Immune responses

Question 1

Define the immune system

Answer 1

Defence mechanism designed to combat microscopic enemies by recognising, disabling, disposing and remembering them

Question 2

What body structures protect us ?

Answer 2

Stomach acid, nose hairs, skin, sputum

Question 3

What are the immature, innate physical barriers in infants ?

Answer 3

Skin - higher PH levels (6.6)
GI tract - produce small amounts of gastric acid, increases around 3 weeks, at birth GI tract sterile
Respiratory tract - length is shorter, IgA levels initially low
Urinary tract - Inability to maintain hygiene and short urethra (increased infection risk)

Question 4

What is a neutrophil ?

Answer 4

Produced in bone marrow, part of WBC. First responders in accute inflammation in innate immunity. They are phagocytic (surround and engulf germs)

Question 5

What is a monocyte ?

Answer 5

Produced in bone marrow. Part of WBC. Transorm into dendritic cells (alert) and macrophages (phagocytic)

Question 6

What is a macrophage ?

Answer 6

Mature forms of monocytes that have migrated into tissues. Play a role in innate and adaptive immune responses. Phagocytic and secrete cytokines which trigger inflammation and activate other immune cells.

Question 7

How do macrophages heal damaged tissues ?

Answer 7

Clear dead cells and debris

Question 8

What do macrophages produce which causes chronic inflammation ?

Answer 8

a lot of the tissue damage

Question 9

What doe basophils and eosinophils do ?

Answer 9

Defend against parasitic worms and ticks which are too big to be engulfed by neutrophils and macrophages. Involved in allergy and form minor component in WBC count

Question 10

What are lymphocytes responsible for ?

Answer 10

Adoptive immune response via 2 different types of cells

Question 11

What are the 2 types of lymphocytes ?

Answer 11

B cells and T cells

Question 12

What do B cells do ?

Answer 12

Produce antibodies (proteins targeting viruses etc). When antigen attaches to B cell receptor, B cell is stimulated.B cell learns to recognise different antigens and to produce specific antibodies to attack each one

Question 13

What do T cells do ?

Answer 13

Mature in thymus gland during childhood, released into blood semi mature (not encountered antigen - invading microorganism). They control body immune response and directly kill infected cells.Cytotoxic - attach to antogens and eliminate them by creating holes in cell membrane and inserting enzymes.
Helper - help B cells produce antibodies and activate cytotoxic cells.
Suppressor - produce substance to regulate immune system response
Memory - recognise antigen from past exposure and prevent repeat infections.

Question 14

What is a NK lymphocyte cell ?

Answer 14

Natural killer cell that has small particles that contain enzymes with ability to eliminate tumour cells or cells infected with a virus

Question 15

What is a mast cell ?

Answer 15

Found in tissues, role in immunity against parasites. Contains granules of histamine. involved in acute inflammation and allergy

Question 16

What are dendritic cells ?

Answer 16

Present in tissues and lymph nodes. Display fragments of microorganisms (antigens) on their surface which helps to activate T cells. Also called antigen presenting cells

Question 17

What are Langerhans cells

Answer 17

Antigen presenting cells found in the skin

Question 18

When does the adoptive immune response start ?

Answer 18

when innate response is unsuccessful. Approx 4 days

Question 19

The adoptive immune response is controlled by what ?

Answer 19

Lymphatic system, cell debris and microorganisms drained into lymphatic vessels and taken to local lymph nodes where AIR is stimulated

Question 20

What are antibodies ?

Answer 20

Also called immunoglobulins are Y shaped protein molecules that help to fight against foreign antigens.

Question 21

What is an antigen ?

Answer 21

Any substance that stimulates immune system to produce antibodies.
Bacteria, virus, fungi

Question 22

Describe the B cell response to AIMIR

Answer 22

Diversity of B cells, different B cells have different receptors for different types of antigens.
Encounter antigen, B cell produces clones. Some produce antibodies to destroy pathogens. Some mature into B memory cells and get stored in lymph nodes to respond to future infection of the same antigen. May need a T helper to become active.

Question 23

What is a B cells war strategy ?

Answer 23

Recognise enemy )B cell receptor)
Receive signal for activation -
show antigen to CD4 T cells
recognise multiple crosslinking

Question 24

What do B cells transform into ?

Answer 24

Plasma cell (secretes antibodies)
Memory B cell (fast recognition in the future)

Question 25

What are antibodies ?

Answer 25

Produced by plasma cell, established from B cell. Unique cell with 1 specific antigen binding site capable of binding to 1 specific antigen.

Question 26

Antibodies of the same class are called what ?

Answer 26

Immunoglobulins

Question 27

What are the 5 different classes of immunoglobulin ?

Answer 27

IgA, IgD, IgE, IgG, IgM

Question 28

What are the 3 different activities antibodies do ?

Answer 28

Neutralisation, opsonisation, complement fixation

Question 29

What is neutralisation ?

Answer 29

Coat pathogen to prevent it from interacting with host cell surface

Question 30

What is opsonisation ?

Answer 30

Coat pathogen to attract and encourage phagocytic cells

Question 31

What is complement fixation ?

Answer 31

Coat pathogen to activate the complement system of blood proteins to kill the pathogen

Question 32

Describe the T cell mediated immune response

Answer 32

Invading organisms engulfed by antigen presenting cells, macrophages and dendritic cells The ACPS move to local lymph node and present the antigen to naïve T cells. Cloning then commences

Question 33

Describe what is involved in the T cell cloning process

Answer 33

T helper cells activate B cell processes, calls other inflammatory cells, regulates processes, stop autoimmunity T cytotoxic cells kill infected cell by introducing toxic proteins

Question 34

What are the cell toxic proteins in the cloning process ?

Answer 34

Perforin )forms hole in target membrane) Gransymes (reprogrammes cell to die early, inducing apoptosis) Granulysin (stabs holes in cell membrane to detsory it)

Question 35

What is the difference between active and passive immunity ?

Answer 35

Active - simulation of adaptive immune response Natural - through infection Vaccine induced - Introduce whole microorganism, part of stimulate one's own cells to make part of it Passive - antibodies against pathogen given to person, via breastmilk, immunoglobulin's preparations

Question 36

Describe passive immunity in infants

Answer 36

Natural passive Starts during gestation In utero IgG antibodies transferred to foetus via placenta Once born antibodies continue to be part of immune system until decline around 3 - 6 months

Question 37

Why is breastmilk good ?

Answer 37

Provides infants with protective bioactive components

Question 38

What key ingredients is in breastmilk which supports infant immunity ?

Answer 38

IgA, maternal lymphocytes, lactoferrin, fibronectin, lysozyme, breastmilk promotes the growth of normal gut flora

Question 39

What is the broncho - entero - mammary pathway ?

Answer 39

Pathway at end of pregnancy where lactogenic hormones influence the migration of lymphocytes from aggregates in the gut to mammary glands

Question 40

Describe what happens during vaccination ?

Answer 40

Activation of adaptive immune response - B and T cells recognise antigen, clonal expansion, fight infection. Some cells become memory cells

Question 41

Define vaccination

Answer 41

Introducing microbial antigens to induce a primary response