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BMS109 Introduction to Biomedical Science > Pathobiology > Flashcards

Pathobiology Flashcards

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Biology 101 flashcards
1
Q

What is disease?

A

A state in which the health of the human organism is impaired.
A consequence of a failure of homeostasis.

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2
Q

Define homeostasis.

A

Maintaining an appropriate steady state of the internal environment despite changes in the external environment.
Allows constancy in functions of organs, tissues, cells, organelles and proteins.
Limits for an ectothermic animal.
Coined by Claude Barnard.

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3
Q

Define pathogenesis.

A

The pathological/biological mechanism which results in clinically evident disease.

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4
Q

Define aetiology.

A

The specific cause of a disease.

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5
Q

Define predisposition

A

A susceptibility or tendency to develop a disease, which depends on other risk factors to become clinically evident.

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6
Q

Define risk factor.

A

A variable exposure or biological characteristic which makes a disease more likely.

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7
Q

Define genotype, phenotype and environment. State how they are related.

A

Genotype is the inherited, genetic constitution of an organism.
Phenotype is a physical or behavioural characteristic.
Environment includes food availability, predators, competitors, climate, mate choice, drugs, environmental toxins etc.
Genes interact with environmental factors to determine an organisms phenotype.

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8
Q

Name the intrinsic factors that are causes of disease.

A

Genetic: sickle cell disease or CF.
Metabolic: diabetes or gallstones.
Cellular Autoimmune: rheumatoid arthritis.
Cellular Degenerative: Alzheimer’s.
Structural Congenital: spina bifida.
Structural Acquired: atheroma or osteoarthritis.

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9
Q

Name the extrinsic factors that are causes of disease.

A

Physical:
Trauma - Bone fracture
Radiation - Cancer
Temperature - Burns or frostbite

Chemical:
Toxic substances - Tobacco
Inflammatory agents - Asthma

Biological:
Bacterial - Infections
Virus - AIDs or hepatitis
Fungi or parasites - Athlete’s foot

Nutritional:
Various - Malnutrition

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10
Q

What are the 2 factors that contribute to disease risks and what is their relationship?

A

Genetic factors and environmental factors.
They vary considerably in proportion between diseases.
Cystic fibrosis is only genetic, traumatic head injury is only environmental. Diabetes is in the middle.

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11
Q

What is DALYs

A

Disability Adjusted Life Years: the sum of years of potential life lost due to premature mortality and the years of productive life lost due to disability.

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12
Q

Life expectancy varies..

A

..between social groups according to the social gradient.

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13
Q

What are the specific changes in function and structure that characterise each disease?

A

Gross/macroscopic changes in organs.
Light microscope level.
Electron microscope level.
Molecular level.

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14
Q

What are the manifestations of disease?

A

The functional consequences of the morphologic changes that occur in the disease process.
Detected in clinical signs and symptoms which may require tests. Consider pathology: How does the disease produce the morphologic changes?

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15
Q

Understanding the pathogenetic mechanisms provides..

A

..the knowledge base for rational development and evaluation of interventions to prevent or treat disease.

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16
Q

Who was the founder of Biochemical Genetics and concept ‘Inborn Errors of Metabolism’?

A

Archibald Garrod 1909.

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17
Q

Describe ‘Inborn Errors of Metabolism’ concept.

A

In example of ALKAPTONURIA:
Homogentistic acid accumulates in the joints causing cartilage damage and back pain. This precipitates as kidney or prostate stones so high levels of blackening urine are excreted; allowing a diagnosis.
Autosomal recessive Mendelien trait.
Discovery of Cystinuria, Albinism etc.

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18
Q

Describe Mendelien Inheritence.

A

Inheritance following Mendel’s Laws as per the pea plant examples.

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19
Q

Name the Mendelien patterns of inherited human diseases.

A

Autosomal recessive: CF
Autosomal dominant: Huntington’s
Autosomal co-dominant: Sickle cell anaemia
X-linked: Haemophilia

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20
Q

What causes sickle cell anaemia?

A

Single point mutation in the amino acid 6 codon in the beta globin subunit Glu -> Val.

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21
Q

What is the sickle cell anaemia allele phenomenon/sickle cell trait?

A

Heterozygotes have increased resistance to malaria due to co-dominance between them; Sickle Cell Trait.

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22
Q

What is karyotyping?

A

Distinguishing each chromosome to map genes to specific chromosomal locations and mapping human disease genes.

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23
Q

What is Aniridia?

A

Loss of the iris through an autosomal dominant phenotype caused by deletion/loss-of-function point mutations in one copy of the gene.

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24
Q

What is Duchenne Muscular Dystrophy?

A

An X-linked disease of progressive muscle damage and wasting disease. Lethal in childhood or early adulthood.

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25
Q

What is the largest known human gene?

A

Dystrophin protein which is part of a bridging complex connecting each muscle fibre to the extra cellular matrix - maintains tissue integrity.

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26
Q

What is Huntington’s Disease?

A

A progressive, late onset inherited neurodegenerative disorder characterised as a dementia and movement disorder.
Massive neuronal loss in the basal ganglia (caudate nucleus and putamen) and dilation of the lateral ventricles.

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27
Q

What is the molecular pathology of Huntington’s Disease?

A

The polyglutamine tract is increased in HD proteins from 10-35 glutamine residues in wild type to 36-121 glutamine residues in mutant. The mutant Huntingtin protein is toxic to neurons.

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28
Q

Some animal virus genomes..

A

..contain genes that cause cancer.
Rous Sarcoma Virus 1911; v-src oncogene from the chicken genome. Encodes an abnormally hyperactive version of a tyrosine kinase encoded by c-src proto-oncogene.

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29
Q

Viral oncogenes..

A

..are dominant, gain-of-function mutant alleles of cellular genes.

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30
Q

Chromosomal rearrangements..

A

..can cause cancer if they disrupt, truncate or reassemble cellular proto-oncogenes.

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31
Q

Chronic Myelogenous Leukaemia..

A

..caused by a chromosomal translocation in haemopoietic progenitor cells.
Creates the ‘Philadelphia Chromosome’.

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32
Q

How can loss-of-function mutations cause cancer?

A

They inactivate tumour suppressor genes eg. Retinoblastoma.

33
Q

Describe Retinoblastoma.

A

Rare retinal unilateral or bilateral tumour either hereditary (typically bilateral) non-hereditary (typically unilateral).

34
Q

Retinoblastoma; Alfred Knudson’s Two-Hit Hypothesis

A

Hypothesis that it is caused by mutations in tumour suppressor gene.
Individuals born heterozygous for a recessive mutation will develop bilateral tumours if independent secondary mutations inactivate remaining wild type copy in cells of each eye.

35
Q

Name two causes of cancer.

A

Proto-oncogenes: Dominant, gain-of-function mutations.

Tumour Suppressor Genes: Recessive, loss-of-function mutations.

36
Q

Why can’t all diseases be catalogued according to Mendelian Inheritance?

A

Multiple genes interacting with each other and the environment in chronic non-communicable diseases.
E.G. Heart disease, diabetes etc.

37
Q

What is a Single Nucleotide Polymorphism? How many are in the human genome?

A

Variation in a single nucleotide at a specific genomic point with an appreciable difference between a population. Randomly distributed across the genome.
3x10^7.

38
Q

What do 500,000 SNPs in the human genome give us?

A

A detailed map of DNA sequence variation across the genome.

39
Q

How can SNPs be used to identify DNA sequences associated with common disease?

A

Genome Wide Association Studies.
Use a case vs control comparison to identify SNPs found in patients compared to the control. These can be thus associated with the disease and their potentially causative roles.

40
Q

What is gene imprinting?

A

Only applies to some genes.
Methylation of DNA sequences that prevent the transcription of the gene. This is removed when sperm and egg fuse then the pattern reapplied according to the sex of the embryo - gametogenesis.

41
Q

Give an example of a paternal imprint and of a maternal imprint.

A

Paternal: UBE3A.
Maternal: SNORD116.

42
Q

Name 2 imprinting disorders.

A

Prader-Willi Syndrome: No functional SNORD116.

Angelman Syndrome: No functional UBE3A.

43
Q

Define epidemiology.

A

Studies patterns of disease frequency in human population and disease distribution by person, place and time.

44
Q

What is assumed when studying epidemiology?

A

1 Does not occur randomly.

2 Has identifiable causes.

45
Q

What 4 things does epidemiologic research look at?

A

1 Describe the health status of a population.
2 Explain the aetiology of disease.
3 Predict the disease occurrence.
4 Control the disease distribution.

46
Q

What is the epidemiological triangle include?

A 
1 Host (Intrinsic factors)
2 Agent
3 Environment (Extrinsic factors)
47
Q

Define epidemic.

A

Widespread disease outbreak amongst a population.

48
Q

Define pandemic.

A

An epidemic crossing populations.

49
Q

What is cholera?

A

Waterborne disease characterised by poor access to safe water and inadequate disposal of sewage.
Epidemiological work by John Snow proved the link but the causative organism discovered later by Koch.

50
Q

What is an association vs causation?

A

An association is observed, say between cancer and gambling, then the causation is presumed until proven.

51
Q

Give some mortality facts associated with smoking.

A

Lose 7.5 years off average life expectancy.
1/5 of all deaths across all ages.
120,000 a year in the UK.
4 million deaths a year worldwide.

52
Q

What are the major health consequences of smoking?

A

Cancer (Lung, mouth, throat, oesophagus, bladder, cervix, kidney, pancreas).
Respiratory disease (COPD).
Vascular disease (Coronary heart disease, stroke, peripheral vascular disease).
Pregnancy and birth complications.

53
Q

How can smoking lead to premature birth?

A 
Fetal hypoxia.
Increased risk of membrane rupture.
Restricted placental blood flow.
Altered cell signalling.
Maternal endocrine/paracrine changes.
54
Q

Explain the different mechanisms of how tobacco causes pulmonary emphysema.

A

Tobacco causes chronic chemical injury which causes damage to the alveoli by neutrophils. Proteases (elastase) break down the elastin.
Oxidants and free radicals inhibit antitrypsin (protease inhibitor) lowering protection from proteases.
Lowered ciliary action and chronic bronchitis (excess of mucus) lead to increased infections.

55
Q

What is Beurger’s disease?

A

Peripheral vascular disease brought on by smoking which can lead to amputation.

56
Q

What is Occupation Lung Disease?

A

Rhinitis, Laryngitis, Tracheitis, Bronchitis, Bronchiolitis, Asthma, COPD, Cancer and Interstitial Disease.

57
Q

Name the critical factors when determining if exposure causes disease.

A 
Chemical and biological composition.
Shape and size of particles.
Dose - concentration and duration.
Pre-existing health or genetic status.
Concurrent exposure to other toxic agents.
58
Q

Name the 2 responses from exposure.

A

Allergic.

Pneumoconiosis (dusts).

59
Q

Name the 4 reactions from pneumoconiosis.

A

Inert (coal miner’s).
Fibrous (asbestosis).
Allergic (extrinsic allergic alveolitis).
Neoplastic (Lung carcinoma).

60
Q

What is a pathogen? Name some examples and the 3 types.

A

Causes disease. 1/3 human deaths.
Virus, bacteria, protozoans, fungi, worms, prions.
Obligate: Can only survive in the host.
Facultative: Present in the environment, waiting for host.
Opportunistic: Normally benign but cause disease in compromised host.

61
Q

Why do pathogens make us sick?

A

Symptoms help spread the pathogen (diarrhoea).
Pathogen kills cells to replicate.
Sometimes symptoms appear to have no advantage or are part of host’s response.

62
Q

What are virulence genes?

A

Genes that mean two closely related species are different; one is pathogenic and one harmless.

63
Q

Bacteria cause..

A

..cholera, food poisoning, syphilis and gonorrhoea.

64
Q

Eukaryotes cause..

A

..malaria, thrush and athlete’s foot.

65
Q

Viruses cause..

A

..AIDs, smallpox and common cold.

66
Q

Describe complex nature of fungi.

A

Dimorphism: Grows as mould in the soil then yeast morphology in a warm body.

67
Q

Describe complex nature of protozoa.

A

Plasmodium falciparum causes malaria through Anopheles mosquito - sporozoites cause production of gametes in human then fertilised by mosquito.

68
Q

What barriers do pathogens need to overcome?

A

1 Bacterial and fungal flora.
2 Epithelia held together by tight junctions. (Breaks quickly recognised by WBCs).
3 Mucous secretions.

69
Q

Why do pathogens breach the cell membrane?

A

Inject toxins or replicate inside the cell.

70
Q

Why do pathogens release toxins?

A

Kills host cell to provide nutrients and killing WBCs helps pathogen evade immune system.

71
Q

Give specific examples of pathogens overcoming barriers.

A

E. coli make the host cell make an actin pedestal to hold them in place.
Bacteria hide inside cells. L. pneumophila replicates inside the macrophage or can enter non phagocytotic cells (zipper or trigger mechanisms).
Listeria secrete hemolysin to break down phagosome membrane (stopped inside the cell by PEST) and then replicate inside the cell. Actin tails then push them into the next cell.

72
Q

How do antibiotics work?

A

Stop bacterial growth by disrupting cellular processes.

73
Q

Give some examples of how pathogens can modify the behaviour of the host to suit its needs.

A

Yersinia pestis blocks flea’s digestive tract so it starves and bites more.
Lyssavirus sp. causes rabies where biting spreads the disease.
Toxoplasma gondii completes life cycle in cats but travels by rat as infected rats lose their feat of cats.
Cordyceps sinensis infects act which climbs up branch and dies. The body gives the fungus a source of nutrition while it grows then spores are released.

74
Q

Why are viruses the ultimate pathogen?

A 
Typical DNA virus lifecyle.
Types of genomes.
Entry and exit from the cell.
Tumour formation by DNA viruses.
Retroviral life cycle.
Tumour formation by retroviruses.
75
Q

Describe the basics of a virus.

A

Encapsulated in a capsid (coat protein).
Rely on host cell machinery and stops functions it doesn’t need like synthesis.
Exit the cell when it lyses or in budding (HIV).

76
Q

How are viruses classed?

A

Their genome type and how their mRNA strand is made.

77
Q

What are the different ways a virus can enter a cell?

A

All need receptors.
Fusion.
Endocytosis.
Uncoating.

78
Q

Papillomavirus.

A

Causes 6% of all human cancer.
Pap smear can give early detection/curative treatment.
Contains several oncogenes.
E6 and E7 normally turn up a hosts DNA replication machinery.
When integrated to a cell, they give unregulated cell proliferation.

79
Q

Retroviruses.

A

Cause cancer by incorporating human proto-oncogenes into their genome.

BMS109 Introduction to Biomedical Science (6 decks)

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