Pathogens

Question 1

Pathogens

Answer 1

infectious agents that cause disease or infection

Question 2

Types of pathogens

Answer 2

• bacteria
• viruses
• protozoans
• fungi
• parasitic worms
• prions (infections proteins)

Question 3

Three lines of Body’s Defense

Answer 3

1) Chemical and physical barriers
2) Internal cellular and chemical defenses
3) Immune responses

Question 4

Physical Barriers

Answer 4

skin and mucous membranes

Question 5

Chemical barriers

Answer 5

hydrochloric acid, pepsin, and saliva

Question 6

interferons

Answer 6

• proteins released by virus-infected cells
• attract natural killer cells and macrophages
• signal neighboring cells to produce proteins that inhibit viruses replication

Question 7

compliment system

Answer 7

group of proteins that enhance body defenses

Question 8

Functions of compliment system

Answer 8

• circulate in blood, activate when infection is detected
• punch holes in membranes of invading cells
• attract macrophages and neutrophils
• stimulate blood vessel widening (inflammation)

Question 9

What causes the redness of inflammation?

Answer 9

blood vessels dilating in response to histamine

Question 10

What causes the heat of inflammation?

Answer 10

increased blood flow; increases metabolic rate of cells in infected area

Question 11

What do T Lymphocytes protect against?

Answer 11

cellular pathogens and abnormal cells

Question 12

What do B Lymphocytes protect against?

Answer 12

extracellular toxins, viruses, bacteria

Question 13

major histocompatibility complex (MHC) “markers”

Answer 13

proteins that label the body cells as “self” or “good”

Question 14

antigens

Answer 14

molecules on the surface of invading cells recognized by defensive cells as “enemy”

Question 15

Steps of Adaptive Immune Response

Answer 15

1) Threat
2) Detection
3) Alert
4) Alarm (activation)
5) Attack (defense)
6) Continued surveillance

Question 16

Helper T Cells

Answer 16

contain different receptors that recognize specific antigens

Question 17

Threat

Answer 17

pathogen evades first two lines of defense and enters body

Question 18

Detection

Answer 18

macrophages (or B cells) encounter pathogen, engulfs and digests it; then places some antigens from pathogen onto its surface

Question 19

Alert

Answer 19

‘antigen presenting cell’ encounters a specific Helper T cell that recognizes the antigen

Question 20

Alarm (activation)

Answer 20

helper T cell secretes message that activates T cells or B cells with ability to recognize the particular antigen

Question 21

Attack (defense)

Answer 21

appropriate B and T cells activate and start rapid mitotic division making ‘effector cells’ that recognize and attack the invading pathogen

Question 22

Continued surveillance

Answer 22

• memory cells can recognize and respond to specific antigen if it re-invades
• second response to an antigen is much quicker and more robust