Lymphatic System and Immunity, Key Concepts

Question 1

Clinical Note- What is Lymphedema?

Answer 1

• Blockage of lymph drainage
• interstitial fluid increases and causes severe swelling
• fluid becomes essentially stagnant
• accumulation of toxins and pathogens

Question 2

Do the cells, tissues and organs of the lymphatic system have a pivotal role in the body’s defences against a variety of different pathogens or disease causing organisms?

Answer 2

Yes

Question 3

Leukocyte

Answer 3

Cells of the immune system that helps fight disease and infection

Question 4

What are the primary cells of the lymphatic system, that are central to the immune response against pathogenic threats to the body, called?

Answer 4

Lymphocytes

Question 5

What are the three classes of lymphocytes?

Answer 5

T-cells
B cells
and Natural Killer Cells

Question 6

Where are lymphocytes produced, maintained and distributed?

Answer 6

The lymphatic system

Question 7

What helps to maintain blood volume and composition of interstitial fluid?

Answer 7

the lymphatic system

Question 8

What is innate immunity also known as?

Answer 8

non-specific immunity

Question 9

What are the seven major categories of innate defences?

Answer 9

1. physical barriers
2. phagocytes
3. immunological survellience
4. interferons
5. complement
6. inflammatory response
7. fever

Question 10

Does each defence mechanism distinguish one type of threat from another?

Answer 10

No, i.e. the response is the same, regardless of the type of invading agent

Question 11

Specific Defence Mechanisms

Answer 11

• Cell mediated immunity involves close physical contact between activated cytotoxic T cells, and foreign, abnormal or infected cells
• Antibody mediated immunity involves the production of specific antibodies by plasma cells derived from activate Bcells

Question 12

MHC proteins and antigen presentation

Answer 12

• Class I MHC proteins are always present in membranes of nucleated cells
• Antigen presentation by Class I MHC proteins is triggered by viral or bacterial infection of a body cell
• Infection results in abnormal peptides within the cytoplasm
• Abnormal peptides are incorporated into the Class I MHC proteins as they are synthesised at the ER
• Exported to the Golgi and then transported in vesicles to the PM
• The abnormal peptides are displayed by Class I MHC proteins on the PM
• Class II MHC proteins are only present in membranes of antigen presenting cells and lymphocytes
• Class II MHC proteins appear in the plasma membrane only when the cell is processing antigens

Question 13

For a phagocytic cell:

Answer 13

• Extracellular pathogen is engulfed
• Lysosomal action produces antigenic fragments
• Endoplasmic reticulum produces Class II MHC proteins
• Antigenic fragments become bound to Class II MHC proteins in vesicles which are then transported to, and displayed on, the plasma membrane