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A Level Biology OCR B > 11. Diseases > Flashcards

11. Diseases Flashcards

(107 cards)

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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
Risk Areas for TB
``` Homeless Poor housing Overcrowding Refugees Areas with high rate of tourism Areas with high rate of migration Malnutrition/Weakened immune system HIV positive patients ```
26
Why are HIV positive patients at risk of TB?
HIV reactivates dormant TB bacteria
27
How is TB diagnosed?
Microscopic analysis of sputum | Chest X-rays
28
How long can it take to diagnose TB?
Up to 2 weeks
29
Treatment of TB?
Isolation of patient for infected period (2-4 weeks) | Intensive care and extensive use of antibiotics
30
Treatment of pulmonary TB?
6 month course (taken every day) of isoniazid and rifampicin Plus 2 month course (taken every day) of pyrazinamide and ethambutol
31
Why is a combination of 2 antibiotics used for the 6 months treatment of pulmonary TB?
to prevent multidrug resistance in bacteria
32
How long does treatment last if TB has spread to tissues outside the lungs?
12 months
33
Problems with treatment of TB?
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
34
Prevention of TB?
``` 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) ```
35
How does decreasing air pollution prevent TB?
Decreases inflammation which decreases risk of infection
36
Define: notifiable disease
disease that has to be reported to the local health authorities if a new case arises
37
Why is data collected on notifiable diseases?
``` 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 ```
38
What does HIV stand for?
Human immuno-deficieny virus
39
What causes HIV?
retrovirus (possesses RNA)
40
What does HIV use as its host cell?
T-helper cells (T4 helper lymphocytes), macrophages and brain cells
41
What does reverse transcriptase do in HIV?
creates double stranded DNA copy of virus genome from single stranded RNA once inside host cell
42
What happens when HIV invades body?
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
43
What is a provirus?
Viral DNA copy integrated with T-helper cell DNA
44
What affect does destroying more and more T-helper cells have?
Increased susceptibility to other infections and diseases
45
Define: Opportunistic Infections
infections that only seize advantage when immune system is not working efficiently and is weakened.
46
Transmission of HIV?
Direct contact with bodily fluids of an infected person
47
Examples of methods of transmission of HIV?
Unprotected sex with infected person Contaminated syringes/needles Mother to foetus across placenta Mother to baby during child birth or via breast milk
48
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?
Acellular particles
49
What can't HIV carry out?
``` 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
What type of nucleic acid does the HIV virus contain?
RNA
51
Which 2 enzymes does HIV have?
Protease | Reverse transcriptase
52
What protects the genetic material of a virus?
Protein coat called capsid
53
What is the capsid made of?
Protein units called capsomeres
54
What is a HIV virus surrounded by?
Viral envelope
55
Risk areas for HIV?
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
Why are homosexual males at risk of HIV?
Rectum has thin lining and less lubrication
57
Symptoms of HIV?
Weight loss Fatigue Susceptible to opportunistic disease
58
Diagnosis of HIV?
Presence of antibodies to HIV (~6 weeks --> 6 months) | Repeated every 3 months
59
Prevention of HIV?
``` Knowledge Monogamy Protected sex Needle exchange Blood screening Contact tracing Give up drugs Prevent needle sharing Abstinence ```
60
What happens in the education program of HIV?
Encouraging use of protected sex Screening blood for HIV before transfusions Being tested if at risk group Discouraging infected mothers from breastfeeding
61
Social consequences of HIV?
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
Problems of HIV?
``` Latent period (asymptomatic carriers) Mass screening of population not possible due to -cost -worry/fear -social/ethical/religious beliefs -drug resistant patients ```
63
Treatment of HIV?
Cannot cure HIV/AIDS but can treat secondary infections | Antiviral treatments can limit reproduction of virus
64
Example of antiviral treatments given when diagnosed with HIV/AIDS and how it works?
Zidovudine - blocks reverse transcriptase
65
Problems with vaccines against HIV?
Virus resides inside cells so difficult to access Virus has high mutation rate Virus has high variety of antigens on its surface
66
Ethical/Social concerns associated with HIV?
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
Define: Epidemiology
study of patterns, distributions and causes of disease in a population
68
Define: Morbidity
number of people in a population that have the disease
69
Define: Mortality
number of people that have died from the disease in a population
70
Define: Endemic
disease that is always present in a population
71
Define: Epidemic
disease that shows sudden increase in incidence in a population
72
Define: Pandemic
disease that shows sudden increase ins several populations (i.e the whole world)
73
Define: Prevalence
number of people who have the disease in a given period of time
74
Define: Incidence
number of new cases of the diseases in a population per year
75
List several control measures
``` 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
Examples of infectious diseases
Chicken Pox Influenza Severe acute respiratory syndrome (SARS)
77
Where is chicken pox endemic to?
UK
78
When is chicken pox most common?
Winter and spring
79
Prevalence of chicken pox?
Varies from year to year
80
When is influenza common in the UK?
Winter
81
Why is there no herd immunity to influenza?
Has high mutation rate producing new different strains
82
Why is SARS potentially life-threatening?
can lead to life-threatening form of pneumonia
83
Where and when did SARS originate?
South China in 2002
84
Examples of Notifiable diseases?
``` Measles Mumps Whooping Cough Rubella Viral hepatitis TB Anthrax Poliomyelitis Anthrax Malaria Cholera Food Poisoning ```
85
First stage of culturing microorganisms?
Preparation of nutrient medium
86
What happens during the first stage of culturing microorganisms?
Nutrients supplied in a nutrient medium (agar/broth) | Aseptic conditions essential
87
Second stage of culturing microorganisms?
Inoculation
88
What happens during the second stage of culturing microorganisms?
Inoculating broth/agar | Aseptically done
89
Third stage of culturing microorganisms?
Identifying Bacteria
90
What are the 3 different methods of identifying bacteria?
1) Use of Gram Staining 2) Colony Morphology 3) Cell Morphology
91
Staining Procedure of Gram Staining?
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
What colour are Gram-negative bacteria stained?
Pink
93
What colour are Gram-positive bacteria stained?
Purple
94
Why are Gram-negative bacteria stained pink?
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
Why are Gram-positive bacteria stained purple?
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
Advantages of Gram-staining method?
Quick | Relatively easy
97
Disadvantages of Gram-staining method?
Only categorises bacteria into 2 groups | Relies on procedure being carried out correctly
98
What is Colony morphology?
Observing colonies under microscope
99
What is a colony?
Small cluster of millions of cloned bacterial cells on surface of agar
100
What are you looking at when observing colonies?
Colour Shape (rod/spherical/cork-screw) Edges (smooth/wavy) Shiny or matt appearance
101
Advantages of Colony Morphology?
Quick | Low skill level required as no staining involved
102
Disadvantages of Colony Morphology?
Unreliable method of identification as many different will have common morphology
103
3 types of Cell Morphology?
Cocci Bacilli Spirilla
104
Examples of cocci and bacilli?
Cocci - staphylococcus aureus | Bacilli - mycobacterium tuberculosis
105
Advantages of Cell Morphology?
Quick | Low skill level
106
Disadvantages of cell morphology?
Unreliable method as many different types of bacilli could lead to misidentification
107
What can serial dilutions be used for?
Culturing micro-organisms

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