Lecture 17- Immune System

Question 1

Phagocytes

Answer 1

destroy pathogens by engulfing them, acidifying the phagolysosome and digesting the contents.

When phagocytes cannot ingest their targets, they may release chemicals that are lethal to pathoge

Question 2

Natural killer cells

Answer 2

function like T lymphocytes but are part of innate immunity.

They lyse and kill cancer cells and virus-infected cells before the adaptive immune response is activated.

Question 3

Inflammation

Answer 3

Occurs when body tissues are injured

Limits the spread of damage, disposes of debris and pathogens, alerts the adaptive immune system, and sets up repair.

four main signs of acute inflammation are:
redness
heat
swelling
pain.

Question 4

Pro inflammatory chemicals

Answer 4

Causes vasodilation and increased capillary permeability

Allows fluid containing clotting factors and antibodies to enter the tissues followed by neutrophils and macrophages

Question 5

Antimicrobial proteins

Answer 5

Enhance innate defences by attacking microorganisms directly or by hindering their ability to reproduce

Question 6

Interferons (IFNs)

Answer 6

small proteins produces by virus infected cells that help protect surrounding heathy cells by telling the tot make proteins that interfere with viral replication

Question 7

Complement cascade

Answer 7

Group of plasma proteins that Can assemble a membrane attack complex to kill a cell by punching a hole int he plasma membrane, making the cell leak

Question 8

Microbe associated molecular patterns

Answer 8

Often indicate something is trying to infect yo

Question 9

Adaptive defences

Answer 9

Recognize and destroy the specific antigen that initiated the response

Question 10

What does Adaptive immune response include?

Answer 10

Systemic response
Has memory
Includes both cellular immunity and humoral immunity

Question 11

Cellular immunity

Answer 11

Based on direct attack of microorganisms by T lymphocytes and has living cells as its protective factor

Question 12

Humoral immunity

Answer 12

Provided by antibodies present int he body’s “humours” or fluids produced by B lymphocytes

Antibodies are proteins that target and bind to extracellular antigens.

Clonal expansion ( mitosis) develops clones into plasma cells and the remaining cells into memory B cells.

Question 13

Clonal selection

Answer 13

Antigen binding with a particular lymphocyte selects that lymphocyte for further development

Question 14

Colonal expansion

Answer 14

producing a group of cells with an identical ability to bind this antigen.

Question 15

Effector cells

Answer 15

actively fight the infection.

Question 16

Memory cells

Answer 16

Respond quickly to future encounters with this antigen

Question 17

Antigen presenting cells (APCs)

Answer 17

phagocytose pathogens and present antigen fragments in major histocompatibility complex II (MHC II) molecules on their surfaces, where they can activate T cells.

Question 18

Dendritic cells

Answer 18

Located near external body surfaces (skin) phagocytose antigens and migrate to lymphoid organs to present antigens to T cells

Question 19

Macrophages

Answer 19

Found in lymphoid organs and connective tissues and present antigens to T cells

Question 20

B lymphocytes

Answer 20

Present antigens to T cells in order to become more fully activates B cells

Question 21

What are the two major groups of T cells based on cluster of differentiation?

Answer 21

CD4+ cells

CD8+ cells

Question 22

CD4+ cells

Answer 22

Helper T cells that activate B cells, T cells and macrophages, some are regulatory T cells hat inhibit overly aggressive responses

Activated by Class II MHC ( 2 X 4 = 8)

Question 23

CD8+ cells

Answer 23

Cytotoxic T lymphocytes that destroy cells or foreign substances

Activated by Class I MHC ( 1 X 8 = 8)

Question 24

Class I MHCs

Answer 24

found on all body cells except RBCs and display antigens synthesized from within the cell

if infected, may also include fragments of foreign antigens.

If cells mutate so they no longer produce MHC I, they will be destroyed by NK cells.

Question 25

Class II MHCs

Answer 25

only on antigen-presenting cells (dendritic cells, macrophages and B cells) and display antigen fragments from phagocytosis.

Question 26

Helper T cells

Answer 26

TH1cells- work with macrophages and CD8+ cytotoxic T lymphocytes to activate cell-mediated immune responses against intracellular threats.

TH2 cells- work with B cells, eosinophils and mast cells to stimulate B cell proliferation and increase antibody production against extracellular threats.

Question 27

What are the ways antibodies help fight off infection?

Answer 27

Neutralization

Opsonization

Complement fixation and activation

Question 28

Neutralization

Answer 28

occurs when antibodies block specific sites on viruses or toxins, causing them to lose their infectious or toxic effects.

Question 29

Opsonization

Answer 29

occurs when antibodies stick to antigens and make it easier for phagocytes to engulf pathogens.

Question 30

Complement fixation and activation

Answer 30

occur when complement proteins bind to antibodies attached to antigens and lead to lysis of the cell.

Question 31

Primary immune response

Answer 31

occurs on first exposure to a particular antigen, with a lag time of about 3-6 days.

The antibody titre in the blood rises, peaking in about 10 days, and then declines.

Question 32

Secondary immune response

Answer 32

occurs when someone is exposed to the same antigen for a second time.

Mobilization of B cells takes only a few hours and rises to a much higher peak concentration after only 2-3 days, producing antibodies with a higher binding affinity for the antigen, and can persist for weeks or months.