Unit 4 AOS1 biology

What is disease

Anything that impairs the normal function of a cell/organism

What is an infectious disease

A disease that can be transmitted between organisms. e.g through the air, water droplets

What is a pathogen

A disease causing agent

What is a prion and give an example

A type of pathogen that stems from misfolded proteins. eg Mad cows disease, Kuru

What is an antigen

Any molecule that may trigger an immune response

What is a self molecule

Cell, tissue, molecules that have markers that are belonging to self

What is a non self molecule

Cellular molecules that are recognized as foreign.

What is a self antigen

A cell that has MHC markers on its surface so that the immune system is able to distinguish it from non self material.

What is MHC 1

A molecule expressed on all nucleated cells in the body. They mark cells as self so that the immune system doesn’t attack them.

What is MHC II

Markers shown on cells to express that they have consumed an antigen/ foreign material

What is an auto immune disease

A failure of the immune system to identify self cells. Therefore the immune system attacks self cells.

What is an allergen

Anything that can cause an allergic reaction

What is an allergic reaction

An over reaction of our immune system to something that is not normally considered harmful.

What is an inflammatory response

A response caused by the release of histamine from cells. Blood flows to injured area bringing with it immune cells to clear debris and fight pathogens.

What are examples of pathogens

Bacteria, protozoans, fungal, virus, prions

What is a bacterial pathogen

A cellular, prokaryote disease

What is a protozoan pathogen

A cellular eukaryote disease

What is a fungal pathogen

A cellular eukaryotic disease

What is a virus pathogen

A non cellular nucleic acid surrounded by a protein coat

What is a prion pathogen

A non cellular disease involving misfolded proteins that when come into contact with other proteins cause them to misfold.

What is the first line of defense

The body’s innate surface barrier that works to prevent pathogens from entering

What are physical barriers in plants for the first line of defense

Thick waxy cuticle, thick bark, thorns, Gall formation, closing stomata

What are chemical barriers in plants for the first line of defense

Enzymes, phenols(repel microorganisms), defensins, sapohins, toxins

What are physical barriers in animals for the first line of defense

Intact skin, mucus membranes

What are chemical barriers in animals for the first line of defense

Stomach acid, Acid in sweat, lysoszymes, digestive enzymes

What is the second line of defense

A component of the innate immune system characterized by the non specific and immediate response to injury and pathogens

What are phagocytes and give examples

A group of leukocytes that engulf non self cells by phagocytosis and digest them using lysosomes. Neutrophils, macrophages and dendritic cells

What is phagocytosis

A process where a phagocytes binds to an antigen and is then engulfed by a form of endocytosis, creating a phagosome. Phagosome then fuses with a lysosome to form a phagolysosome where digestive enzymes breakdown foreign particles and debris is released by exocytosis.

What is a neutrophil

Most common type of leukocytes in the body. It engages in phagocytosis of pathogens and foreign material. It releases cytokines and is associated with inflammation and bacterial infections.

What is a cytokine

A signaling molecule that guides immune cells to the site of infection

What is a macrophage

A type of leukocyte that engages in phagocytosis and antigen presentation. It also releases cytokines

What is an Antigen presenting cell (APC)

A sub group of phagocytes that display consumes foreign particle on the surface of a cell by the use of a MHC II marker. These markers are used to stimulate the third line of defense.

What is a dendritic cell

A type of leukocyte that engages in phagocytosis and antigen presentation

What is a natural killer cell (NK cells)

Large granulated cells that attack abnormal and viral infected cells. They contain two receptors. A killing inhibitory receptor that examines MHC I markers and a Killer activation receptor that binds to molecules of cells under stress eg. cancer, viral infection. When they find a self cell displaying a non self antigen they release a death ligand that signals the cell to die by apoptosis.

What is a mast cell

Cells that are found in connective tissue and when they detect injury or an allergen stimulated by an antigen they release histamine to stimulate an immune response.

What is an Eosinophil cell

A large granulated cell contain toxic chemical mediators such as RNases, DNasas and proteases to help destroy invading pathogens. They target pathogens to large to be phagocyted and then degranulate on contact and release chemical mediators.

What are Interferons

A type of cytokine released by infected cells. The proteins interact with other cells warning them of a virus. They interact with the receptors to make neighbouring cells more resistant to viral invasion

What are complement proteins

Proteins found in the blood that undergo reactions in the presence of pathogens.

Opsonisation - proteins coat pathogen to make it easier to identify for phagocytes

Chemotaxis - Proteins gather near pathogen to attract phagocytes

Lysis - Proteins coat pathogens and cause membrane attack complex(MAC) they then create pores in membrane and destroy it.

What is a fever

A innate response to infection as pathogens cannot survive the increased temperature. A prolonged fever can denture enzymes but also make the immune system function better

What are the steps in an inflammatory response

Initiation- cells are damaged or pathogens enter site, mast cells release histamine

Vasodilation - Release of histamine causes blood vessals to widen

Migration - Phagocytes are guided to site of infection and complement proteins are activated.

What is a non self antigen

Antigens that the immune system reads as foreign or not belonging to the individual and activates an immune response.

What are mircobiological barrier to pathogens

Natural flora

What is the third line of defense

The bodies specific adaptive response to a pathogen

What are the steps in the humoral response to a pathogen

Phagocyte engulfs antigen and displays it on its MHC II markers.

APC presents to helper T cell

Helper T cell travels to lymph and activates a naive B cell with a specific surface antigen by cytokine signalling,

B cell divides by colonial selection to form plasma B cells and memory B cells

Plasma cells produce specific antibodies to the antigen

Antibodies bind to antigen and neutralise it.

What does an antigen- antibody complex do

Stop antigens from dividing and inactivates/neutralises them. By immobolising them, opsonisation and activating complement proteins.

What are the steps in a the cell mediated response

Phagocyte identifys a non self or viral infected cell and becomes an APC

APC activates a helper T cell

Helper T cell activates a naive T cell through cytokine signalling

Naive T cell divide into a cytotoxic T cell and a memory T cell

Cytotoxic T cell locates cells with a specific non self antigen and secretes chemicals such as perforins that activate apoptosis.

What is the lymphatic system

A complex system made up of vessels, tissues and organs that play an important role in the circulatory and immune system.

What is the function of the lymphatic system

It transports APCs to secondary lymphoid organs for antigen recognition.

It is the site of White blood cells production

It removes and circulates fluid around out tissues

What are the components of the primary and secondary lymph tissue

Primary: Bone marrow, thymus

Secondary: Lymph nodes, spleen, tonsils and gall bladder

What do lymph nodes do

It is the site of antigen presentation and scans/traps foreign antigens. They also are where naive B and T cells are activated and can then be stimulate to divide by clonal expansion,