Acquired Immunity & The Lymphatic System

Question 1

Innate immunity/Acquired immunity

Question 2

immune cells

Question 3

Macrophages

Monocyte

Basophils

Eosinophils

Neutrophil

Answer 3

Are monocytes that have migrated tothe tissue and therefore become macrophages. Are phagocytic.

Circulate in the blood and arephagocytic. Sit in the spleen inreserve for launching an immuneresponse

Associated with allergic reactions andare responsible for the rapid responsein allergies

Special role in removal of parasitesand also stimulate allergic responsesby releasing chemicals

Active scavengers who engulfbacteria by phagocytosis and protectagainst bacteria

Question 4

maturation of T cells and B cells

Answer 4

lls develop from pre-T cells thatmigrate from red bone marrow intothe thymus, where they mature* Most T cells arise beforepuberty, but they continue tomature and leave the thymusthroughout life

B cells complete their developmentin red bone marrow, a process thatcontinues throughout life.

Question 5

B Lymphocytes

Answer 5

On activation by antigen, B lymphocytes changeto a plasma cells or memory B cells
Plasma cells are essentially ‘Antibody Factories’.They synthesise and secrete antibodies (globulins)into the body’s fluids.* Secrete at a rate of 2,000 antibody moleculesevery second for about 4-5 days then plasma celldies.* Each plasma cell will make one specific antibody.* Memory B cells remain in the body after theinfection has gone, enables rapid response if theantigen presents again.* This immunological memory

Question 6

Antibodies - Immunoglobulins

Answer 6

Antibodies secreted by B cells are alsoknown as immunoglobulins.* Antibodies/Immunoglobulins bind toantigens on foreign pathogens by labellingthem as targets.* Neutralises bacterial toxins.* Activates the complement system.* There are five classes of immunoglobulinIgA, IgD, IgE, IgG, IgM.* They are different classes based on theirbiochemical structure.* The different classes of immunoglobulinare found in different areas of the body.

Question 7

What are the 5 classses of immunoglubins and where are they found

Answer 7

IgA – Found in bodily secretions (breast milk, saliva),coating the epithelium membrane in order to preventthe antigen entering the body.* IgD – Made by B-cells and is on their surface whichattracts antigens which in turn activate the B-cells.* IgE – Found on cell membranes, when it binds with theantigen it activates the inflammatory response.* IgG – Attacks different pathogens and crosses theplacenta to protect the foetus.* IgM – Large quantities are produced during the primaryphase of immunological memory and activates thecomplement system.

Question 8

Immunological Memory

Answer 8

Immunological memory is due to the presence of long-lasting antibodies and very long-lived lymphocytes thatarise.

Some B cells do not proliferateinto plasma cells but becomememory cells (live much longerthan plasma cells).* If the body encounters thesame antigen the memory cellsare primed and ready for actionsecondary response

Question 9

T Lymphocyte

Answer 9

T Lymphocytes
T- cells supports cell mediatedresponse. T-cells need to have the antigenpresented to them in order forthem to become activated. Macrophages engulf and digestthe antigen and then they displayon their cell membrane. The antigen is presented by themacrophage to the T-cell and thisactivates the t cell. The T-cell then divides into fourspecialist cells.

Question 10

Helper & Regulatory T-cells

Answer 10

Helper T cell Regulatory T-cellsBrakes – turn off T and BcellsLimits the potential of theimmune response

Promote immunologicaltolerance and helps toprevent autoimmunecomplications Produce cytokineswhich support andpromote cytotoxic T-cells and macrophages Co-operate with B-cellsto produce antibodies

Question 11

Memory and Suppressor T-cells

Answer 11

Memory T cells
Provide cell –mediated immunity* Will respond rapidly tothe same antigen* Primary* Secondary

supressor R cells
Turns off the immuneresponse once thethreat has been dealtwith

Question 12

functions of the lynthatic system

Answer 12

Play an important role in acquired immune response byreacting to the presence of potentially harmful antigens.
2. Preserves fluid balance by returning fluids from tissuesback to the blood*
Fluid leaks out of capillaries being responsible for tissuehydration and nutrition approx. 8 litres/day
3. Lymphatic vessel network helps transport nutrients &waste products in the body.
4. Absorption and transport of fats from the digestivesystem

Question 13

Thyroid gland

Answer 13

The thymus gland grows to its largest size during childhood and makes all the T cells we need before we become teenagers. After this, it gradually gets smaller, becomes less active and is replaced by fatty tissue. The thymus also produces a hormone called thymosin that helps make and develop T cells.
y age 75 it is little more than fatty tissue It is a dual endocrine & lymph gland it produces ahormone Thymosin which regulates production &maturity of the T cells. At birth, the infant has a large pool of T & B cellshowever they are naïve and largely incapable totriggering a memory response

Question 14

Spleen

Answer 14

Situated in the abdomen*
Dark purple coloured largest accumulationof lymphoid tissue*
12cms long, 7cms wide, 2.5cms thick* Abundant phagocytic cells —defenceagainst antigens in blood* Site of destruction of aged erythrocytes* Production site of activated lymphocyteswhich are delivered to the blood.