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KPH - Week 1 > Abnormal Development - Teratogens and Teratogenesis > Flashcards

Abnormal Development - Teratogens and Teratogenesis Flashcards

1
Q

Define Teratogenesis

A
  • The process of inducing structural or functional malformations in a developing embryo as a result of exposure to a teratogen
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2
Q

Define Teratogen

A

A substance which can lead to the development of structural AND/OR functional defects in the developing embryo/fetus.

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3
Q

Abnormalities of a single structure in a developing embryo can be classified by 3 terms. What are these terms, and what do they mean?

A
  • Malformation - Structural defect of part of or the entirety of a organ as a result of an abnormal process that is required for said organs development (Spina bifida)
  • Disruption - Defect of an organ as a result of a process that interferes with an originally normal, unaffected developmental process (Thalidamide)
  • Deformation - structural abnormality caused by mechanical forces - Amniotic band syndrome
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4
Q

There are 3 terms used to describe abnormal development involving defects to more than one structure. Name and describe them.

A
  • Sequence - group of malformations that arise as a result of a disturbance to a single development process - Potter Seqeunce
  • Syndrome - group of malformations of different structures due to a single primary cause, but acting through multiple developmental pathways - Downs Syndrome
  • Association - Group of anomalies seen in more than one individual that cannot be attributed to a single cause.
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5
Q

Define Teratology

A
  • Study of abnormal development of congenital defects.
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6
Q

What weeks in the development is most sensitive to teratogens?

A

Weeks 3-8

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7
Q

What are the three main potential complications of teratogen exposure?

A
  • Death of embryo
  • Malformation of embryonic structure, such as the heart
  • Functional perturbation of fetus (mental retardation)
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8
Q

After the embryonic period (weeks 3-8), which is the next most sensitive region to teratogens? Which time period

A

Weeks 9-38 (Fetal period)

Weeks (1-2) Pre-germ layer stages

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9
Q

Summarise the main outcomes of teratogen exposure during weeks 1-2 of development

A
  • Death of embryo
  • No effect
    • It is possible only a few cells can be damaged, the embryo can compensate for this (called regulatory development)
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10
Q

Broadly, what is happening during weeks 3-8 of development? Summarise the main outcomes of teratogen exposure during weeks 3 -8, and why it is very much time dependent.

A
  • Development of organs is occuring - each organ stage has it’s own period of maximum sensitivity
  • Type of defect depends on which organ system is most active at this time
  • Structural defects can occur of the organs affected - of course also possible that nothing will happen
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11
Q

Summarise the main effects of tertaogen exposure during weeks 9-38

A
  • More functional defects at this stage, structural abnormalities typically not as severe
  • Effects depend what organ system is must susceptivle at this time - main ones are brain and uroigenital system.
  • Nervous system takes LONGEST to develop
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12
Q

What are the 5 classes of teratogens

A
  • Drugs and chemicals
  • Industrial pollutants
  • Exogenous Hormones
  • Infectious Agents
  • Mehcnial features

BOLD = ENVIRONMENTAL

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13
Q

Give examples of drug/chemical teratogens

A
  • Thalidomide
  • Tetracylines (antibiotics)
  • Streptomycin
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14
Q

What is the postulated teratogenesis of Thalodimide? What are the resulting effects

A
  • Blood vessels are damaged in developing limbs, causing damage to cells in progress zone of developing limb buds - proximal structures to not develop
  • AMELIA (FULL ABSENCE) or MEROMELIA (PARTIAL absence) of limbs
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15
Q

Explain how tetracylines can cause teratogenesis and it’s resulting effects

A
  • able to cross placenta
  • Deposited in bones and teeth at sites of calcification
    • Results in discoulouration of teeth
    • Enamel formation is affectedd
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16
Q

What are the effects of Strepotmycin as a teratogen?

A

can Cause inner ear defects

17
Q

Effects of non-prescription painkillers is a bit unclear. Whilst there doesn’t appear to be any major immediate effects of development, what factor might be influenced?

A
  • Both child and possibly grand child fertility
  • NHS says its safe to take however
18
Q

Epilepsy medication is thought to cause development defects. How is it thought to do this? What condition can this result in? GIve an example of such medication.

A
  • Interferes with folate metabolism
  • Can result in Fetal Hydatoin syndrome (lots of craniofacial defects, digits hypolasia, mental defficiencies

Example of anti-convulsant medication is DIPHENYLYHYDATOIN

19
Q

Methatrexate is thought to be a teratogen. What aspect of metabolism is it thought to affect to cause these affects? What sort of effects does it cause?

A
  • Folate
  • Craniofacial defects,
20
Q

Methotrexate is used for what diseases?

A
  • Cancer
  • RA
  • Lupus
  • Psoriasis
21
Q

Antineoplastic drugs are thought to be highly ??????

A

Teratogenic

22
Q

Vitamin A is used for acne treatment and is thought to be a teratogen. What tertogenic effects can it have?

A
  • Neural crest derivative abnormalities such as facial features, heart and thymus
23
Q

Exogenous hormones can also be teratogens. Give examples and their effects

A
  • Exogenous testosterone (by a female bodybuilder)
    • Masculinsation of female genitalia (enlarged clitoris, scrotum like structure)
  • BPA containing bottles (is a synthetic oestrogen)
    • ​Male offspring have increased incidence of testis malformation and abnormal sperm
24
Q

Alcohol depedent mothers who rely on spirits daily can result in Fetal alcohol syndrome. Explain how alcohol teratogenesis occurs and what it results in (both in blood and in physical presentation)

A
  • Alcohol is able to cross the placenta, but cannot be metabolised by fetal liver
  • Fetus will have high blood alcohol concentration
    • Foetus lacks oxygen and nutrients
    • white matter brain development affected
  • Physical Deformities
    • Low birthweight
    • Facial deformities
    • small head circumference
    • developmental delay
    • Poor motor skills
    • memory problems
    • behavioural problems
    • mental/behavioural problems
25
Q

FAS can cause thinning of what brain structure?

A

Corpus Callosum.

26
Q

Heroin addiction causes addiction for the fetus during pregancny. Often prescried meth

A
27
Q

Cocaine during pregnanyc can result in what?

A
  • premature labour
  • spontaneous absorption
  • malformations of heart - genitourinary system
28
Q

Give examples of infectious agents which can act as teratogens - these can cross the placenta - these are viral

A
  • Herpes Simplex virus - mental retardation
  • Cytomegalovirus - spontaenous abortion, deafness, cerebral palsay
  • Rubella in the first 3 months
    • Week 6 - cataracts
    • Week 9 - destruction of organ of corti
29
Q

Give an example of a protozoan parasite teratogen and the resulting effects - can pass onto placenta

A
  • Toxoplasmia gondii
    • microencephaly, hydrocephalus
    • Mother can be symptomless
    • parasite found in raw uncooked meat, unwashed fruit and vegetables, cat litter
30
Q

Hyperthermia can result in teratogenesis. Viral infections can cause this, as well as what recreational activity?

A
  • Saunas and hot tubs
31
Q

Ionising radiation ( can have drastic effects of development:

A

Abortions

death within first year

Severe birth defects

32
Q

Failure to clean up toxic waste is an example of what type of teratogen?

A

Industrial Pollutant

33
Q

Describe how malformations can result from abnormal growth and examples

A
34
Q

How do you prove teratogens

A

KPH - Week 1 (6 decks)

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