Stage 1 infectious diseases

define pathogen

any organism or agent that causes disease

What are infectious diseases and what are they caused by?

They are diseases that can spread and are caused by pathogens

Characteristics of pathogens

Small and microscopic, able to invade host and multiply, can disrupt normal bodily functions, adapted to aide immune response

what are cellular pathogens? Give examples

They are living pathogens and can be parasites, protozoan, fungi, or bacteria

what are acellular pathogens? Give examples

They are nonliving pathogens and can be viruses or prions.

What is virulence?

The measure of the ability of a pathogen to cause disease

How is virulence determined?

Virulence factors of pathogen, the host, environmental conditions

Microbes protect us by…

killing pathogens, out-competing pathogens, helping immune system respond

Pathogen survival depends on…

Their ability to enter cells, availability of nutrients and removal of waste, environmental conditions, ability to replicate and transfer to new hosts

What environmental conditions affect pathogen survival

Temperature, pH, moisture, anchorage, and space

what is endocytosis

Hast cell membrane forms internal cavity near pathogen, membrane engulfs it, pinches off to form vesicle and break away from host cell membrane

What do viruses need to replicate

a host

Step 1 of virus replication

Virus adheres to cell using proteins that attach to receptor proteins found on the cell membrane

Step 2 of virus replication

Virus either enters the cell or releases its genetic information (DNA/RNA)

Step 3 of virus replication

Virus hijacks the cell and uses the cell to create more of the virus

Step 4 of virus replication

Virus released to go infect more things

How does bacteria reproduce?

Asexually through binary fusion

What is an MHC

proteins found on the surface of the cell that helps immune system recognise foreign proteins

What nutrients does bacteria need to grow in ideal conditions

Glucose for respiration, Amino acid to build proteins

Aeration allows pathogens…

access to O2 for cell respiration

What waste must be removed for pathogens to thrive?

exchange of wastes (CO2) can cause acidic if not removed

Apoptosis definition

Cell didn't attach properly and died

What does the immune system's first line of defence do

prevents pathogen entry

Examples of a physical barriers

skin, mucous membrane

Examples of chemical barriers

Tears and stomach acid

What are mucous membranes

Layers of tissue that produce mucous

What does mucus do

Traps pathogens and inhabits beneficial microbes, lubricates eyes, protects from stomach acid, keeps delicate tissues from drying and cracking

What does the second line of defence do

Rapidly attacks pathogen with non-specific cells

What is the complement system?

It is part of the second line of defence, it is a group of at least 20 proteins that circulate the blood and assist other defence mechanisms

What does the complement system do?

Helps other defence mechanisms, cripples enemies, contacts immune system, and rips apart pathogens until they die

What is phagocytosis

A form of endocytosis where the cell membrane forms a vesicle around it

What are natural killer cells?

cells that secrete toxins that destroy cells infected with viruses or cancer

When does inflammation occur?

When white blood cells release cytokine and histamine proteins to that area.

What does histamine do

dilates the blood vessels

What happens when the blood vessels dilate

Increases blood flow, fluid releases into surrounding tissue (swelling), immune cells enter easily and attract more

Who sends the chemical signals which increases blood flow?

The damaged cells

Step 1 of the inflammatory response

Pathogen enters

Step 2 of the inflammatory response

histamine releases

Step 3 of the inflammatory response

Histamine causes vasodilation and membrane permeability

what is vasodilation?

When the blood vessels dilate with histamine

How does a fever occur

Macrophages release substances that causes body thermostat to rise.

Who activates the adaptive immune response

Phagocytes

What kind of organism has an adaptive immune system

Vertebrates

Where do B cells sit when inactive?

Lymph nodes, spleen and tonsils

Where does the adaptive immune system protect?

The entire body - immunity not isolated to infected part

Main features of the adaptive immune system

Recognises and targets specific cells and stores information from past exposures so it can react quicker

True or false: The adaptive immune system has memory

True

What happens when a B cell binds to a specific antigen

It clones itself

What do the B cell clones do?

They produce and secrete specific antibodies that deal with antigens

Where are antigens

They sit on the outside of the pathogen cell

How many antibodies fit each antigen

one

What is the purpose of Memory cells

Store information about pathogens for a faster reaction during second exposure

What is the basis for long term immunity?

Memory cells

What shapes an antibody

a Y

How does the adaptive immune response do?

Provides a targeted immunity with specific cells

What are antigens

any substance that mobilises the immune system and provokes immune response

The antigen-binding site has a ……. shape to the shape of a specific antigen

Complementary

What is passive immunity?

receiving antibodies and having them react

What is active immunity?

producing antibodies and having them react

Passive immunity provides….

immediate protection but lasts a short time

What are monoclonal antibiotics?

Artificially made antibodies derived from a single B cell

What can vaccines be made from?

Inactivated bacterial toxins, killed/weakened pathogens, or gene encoding microbial proteins.

what does the length of immunity rely on?

Life of the memory cells

Vaccine causes disease: true or false?

False

What happens when the body is first exposed to the pathogen (via vaccine)

Plasma B cells create and release specific antibodies that bind to specific antigens and then memory cells are created and stored

What happens when the body is secondly exposed to the pathogen (via vaccine)

Memory cells trigger more potent secondary immune response, disease might not develop and therefore individual is immune

What are the benefits of vaccines

Disease eradication, herd immunity, reduces healthcare costs

What is herd immunity?

When most people are vaccinated so it won't spread like wildfire

What does eliminated mean?

the disease isn't circulating a region anymore

What does eradicated mean?

The disease isn't circulating in the world anymore

Narrow spectrum antibiotics are…

effective against specific bacteria

Broad spectrum antibiotics are…

effective against many bacterias

Antibiotics cause bacteria cell death by…

destroying the cell wall (put hole in wall), destroying or inhibiting enzymes (preventing key life function), blocking protein synthesis (prevents them making essential proteins)

Why don't antibiotics attack human cells?

eukaryotic cells do not possess the same features meaning they only attack the pathogen

how does natural selection affect antibiotic resistance

The bacteria that survives the antibiotics the reproduce, making them all resistant

how do random mutations occur in regards to antibiotic resistance

Errors in DNA replication or exposure to mutagens (Chemical or radiation)

How quickly do resistant genes multiply

every 20 minutes

What are the two ways bacteria can pass on their resistant qualities

Conjugation and Gene transfer

How does conjugation occur (antibiotic resistance)

The cells connect through pili to share genes

how does gene transfer occur (antibiotic resistance)

Upon cell death

What are the antibiotic resistant traits the cells get?

increased cell wall production (stronger), Block cell entry, Alter the target of antibiotics, use enzymes on antibiotics, increase its removal

how do cells alter the target of antibiotics

They change bacteria proteins so antibiotics can't target or bind

how do cells use enzymes on antibiotics

Change the shape to inactivate or breakdown antibiotics

How can antibiotic resistance be built?

Through overprescription or misuse of antibiotics

A vector is something that….

is infected (but not AFFECTED) by a disease and can spread the disease

Example of a vector

Mosquitoes with malaria

State modes of disease transmission

airborne, dust, direct contact, faeces, food, animals

Why aren't pathogens able to cause disease in all organisms?

The infection mechanisms of certain pathogens do not adhere to the biology of all organisms. For example, a virus does not have the complementary proteins that allows it to enter all cells

What is a neutrophil

A kind of phagocyte

what is a macrophage

A kind of phagocyte

Who carries out cell mediated immunity?

T cells

What do helper T cells do?

activate cytotoxic cells and present antigens to immature B cells

What do suppressor T cells do

prevent immune responses from continuing once all antigens have been removed

What do cytotoxic T cells do?

detect cancerous or infected cells and destroy on contact.

are cytotoxic T cells and neural killer cells the same thing?

No! Natural killer cells are part of the INNATE immune response and cytotoxic T cells are part of the ADAPTIVE immune response. However, they basically do they same thing

What is humoral immunity?

The production and action of antibodies

Who carries out the humoral response?

B cells

Humoral response step 1

foreign antigen invades body

Humoral response step 2

Macrophages engulf antigen and display it on their surface as they travel to lymph nodes

Humoral response step 3

Antigen is presented to T helper cells which present it to B cells