quiz 5

Question 1

Location of lymphoid organs and tissues

Answer 1

• primary lymphoid organs: T-cell maturation (thymus) , B-cell maturation (bond marrow)
• secondary lymphoid organs: lymph nodes, spleen, tonsils, peyers patches in the intestine, appednix

Question 2

Types of immune cells in lymph nodes

Answer 2

• lymphocytes: b-cel and t-cell
• macrophages: engulf and digest pathogens and present antigens
• dendritic cells: antigen presenting cells that activate t-cells

Question 3

Thymus Vs Bone marrow function

Answer 3

Thymus: site of T-cell maturation and differentiation

Bone marrow: site of B-cell maturation , and production of all blood cells, including lymphocytes

Question 4

Nonspecific (innate) VS adaptive immunity

Answer 4

innate: first line of defense, non specific, includes physical barriers, phagocytes, inflammation

adaptive immunity: specific response, involves lymphocytes (B-cells and T-cells) and memory cells for long lasting protection

Question 5

lines of immune defense

Answer 5

1st. physical and chemical barriers

2nd. innate immune response

3rd. adaptive immune response (b-cells producing antibodies, T-cells targetting infected cells)

Question 6

PAMPS and PRRs in Non-specific immunity

Answer 6

PAMPS: molecuels found on pathogens

PRRS: receptors on immune cells that recognize PAMPS.

Question 7

Leukocyte Abundance

Answer 7

Neutrophils: 50-70%
Lymphocytes: 20-40
Monocytes: 2-8
Eosinophils: 1-4
Basophils 0.5-1

Question 8

Steps in inflammation

Answer 8

1. Injury/infection: pathogens enter the body
2. chemical signals: release of histamines, prostaglandins, and cytokines
3. vasodilation: bood vessels expand, increasing blood flow to the area
4. increased permeability: fluid proteins and immune cells leave the blood stream and enter the affected tissues
5. phagocytosis: macrophages and neutrophils engulf pathogens
6. Repair: tissue healing and regeneration.

Question 9

General Steps in Phagocytosis

Answer 9

1. chemotaxis: movement of phagocytes toward the site of infection
2. recognition and attachment: phagocytes recognize PAMPS on the pathogen
3. Engulfment: Pathogen is engulfed into a phagosome
4. Phagosome fusion: phagosomes fuse with a lysosome, forming a phagolysosome
5. digestion: enzymes in the lysosom
   e digest the pathogen
6. exocytosis: waste material is expelled from the phagocyte.

Question 10

Diapedesis

Answer 10

• Diapedesis is the process by which leuocytes move out of the capillaries and into the tissues
• This occurs in response to signals from pathogens and damaged tissues

steps:
1. rolling: leukocytes slow down and roll along the endothelial surface
2. Adhesion: leukocytes adhere to the endothelial cells through interactions between adhesion molecules
3. transmigration: leukocytes squeeze between endothelial cells and migrate into the tissue.

Question 11

Chemotaxis

Answer 11

• Chemotaxis is the movement of leukocytes towards the site of infection or inflammation in response to chemical signals
• Leukocytes follow a gradient of chemotactic factors, which are molecules that attract them to the site of infection.

Question 12

Chemotactic Factors

Answer 12

• Exogenous: derived from microbial sources
• Endogenous: produced by host cells.

Question 13

Exogenous Vs. Endogenous pyrogens

Answer 13

Exogenous:
- external substances that induce fever
- usually microbial products such as LPS from the outer membrane of Gram negative bacteria
- these trigger an immune response that leads to the production of endogenous pyrogens .

Endogenous:
- Produced by the body in response to infection or inflammation
- include cytoines such as interleukin (IL-6) (IL-6) and tumor facotrs
- these cytokines act on the hypothalamus to increase the bodys set point for temperature, leading to fever.

Question 14

Interferon (IFN)

Answer 14

A group of signalling proteins released by host cells in response to the presence of pathogens such as viruses, bacteria, and parasites.

1. Detection : cells detect the presence of viral RNA/DNA
2. Production: Infected cells produce and secrete interferons.
3. Signal transduction: Interferons bind to receptors on neighboring cells, triggering a signaling cascade
4. antiviral state: induced the expression of antivrial proteins:
   - inhibit viral replicaiton
   - enhance the degradation of viral RNA.

Question 15

Four cardinal Features of inflammation and reasons for their formation

Answer 15

1. Redness (rubor):
   - caused by the increased blood flow due to vasodilation of the blood vessels
   - mediated by histamines, prostaglandins, and other vasodilators released by injured tissues and immune cells
2. Heat (calor)
   - also due to increased by blood flow
   - blood carries heat from the core of teh body to the affected area, contributing to the warmth observed during inflammation
3. Swelling (tumor)
   - result of increased permeability of blood vessels
   - allows fluids, protiens, and leukocytes
4. Pain (dolor):
   - caused by the release of chemicals such as bardykinin and histamine
   - these chemicals sensitize nerve endings, making the affected area more sensitive to pain.

Question 16

Complement Protein Pathways

Answer 16

A part of the immune system that enhances the ability of antibodies and phagocytic cells to clear pathogens.

1. Classical pathway
   - part of the specific adaptive immunity
   - activated by antigen antibody complexes
2. MB-lectin pathway
   - part of innate immunity
   - activated by mannose binding lectin (MBL) binding to mannose residues on the surface of pathogens
3. Alternative pathway:
   - also part of the nonspecific immunity
   - activated directly by pathogen surfaces without the need for antibodies.

C proteins:
- complement proteins are synthesized in the liver
- they circulate in the blood in an inactive form
- upon activation, they trigger a cascasde leading to the formation of a membrane attack cmplex that can lyse pathogen.

Question 17

Lineages of white blood cells

Answer 17

Hematopoiesis:
- the process of forming blood cellular components
- occurs in the bone marrow

Lineages:
1. myeloid lineage
2. lymphoid lineage

Differnetiation
- all blood cells originate from the hematopoietic stem cells in the bone marrow
- HSCs differentiate into their myeloid or lympohid progenitor cells, which then further differentiate into various types of blood cells .

Question 18

Types of Anthrax and their causes

Answer 18

Anthrax: caused by bacterium bacillus anthracis

Types:
1. cutaneous anthrax
- infectino through cuts or abrasions on the skin
- most common form

2. inhalation anthrax
   - infection through inhalation of spores
   - most severe form
3. Gastorinestirnal Anthrax:
   - infection through ingestion of contaminate dfood or water
   -rare but serious
4. injection anthrax
   - infection through injecting drugs contaiminated with anthrax spores
   - rare and primairly seen in intravenous drug users

Question 19

Gangrene
- symptoms and causes

Answer 19

Gangrene: The death of body tissue due to a lack of blood flow or a serious bacterial infection

symptoms:
- discoloration of skin, red then black /brown
- severe pain follwe dby numbness
- severe pain followed by numbness
- swelling and formation of blisters filled with fluid
- fould smelling discharge

Gas gangrene
- cuaesd by cllostridium perfringens
- bacteria produce gas within tissue, leading to tissue death and systemic infection.

Question 20

Virulence factor of bacteria

Answer 20

Moleucles produced by pathogens that contribute to the pathogenicity and enable them to acheive
- colonization of the host
-evasion of the hosts immune response
-entry into and exit out of cells

Question 21

MRSA, Cellulitis, Folliculitis

Answer 21

MRSA
- stands for staph
- named for its resistance to methicillin and other beta lactam antibitoics

Cause: staph that have aquared resistance genes

Cellulitis:
- a bacterial infection of the skin and underlying tissues
- symtomps: redness, swelling, warmth, pain

Follicultis:
- inflammation of hair follicles, often cuased by a bacterial infection
- symptoms include red, swollen bumps that may be filled with pus

Question 22

Antigen (ag), Antibody (Ab), Epitope

Answer 22

Antigen:
- a substance that is recognized by the immune system as forgein
- can be proteins, polysaccharides, lipids, nucleic acids
- tiriggers an immune response

Antibody :
- proteins produced by B cells (plasma) in response to antigens
- specifically binds to anitvens to neutralize them for destruction
- 5 main classes of antibodies: IgM, IgA, I
gG, IgE

Epitope:
- specific part of the antigen that is recognized and bound by an antibody

Question 23

Hematopoiesis

Answer 23

• The process of forming blood cellular components
• occurs in the bone marrow
• all blood cells originate from multipotent hematopoietic stem cells.

Question 24

Plasma Cells

Answer 24

• differentiated B cells that produce large quantities of antibodies
• short lived but highly active in secreting antibodies to fight current infection

Question 25

Memory B Cells

Answer 25

- Long lived cells that remain in the body after an infection has been cleared. - provide rapid and robust antibody production upon re-exposure to the same antigen

Question 26

Effector T cells

Answer 26

- activated T cells that actively engage in elimnating infected cells or pathogens

Question 27

igM , igA, igD, igG, igE

Answer 27

M - first antibody produced in response to an infection A- found in mucosal area and in secretions. provides localized protection on mucosal surfaces D- found on the surface of B cells as a receptor. Involved in initiating B cell activation G: Most abundant antibody in blood and extracellular fluid. provides the majority of antibody based immunity against pathogens. E: involved in allergic reactions and defense against parasitic infections. binds to mast cells and basophils, causing them to release histamine.

Question 27

Memory T cells

Answer 27

- long lived T cells that persist after an infection has been cleared - provide a quicker and more effective response upon re-exposure to the same antigen.

Question 28

Number of antigen binding site per immunoglobin (Ig)

Answer 28

- each immunoglobin molecule has two antigen binding sites - these sites are located at the tips of the Y shaped structure of the antibody and are formed by the variable regions of the heavy and light chains.