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A Level Biology OCR B > 11. Diseases > Flashcards

11. Diseases Flashcards

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1
Q

Define: Disease

A

malfunction of body or mind which adversely affects the health of an individual
i.e condition that impairs normal functioning of an organism

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2
Q

Define: Pathogen

A

micro-organism that causes disease

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3
Q

4 types of pathogen

A

Bacteria
Virus
Fungus
Protoctista

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4
Q

How do bacteria harm the body?

A

Produce toxins –> cell damage –> causing symptoms

Secrete enzymes which allow pathogens to spread through tissues

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5
Q

How do viruses harm the body?

A

Damage host cells and tissues by invading specific target cells
Prevent tissue functioning normally
When sufficient viral particles produced, host cell is ruptured, releasing viral particles to invade new host cells
Some viruses bud off host cell and remain hidden from immune system in membrane bound sacs

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6
Q

What does viral nucleic acid inhibit?

A

normal call DNA, RNA and protein synthesis

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7
Q

How do fungi harm the body?

A

secrete enzymes which allow pathogens to spread through tissues

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8
Q

Define: Communicable Disease

A

Diseases which can spread between individual organisms

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9
Q

Describe what is meant by direct transmission?

A

Transmitted directly from infected person to uninfected person (e.g. droplets, sex, physical contact)

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10
Q

Describe what is meant by indirect transmission?

A

transmitted via an intermediate (e.g. air, water, food, vector)

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11
Q

3 Factors that affect the spread of communicable diseases

A

Overcrowding
Climate
Social factors (e.g. health care, health education)

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12
Q

Cause of Tuberculosis

A

Mycobacterium tuberculosis

Mycobacterium bovis

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13
Q

Transmission of Tuberculosis

A

Spread by droplet infection

uninfected person inhales infected droplets released by an infected person when they sneeze/cough

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14
Q

Transmission of Mycobacterium bovis

A

spread via contaminated meat and unpasteurised milk

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15
Q

First site of TB infection?

A

Lung tissues

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16
Q

Symptoms of TB primary infection?

A

Fever
Weight loss
Fatigue

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17
Q

Why is weight loss a symptom of TB primary infection?

A

Mycobacterium tuberculosis releases hormones which decrease appetite

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18
Q

What happens during the primary infection of TB?

A

Mycobacterium tuberculosis multiplies and destroys lung tissue

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19
Q

What should a healthy person’s reaction be to the primary infection of TB?

A

Immune system should deal with infection with no further complication

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20
Q

Who is likely to contract a TB secondary infection?

A

The Immune-compromised

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21
Q

What happens during the secondary infection of TB?

A

Phagocytic cells and other cells accumulate around infected cells forming a tubercle (granuloma)

Lung tissue damaged, sputum becomes blood stained

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22
Q

Symptoms of TB secondary infection?

A

Chest pains

Night Sweats

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23
Q

During TB secondary infection, what happens to

a) lung tissue
b) sputum

A

a) lung tissue becomes damaged

b) sputum becomes blood stained

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24
Q

Where can secondary TB spread to?

A

Immune system
Bones
Gut
Kidney

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25
Q

Risk Areas for TB

A 
Homeless
Poor housing
Overcrowding
Refugees
Areas with high rate of tourism
Areas with high rate of migration
Malnutrition/Weakened immune system
HIV positive patients
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26
Q

Why are HIV positive patients at risk of TB?

A

HIV reactivates dormant TB bacteria

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27
Q

How is TB diagnosed?

A

Microscopic analysis of sputum

Chest X-rays

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28
Q

How long can it take to diagnose TB?

A

Up to 2 weeks

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29
Q

Treatment of TB?

A

Isolation of patient for infected period (2-4 weeks)

Intensive care and extensive use of antibiotics

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30
Q

Treatment of pulmonary TB?

A

6 month course (taken every day) of isoniazid and rifampicin
Plus 2 month course (taken every day) of pyrazinamide and ethambutol

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31
Q

Why is a combination of 2 antibiotics used for the 6 months treatment of pulmonary TB?

A

to prevent multidrug resistance in bacteria

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32
Q

How long does treatment last if TB has spread to tissues outside the lungs?

A

12 months

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33
Q

Problems with treatment of TB?

A

Length - patients fail to complete course
Cost- each TB patient has a TB treatment assigned to them, expensive to isolate patients
High Number of MDR-TB bacteria
Some strains of XDR-TB bacteria
Difficulties in contact tracing
Difficult to detect carriers of TB
Latent TB can occur

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34
Q

Prevention of TB?

A 
Reduce overcrowding
Improve ventilation
Improve health and nutrition
Decrease air pollution
Pasteurise milk
BCG vaccine
Routine testing of cattle
DOTS (direct observation treatment, short coure)
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35
Q

How does decreasing air pollution prevent TB?

A

Decreases inflammation which decreases risk of infection

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36
Q

Define: notifiable disease

A

disease that has to be reported to the local health authorities if a new case arises

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37
Q

Why is data collected on notifiable diseases?

A 
To allow:
 trends to be monitored
awareness to be raised
vaccination programmes to be improved and directed
contact tracing to be carried out
infected individuals to be isolated
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38
Q

What does HIV stand for?

A

Human immuno-deficieny virus

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39
Q

What causes HIV?

A

retrovirus (possesses RNA)

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40
Q

What does HIV use as its host cell?

A

T-helper cells (T4 helper lymphocytes), macrophages and brain cells

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41
Q

What does reverse transcriptase do in HIV?

A

creates double stranded DNA copy of virus genome from single stranded RNA once inside host cell

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42
Q

What happens when HIV invades body?

A

Virus enters T4 helper lymphocytes (host cell)
Reverse transcriptase creates double stranded DNA copy of virus genome for single stranded RNA
Provirus forms
Provirus is copied before T helper cell divides
Viral DNA activated which causes synthesis of viral RNA and viral proteins, producing more viral particles
T-helper cell ruptures

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43
Q

What is a provirus?

A

Viral DNA copy integrated with T-helper cell DNA

44
Q

What affect does destroying more and more T-helper cells have?

A

Increased susceptibility to other infections and diseases

45
Q

Define: Opportunistic Infections

A

infections that only seize advantage when immune system is not working efficiently and is weakened.

46
Q

Transmission of HIV?

A

Direct contact with bodily fluids of an infected person

47
Q

Examples of methods of transmission of HIV?

A

Unprotected sex with infected person
Contaminated syringes/needles
Mother to foetus across placenta
Mother to baby during child birth or via breast milk

48
Q

HIV viral particles cannot replicate on their own as they are not made of cells. What term is used to describe these types of particles?

A

Acellular particles

49
Q

What can’t HIV carry out?

A 
Normal living processes:
can't reproduce on their own
don't grow
don't divide
don't transform energy
lack machinery for protein synthesis
50
Q

What type of nucleic acid does the HIV virus contain?

A

RNA

51
Q

Which 2 enzymes does HIV have?

A

Protease

Reverse transcriptase

52
Q

What protects the genetic material of a virus?

A

Protein coat called capsid

53
Q

What is the capsid made of?

A

Protein units called capsomeres

54
Q

What is a HIV virus surrounded by?

A

Viral envelope

55
Q

Risk areas for HIV?

A

areas with poor knowledge of the spread of HIV
areas with high prostitution
areas with high degree movement (e.g. ports)
homosexual males
haemophiliacs
promiscuous individuals

56
Q

Why are homosexual males at risk of HIV?

A

Rectum has thin lining and less lubrication

57
Q

Symptoms of HIV?

A

Weight loss
Fatigue
Susceptible to opportunistic disease

58
Q

Diagnosis of HIV?

A

Presence of antibodies to HIV (~6 weeks –> 6 months)

Repeated every 3 months

59
Q

Prevention of HIV?

A 
Knowledge
Monogamy
Protected sex
Needle exchange
Blood screening
Contact tracing
Give up drugs
Prevent needle sharing
Abstinence
60
Q

What happens in the education program of HIV?

A

Encouraging use of protected sex
Screening blood for HIV before transfusions
Being tested if at risk group
Discouraging infected mothers from breastfeeding

61
Q

Social consequences of HIV?

A

Cost of research/NHS
Infected young mothers need to find childcare
Infected young males/females decreases workforce
HIV Hotspots have less tourism
Famine due to inability to work

62
Q

Problems of HIV?

A 
Latent period (asymptomatic carriers)
Mass screening of population not possible due to
-cost
-worry/fear
-social/ethical/religious beliefs
-drug resistant patients
63
Q

Treatment of HIV?

A

Cannot cure HIV/AIDS but can treat secondary infections

Antiviral treatments can limit reproduction of virus

64
Q

Example of antiviral treatments given when diagnosed with HIV/AIDS and how it works?

A

Zidovudine - blocks reverse transcriptase

65
Q

Problems with vaccines against HIV?

A

Virus resides inside cells so difficult to access
Virus has high mutation rate
Virus has high variety of antigens on its surface

66
Q

Ethical/Social concerns associated with HIV?

A

HIV testing requires consent from patient
Stigma attached to sexual partners/children/health care professionals
Discrimination from insurers/employers
Distress caused by false positives
Conflict about informing sexual partner of HIV+ partner
Restriction to travel to some countries

67
Q

Define: Epidemiology

A

study of patterns, distributions and causes of disease in a population

68
Q

Define: Morbidity

A

number of people in a population that have the disease

69
Q

Define: Mortality

A

number of people that have died from the disease in a population

70
Q

Define: Endemic

A

disease that is always present in a population

71
Q

Define: Epidemic

A

disease that shows sudden increase in incidence in a population

72
Q

Define: Pandemic

A

disease that shows sudden increase ins several populations (i.e the whole world)

73
Q

Define: Prevalence

A

number of people who have the disease in a given period of time

74
Q

Define: Incidence

A

number of new cases of the diseases in a population per year

75
Q

List several control measures

A 
education programmes
vaccination programmes
provision of appropriate medicine drugs
improving hygiene
improving housing to reduce overcrowding
improving nutrition
provision of clean water
controlling population movements
76
Q

Examples of infectious diseases

A

Chicken Pox
Influenza
Severe acute respiratory syndrome (SARS)

77
Q

Where is chicken pox endemic to?

A

UK

78
Q

When is chicken pox most common?

A

Winter and spring

79
Q

Prevalence of chicken pox?

A

Varies from year to year

80
Q

When is influenza common in the UK?

A

Winter

81
Q

Why is there no herd immunity to influenza?

A

Has high mutation rate producing new different strains

82
Q

Why is SARS potentially life-threatening?

A

can lead to life-threatening form of pneumonia

83
Q

Where and when did SARS originate?

A

South China in 2002

84
Q

Examples of Notifiable diseases?

A 
Measles
Mumps
Whooping Cough
Rubella
Viral hepatitis
TB
Anthrax
Poliomyelitis
Anthrax
Malaria
Cholera
Food Poisoning
85
Q

First stage of culturing microorganisms?

A

Preparation of nutrient medium

86
Q

What happens during the first stage of culturing microorganisms?

A

Nutrients supplied in a nutrient medium (agar/broth)

Aseptic conditions essential

87
Q

Second stage of culturing microorganisms?

A

Inoculation

88
Q

What happens during the second stage of culturing microorganisms?

A

Inoculating broth/agar

Aseptically done

89
Q

Third stage of culturing microorganisms?

A

Identifying Bacteria

90
Q

What are the 3 different methods of identifying bacteria?

A

1) Use of Gram Staining
2) Colony Morphology
3) Cell Morphology

91
Q

Staining Procedure of Gram Staining?

A

Prepared slides stained with crystal violet for 30secs
Wash stained slide briefly with distilled water
Flood slide in petri dish with Gram’s iodine
After 1 min, rinse slide with distilled water
Then rinse with 95%alcohol and 5% water
Add Safranin (counterstain) and leave for 30 secs
Blot slide
Allow slide to airdry

92
Q

What colour are Gram-negative bacteria stained?

A

Pink

93
Q

What colour are Gram-positive bacteria stained?

A

Purple

94
Q

Why are Gram-negative bacteria stained pink?

A

Thin peptidoglycan wall covered with lipopolysaccharide layer
Crystal violet binds but alcohol added later in test washes away outer layer –> leaching of violet stain
Safranin stains remaining peptidoglycan layer pink

95
Q

Why are Gram-positive bacteria stained purple?

A

Thick peptidoglycan wall not covered with lipopolysaccharide layer
Crystal violet binds to peptidoglycan wall
Alcohol doesn’t remove purple stain
Safranin has no affect

96
Q

Advantages of Gram-staining method?

A

Quick

Relatively easy

97
Q

Disadvantages of Gram-staining method?

A

Only categorises bacteria into 2 groups

Relies on procedure being carried out correctly

98
Q

What is Colony morphology?

A

Observing colonies under microscope

99
Q

What is a colony?

A

Small cluster of millions of cloned bacterial cells on surface of agar

100
Q

What are you looking at when observing colonies?

A

Colour
Shape (rod/spherical/cork-screw)
Edges (smooth/wavy)
Shiny or matt appearance

101
Q

Advantages of Colony Morphology?

A

Quick

Low skill level required as no staining involved

102
Q

Disadvantages of Colony Morphology?

A

Unreliable method of identification as many different will have common morphology

103
Q

3 types of Cell Morphology?

A

Cocci
Bacilli
Spirilla

104
Q

Examples of cocci and bacilli?

A

Cocci - staphylococcus aureus

Bacilli - mycobacterium tuberculosis

105
Q

Advantages of Cell Morphology?

A

Quick

Low skill level

106
Q

Disadvantages of cell morphology?

A

Unreliable method as many different types of bacilli could lead to misidentification

107
Q

What can serial dilutions be used for?

A

Culturing micro-organisms

A Level Biology OCR B (3 decks)

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