Biology Unit 4 AOS1 checklist questions

CHAPTER 7 DOT POINTS

What are antigens?

any molecule that interacts with the immune system and can trigger an immune response

How does the immune system recognise self from non-self?

mhc class 1 markers are located on the surface of all nucleated cells, marking the cell as either belonging to the organism, self antigens, or as foreign, non-self antigens, and if the cell is determined to be foreign, the immune system is activated and attempts to eliminate it

What are autoimmune disease?

autoimmune diseases are a type of malfunction involving antigens, in which an individual’s immune system initiates an immune response against their own cells believing them to be foreign

What are allergens?

non-pathogenic antigen that triggers an immune response called an allergic reaction

How do allergens impact the body?

allergens impact the body as they involve an overreaction or strong immune response to a non-pathogenic antigen

Red blood cells do not contain MHC markers. What surface antigen do they have?

red blood cells don’t have a nucleus therefore don’t contain MHC markers as they are expressed on nucleated cells, but rather red blood cells have the rhesus antigen as a surface antigen

Why is it important doctors match the right blood type when treating a patient?

if the rhesus antigen is not matched correctly between donor and patient then the patient may initiate an immune response against the transplant as it recognises the rhesus antigen as foreign

What are pathogens?

an agent that causes disease

What is bacteria?

a unicellular pathogen that reproduces asexually through binary fission and spreads disease by the production of toxins and enzymes affecting the function of cells or cause cell death

what is a virus?

an infectious agent composed of genetic material inside a protein coat called capsid and sometimes enclosed in a lipid envelope. viruses do not reproduce but rather insert genetic material into a host cell and using cell reproduction to reproduce. viruses cause disease through lysis of the cell during viral replication affecting gene expression

what is fungi?

a eukaryotic organism containing long branching filaments called hyphae which reproduces through both asexual and sexual reproduction via spore formation

what are worms?

a multicellular invertebrate parasite reproducing sexually via the life cycle

what are prions?

abnormally folded proteins with the ability to induce misfolding in other nearby proteins thereby spreading through tissues as they cannot reproduce. they are found only in mammals and only affect the neural area

what is the main purpose for the first line of defence?

a component of the immune system providing barriers to prevent pathogenic invasion which are non-specific or generalised

Briefly outline the physical barriers in animals and examples.

barriers that prevent or impede entry of pathogens such as intact skin, mucus secretion and cilia

Briefly outline the chemical barriers in animals and examples.

barriers that act to inhibit the growth or development of pathogens and/or act to destroy pathogens such as through acidic sweat, stomach acids, lysozymes and enzymes.

Briefly outline the microbiological barriers in animals and examples.

barriers that can prevent the growth or colonisation of pathogenic microorganisms as they compete for space and resources such as flora in the gastrointestinal tract

What are the types of barriers in animals?

physical, chemical, microbiological

Briefly outline the physical barriers in plants and examples.

barriers that prevent or impede entry of pathogens such as waxy cuticles on leaves, formation of galls, and thick bark

Briefly outline the chemical barrier in plants and examples.

barriers that inhibit the growth or development of pathogens and/or act to destroy pathogens such as through the production of chemicals like defensins

What are the types of barriers plants have?

physical and chemical

What are two key features of the second line of defence?

apart of the innate immune system and consists of cellular and non-cellular components

What are leukocytes?

a group of blood cells responsible for protecting the body against pathogens and foreign material

What are phagocytes?

a group of leukocytes that are responsible for the endocytosis and destruction of pathogens, foreign material and cell debris. they include neutrophils, macrophages and dendritic cells

What is phagocytosis?

the process in which phagocytes consume and destroy foreign or dead material present in the body by engulfing it in endocytosis

Which cells do phagocytosis?

neutrophils
dendritic cells
macrophages

What is the other special function of neutrophils, macrophages and dendritic cells?

to communicate with the immune system phagocytes release cytokines which can help guide immune cells to the site of infection

What are natural killer cells?

large granulated leukocytes which target abnormal and virally infected cells, responsible for recognising and destroying them

what is the main role of NKC?

detect the presence of MHC class 1 markers to determine if a cell is self or not and if recognising a non-self antigen, kills the cell

What can NKC not do?

recognise and target healthy cells

What are mast cells?

reside in the connective tissues, a type of leukocyte responsible for releasing histamines after detecting an allergic and inflammatory response

What is the main function of a mast cell?

after detecting injury in surrounding cells, degranulating and releasing histamines

What are eosinophils?

a large granular leukocyte

What is the main role of an eosinophil?

responsible for the release of toxic chemical mediators such as DNases or RNases to help destroy invading pathogens, typically targeting pathogens too large to be phaocytosed

What are interferons?

a non-cellular component and a type of cytokine which interact with receptors of neighbouring cells to make them less susceptible to viral infection

What are complement proteins?

a non-cellular component of the immune response involving proteins reacting with each other in a series of complement cascades

What is chemotaxis?

complement proteins gather near a pathogen and attract phagocytes to it, making it more likely to be destroyed

What is opsonisation?

complement proteins stick on the outside surface of pathogens and make it easier for cells of the immune system to recognise them as foreign

What is lysis?

complement proteins join together on the surface of pathogens forming a membrane attack complex which creates pores in the membrane, destroying the pathogen by causing a sudden influx of fluid into the pathogen causing it to burst

What is the purpose of a fever?

a temporary increase in body temperature aiming to initiate countermeasures as many pathogens cannot survive at elevated temperatures as well as bolster the immune defence strength

What does the inflammatory response hope to achieve?

increase blood flow to the area of infection to bring a greater number of immune cells and components to clear debris and fight pathogens that may have entered the body

Is the inflammatory response specific or non-specific?

non-specific process as it acts in the same way regardless of the pathogen present or injury occurred

What are the three steps of the inflammatory response?

initiation
vasodilation
migration

What is initiation?

Involves cytokines being secreted from activated macrophages and damaged cells, as well as mast cells degranulating, causing the release of histamines

What is vasodiliation?

histamines released travel to nearby blood vessels and binds to specific receptors, causing blood vessels to widen, increasing blood flow to the injury site, and the formation of gaps in the vessel wall increases its permeability to cells of the immune system

What is migration?

dilated blood vessels with increased leakiness allow for a number of innate immune system components to leave the bloodstream and enter the site of injury

phagocytes are guided by the cytokines to the site of injury which phagocytose pathogens and digest them using enzymes such as lysozymes

complement proteins are attracted to pathogens and make it easier for phagocytes to destroy them

Why does the infected area appear red, swollen and hot?

the increase blood flow and fluid to the affected tissues

What is the difference between the innate immune response and the adaptive immune response?

the innate immune response is non-specific and generalised while the adaptive immune response is specific to a pathogen and contains an immunological memory

What are the cells in the third line of defence called?

cytotoxic t cells
t helper cells
b and t lymphocyte memory cells
b lymphocyte plasma cells

How is the third line of defence initiated?

after phagocytosis, antigen presenting cells travel via the lymphatic system to lymph nodes and the interactions between an antigen presenting cell and a t-helper cell initiate the third line of defence

Describe the humoral immune response.

an adaptive immune response in which extracellular pathogens are targeted by specific antibodies produced by plasma cells

What pathogens does the humoral immune response target?

pathogens with an antigen complementary to the shape of the antigen-binding site on the receptor of a B cell

Which cells does the humoral immune response use?

b plasma cells
b memory cells
t helper cells

Outline the steps of what happens in the humoral immune response.

clonal selection occurs when a B cell with a receptor matching a pathogen’s antigen is activated, then a matching t helper cell releases cytokines that stimulate the b cell to clone and differentiate into plasma cells and memory B cells, the plasma cells produce antibodies to fight the pathogen, while memory cells remain for future immunity

What are antibodies?

y-shaped quaternary structured proteins made of two heavy and two light chains, held together by disulphide bonds, which have a constant region- stem and a variable region- arms, which form two identical antigen-binding sites, and these sites bind to specific antigens on pathogens, allowing each antibody to attach to two pathogens at the same time

What function are antibodies able to do?

neutralisation
agglutination
immobilisation
opsonisation
activation of complement proteins

Describe the cell-mediated immune response.

cytotoxic t cells, a type of t lymphocyte, are central to cell-mediated immunity, as they check mhc class 1 markers on all nucleated cells, which normally show self-antigens, and if a cell is infected, mhc 1 presents foreign viral antigens, cytotoxic t cells detect these and target the infected cells for destruction to help eliminate the infection

Which pathogens does the cell-mediated immune response target?

pathogens with matching antigens to that of t helper cells

Which cells does the cell-mediated immune response use?

t helper cells
naive t cells
cytotoxic t cells
t memory cells

Outlines the steps of the cell-mediated immune response

during clonal selection, a naive t cell with a receptor matching a presented antigen is selected by antigen-presenting cells, cytokines from a helper t cell stimulate it to undergo clonal expansion and differentiation into cytotoxic t cells and t memory cells, the cytotoxic t cells travel to the infection site, where they recognise infected cells via mhc 1–antigen complexes and release chemicals like perforin to trigger apoptosis, destroying infected cells

What does it mean by immunological memory?

a key component of both cell-mediated and humoral adaptive immune responses by the creation of b and t memory cells

What are the benefits of the immunological memory of b memory cells?

b memory cells rapidly divide and form new antibody-producing plasma cells for when they encounter an antigen that matches their receptor and constantly secrete low amounts of their antibody

What are the main functions of the lymphatic system?

to transport antigen-presenting cells to secondary lymphoid tissues for antigen recognition and initiation of the adaptive immune response and produce leukocytes

What are the steps of the lymphatic system?

lymphatic drainage
lymphatic flow
lymphatic surveillance

What is lymphatic drainage?

during inflammation, more fluid leaks from blood vessels into tissues, allowing immune cells to enter, lymphatic capillaries collect this fluid, now called lymph, along with pathogens and antigen-presenting cells, the lymph is carried through the lymphatic system to lymph nodes, where immune responses can be triggered against any pathogens present

What is lymphatic flow?

lymphatic capillaries join to form larger vessels that carry increasing amounts of lymph these vessels have thin walls and rely on nearby muscle movements, not the heart, to move fluid, one-way valves inside the vessels ensure lymph flows only in one direction—away from tissues and toward lymph nodes for immune surveillance and drainage

What is lymphatic surveillance?

lymph from tissues enters lymph nodes through afferent vessels, where it passes through clusters of b and t cells and if a matching lymphocyte is found, clonal selection begins, activated cells and antibodies then exit via efferent vessels and re-enter blood circulation near the heart, this transport and activation process causes the adaptive immune response to be slower than the immediate innate response.

What are the primary lymphoid tissues?

thymus
bone marrow

What is the role of the primary lymphoid tissues?

responsible for the creation and maturation of lymphocytes

What are the secondary lymphoid tissues?

tonsils
lymph nodes
spleen

What is the main role of the secondary lymphoid tissues?

responsible for maintaining mature lymphocytes and initiating the adaptive immune response

what is specificity?

the adaptive immune system responds to each distinct pathogen in a unique and tailored manner

what is immunological memory?

the adaptive immune system results in the production of cells that allow the body to respond to future re-infections by a previously encountered pathogen quickly and effectively

what is neutralisation? - antibodies

can block the sites of pathogens being used to attack the host cell and block the active site of toxins

what is agglutination? - antibodies

antibodies can bind together with antigens on two seperate pathogens, forming large antigen-antibody complexes making it easier for phagocytes to recognise the pathogen as foreign bodies and destroy them

what is immobilisation? - antibodies

can restrict the movement of pathogens around the body through the formation of large antigen-antibody complexes

what is opsonisation? - antibodies

can bind directly to the surface of a pathogen to make it easier to phagocytose

what is the activation of complement proteins? - antibodies

antibodies are attached to the surface of pathogens can facilitate the actions of complement proteins, including the formation of membrane attack complexes

What are the benefits of the immunological memory of t memory cells?

t memory cells proliferate rapidly into t helper cells and cytotoxic t cells upon stimulation by an antigen-presenting cell which is presenting previously encountered antigens meaning that a re-infection defences have large amounts of cells to rapidly kill any infected cells