Immune system

Question 1

Define the term “Immunity”

Answer 1

The ability of the body to defend itself against disease-causing organisms.

Question 2

Identify the organs, tissues and cells which help the body fight infection.

Answer 2

Organs = the thymus and bone marrow, lymph nodes and vessels, spleen, and skin.

Tissues = ???

Cells = lymphocytes, macrophages, neutrophils, basophils, mast cells, eosinophils and natural killer cells.

Question 3

Describe the role of non-specific immunity - including natural barriers.

Answer 3

It protects against all pathogens.

• Physical and chemical barriers.
• Non-specific phagocytic immune cells that respond to each pathogen using the same mechanism.

Question 4

Outline the importance of specific immunity.

Answer 4

-Provides protection against one specific substance but no others
-Protect against a specific foreign substance. E.g. Measles virus (a specific pathogen)
-Lymphocytes (B & T lymphocytes) and macrophages play a key role

Question 5

Explain the term antigen.

Answer 5

Any substance capable of mobilising the body’s immune system and provoking an immune response.

Question 6

Briefly describe humoral immunity to include the role of B and T lymphocytes.

Answer 6

Humoural immunity = adaptive immune response = from vaccines or having a pathology before. B lymphocytes and the memory cells produce antibodies.

Question 7

Briefly describe cell-mediated immunity to include the role of T lymphocytes.

Answer 7

T cells attack antigens directly through cell-to-cell contact:

1) Ingestion of antigen (pathogen) by a macrophage, macrophage digest antigen & pushed to the membrane surface (antigen presentation)
2) T cells bind to antigens & are activated (T cell activation)
3) T cell divides repeatedly, resulting in large numbers (clones), a group of identical cells formed by the same parent cell
- Four subgroups w/in clone: killer T cells, helper T cells, suppressor T cells, and memory T cells.

Question 8

Name the first 2 types of antibodies and indicate their major functions.

Answer 8

IgA = Found in saliva, tears, mucus, breast milk and intestinal fluid, IgA protects against ingested and inhaled pathogens.

IgD = This antibody is found on the surface of your B cells. Though its exact function is unclear, experts think that IgD supports B cell maturation and activation.

Question 9

7.1 Describe the functions of the lymphatic system

Answer 9

1. Drains excess interstitial fluid.
2. Transport dietary lipids
3. Carries out immune responses.

Question 10

Explain the importance of the lymphatic system in the immune response.

Answer 10

The lymph nodes and other lymphatic structures (like the spleen and thymus) hold special white blood cells called lymphocytes.

These can rapidly multiply and release antibodies in response to bacteria, viruses, and a range of other stimuli from dead or dying cells and abnormally behaving cells such as cancer cells.

Question 11

Discuss and identify the major lymphoid tissues and lymph nodes.

Answer 11

Major Lymphoid Tissues

Bone Marrow, Thymus, Spleen, Lymph Nodes, Tonsils,
Peyer’s Patches, Appendix,

Major Lymph Nodes

Cervical Lymph Nodes, Axillary Lymph Nodes, Inguinal Lymph Nodes, Mesenteric Lymph Nodes, Mediastinal Lymph Nodes.

Question 12

What is the role of lymphocytes in the immune response?

Answer 12

• Antibody production,
• Direct cell-mediated killing of virus-infected and tumour cells,
• Regulation of the immune response.

Question 13

What is the role of macrophages in the immune response?

Answer 13

Following phagocytosis of foreign material, macrophages process the antigen for use by the lymphocytes, thus initiating an immune response. Macrophages also stimulate the proliferation of lymphocytes.

Question 14

What is the role of neutrophils in the immune response?

Answer 14

Phagocytize (eat) bacteria and also, destroy bacterial toxins in body fluids.

Question 15

What is the role of basophils in the immune response?

Answer 15

• Releasing histamines to trigger allergic reactions or during asthma attacks.
• Releasing cytokines and leukotrienes that further aid the immune system in defending against foreign material.

Question 16

What is the role of mast cells in the immune response?

Answer 16

When stimulated, it releases histamine, serotonin, and heparin, initiating an inflammatory response.

Question 17

What is the role of eosinophils in the immune response ?

Answer 17

Eosinophils play a major role in immunity to parasites, particularly helminths, which are relatively resistant to destruction by neutrophils and macrophages.

Question 18

What is the role of natural killer cells in the immune response?

Answer 18

Provide first line of defense against many viruses. As they can distinguish between infected and uninfected host cells they are able to target and kill infected cells.

Question 19

Name some different lymphocytes in the Reticular connective tissue.

Answer 19

B lymphocytes (B cells): These cells produce antibodies as part of the humoral immune response. They are often found in the lymph nodes, spleen, and other lymphoid tissues.

T lymphocytes (T cells) play a central role in cell-mediated immunity. They directly attack infected cells, activate other immune cells, and regulate the immune response. T cells are also prevalent in lymphoid tissues.

Natural Killer (NK) cells: These lymphocytes are involved in the innate immune response. They are capable of destroying virus-infected cells and tumours without prior sensitization.

Question 20

What is the function of the right lymphatic duct?

Answer 20

Drains the right thorax, upper limb, head and neck.

Question 21

What is the function of the lympathic duct?

Answer 21

To transport lymph back into the circulatory system.

Question 22

Where are lymph nodes located?

Answer 22

Located throughout the body, most prevalent in the neck, axilla, groin and along all major lymphatic vessels in the body cavities.

Question 23

Give an example of lysozyme enzyme disease defences that provide non-specific immunity.

Answer 23

Lysozyme enzymes in tears, digest the bacterial cell wall.

Question 24

Give an example of mucus disease defences that provide non-specific immunity.

Answer 24

Mucus, which traps bacteria and small particles

Question 25

Give an example of skin disease defences that provide non-specific immunity.

Answer 25

Skin, a physical barrier

Question 26

Give an example of pH of sweat disease defences that provide non-specific immunity.

Answer 26

Low pH of sweat, prevents growth of bacteria

Question 27

Give an example of a fever disease defences that provide non-specific immunity.

Answer 27

Fever, temperature denatures microbial enzymes

Question 28

Explain the term antibody.

Answer 28

Antibodies are part of the human immune system. Basically, they identify bad bacteria and viruses and track them down to fight back.

Question 29

What are the five cardinal (main) symptoms associated with inflammation?

Answer 29

• Rubor (redness)
• Calor (heat)
• Tumour (swelling)
• Dolor (pain)
• Laesio functae (loss of function)

Question 30

What is rubor (redness) caused by?

Answer 30

Histine-mediated vasodilation of aterioles

Question 31

Describe the structure of lymphatic capillaries.

Answer 31

Lymphatic capillaries have thin walls, only as thick as a single cell. The cells overlap each other so that interstitial fluid easily enters the capillaries.

Question 32

What is the function of lymphatic capillaries?

Answer 32

Balance body fluid.

interstitial fluid (fluid found in the spaces around cells) leaks from blood capillaries into your tissues. Lymph capillaries pick up this fluid and help return it to your circulatory system.

Question 33

Outline the physiological process of immunity in the context of passive immunity.

Answer 33

Natural passive immunity is when a baby becomes immune after receiving antibodies from the mother through the placenta and breast milk.

Artificial passive immunity is when you become immune after being injected with antibodies from someone else.

Question 34

What are the differences between active and passive immunity?

Answer 34

Active immunity requires exposure to a pathogen, whereas passive does not.

The protection from passive immunity has an immediate effect, whereas active immunity takes time to develop.

Memory cells are produced in active immunity but aren’t in passive immunity.

Protection is long-term in active immunity, but passive immunity only provides short-term immunity because the antibodies are given to break down.

Question 35

Outline the physiological process of immunity in the context of active immunity.

Answer 35

Natural active immunity is when you produce your own antibodies in response to catching a disease, so you become immune because you produced memory cells.

Artificial active immunity is when a harmless version of the pathogen is injected, so the body creates antibodies and memory cells so you will be immune.

Question 36

Name the last 3 types of antibodies and indicate their major functions.

Answer 36

IgE = Found mainly in your skin, lungs and mucus membranes, IgE antibodies cause your mast cells (a type of white blood cell) to release histamine and other chemicals into your bloodstream. IgE antibodies can cause allergic reactions.

IgG = Found in blood and tissue fluids. It helps protect your body from viral and bacterial infections.

IgM = Found in your blood and lymph system, act as the first line of defense against infections and plays a large role in immune regulation.