Defense Against Diseases

Question 1

Differences Between Innate and Adaptive Immune System

Answer 1

Inherited
Acquired

Non-specific
Specific

No memory
Long-term memory

Rapid
Slow

Low effectiveness
High effectiveness

Coordinated by phagocytes
Coordinted by lymphocytes

Question 2

Non-Specific Defense Mechanisms and Two Forms

Answer 2

Mechanisms that do not distinguish between one type of pathogen and another, but respond to all of them in the same way

First line of defense consists of surface barriers that prevent the entry of pathogens into the body which is coordinated by skin and mucous membranes

Second line of defense operates once the pathogen reaches the blood which is coordinated by phagocytes

Question 3

Types of Lymphocytes

Answer 3

T Cells:

Regulator cells that activate B cells
Made in the bone marrow
Have receptor proteins on their surfaces

B Cells:
Antibody producting cells that recognize and target a speciic pathogen
Made in the bone marow and remain until maturation
Each B cell has the ability to produce a single specific type of antibody which allows the immune system to precisely target and neutralize different pathogens

Question 4

Herd Immunity

Answer 4

Describes how a population can be protected from a contagious disease

If more indivduals become immune to a disease, the chain of transmission starts to break. With the high ammount of immune individuals, there are fewer people susceptible to the disease. Even poeple who are not vaccinated can benefit from herd immunity as the widespread immunity in the community reduces their chances of encountering the disease. This is particularly important for people who can’t be vaccinated due to medical reasons.

Question 5

Evolution of Resistance to Antibiotics

Answer 5

Mutations in some bacteria have evolved antibioric resistance genes, and these strains can proliferate very quickly following the initial mutation and pass the resistant genes to other bacteria. THis frequency can increase in population and thus replace non-resistant over time

Some bacteria are also naturally resistant due to the lack of peptidoglycan in cell walls and having a capsule

Question 6

Plasma Cells and Memory Cells

Answer 6

Plasma cells produce large amounts of specific antibodies which binds to specific antigen on the pathogen to destroy them, usually last a few days

Memory cells remain in the blood to provide long-term protection. They multiply rapidly to produce an instant supply of plasma cells to procide a rapid and effective response to subsequent infections

Question 7

Analyzing Percentage Change in COVID-19

Answer 7

Change divided by original times 100

Day 1: 1000
Day 7: 800

800-100/100*100 = -20% decrease

Question 8

Zoonoses

Answer 8

Infectous diseases that can be transmitted from animals to humans

Question 9

AIDS Causes, Effects, and Method of Transmission

Answer 9

HIV is the main cause of aids, wher HIV binds to T cells and destroys them which decreases their number over time. THis leads to a decrease in the amount of antibodies produced as they play an important role in stimulating B cells to produce antibodies

The immune system gets weakened and the body becomes more vulnerable to pathogens, where normally harmless microorganisms can take advantage and cause infections

Vaginal and anal intercourse, sharing hypodermic needles, cuts during childbirth, and placenta from mother to child are examples of transmission

Question 10

Antibiotics

Answer 10

Produced by microorganisms to kill or control growth of other microorganisms

They’re effective against bacteria as it can interfere with protein synthesis which blocks metabolism processes, and prevent them from being able to form a cell wall by inhibiting the formation of peptidoglycan and inhibits nucleic acid synthesis to prevent bacteria from replicating.

Not effective against viruses as they’re non living, have no cellular structure, rely on host cell, and lack a metabolism

Not effective against humans as they have different metabolic pathways and don’t have a cell wall

Question 11

Blood Proteins Involved in Defense Mechanisms

Answer 11

Clotting factors intitate clotting process

Thrombin converts fibrinogen into fibrin
Fibrin permits blood clotting

Antibodies made by lymphocytes are responsible for specific immunity against pathogens

Enzymes in WBC’s may digest pathogens

Question 12

Specific Defense Mechanisms

Answer 12

Mechanisms that do distinguish between different pathogens, it’s less rapid but provides long lasting immunity

Third line of defense is specific to pathogens and provides a long-term memory against them which is coordinated by lymphocytes

Question 13

Types of Antigens

Answer 13

Non-self markers are present on foreign bodies in the blood

Self markers are present on te surface of our own cells. WHile our immune system typically tolerates self markers, they can be problematic in blood transfusion and organ transplantation because the immune system would trigger a repsonse if they are mismatched

Question 14

Antibody Structure

Answer 14

Y-shaped structure

Y stem is the constant region because all immunoglobulins share the same amino acid sequence, aids in the destruction of pathogens

Ends of Y are variable regions with 2 binding sites where the antigens bind to form a highly specific antigen antibody complex

Question 15

What is a Pathogen

Answer 15

An organism or virus that causes a disease

Question 16

Sealing of Cut in Skin by Blood Clotting

Answer 16

When a blood vessel gets cut, vasoconstriction occurs to reduce blood flow to damaged area

Damaged cells release chemicals that attract platelets to form a temporary plug, and platelets release clotting factors into the plasma at a wound site

Clotting factors cause prothrombin to turn into thrombin, and thrombin catalyzes the conversion of fibrinogen, a soluble plasma protein into an insoluble fibrous protein fibrin

The fibrin molecules then attach to one another to form a big network which form clots trapping the blood

Question 17

Species Specific and Cross Species Virus

Answer 17

Pathogen’s capacity to cause disease is limited to host species

Pathogen ability to cause disease has a range of hosts belonging to different species, known as zoonoses

Question 18

Basis of Immunity

Answer 18

Immunity is based on the recognition of foreign molecules

All living organisms and viruses have surface molecules, and surface molecules are unique to each organism and virus.

An individual’s immune system cand detect foreign cells by recognizing certain surface molecules (antigens) not present on the surface of its own cells

Question 19

Third Line of Defense and Activation of B Cells from T Cells

Answer 19

A phagocyte engulfs a pathogen and becomes an antigen-presenting cell (APC), displaying the antigen on its surface. A helper T cell with a matching antigen binds to the APC, gets activated, and releases cytokines. This causes the helper T cell to proliferate, creating more helper T cells specific to the antigen which creates cytokines again, making it a positive feedback loop.

Separately, a B cell binds to the same antigen, engulfs it through endycytosis, and displays it on its surface. An activated helper T cell then binds to the B cell and releases cytokines, fully activating the B cell.

The activated B cell undergoes clonal expansion, dividing repeatedly and differentiates into plasma cells, which produce antibodies, and memory cells, which provide long-term immunity.

Question 20

Differences between Primary and Secondary Response

Answer 20

First exposure to a specific antigen
Subsequent exposure to the same antigen

One week delay
Within hours

Weak potentcy
More potent

Short life, for only a few weeks
Long lasting, for many months

Question 21

Vaccines

Answer 21

Vaccines trigger the immune system to make antibodies against a specific pathogen. They usually contain a weakned or killed form of the pathogen

Vaccines are injected or given orally, with the antigens in the vaccine causing the production of plasma and memory cells. The primary response is slow so the number of antibodies produced is not so high. However, the vaccinated person now has immunity due to the presence of memory cells, so if it encounters a live pathogen it recognizes the pathogen through memory cells and results in a secondary response

Question 22

Primary and Secondary Response

Answer 22

When the pathogen is first detected, the immune system starts to produce antibodies but it takes a few ays before the number of antibodies in the blood rises to a level where it can fight the infection

In secondary response, the immune system recognizes the pathogen if the body is infected again, so the immune system can act more quickly with antibody production rising sooner

Question 23

Zoonoses Transmission and Examples

Answer 23

Direct contact: bites, scratches or contact with infected animal. Example is rabies which is caused by dog bites

Indirect contact: contact with contaminated surfaces or environments. Example is tuberculosis caused by bacteria through inhaling airborne droplets or ingestion of meat from infected cattle

Vector-borne transmission: Insects or other organisms feed on infected animals then bite humans. Example is Japanese encephalitis which is spread by mosquitos that feed on infected pigs or wading birds

Foodborne transmission: Consuming contaminated animal food products. Example is salmonella which comes from contaminated eggs and E.coli from undercooked meat

Question 24

Antibodies (Immunoglobulins)

Answer 24

Proteins that defend the body against pathogens by binding to specific antigens on the surface of said pathogens and stimulatinf destruction

Question 25

Skin as a Primary Defense

Answer 25

Physical Barrier: composed of thick layer of dead cells on surface that prevent pathogen entry

Chemical Barrier: contain sebaceous glands that secrete sebum, an oily substance that helps keep the skin lubricated and waterproof. Swear glands produce sweat which contain lysozyme and creates a salty and acidic environment on the skin which inhibits microbial growth

Question 26

Mucous Membrane as a Primary Defense

Answer 26

Physics Barrier: soft and moist areas found in the trachea, nose, vagina and urethra which are lined with goblet cells that produce sticky mucus to trap pathogens which are then expelled up the trachea and out of the body

Chemical Barrier: contain lysozyme enzymes that break down the pathogens, and lined with cilia which are capable of wave-like movements that move trapped pathogens up and out

Question 27

Benefits and Dangers of Vaccination

Answer 27

Herd Immunity
Prevent Disease
Speed up the body’s response to disease

Allergic reactions
May produced mild symptoms of the disease
Immunity might not be life-long

Question 28

Antigens

Answer 28

An antigen is a protein/glycoprotein displayed on the outer surface of a pathogen which stimulates immune response, acting as a recognition molecule for the immune system

Each antigen has a unique structure, which leads to production of highly specific antibodies

Question 29

What is Immunity

Answer 29

The body’s ability to resist and eliminate an infectous disease

Question 30

Lymphocytes

Answer 30

Responsible for specific immunity, they produce antibodies to a specific pathogen, and recognize and destroy pathogens and foreign cells

Lymphocyes are found in the bloodstream or concentrated in lymph nodes

Question 31

Stages of HIV Infection

Answer 31

Acute HIV: flu-like symptoms that occur days to weeks after contracting HIV

Chronic HIV: dormant, can last for several years

AIDS: makes a person vulnerable to oppurtunistic infections and AIDS-defining conditions

Question 32

Phagocytosis

Answer 32

The process by which solid materials are ingested by a cell

Phagocytes recognize pathogens as non-self based on the recognition of surface proteins that make up all cells annd viruses

The pathogen gets engulfed by phagocytoses and the pathogen gets enclosed into a membrane-bound vesicle called a phagosome

Lysosomes within the phagocytes fuse with the phagosome and release lysosomes enzymes to digest and kill the pathogens

Pathogen antigens may be presented on the surface of the phagocyte to stimulate the third line of defense