an old-style telephone receiver. The primary function of eosinophils is to respond to and destroy parasitic worms. 3% of the 𝑊𝐵𝑆 are eosinophils, and they are painted red. They also participate in allergic reaction and they have lobed nucleus.

Question 17

Basophils

Answer 17

These cells stimulate the start of the immune response by releasing molecules like histamine that start vasodilation, permeability and 𝑊𝐵𝑆 mobilization. Basophils are 1% from all the 𝑊𝐵𝑆, and they are painted blue.

Question 18

Agranulocytes WBC

Answer 18

Agranulocytes, which include lymphocytes and monocytes, are a type of white blood cell that, unlike granulocytes, lack visible granules.
agranulocytes are also characterized by a single, large nucleus (the nucleus is not lobed).
There are 3 types of agranulocytes:
*Monocytes
*Lymphocytes

Question 19

Monocytes

Answer 19

these are phagocytes antigen presenting cells; they kill a pathogen, and present its part on their membrane to the rest of the immune system (for the system to develop antibodies). These are the biggest white blood cells, and they are up to 6% of all of the WBC.
*Macrophage – these are monocytes that are active in tissues instead of roaming in the blood.

Question 20

Lymphocytes

Answer 20

Circulate in the blood and lymph fluids, but reside in lymphoid organs. Lymphocytes are around 30% of the 𝑊𝐵𝐶, and they are divided into 3 main types:

• 𝐵 cells
• 𝑇 cells
• Natural killer cells (𝑁𝐾 cells)

Question 21

𝐵 cells

Answer 21

A lymphocyte, produce and release specific antibodies to kill presented pathogens. Can also
produce memory cells that give us immune memory to trigger quicker response if we get
exposed to the same pathogens.

Question 22

𝑇 cells

Answer 22

A lymphocyte, divided to 3:
* 𝑇4 – also called 𝑇 helper cells. Have 𝑐𝑑4 protein on them. They bind to antigen presenting cells and stimulate the proliferation of proper 𝐵 cells. These cells
invoke immune response. These are also antigen presenting cells.
* 𝑇8 – cytotoxic 𝑇 cell that have 𝑐𝑑8 protein on them. They directly destroy
pathogens cells by secreting toxic chemicals. These cell destroy infected cells and
cancerous ones.
* 𝑇𝑠 – 𝑇 suppresser cells that suppress the immune system.

Question 23

Natural killer cells (𝑁𝐾 cells)

Answer 23

A lymphocyte, destroy viral infected cells and tumor cells. The only lymphocytes that are not a part of the adaptive immunity.

Question 24

Innate Immunity System

Answer 24

The basic response immune cells carry out without learning the pathogens. It is not specific response; it
attacks foreign objects equally with an immediate general non-specific attack.
* Non-specific response against pathogens.
* Antigen independent response.
* Maximal response against pathogens.
* Not antigen specific.
* No lasting immunity.

Question 25

Mechanism of defense of Innate Immunity system

Answer 25

- Anatomical - Cellular - Humoral

Question 26

Mechanism of defense of Innate Immunity system Anatomical examples

Answer 26

* Mechanical – like skin, mucus and coughing (expels things out the body). * Chemical – like stomach 𝑝𝐻, lysosomes in the saliva and tears and other secretions of the body. * Biological – like bacteria in the 𝐺𝐼𝑇 and flora of the skin.

Question 27

Mechanism of defense of Innate Immunity system Cellular examples

Answer 27

Neutrophils, Eosinophils, Basophils, monocytes/macrophagocytes and natural killer cells(𝑊𝐵𝐶 response).

Question 28

Mechanism of defense of Innate Immunity system Humoral examples

Answer 28

* Histamine – a compound release from basophils and 𝑀𝐴𝑆𝑇 cells which stimulates the inflammatory response. * Cytokines – a compound (protein) released from 𝑊𝐵𝐶 which regulates the immune response and involves in 𝑊𝐵𝐶 mobilization. They are intercellular communication molecule. * Clotting system: 1. Primary cloth – a clot is formed in response to endothelial injury. Platelet adhere together and form a platelet plug called. 2. Secondary cloth – coagulation factors intricate and form a fibrin patch above platelet plug. * Coagulation cascade – circulating proteins (𝐶1 −𝐶9) which form a membrane attack complex (𝑀𝐴𝐶) which destroys pathogens or marks them for phagocytosis.

Question 29

Adaptive (Acquired) Immunity System

Answer 29

An acquired response where immune cells learn to recognize and response to specific antigens. Triggers a specific response. * Specific response against pathogens. * Antigen dependent response. * Time lag response. * Exposure results in memory cells.

Question 30

Mechanism of defense of Adaptive (Acquired) Immunity System

Answer 30

* Cellular – lymphocytes produced in the bone marrow and mature in the thymus. * Humoral – 𝐵 cells produced in the bone marrow and mature in the spleen and lymph nodes. Antigens stimulate 𝐵 cells proliferation and upon activation they are called plasma cells that produce antibodies. 𝐵 cells produce memory cells that remain in the lymph nodes to be used again against another encounter with the specific pathogen.

Question 31

Immunization

Answer 31

The process by which the body becomes protected against a specific pathogen (has antibodies against that pathogen)

Question 32

Active Immunization

Answer 32

- crated naturally by disease or infection. - crated unnaturally by injection of weak or dead pathogen - The effect is Long due to creation of memory cells

Question 33

Passive Immunization

Answer 33

- Created naturally by pregnancy (comes from the mother). - Created unnaturally by Injection of antigens - The effect is short due to lack of memory cells.

Question 34

Pathology of the immune system

Answer 34

- Human immunodeficiency virus (𝐻𝐼𝑉) - Autoimmunity - Diabetes mellitus type 1 - Allergy - Leukopenia - Leukocytosis

Question 35

Human immunodeficiency virus (𝐻𝐼𝑉)

Answer 35

causes 𝐻𝐼𝑉 infection and 𝐴𝐼𝐷 (acquired immunodeficiency syndrome), transmitted by blood exposure to the pathogen, sexual intercourse and breast milk. This virus attacks 𝑇4 lymphocytes. The 𝐻𝐼𝑉 suppress the immune system, making the patients more susceptible to diseases. phages: 1. Acute – flue like illness. 2. Latent – carrier state. This phage last 3 to 10 years. 3. 𝐴𝐼𝐷 – death within 10 months.

Question 36

Autoimmunity

Answer 36

Destruction of healthy human cells by the immune system; occurs when it can’t distinguish between self and non-self cells.

Question 37

Diabetes mellitus type 1

Answer 37

Immune system destroys cells that are responsible for secreting insulin. Leads to the body’s inability to maintain constant glucose levels in the blood.

Question 38

Allergy

Answer 38

Immune system responds to a “false alarm” of normally harmless material like pollen of feed particles that are mistaken for a treat and trigger an immune response.

Question 39

Leukopenia

Answer 39

Decrease in the amount of white blood cells in the blood.

Question 40

Leukocytosis

Answer 40

Increase in the amount of white blood cells in the blood.

Question 41

Antigens

Answer 41

IgM – antigen that is presented in the blood when the body is exposed to acute disease. IgG – antigen that accounts for cell memory. It shows when exposed to old disease. It also contains the memory of all previous disease. IgA – defends the respiratory truck. It is a located antigen. IgE – antigen presented when being exposed to allergy of parasite.