Immune System 1

Question 1

Why do we need an Immune System?

Answer 1

We are Constantly coming in contact with potentially harmful substances:

• Pathogens: viruses and microbes (bacteria, fungi, parasites).
• Abnormal cells originating in body.
• External and internal (innate / adaptive) defenses all working together

Question 1

What is the Immune System?

Answer 1

Immune system – collective of things that provide immunity.

• Immunity: ability to resist or eliminate.
• Susceptibility: lack of resistance

Question 2

What are The Actions performed by the Immune System?

4

Answer 2

• Defending against invading pathogens.
• Removing worn out cells damaged by time, trauma or disease.
• Facilitating wound healing and tissue repair.
• Identifying and destroying abnormal cells originating in body (immune surveillance).

Question 3

What are External Defences?

Answer 3

• Barriers; not immune responses.
• 1st line of defense.
• Immediate

Question 4

What are Examples of Physical External Defences?

4

Answer 4

• Skin – when intact – prevent crossing.
• Hairs – nasal cavity – filter.
• Mucus – upper respiratory and GI tracts – sticky and bind.
• Reflexes – coughing / sneezing – expelling

Question 5

What are Examples of Chemical External Defences?

3

Answer 5

• Sebum – oil on skin surface / slightly acidic, poor environment for pathogen growth.
• Lysozyme – in tears, perspiration, saliva, nasal secretions, tissue fluids – antimicrobial properties can break some pathogen cell membranes.
• Stomach acid – highly acidic, can kill some pathogens

Question 6

What are Leukocytes? Where are they formed?

Answer 6

White blood cells.
Formed in red bone marrow by leukopoiesis.

Question 7

What are Pluripotent Stem Cells?

Answer 7

Give rise to myeloid and lymphoid stem cells - progenitor cells – precursor cells (blast cells)

Question 8

What do Myeloid Cells give rise to?

4

Answer 8

• Eosinophils
• Basophils
• Neutrophils.
• Monocytes – form macrophages

Question 9

What do Lymphoid Cells give rise to?

three

Answer 9

• B lymphocytes – form plasma cells.
• T lymphocytes.
• Natural killer (NK) cells

Question 10

From Myeloid Cells:

What are Neutrophils?

Function, Response Time, Lifespan

Answer 10

Neutrophils are primarily involved in the phagocytosis of pathogens or cellular debris. They can also release cytokines, signaling molecules that play a role in immune responses.

Neutrophils have a rapid response time, arriving at the site of infection or injury within hours.

Neutrophils have a relatively short lifespan, living for only minutes to a few days

Question 11

From Myeloid Cells:

What are Monocytes?

Function, Response Time, Lifespan

Answer 11

Upon reaching tissues, monocytes undergo differentiation into macrophages. They engulf (phagocytosis) pathogens or cellular debris, release cytokines (signaling molecules)

Monocytes typically arrive at the site of infection or inflammation later than other immune cells, taking days to migrate from the bloodstream to tissues.

Macrophages have a longer lifespan compared to certain other immune cells. They can persist in tissues for an extended period, typically ranging from months to even longer durations.

Question 12

From Lymphoid Cells:

What are B Lymphocytes?

Answer 12

Type of WBC responsible for the production of antibodies.
Upon encountering an antigen, B cells can differentiate into plasma cells which produce antibodies for antibody-mediated immune responses

Question 13

From Lymphoid Cells:

What are T Lymphocytes?

Answer 13

assist in lymphocyte activation by releasing cytotoxic chemicals for cell-mediated immune responses

Question 14

From Lymphoid Cells:

What are Natural Killer (NK) Cells?

Answer 14

release cytotoxic chemicals for cell mediated immune responses

Question 15

What are Common Charcateristics seen in Lymphoid cells?

2

Answer 15

All lymphoid cells are:

• Generally slower to respond (days, weeks)
• Very long lived (months, can be decades)

Question 16

Internal defence:

What are the 2 Types of Immune Responses?

Answer 16

• Innate
• Adaptive

Question 17

What is the Encounter Stage?

Answer 17

The encounter stage represents the initial interaction between pathogens and immune cells

Question 18

Where are Common Locations for Encounter of Pathogens?

Answer 18

Resident immune cells, such as macrophages, dendritic cells, and lymphocytes, are strategically located in various tissues, especially in lymph nodes, the spleen, and other lymphatic tissues.

These immune cell populations serve as surveillance points, as the circulation brings pathogens into these locations

Resident immune cell populations

Question 19

Where else can Pathogens be Encountered if not in Tissues?

Answer 19

Pathogens and immune cells can also encounter each other in the bloodstream and lymphatic vessels.

Circulating immune cells, including lymphocytes and certain phagocytes, patrol the bloodstream and lymphatic system, actively searching for signs of infection

Circulation

Question 20

What are Innate Immune Responses?

Answer 20

• Non-specific / general.
• 2nd line of defense.
• Rapid response, but limited

Question 21

What is the Recognition Stage?

Answer 21

The recognition stage involves the specific binding of immune cells to pathogens, marking the initiation of the immune response

Question 22

In the recognition Stage:

What does it mean to have General or non-specific recognition?

Answer 22

In the initial phases of the immune response, there is a general or non-specific recognition of pathogens. This early response helps the immune system quickly identify and respond to a broad range of potential threats

Question 23

In the recognition Stage:

What is the Function of Toll Receptors or Toll Proteins?

Answer 23

Toll receptors or toll proteins on immune cell membrane act as pattern- recognition receptors

They have the ability to Bind large numbers of pathogen-associated molecular patterns and trigger innate immune responses

Question 24

How are the Pathogens Recognized?

Answer 24

The “recognition” in this context often involves the detection of carbohydrates or lipids on the surface of pathogens. These components can serve as important molecular patterns for immune recognition.

Question 25

What is the Difference between Innate and Adaptive Responses?

Answer 25

Often innate responses are to contain and limit spread while adaptive mounts a more specific response