Immunity (Final Exam)

Question 1

Why is immunity important?

Answer 1

Because “novel” diseases are emerging and hosts need to defend against them to survive and reproduce.

(Pathogen influences the hosts evolution and vice-versa)

Question 2

What does the animal immune system consist of?

Answer 2

1. Physical Barriers
2. Chemical defenses
3. Cellular defenses
4. Inflammatory response
5. Behaviors like hygiene and social distancing

Question 3

Describe what innate immunity is.

Answer 3

Immunity that does not rely on previous exposure (your born with it)

Question 4

What are the two types of innate immunity?

Answer 4

1. Humoral Innate Immunity - involves various substances found in bodily fluids that interfere with pathogen growth/help dispose them
2. Cellular Innate Immunity - involves cells called phagocytes that eat pathogens, and other cells called natural killer cells that destroy abnormal body cells

Question 5

Describe what acquired immunity is.

Answer 5

Acquired or “adaptive” immunity recognizes a pathogen’s antigens (such as toxins/proteins), and provides a immunological memory so that it can fight off a pathogen better later

Question 6

What are the physical barriers in the animal immune system?

Answer 6

Integument and mucous membranes

Question 7

How does the animal immune system use chemical defenses (ex. lysozyme) to inhibit pathogen growth?

Answer 7

They secrete chemicals (lysozyme) that contain antimicrobial substances or create an environment that inhibits pathogen growth

Question 8

What are cytokines?

Answer 8

They are tiny signaling chemicals that are created by immune cells (or other cells) that tell neighboring cells to initiate a immune response.

Question 9

Describe the mechanism of the complement system.

Answer 9

When the system is triggered, proteins in the blood stream are split by enzymes to release cytokines which amplify the response.

This mechanism results in phagocyte attraction and stimulate inflammation

Question 10

How do AMP’s (antimicrobial peptides) act as chemical defenses?

Answer 10

When the organism contacts the foreign pathogen, AMP’s are released and attach to cells which make holes in their membranes.

Question 11

Describe what phagocytosis is and the general process in detail.

Answer 11

Phagocytosis is the recognition of non-self materials, and clearing of aging cells/cellular debris

Phagocytes engulf particles, and are digested by lysosomes

Question 12

What is the Major Histocompatibility Complex?

Answer 12

The MHC is the surface receptor on the phagocyte on which it may present the pathogens antigen, which can activate other parts of the immune system

Question 13

How do amoebocytes, hemocytes, and coelomocytes in invertebrates act as defense cells?

Answer 13

They engulf small particles, and they encapsulate large particles

Ex. Arthropods encapsulate with melanin.

Question 14

What is the primary component of the acquired immune system, and where are they made?

Answer 14

Lymphocytes and RBC’s and they are made in the bone marrow from stem cells

Question 15

Where are T-cells and B-cells made?

Answer 15

B-cells come from lymphoblasts, which come from stem cells in the bone marrow

T-cells are made in the bone marrow as well and also come from lymphoblasts, but mature in the thymus gland

Question 16

Describe how B-cells function.

Answer 16

They circulate in the blood after maturation, and they have millions of receptors on their surface that are specific to an antigen (membrane bound antibodies)

When the B-cell encounters the matching antigen, it will divide to become a plasma cell, which are higher in numbers and secrete more antibodies that identify more antigens like the original in the body

Question 17

Describe the diversity of T-cells and how they prevent attacks on body cells.

Answer 17

During their development, they undergo much genetic recombination.

To prevent attacks they can only recognize antigens that are bound to MGH’s on other cells

Question 18

Explain the three types of T-cells

Answer 18

1. Helper T-cells - activate cytotoxic T-cells, B-cells, and other immune cells
2. Cytotoxic T-cells - kill pathogens and infected host cells
3. T-regulatory cells help distinguish between self and non-self molecules, reducing risk of autoimmune disorders

Question 19

What is the difference between cell mediated and humoral immunity?

Answer 19

1. Cell mediated immunity is carried out by T-cells, B-cells, and other antigen presenting cells
2. Humoral immunity is the acquired immune response that relies on serum antibodies produced by plasma cells

Question 20

What are antibodies also called and what makes them specific to an antigen?

Answer 20

Immunoglobulins

They are composed of two identical light chains, and two identical heavy chains making a Y-shape

They amino acid sequence near the end of the Y varies in both chains which makes them specific.

Question 21

How do antibodies mediate destruction of an invader?

Answer 21

1. The pathogen may get coated with them which stimulates macrophages
2. Can prevent molecules form binding to their target cells