Immune system

Question 1

what are the 3 purposes of the immune system?

Answer 1

• to protect the individual from a range of threats that could alter homeostasis
• to clean the body (clear dead, damaged or misfunctioning cells)
• to aid healing after injury

Question 2

what are the 6 threats that could alter homeostasis?

Answer 2

• bacteria
• viruses
• fungi
• parasites
• foreign cells
• cancer cells

Question 3

what is the main role of WBC’s (leukocytes)?

Answer 3

in defence and immunity

Question 4

what are the smallest and largest types of WBCs?

Answer 4

Smallest: Lymphocytes
Largest: Monocytes

Question 5

what are the 6 secondary lymphoid tissues in the body?

Answer 5

• adenoids
• tonsils
• lymph nodes
• spleen
• peyer’s patch in small intestines
• lymphatics

Question 6

what are the 2 primary lymphoid tissues in the body?

Answer 6

• thymus
• bone marrow

Question 7

define primary lymphoid organ

Answer 7

site of immune cell production and development

Question 8

define secondary lymphoid organ

Answer 8

sites of lymphocyte maturation, antigen entrapment (and blood cell distruction)

Question 9

where is the main site of adult haematopoiesis?

Answer 9

bone marrow
- pelvis
- sternum
- vertebrae
- ribs
- heads of femur / humerus

Question 10

what is the site of T-cell maturation

Answer 10

the thymus gland

Question 11

where is the thymus gland located?

Answer 11

behind the sternum, lower than the thyroid gland

Question 12

what happens to T-cells in the thymus?

Answer 12

• go to mature
• screening of T-cells to check they don’t react to self molecules

Question 13

one is one contributing factor to the reduced immune system with age?

Answer 13

the thymus decrease in size with age

Question 14

what is the max weight of the thymus?

Answer 14

35g

Question 15

what is the average weight of the thymus at 70 years old?

Answer 15

5g

Question 16

what does MALT stand for?

Answer 16

mucosal associated lymphoid tissue

Question 17

why is the MALT functionally very important?

Answer 17

contains more antibody producing plasma cells than the spleen, lymph nodes and bone marrow combined

Question 18

what does the MALT include?

Answer 18

• tonsils
• peyer’s patches
• appendix
• lymphoid follicles in the intestines
• lymphoid follicles in mucous membranes lining the airway and genital tracts

Question 19

where is the spleen found in the body?

Answer 19

The spleen is an ovoid organ found in the upper left abdominal cavity

Question 20

what are the 4 main functions of the spleen?

Answer 20

• filters blood
• immune response
• stores approx. 5% of total RBCs, 30% of platelets
• site of extramedullary haematopoiesis

Question 21

how much fluid is lost. from the capillaries per day? why?

Answer 21

~4L to become lymph

Question 22

what are lymph nodes?

Answer 22

small bags (capsules) filled with lymphocytes and other immune cells that filter the lymph looking for pathogens

Question 23

where are the main sites for lymph nodes?

Answer 23

axillary, inguinal, submandibular (abdomen, chest)

Question 24

how many lymph nodes are in the human body?

Answer 24

500-600

Question 25

what are the 3 non-specific defenses?

Answer 25

• innate immune cells (phagocytosis, immune surveleillance)
• defence at body surfaces (physical barrier, natural antimicrobial substances)
• inflammation

Question 26

what is the specific defense?

Answer 26

adaptive immune system
- cell mediated immunity (T-cell)
- humoral immunity (B-lymphocytes)

Question 27

what is lysozyme?

Answer 27

anti-microbial enzyme that attacks bacterial cell walls

Question 28

what is an interferon?

Answer 28

a type of cytokine

Question 29

what are the 3 main features of non-specific/innate immunity?

Answer 29

• fast
• non-specific
• generic

Question 30

name 2 innate immune processes

Answer 30

• phagocytosis
• immunological surveillance

Question 31

what is another name for the monocyte-macrophage system?

Answer 31

reticuloendothelial system

Question 32

state 3 key points about the monocyte-macrophage system

Answer 32

• Mobile macrophages
• Fixed macrophages at key sites (figure)
• Link both non-specific and specific immune systems

Question 33

give 5 physical barrier defences

Answer 33

• skin / epithelial membranes
• hair
• mucus
• cilia
• one-way urine flow

Question 34

give 7 natural antimicrobial defences

Answer 34

• lysozyme in tears
• saliva
• HCl in stomach
• skin flora
• pH of urine (acidic)
• sweat
• pH and flora of the vagina

Question 35

what is the purpose of inflamation?

Answer 35

• isolate/inactivate tissue damage
• benificial to enable healing

Question 36

what are the 6 main features of adaptive immune responses?

Answer 36

• Specific (unique to Ag)
• Highly specialised (cell mediated / humoral)
• Time lag (slow to get going)
• Memory (faster 2nd time)
• antigen specific
• dependent on highly specialised cells

Question 37

what are the 4 main types of T-cell?

Answer 37

• supressor T-cell
• Helper T-cell
• memory T-cell
• Cytotoxic T-cell

Question 38

what are the 3 functions of supressor T-cells?

Answer 38

• turn off immune response
• protect foetus
• help prevent auto-immunity

Question 39

what are the 2 functions of helper T-cells?

Answer 39

• produce cytokines
• activate B-cells

Question 40

what is the function of memory T-cells?

Answer 40

long lived cells providing immunity (remember previous pathogens)

Question 41

what is the function of cytotoxic T-cells?

Answer 41

actively kill cells

Question 42

where are B-cells produced? where do they mature?

Answer 42

bone marrow

Question 43

what is the function of B-cells?

Answer 43

• provide humoral (antibody) immunity
• each B-cell is able to recognise a different antigen

Question 44

what are 3 functions of antibodies?

Answer 44

• neutralise toxins
• mark pathogens for phagocytosis
• trigger complement activity