Lymphoid and Immune Systems

Question 1

components of lymphoid system

Answer 1

1. lymphatic system circulate body fluid to remove infections & transport WBC.
2. lymphoid organs & tissues: stem cells that differentiate into the various WBC also trapped & destroyed or an immune response generated.
3. WBC Protect the body from foreign
   materials
4. cytokines chemical messengers that recruit and/or activate WBC

Question 2

First Line of Defence physical

Answer 2

Intact skin & mucous membranes epithelial cells form a formidable barrier

Hairs (skin & nose) trap foreign materials

Cilia move foreign materials from the respiratory tract towards the throat

Normal Flora prevent pathogen colonisation
colonise areas of the skin

Question 3

chemical

Answer 3

Sweat, saliva & tears destroys bacteria

Sebum inhibits pathogen growth & toxic to some bacteria

Mucus traps foreign materials in respiratory and digestive tracts

Gastric Juice destroy ingested foreign materials

Question 4

Second Line of Defence

Answer 4

Macrophages & neutrophils Phagocytose and destroy foreign material via lysosomal enzymes

NK cells Destroy virus-infected cells & cancerous cells

Interferons- inhibit with viral replication

Complement- Directly destroy cellular target by forming a membrane attack complex

Pyrogens Induce fever

Inflammation Isolates and removes foreign materials, repairs damaged tissues

Question 5

define terms

Answer 5

Antigens-molecule capable of inducing an immune response
immunocompetence-The ability to recognise and bind to one specific antigen
immunological memory- the ability to remember antigens
Self-tolerance- the ability to recognise “self-antigens” from “non-self-antigens

Question 6

adaptive defence

Answer 6

Antigen presenting cells phagocytose and present antigens to T cells to activates T cells

Helper T cells Turns on an immune response

Cytotoxic T cells Directly destroys cellular antigens

B cells Differentiates into plasma cells

Plasma cells Produces and secretes antibodies

Antibodies Inactivates and tags antigens for destruction

Question 7

primary immune response

Answer 7

humoral response produces a small amount of antibody à IgM
is produced first, then IgG

Question 8

secondary immune
response

Answer 8

rapidly produce a powerful,
long-lasting response that protects from illness
Ø humoral response produces a large amount of IgG antibody

Question 9

Vaccines

Answer 9

Expose an individual to a weak antigen
antigen
first antigen encounter activates a primary immune response & generate memory T and B cells

Question 10

Immunodeficiency diseases

Answer 10

body’s immune defences
are compromised or absent and unable to
mount an effective immune response

Question 11

Autoimmune

Answer 11

body’s immune defences target normal cells and tissues

Question 12

Hypersensitivities

Answer 12

body’s immune defences respond
to a harmless allergen that is perceived as a threat
allergen binds to IgE on mast cells & basophils
à triggers the release of histamine which:
* stimulates bronchoconstriction, mucus
production & vasodilation
* increases blood vessel permeability

Question 13

antibody defensive mechanism

Answer 13

agglutination: antibody binds multiple cellular antigens or foreign particles to form antigen-antibody complex that are easily phagocytose

precipitation: antibodies bind multiple soluble antigens to form insoluble antigen-antibody complex that precipitate out of solution and phagocytose

Neutralisation: Antibodies bind to
antigens to block their attachment to
body cells= phagocytose

Complement activation: Antibodies bind
antigen & activate complement which
results in lysis or opsonisation