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Block 11 > Week 3 > Flashcards

Week 3 Flashcards

1
Q

Infectious causes of congential anomalies

A

TORCHS.
Toxoplasmosis
Other agents
Rubella
Cytomegalo virus
Herpes
Syphillis

Causes secondary anomalies (external factors).
Primary = genetic

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2
Q

Nutritional causes of congenital anomalies

A

Iodine.
Folate.
Obesity.
Diabetes.
Excess vitamin A.

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3
Q

Enviromental causes of congenital anomalies

A

Pesticides.
Medications (anti epileptics).
Alcohol.
Tobacco.
Radiation.

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4
Q

Classification of embryogenesis disturbances

A

Polytopic field defect (2-4 wks)
- Scattered pattern (eg. trilaminar disc)

Monotropic field defect (4-8wks)
- Localized defect

Fetal period - Organogenesis (>9wks)
- defective organs

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5
Q

Polytopic field Defects

A

VACTERL
- Vertebral anomalies
- Anal atresia
- Cardiac anomalies
- Tracheo-oesophageal fistula
- Reneal anomalies
- Limb anomalies

Embryo = 2-4 weeks

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6
Q

Monotopic Field Defects

A

Cleft lip/palate.
Tracheo-esophageal fistula.
Holoprosencephaly.

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7
Q

Disruption anomaly example

A

Amniotic bands.
- strips of amiotic membrane around the fetus.

Poland anomaly.
- Interruption of subclavian artery vascular supply due to maternal use of cocaine. underdevelopment of pectoralis major on affected side.

Disruption = development started normal but then went wrong.

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8
Q

Sequence anomalies

A

Potter sequence.
- Renal agenesis > oligohydramnios> pulmonary hypoplasia > limb position defects

Pierre Robin sequence.
- Mandibular hypoplasia > tongue cannot drop > impaired palate development

Sequence = one problem resulting in a cascade of events

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9
Q

Di George Syndrome

A

Partial deletion of chromosome 22.
Characterized by a range of anomalies.
Includes failure of developement of 3rd & 4th pharyngeal pouch.

Syndrome = collection of SIGNS + SYMPTOMS

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10
Q

CHARGE syndrome

A

CHD7 heterozygous mutation.
Coloboma (eye defect).
Heart defects.
choanal Atresia.
growth & development Retardation.
Genital hypoplasia.
Ear defects.

single gene mutations typically involve transcription cofactors.

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11
Q

Spina Bifida

A

Defects in closure of caudal neural tube.
Can occur anywhere, most commonly in lumbosacral region.

Hydrocephalus nearly always occurs.
Neurological deficits can happen.

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12
Q

Fetal Alcohol Syndrome

A

Neural crest migration and brain development sensitive to alcohol.
1/100 births.

Smooth philturm. Thin upper lip. Small head. Flat midface. Small eye openings.

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13
Q

Congenital Rubella Syndrome

A

Fetus infected with rubella.
Infection affects development of organs of special sense plus heart and others.

Microcephaly. Cataracts. PDA (Patent Ductus Arteriosus).

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14
Q

Screening
When?

A

Pre-conception (genetic counselling).

Antenatal
1st trimester: Triple test, Nuchal fold
2nd (20wk): Anomaly scan

Newborn screening examination.

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15
Q

Fetal Circulation

A

Internal iliac artery > umbilical arteries > intervillous space in placenta > L umbilical vein > ductus venosus > inferior vena cava > right atrium > left atrium > L ventricle > aorta

Ductus venosus (liver bypass).
Ductus arteriosus (bypass lungs).
Formamen ovale (bypass right ventricle & lungs)

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16
Q

Parts of fetal circulation in adulthood

ie ligamentums

A

Ductus venosus - Ligamentum venosum
Ductus arteriosus - Ligamentum arteriosum
Umbilical vein - ligamentum teres
Umbilical arteries - medial umbilical ligaments
Forament ovale - fossa ovalis

17
Q

Changes in circulation at birth

A

No placental return:
Decreased vascular flow in IVC = decreased flow to RA
Increased systemic vascular resistance
Increase LV workload

First breath:
Decreased pulmonary vascular resistance.
Increased left atrium pressure.
Septum secundum forced closed on septum primum = fossa ovalis.

18
Q

Ductus Venosus

A

DV connects umbilical vein supplying oxygenated blood to the IVC.
Blood enters RA.
Bypassing liver, saturation is maintained (from 75 to 60%).

19
Q

Foramen Ovale

A

RA pressure is higher than LA.
Forces FO to open and bloodflow to LA.
Free border of septum secundum forms crest - Crista dividens.
Creates 2 streams of blood flow.
Majority flow to LA.

Minor flows to RV where it mixes with blood from SVC (deoxygenated).

20
Q

What causes closure of ductus ateriosus and venosum?

A

Increased oxygenation + reduced placental prostaglandin E2. Vascular spasm.
Ductus arteriosus closes 24-48hrs.
Ductus venosus closes more slowly.

21
Q

Conditions causing duct dependent systemic circulation

A
  1. Coarctation of Aorta.
  2. Critical aortic valve stenosis.
  3. Hypoplastic left heart syndrome.

Blood flows pulmonary artery > aorta

  1. narrowing in the aorta
  2. aortic valve stenosis
  3. small LV
22
Q

Conditions that cause duct dependent pulmonary circulation

A
  1. Pulmonary atresia
  2. Tricuspid atresia
  3. Critical pulmonary stenosis
  4. Tetrology of fallot

Blood flows Aorta > pulmonary artery

  1. Fused pulmonary valve - requires patent foramen ovale
  2. fused tricuspid - requires patent forament ovale
23
Q

Ductus Arteriosus

A

Shunts from RV and PT to Aorta.
Minimizing drop in O2 saturation.

24
Q

Development of Lungs

A

Week8-16: Pseudoglandular stage
- Duct system formation in the bronchopulmonary segment (Bronchioles).
W16-26: Canalicular stage
- Formation of terminal respiratory bronchioles.
W26-term: Terminal sac stage
- Terminal sacs begin to bud.
- Differentiation of Type 1 & 2 pneumocytes.

25
Q

Teratogen

A

An agent that directly or indirectly causes structural/functional abnormalities in the fetus or child after birth.

26
Q

Priniciples of Teratogenesis

A
  1. Teratogenicity - physical/chemical agents.
  2. Behavioural teratology
  3. Transplacental carcinogenicity - mother unaffect, offspring has cancer
  4. Mutagenicity - 2 types:
    i) Germ cells (sex cells - inherited defects)
    ii) Somatic cells
27
Q

Factors affecting teratogen exposure

between individuals

A

Time of exposure.
Susceptibility.
Dose.
Route of exposure.

Time: Embryonic period (~9wks, 1st trimester) is very susceptibile.
Susceptibility: Previous obstetric history important factor. Genetics.

28
Q

Two types of inheritance that cause birth abnormalities

A
  1. Monogenic/Mendelian - recognizable patterns
  2. Multifactorial/Polygenic - degree of sensitivity is variable (ie. Spina Bifida)

  1. causes = single gene mutation
  2. Environment + mutation, multiple gene mutation
    70% of spina bifida can be prevented via maternal folic supplementation.
29
Q

Teratogenicity Data

A

Medications advised to be avoided during pregnancy.
Lack of data due to inadequate study sizes.
Data gathered from epidemiological studies and case reports.

30
Q

Fetotoxic Drugs in T1

Androgen,estrogen, warfarin, retinoids, antiepileptics

A

Androgens - Virilisation of female fetus
Estrogen - Feminisation of male fetus
Warfarin - Nasal hypoplasia, skeletal defects
Retinoids - Craniofacial, CNS, CV defects
Antiepileptics - Facial defects, mental retardation, NT defects

31
Q

Fetotoxic drugs AFTER T1

ACEi, Antidepressants, Narcotics,Benzos

A

ACEi - Oligohydramnios, lung/kidney hypoplasia, growth retardation
Antidepressants - Neontal withdraw symptoms
Narcotics - Neonatal respiratory depression
Benzos - Floppy infant syndrome, ^, withdrawals

32
Q

Clinical factors when assesing fetus risk

when prescribing

A
  1. Stage of pregnancy
  2. Drug/chemical dose
  3. Maternal clinical condition
  4. Previous obstetrics history
33
Q

Priniciples of prescribing in pregnancy

A
  1. Necesscity (risk vs reward)
  2. Lowest effective dose for shortest period
  3. Stage of pregnancy - avoid T1
  4. Avoid new drugs
  5. Avoid polypharmacy
34
Q

Tetraology of Fallot

A

4 structural defects.
1. Pulmonary stenosis
2. Thicken RV wall
3. Ventricular spetal defect
4. Aorta overrides spetal defect

If RVOTO (RV Outflow Tract Obstruction) is severe pulmonary circulation remains dependent on ductus arterious.

Block 11 (4 decks)

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