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UNSW Embryology

Foundations - Lab 15 - Intro to Human Development

© Dr Mark Hill (2007)

Acknowledgements

6. Critical Periods

These are developmental times (stages) sensitive to insult, be aware of these times, the causes and the potential effects.

Introduction

Critical periods of development refer to times when genetic or materal effects can impact upon the developmental process. The timing of these effects will impact on different systems at different times.

Systems with long periods of development are more susceptible to developmental abnormalities. Which systems take a long time to develop?

The Fetal period is also potentially sensitive to maternal effects that impact upon interuterine growth. Along these lines there is growing evidence that low birth weight, and therefore inhibited fetal growth, may have postnatal effects on lifelong health outcomes. (More? Fetal Origins Hypothesis)

Comments

Dr Mark Hill

We have now had a very quick trip through more than 9 months of development in nearly 2 hours. Before we finish it is worth thinking about times in development when things may go wrong. In UNSW Embryology in every section of System Notes Page 2 refers to abnormalities associated with that system.

These notes and linked materials have been prepared for Educational purposes only. Please email Dr Mark Hill if you wish to make a comment about this current project.

Critical Periods

Key Systems

Look at the following linked sections of notes and consider why and when development of these two systems are also critical.

Respiratory Development

Heart Development

Birth APGAR Score

A birth scoring system developed by Dr Virginia Apgar, first published in 1953 and now used internationally (More? Normal Development - Birth - Apgar | Dr Virginia Apgar). A score is given for each sign at 1 and 5 minutes after the birth (if problems with baby an additional score given at 10 minutes).

 

Sign

0 Points

1 Point

2 Points

A

Activity (Muscle Tone)

Absent

Arms and Legs Flexed

Active Movement

P

Pulse

Absent

Below 100 bpm

Above 100 bpm

G

Grimace (Reflex Irritability)

No Response

Grimace

Sneeze, cough, pulls away

A

Appearance (Skin Color)

Blue-gray, pale all over

Normal, except for extremities

Normal over entire body

R

Respiration

Absent

Slow, irregular

Good, crying

Birth Defects

How do birth defects occur?

Abnormal Development

How are birth defects monitored in Australia?

National Perinatal Statistics Unit (NPSU) | Congenital malformations, 1981-1997 (an example of one of the units reports)

Finished!

This is the Last Page of the current Practical.

Remember these pages are always available for revision, there are many more online detailed notes and we will come back to some concepts in Beginnings, Growth and Development.

Glossary of Terms

Use the alphabetical list below to find definitions of terms that are new to you.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W |X | Y | Z

Google

UNSW Embryology

Quick Movie Links

Movie of Human Embryo Growth (this shows a human embryo growing, all images are to scale)

Movie of Mouse Embryo Growth (this shows a mouse embryo growing)

Quick Links

UNSW Embryology ISBN: 978 0 7334 2436 6

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