topic 4 - health and disease - mr hedditch

Question 1

what is health?

Answer 1

the state of complete physical, mental and social

wellbeing

Question 2

what is disease?

Answer 2

not having complete good health because of the body/mind is not able to function at its maximum efficiency

Question 3

what does acute and chronic mean?

Answer 3

acute - short term illness with symptoms appearing and disappearing quickly

chronic - long term illness with symptoms lasting for months and years

Question 4

what is a communicable and non-communicable disease?

Answer 4

communicable - a disease that can spread between organisms

e.g. flu, chicken pox

non-communicable - are diseases that can’t be spread between organisms

e.g. physical (fractures), mental (depression) and inherited (cystic fibrous) diseases

Question 5

what is a pathogen and the types?

Answer 5

a pathogen is an organism that causes a disease, these include bacteria, viruses, fungi and protoctists

Question 6

how does a bacteria cause a disease?

Answer 6

by producing toxins, damaging cells and causing deaths of the vascular tissues (in plants)

Question 7

what diseases do bacteria cause?

Answer 7

tuberculosis which affects humans/animals
bacterial meningitis which affects humans
ring rot affects potatoes/tomatoes

Question 8

how does a virus cause a disease?

Answer 8

by invading the host cells to insert genetic

material into the hosts DNA. Cells make copies of the virus - they burst out of the hosts cell causing physical damage

Question 9

what diseases do viruses cause?

Answer 9

AIDS/HIV which affects humans
Influenza which affects animals/humans
Tobacco mosaic virus which affects plants

Question 10

how does a fungi cause a disease?

Answer 10

in animals, the microspores species in the skin send out reproductive hyphae - grows to the surface of skin and release spores

in plants - live in the vascular tissue (access nutrients).
Hyphae release extracellular enzymes - they digest surrounding tissues and cause decay - leaves shrivel/die

Question 11

what diseases do fungi cause?

Answer 11

athlete’s foot which affect humans
ringworm which affects cattle
black sigatoka which affects banana plants

Question 12

how do protoctists cause a disease?

Answer 12

by entering host cells and feeding on the contents of cells

Question 13

what diseases do protoctists cause?

Answer 13

malaria which affects animal/humans

tomato/potato late blight which affects potatoes/tomatoes

Question 14

what is an indirect transmission?

Answer 14

when a disease is transmitted from one organism to anther through a vector e.g. water, food, air, insects

Question 15

wha

Answer 15

food and water
spores
airborne droplets
person-to-person physical

Question 16

what are spores?

Answer 16

a spore is a unit of asexual reproduction adapted to spending a long period of time in unfavourable conditions before developing into an offspring of the plant, algae, fungi, or protozoan that created it

Question 17

what is indirect transmission and e.g?

Answer 17

indirect transmission is when a disease is transmitted from
one organism to another via a vector

a vector is another organism that carries the pathogen from one host to another, vectors are usually insects

e.g female Anopheles mosquitoes and dutch elm disease

Question 18

malaria case study?

Answer 18

pathogen - plasmodium falciparum

transmission - vector needed - female Anopheles mosquito
drinks infected blood, then the pathogen is passed to an
uninfected person in the mosquito’s saliva as it feeds

symptoms - fever, headache, sweats, chills and vomiting

treatment - anti-malarial drugs

prevention/control

– prevent completion of the mosquito life cycle;
– vaccination is difficult as there are many antigens (shift);
– treatment is affected by drug resistance;
– sickle cell allele gives some protection

worldwide importance -
found throughout the tropics e.g.
China, India, South America, West Indies

90% of sufferers are in Sub-Saharan Africa

global warming enhances the spread

1.5 – 3 million deaths a year

Question 19

Dutch elm disease?

Answer 19

Dutch elm disease is caused by a member of the sac fungi
(Ascomycota), and is spread by an elm bark beetle vector

in an attempt to block the 
fungus from spreading 
farther, the tree reacts by 
plugging its own xylem tissue
with gum. This prevents the 
delivery of water and minerals to the leaves, which die

roots can also die as a result of lack of sugars from the leaves as photosynthesis stops

Question 20

ways to reduce spread of disease?

Answer 20

good personal hygiene – washing hands (esp. after using the toilet) and wearing protective clothing

using heat/radiation to sterilise surfaces and surgical equipment

disinfecting surfaces

disinfecting cuts/grazes using antiseptics like alcohol

avoiding unprotected sex (use condoms)

Question 21

social factors that contribute to disease transmission?

Answer 21

lack of adequate shelter/homelessness

poor ventilation/overcrowding (e.g. linked to TB)

poor nutrition

poor health – individuals with

HIV/AIDS are likely to contract
other diseases

Question 22

what are the two types plant defences?

Answer 22

passive and active

Question 23

what are physical defences?

Answer 23

cellulose cell wall – acts as a physical barrier and
contains chemical defences

waxy cuticles on stems and the upper surface of leaves
– act as a physical barrier and prevent water collecting,
reducing the spread of water-borne pathogens

lignin – indigestible waterproofing substance found in
xylem vessels

bark - contains chemical defences

ability to close stomata when pathogens are detected through changes to cytoplasmic volume in
guard cells

callose – a large polysaccharide deposited between the cell wall and plasma membrane upon infection

callose can be used to block phloem sieve tubes and close off plasmodesmata to restrict pathogen spread

Question 24

what are passive defences?

Answer 24

passive defences are present before infection occurs

and are aimed at preventing pathogen entry and spread

Question 25

what does tyloses do and what defence is it?

Answer 25

swellings that block xylem vessels to restrict the spread | of pathogens - physical defence

Question 26

what are chemical defences?

Answer 26

plants are capable of producing many different anti-microbial chemicals ``` some of these chemicals are present in plants all the time: • Terpenes • Phenols • Alkaloids • Hydrolytic (digestive) enzyme ```

Question 27

how do plants detect pathogens and what does this stimulate?

Answer 27

plants are able to detect pathogens using receptors (proteins and glycoproteins) in their cell walls detection of an infection stimulates the strengthening of existing physical defences: cell walls become thicker as more cellulose fibres are laid down callose is deposited to block phloem sieve tubes and plasmodesmata oxidative bursts produce highly reactive oxygen molecules which damage the cells of pathogen

Question 28

examples of anti-microbial chemical production when its increased?

Answer 28

saponins destroy the plasma membrane of fungal cells phytoalexins inhibit the growth of pathogens like fungi

Question 29

what necrosis?

Answer 29

infected cells are sacrificed in deliberate "cell suicide" this limits the spread of the pathogen to the rest of the plant intracellular enzymes digest infected cells

Question 30

what are primary defences?

Answer 30

stop pathogens entering the body

Question 31

what are secondary defences?

Answer 31

actions of phagocytes to kill pathogens that make it past the primary defences

Question 32

primary defences expulsive reflexes?

Answer 32

coughing and sneezing are all classed as expulsive reflexes these are automatic responses which are the body's attempt to expel foreign objects from the body sneezes occur when dust or other particles irritate the nasal mucous membranes coughing arises when the mucous membranes in the respiratory tract are irritated

Question 33

what is the eyes primary defence?

Answer 33

tears contain antibodies and antibacterial | chemicals

Question 34

what are ears primary defence?

Answer 34

wax traps pathogens | mucous membrane

Question 35

what are gut defences?

Answer 35

acidic conditions in stomach (low pH) | mucous membrane

Question 36

what are genital areas defences?

Answer 36

acidic conditions in vagina (lactic acid) | mucous membranes

Question 37

what are nose defences?

Answer 37

nose Mucous membrane | nasal hairs trap pathogens

Question 38

what are blood defences?

Answer 38

platelets cause clots to seal wounds (scabs)

Question 39

what are anus defences?

Answer 39

mucus membrane

Question 40

what is inflammation what causes it?

Answer 40

a response to infection where the affected tissue becomes red, swollen, hot and painful this is due to the action of mast cells, which detect the presence of pathogens and release a cell signalling molecule called histamine

Question 41

what does inflammation cause?

Answer 41

causes vasodilation (blood vessels widen) for increased blood flow capillary walls become more permeable to white blood cells and some proteins there is an increased production of tissue fluid which causes swelling excess tissue fluid drains into lymph vessels, where pathogens come into contact with lymphocytes – leads to the specific immune response

Question 42

Why is skin such an effective barrier?

Answer 42

provides a waterproof physical barrier cells are produced by mitosis and migrate towards the surface migrating cells dry out and cytoplasm is replaced by keratin protien keratinised cells are dead and form an effective barrier to infection

Question 43

How do scabs form to seal wounds?

Answer 43

platelets (small cell fragments) and damaged cells release clotting factors to start the clotting process a mesh of fibrin (protein) fibres forms clots dry out to form a scab, which shrinks as it dries to draw the sides of the wound together

Question 44

What is a mucous membrane? Where are they found and how do they work?

Answer 44

epithelial layer contains goblet cells that secrete mucus – traps pathogens (sticky!) epithelial layer also contains ciliated cells that move in a coordinated action to move the mucus primary defences – mucous membranes in the airways mucus is moved to the top of the trachea – can either be coughed up or swallowed (stomach acid will deal with pathogens)

Question 45

how do scars form?

Answer 45

the skin repairs itself by growing new tissue (stem cell) to pull together the wound and fill in any gaps caused by the injury scar tissue is made primarily of a protein called collagen. Scars develop in all shapes and sizes

Question 46

non-specific meaning?

Answer 46

the process of phagocytosis (engulfing and digesting pathogens) occurs in the same way no matter what the pathogen is

Question 47

specific responses meaning?

Answer 47

antigens are recognised and antibodies are produced to kill particular pathogens. This involves white blood cells called B and T lymphocyctes

Question 48

what are antigens?

Answer 48

antigens are molecules found on the surface of all cell they are specific to individual organisms they are usually proteins, glycoproteins or polysaccharides

Question 49

what are phagocytes and what do they do?

Answer 49

phagocytes are non-specific white blood cells can be divided into two types – macrophages and neutrophils they work together to engulf and digest foreign particles (phagocytosis)

Question 50

what are macrophages?

Answer 50

larger than neutrophils and live much longer made in the bone marrow important role in the specific immune response – cause the activation of lymphocytes by acting as antigen-presenting cells

Question 51

what do antigen presenting cells do?

Answer 51

macrophages engulf pathogens but do not fully digest them they attach the pathogen's antigen to a protein molecule called a major histocompatibility complex (MHC) and express it on their own cell surface in this way the macrophage presents the antigen to other cells of the immune system so they can learn to recognise it

Question 52

what are neutrophils?

Answer 52

short lived – often die after engulfing bacteria made in the bone marrow, found in the blood and tissue fluid attracted to infected cells by histamine released from infected cells

Question 53

order of phagocytosis?

Answer 53

plasma proteins attach to the antibodies. The surface of bacteria becomes coated with opsonins (this process is called opsonisation) phagocytes are attracted to the pathogen by proteins and bacterial products (move by chemotaxis) phagocytes bind to antibodies pathogen is enveloped by the phagocyte’s infolding membrane pathogen is trapped inside a vesicle called a phagosome lysosomes fuse with the phagosome and lysin enzymes are released the pathogen is digested and end products are absorbed into the cytoplasm by diffusion/active transport waste products are excreted from the cell by exocytosis

Question 54

define an immune response?

Answer 54

the specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies

Question 55

define an antibody?

Answer 55

protein molecules that can identify and neutralise antigens

Question 56

describe the three ways antibodies work?

Answer 56

Opsonisation: antibodies bind to antigens on a pathogen's surface and act as a binding site for phagocytes – easier for the phagocyte to bind, engulf and digest the pathogen Neutralisation of pathogens: antibodies cover binding sites so the pathogen cannot bind to host cells antibodies can also attach to flagella to prevent movement of pathogens Neutralisation of toxins (acting as anti-toxins): antibodies bind to toxins produced by the pathogen (usually bacteria, e.g. those causing cholera and tetanus) this prevents toxins from affecting host cells any “toxin-antibody complexes” formed will be phagocytosed

Question 57

what's agglutination?

Answer 57

``` each antibody has two binding sites (some larger antibodies have more) so more than one pathogen can bind ``` pathogens become clumped together (agglutinate) and cannot enter host cells

Question 58

describe the structure of an antibody?

Answer 58

``` each antibody is made up of four polypeptides – two heavy chains and two light chains joined to form a "Y" shaped molecule using disulphide bridges ```

Question 59

what does the constant region mean when describing a antibody structure?

Answer 59

allows attachment to phagocytic cells to aid phagocytosis the constant region determines the mechanism used to destroy the antigen

Question 60

what does the hinge region mean when describing a antibody structure?

Answer 60

allows some flexibility | Branches can move further apart to allow more than one antigen to bind at once

Question 61

what are the two types of lymphocytes?

Answer 61

B lymphocytes Humoral immunity Involves antibodies T lymphocytes Cell-mediated immunity Involves body cells

Question 62

where do B and T lymphocytes mature?

Answer 62

B lymphocytes mature in the Bone marrow T lymphocytes mature in the Thymus gland however they are both made in the bone marrow

Question 63

what do B lymphocytes do in humoral immunity?

Answer 63

B lymphocytes (or B cells) display antibodies on their surface in response to detecting foreign antigens these antibodies in the cell’s plasma membrane act as receptors for antigens

Question 64

what is clonal selection?

Answer 64

``` occurs when a B cell encounters and binds to its corresponding antigen and so is “selected” – stimulated to divide repeatedly and produce a large number of clones, all secreting the correct antibody ```

Question 65

what is clonal expansion?

Answer 65

is the rapid increase by mitosis in the number of lymphocytes from just a few to millions in the presence of an infection

Question 66

where are T lymphocytes produced and matured?

Answer 66

thymus | bone marrow

Question 67

four types of T cells?

Answer 67

T helper cells T killer cells T regulator cells T memory cells

Question 68

What are the effects cytokines?

Answer 68

Stimulate B-cells to develop into plasma cells Stimulate macrophages to engulf and digest pathogens by phagocytosis Activate T killer cells

Question 69

Importance of cell signalling in the immune system response?

Answer 69

T helper cells stimulate B cells to differentiate into plasma cells using interleukins ``` Macrophages release monokines which attract other neutrophils by chemotaxis and stimulate B cells to differentiate and produce antibodies ```

Question 70

define natural immunity?

Answer 70

arises as part of normal life | processes – immunity is inherited or acquired through having the disease and successfully fighting it off

Question 71

define artificial immunity?

Answer 71

comes about as a result of being deliberately exposed to antibodies or antigens; e.g. through vaccination

Question 72

define passive immunity?

Answer 72

is where a person gains antibodies from another person, giving them immediate but short-term immunity

Question 73

define active immunity?

Answer 73

is where the immune system is activated by antigens so that lymphocytes begin antibody production. Active immunity can last for many years, or a whole lifetime but needs several days to take effect

Question 74

define autoimmune disease?

Answer 74

diseases caused by an immune response against an organism's own tissues this can occur when an organism's immune system is unable to recognise self-antigens, so assumes they are non-self (or foreign) antigens and attacks the organism's cells

Question 75

what happens in a vaccination?

Answer 75

involves putting a small amount of a dead or attenuated (weakened) form of a pathogen into the body. These act as antigenic material an immune response is triggered, but no symptoms occur the antigens stimulate plasma cells to produce antibodies against the pathogen memory cells are also produced and remain in the blood so next time the antigen is present there will be a rapid immune response (secondary) this is an example of active immunity (artificial)

Question 76

what's a herd vaccination?

Answer 76

using a vaccine to provide immunity to all/almost all of a population so a disease cannot spread when a large number of individuals are vaccinated, non vaccinated individuals are protected due to the break in chains of infection

Question 77

what's a ring vaccination?

Answer 77

using a vaccine to immunise those people around new cases  Family  Nearest towns/villages  Used to control the spread of livestock diseases

Question 78

how to control a epidemic using vaccines?

Answer 78

using routine vaccination programmes (offered to everyone) will lead to herd immunity where the disease is extremely rare or even eradicated completely once this has been achieved in a population, the routine programme can be relaxed – it is extremely unlikely that people will contract the disease

Question 79

ways to produce vaccines?

Answer 79

Killed virulent organisms heat or chemically treated to denature enzymes dead so will not replicate or cause disease but have the same antigens E.g. whooping cough, typhoid, cholera Live non-virulent strains (attenuated) pathogen is weakened so it will not cause severe disease E.g. BCG (TB), rubella Whole live organisms strains that are not as harmful but contain the same antigens E.g. smallpox Ways to produce vaccines Modified toxins (toxoid) Toxins made by the pathogen that are made harmless stimulate antibody production E.g. tetanus and diphtheria Isolated antigens just the glycoproteins E.g. influenza Genetically engineered antigens made by non-pathogenic bacteria after genes have been isolated and put into plasmid DNA E.g. hepititis B

Question 80

problems with taking vaccines orally?

Answer 80

because antigens are proteins they will become engulfed and digested inside the body