Immunology Lecture 9

Question 1

Are infections the same across all people?

Answer 1

No, they can different results in different people.
ie. Tuberculosis in a young patient can be localised and contained.
In an elderly patient, it can be widespread and cause greater damage, causing secondary symptoms.

Question 2

What is a pathogen?

Answer 2

Organism that produces disease in the host.

Question 3

What are the majority of organisms associated with the human body? Are they pathogenic?

Answer 3

Majority are bacterial

Most are non-pathogenic

Question 4

Where is the largest community of bacteria in humans?

Answer 4

Colon

Question 5

Why are bacteria kept within the colon, and on the skin in humans, and other organisms?

Answer 5

Beneficial to some degree, and kept evolutionarily as they outcompete possible pathogens.
Some in the gut also provide some VitB nutrients.

Question 6

Are all bacteria always harmless on the human skin?

Answer 6

No, some are opportunistic, and invade and become pathogenic when immunity is weakened.

Question 7

How does malnutrition compromise immunity?

Answer 7

Lack of protein - lack of antibodies

Question 8

How does alcoholism compromise immunity?

Answer 8

Liver is heavily involved in protein synthesis. Excess alcohol consumption causes cirrhosis.

Question 9

How does leukaemia compromise immunity?

Answer 9

Cancer of the white cells, they cant effectively fight off infection.

Question 10

How does HIV compromise immunity?

Answer 10

Targets immune cells (Th cells), impacting the immune system heavily.

Question 11

Name two primary lymphoid tissue/organs. Name 3 secondary ones.

Answer 11

Primary
Bone marrow and thymus
Secondary
Spleen, lymph nodes, and mucosal associated lymphoid tissue (MALT)

Question 12

How does lymph move through the body?

Answer 12

Muscle contraction.

Question 13

Define leukocyte. What two stem cell lines do they originate from?

Answer 13

White blood cell. Originate from foetal hepatic stem cells, and bone marrow stem cells.

Question 14

What are the two classes of leukocytes?

Answer 14

Monocytes

Lymphocytes

Question 15

What is the ratio of lymphocytes found in blood vs lymph?

Answer 15

10:1

Question 16

What is anaemia characterised by on a blood smear?

Answer 16

Red blood cells have a light centre.

Question 17

How do neutrophils appear under a blood smear?

Answer 17

Well formed nuclear lobed cells.

Question 18

Why do individuals with leukaemia have poor immunity if they have so many leukocytes?

Answer 18

They have many immature leukocytes, using up too many resources, and hence weak immunity.

Question 19

Name the two types of lymphocytes.

Answer 19

B and T cells.

Question 20

How are monocytes and macrophages related?

Answer 20

Monocytes move out into tissue to become macrophages.

Are called monocytes when in the blood circulation.

Question 21

What are dendritic cells?

Answer 21

Highly branched cells that sample antigens from pathogens, and present them to lymphocytes in the lymph node.

Question 22

What are granulocytes? Give 3 examples.

Answer 22

Polymorphonuclear leukocytes

Includes eosinophils, basophils, and neutrophils.

Question 23

What are natural killer cells?

Answer 23

Thought to be lymphocytes. Originate from the bone marrow, seek out cancer cells.

Question 24

What are the 5 types of mononuclear cells?

Answer 24

Monocytes
Macrophages
Dendritic cells
Granulocytes
Natural killer cells

Question 25

Which cell is the precursor to all immune cells?

Answer 25

Haemocytoblast.

Question 26

What is the first line of defence (3)?

Answer 26

Skin, mucous membranes, antibacterial excretions - tears, stomach acid, saliva

Question 27

What is the second line of defence (2)?

Answer 27

Phagocytic cells, antimicrobial proteins - complement proteins.

Question 28

What is the third line of defence (2)?

Answer 28

Lymphocytes, antibodies

Question 29

Which lines of defence are specific/non-specific?

Answer 29

Non-specific – 1 and 2 | Specific – 3

Question 30

Define 4 characteristics of the innate immune system.

Answer 30

Acts quickly, recognises broad range of pathogens, non-specific, and has no memory.

Question 31

Define 4 characteristics of the acquired/adaptive immune system.

Answer 31

Develops slowly after first exposure, very rapid response to subsequent exposures, very specific, has memory.

Question 32

Name 7 features of skin that makes it an effective barrier.

Answer 32

``` Thick layer of keratinocytes Shedding Dryness Mild acidity Competing resident flora Oily – protective If penetrated, skin associated lymphoid tissue underneath ```

Question 33

Name 2 features of mucous membranes that make it an effective barrier.

Answer 33

Epithelium and mucus both resist penetration. | Antimicrobial secretions - lysozyme.

Question 34

How do mucosal associated lymphoid tissue aid the immune system (2)?

Answer 34

M cells are interspersed with epithelial cells. They sample pathogens, and deliver to the MALT below. Also secrete IgA, which binds to pathogens in the lumen, preventing passage across the membrane.

Question 35

What are the 4 signs of inflammation.

Answer 35

Redness Warmth Swelling Pain

Question 36

How are neutrophils induced to enter tissue?

Answer 36

Injured cells release chemical signals, activating selectins on the inner lining of capillaries. Neutrophils roll along the inner lining, and encounter them, inducing them to enter tissue.

Question 37

What causes the warmth, redness, and swelling in inflamed tissue?

Answer 37

Blood vessel dilation and leaking capillaries.

Question 38

What causes pus formation?

Answer 38

Polymorphs and granulocytes passing through diapedesis.

Question 39

Define extravasation.

Answer 39

Migration out of the capillary to the site of injury.

Question 40

What causes pain during inflammation?

Answer 40

Swelling pushing on nerves.

Question 41

What role does inflammation have with pH levels, and what does this activate and eventually result in?

Answer 41

Inflammatory mediators released by injured cells decrease pH. This activates bradykinin, which in turn activates mast cells. They release histamines, a powerful inflammation mediator.

Question 42

Define chronic inflammation.

Answer 42

Inflammation persisting 2 weeks or longer.

Question 43

What can cause chronic inflammation, and how?

Answer 43

Persistence of bacteria. Granulomas form due to continual infiltration of cells, resulting in cell damage.

Question 44

Define granuloma.

Answer 44

A mass packed with dying macrophages and lymphocytes. Upon death, they release more enzymes, causing further harm.