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Zoology Semester 1 > BMS106 Pathobiology - Roehl > Flashcards

BMS106 Pathobiology - Roehl Flashcards

1
Q

What is a disease?

A

Any state in which the health of the organism is impaired

  • a consequence of a failure of homeostasis
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2
Q

What is homeostasis?

A

Maintaining a physiological steady state, despite changes in internal or external processes

  • usually desirable as allows constancy in function of organs, tissues, cells, organelles and proteins
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3
Q

What is pathobiology?

A

Study of biological mechanisms underlying disease processes

  • identifies molecular and cellular interactions that create disease predispositions and enable exposures to produce pathological changes
  • aims to understand disease mechanisms, produce diagnostic tools for disease prevention and to develop new treatments to cure disease
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4
Q

What is aetiology?

A

The primary cause of a specific disease

E.g. Mycobacterium tuberculosis causes tuberculosis, transmitted by air and infecting the lungs

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5
Q

What is pathogenesis?

A

The series of biological changes leading to clinically evident disease

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6
Q

What is pathology?

A

Diagnostic evidence of disease

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7
Q

What are disease risk factors?

A

Intrinsic biological disposition - a susceptibility or tendency to develop a disease - or extrinsic variable exposure which makes a disease more likely

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8
Q

What determines an organisms characteristics?

A

Interactions between intrinsic and extrinsic factors

  • genes interact with factors located in the external environment to determine an organism’s physical characteristics (I.e. phenotypes)
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9
Q

What do some BRCA1 genetic variants cause?

A

Predispositions to breast and ovarian cancer

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10
Q

What can intrinsic risk factors be? Give examples of diseases

A

Metabolic - diabetes, gallstones
Cellular - autoimmune e.g. rheumatoid arthritis; degenerative and aging e.g. Alzheimer’s
Structural - spins bifida, a thermos, Osteoarthritis
Blood - sickle cel anaemia, thalassemia

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11
Q

How can exposure lead to pathogenesis?

A

Variable contact with an extrinsic harmful agent that makes a disease more likely

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12
Q

Give an example of an extrinsic harmful agent and how it can affect disease pathogenesis

A

Smoking increases the risk of developing lung cancer

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13
Q

What can extrinsic risk factors be?

A

Physical, chemical, biological, nutritional

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14
Q

Give agents and examples for physical extrinsic risk factors

A

Trauma - bone fracture

Radiation - Cancer

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15
Q

Give agents and examples for chemical extrinsic risk factors

A

Toxic substances - tobacco lung damage

Inflammatory agents - asthma

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16
Q

Give agents and examples for biological extrinsic risk factors

A

Bacterial - tuberculosis
Virus - AIDS
Protozoa - Malaria

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17
Q

Give agents and examples for nutritional extrinsic risk factors

A

Unbalanced diet - obesity, type 2 diabetes

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18
Q

How can the specific changes in biological structure and function that characterise each disease be recognised?

A

Macroscopic changes in organs
Light microscope level - cells/tissues
Electron microscope level - cells and organelles
Molecular level - e.g. DNA, RNA, proteins, hormones

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19
Q

What is epidemiology?

A

The study of the distribution and determinants of health and disease in populations

Aims to inform public health strategies to control disease

Can also help to understand the pathobiology of a disease

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20
Q

What can geography affect?

A

The prevalence and impacts of many diseases - markedly different in different countries

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21
Q

What are DALYs?

A

Disability Adjusted Life Years - 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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22
Q

What else can affect life expectancy?

A

Deprivation - can differ markedly between social groups within one society

Adults in the poorest fifth of the population are much more likely to be at risk of developing a mental illness than those on average incomes

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23
Q

How are epidemiology and pathobiology complementary?

A

Epidemiologist aims to reduce exposures, pathobiology aims to reduce disease burden through more effective diagnosis and treatment

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24
Q

What is Alkaptonuria?

A

A defect in the enzyme Homogentisate 1,2

Homogentisic acid accumulates in joints, causing cartilage damage and back pain and precipitates as kidney/prostate stones.
High levels are excreted blackening urine (which allows diagnosis)

Discovered by Archibald Garrod

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25
Q

What did Archibald garrod discover about alkaptonuria?

A

That it was a classical autosomal recessive Mendelian trait - this led to the identification of other inherited genetic disorders:

Cystinuria 
Phenylketonuria
Albinism
Glycogen storage disorders
Galactosaemia
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26
Q

What does autosomal mean?

A

associated with one of the 22 non-sex chromosomes

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27
Q

What did William Bateson do?

A

Began to catalogue disease that exhibited Mendelian inheritance

  • skin disorders, eye disorders, neurological disorders, inborn errors of metabolism, anatomical abnormalities
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28
Q

What is brachydactyly?

A

Short digits, small or missing phalanges

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29
Q

Name 2 autosomal recessive Mendelian diseases

A

Alkaptonuria

Cystic fibrosis

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30
Q

Name 2 autosomal dominant Mendelian diseases

A

Brachydactyly

Huntington’s disease

31
Q

Name 2 x-linked Mendelian diseases

A

Duchess muscular dystrophy
X-linked mental retardation
Haemophilia

32
Q

What is sickle-cell anaemia?

A

A painful, sometimes life threatening disorder of erythrocytes
Caused by a single-point mutation in the codon for amino acid 6 in the ß-gloving subunit (turns Glu codon into Val codon) - haemoglobin tetramers containing Hbs tend to form large insoluble polymers which distort erythrocyte shape

Autosomal co-dominant

33
Q

Prevalence of sickle cell anaemia is ~2% in some sub-Saharan countries and the heterozygous carrier frequency is 10-40%.
Why is the frequency of the HBs allele so high?

A

Heterozygous carriers have sickle cell trait (mild suckling) but exhibit increased resistance to malaria - heterozygotes are fitter than both homozygotes.

34
Q

How does karyotyping allow genes to be mapped to specific chromosomal locations?

A

Abnormalities in banding due to mutagenic rearrangements can be recognised and associated with specific phenotypes

35
Q

What is aniridia?

A

An autosomal dominant phenotype caused by deletion or loss-of function point mutations in one copy of the gene

36
Q

What is duchenne muscular dystrophy?

A

An x linked disease causing progressive muscle damage and wasting disease. Lethal in childhood or early adulthood

DMD gene located at chromosome position Xp21

37
Q

How was the DMD gene identified?

A

A DNA sequence that was deleted in the X chromosome of the DMD patient BB and confirmed in other DMD patients
DNA marker for dystrophin protein

38
Q

What is Huntington’s disease?

A

A progressive, late-onset, inherited neurodegenerative disorder (dementia and movement disorder)
Autosomal dominant

39
Q

Whereabouts in the HD brain is massive neuronal loss exhibited?

A

Basal ganglia and dilation of lateral ventricles

40
Q

How large is the HD gene?

A

1.7 X 10^5 base pairs

41
Q

What do HD mutations do?

A

Expand a CAG repeat sequence in the first exon if the HD gene (CAGCAGCAGCAG…), increasing the size of a polyglutamine tract in the HD protein. The expanded polyQ tract makes the mutant Huntington protein toxic to neurones

42
Q

What do some animal virus genomes contain?

A

Genes that cause cancer

  • tumotigenicity of Rous Sarcoma Virus is due to the presence of DNA sequences captured from the chicken genome (the v-src oncogene) - encodes an abnormally hyperactive version of a tyrosine kinase
43
Q

What is an oncogene?

A

A gene that has the potential to cause cancer

44
Q

What are viral oncogenes?

A

Dominant, gain-of-function mutant alleles of cellular genes

45
Q

How can loss-of-function mutations cause cancer?

A

Inactivation of tumour suppressor genes, e.g. retinoblastoma

46
Q

What is retinoblastoma?

A

A rare retinal tumour that can be either hereditary or non-hereditary - tumours may be unilateral or bilateral

Non-hereditary retinoblastomas are typically unilateral
Hereditary blastimas are typically bilateral

Caused by mutations in a tumour supressor gene that normally prevents cells from becoming cancerous

47
Q

What is Alfred Knudson’s two-hit hypothesis regarding retinoblastoma?

A

Caused by inactivation of both alleles of a tumour supressor gene

Hereditary retinoblastoma - inherited germline mutation present in all cells - only one somatic RB mutation required in retinal cell

48
Q

Many chronic non-communicable human diseases are caused by multiple genes interacting both with each other and environmental factors…

A

This makes it impossible to identify “the gene” in such situations, since many genes are involved

Heart Disease
Diabetes
Obesity
Cancer
Hypertension
Schizophrenia 
Autism
Multiple sclerosis
49
Q

What are SNPs?

A

Single Nucleotide Polymorphisms - total of 3 X 10^7 SNPs within the human genome - distributed randomly across the genome

50
Q

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

A

SNPs present in each individual genome within a group of patients compared to SNPs present in the genomes of healthy individuals
Case vs control comparison

SNPs identified that are more frequently found in patients than in healthy individuals - may play potentially causative roles in the disease process.

These studies are called Genome Wide Association Studies (GWAS)

51
Q

What are genomic imprints?

A

Structural modifications to specific regions of particular chromosomes that prevent the transcription of genes within such regions

52
Q

What is an example of how genomic imprints can be made?

A

Methylation of DNA sequences

53
Q

Where are different genomic imprints introduced?

A

Sperm vs eggs

54
Q

Localised methylation of DNA occurs on a specific subset of genes during…

A

Oogenesis vs spermatogenesis

Distinct modified genes for each

55
Q

The imprinted gene is the one that is…

A

Not expressed

56
Q

When are maternal and paternal imprints created?

A

During gametogenesis

57
Q

Imprints are erased in…

A

embryonic precursors of germ cells during embryonic development

58
Q

What is Prader-Willi syndrome?

A

A disease caused by a mutation of the SNORD116 complex that leads to low muscle tone, short stature, cognitive disability, chronic hunger, morbid obesity

59
Q

What is angelman syndrome?

A

A disease caused by a mutation of UBE3A that leads to cognitive disability, sleep disturbance, seizures, jerky movements, frequent smiling

60
Q

What does epidemiology assume?

A

Disease does not occur randomly

Disease has identifiable causes

61
Q

What is epidemiological research used to do?

A
  • describe the health status of a population
  • explain the aetiology of disease
  • predict the disease occurrence
  • control the disease distribution
62
Q

What type of study is very useful in epidemiology?

A

Migrant studies - in order to determine importance of location and environment and lifestyle over genetics on different diseases

63
Q

What proportion of cholera (Vibrio cholera) cases prove fatal in unprepared communities vs well organised and prepared countries?

A

50% vs <1%

64
Q

How many deaths occur each day as a result of smoking in the UK?

A

Over 320

120,000 per year

1/5 of all deaths across all ages

7.5 Years average loss of LE

65
Q

Smoking is highly addictive. What percentage of smokers who want to succeed giving up before age 65 (bearing in mind 70%+ want to)

A

50%

66
Q

What percentage of smokers with a lung removed for lung cancer smoke up again?

A

50%

67
Q

What are the factors behind cigarette addiction?

A

Pharmacology —> nicotine is a highly addictive drug

Learning mechanisms

Social and economic influences

68
Q

What are some major health consequences of smoking?

A

Cancer (lung, mouth, larynx, throat, bladder, kidney etc)

Respiratory disease e.g. COPD

Vascular disease (CHD, stroke, peripheral vascular disease)

Pregnancy and birth complications

69
Q

What is pulmonary emphysema (which can be caused by smoking)?

A

Enlargement of alveoli due to:

  • loss of elastin surrounding alveoli
  • destruction of cells in alveolar walls

Imbalance of more processes than anti-proteases. Inhaling toxins increases proteases (such as metalloprotease) which damage alveolar cells.

Protease balance can also be affected by genetics, for example decreased a-antitrypsin decreases anti-protease

70
Q

What are attracted by IL-8 when it is released by macrophages due to smoking, and what do these do?

A

Neutrophils release the protease elastase

71
Q

What are the consequences of pulmonary emphysema?

A

Decrease in the SA of the respiratory membrane leading to decreased gas exchange

Air becomes trapped in alveoli during exhalation as there is no elastic recoil

72
Q

What are the critical factors that determine whether smoking exposure leads to disease?

A

Chemical and biological composition

Shape and size of particles

Dose (conc and duration)

Pre-existing health or genetic status

Concurrent exposure to other toxic agents

73
Q

What are the 2 broad response types of the body to smoking?

A 
Allergic responses (asthma, laryngitis, rhinitis, alveolitis)
- histamine release by mast cells due to inhaled antigens (IgE)

Pneumoconiosis

74
Q

Asbestos can cause many diseases including…

A

Asbestosis

Zoology Semester 1 (16 decks)

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