Pre-Natal Development

Question 1

Where have living things come from?

Answer 1

They have evolved from common ancestors

Question 2

What species are humans?

Answer 2

Chordates

Question 3

Why are humans are chordates?

Answer 3

They have a spinal cord

Question 4

How many species do chordates comprise?

Answer 4

1/10th

Question 5

What is the history of pre natal development?

Answer 5

Most processes were un known
1590’s - Microscope development
1695 - Hartsoeker and the preformation theory
19th - Improvements demonstrated development didn’t involve simple processes but substantial differentiation

Question 6

What is the preformation theory?

Answer 6

Looked in microscope at sperm and thought he saw a tiny human, belief of womb as an oven where humans wait till they are right size to be born

Question 7

What did the debate around pre natal development lead too?

Answer 7

Scientific debate eg. scala naturae

Question 8

What is scala naturae?

Answer 8

When species are arranged hierarchically

Question 9

What is the recapitulation theory?

Answer 9

Development occurs in stages. Human embryo’s took form of animals lower down the ladder - all animals do this then are born

Question 10

What has technology done?

Answer 10

Allowed us to see changes - photos show that animals look very different when bored, can’t rely on drawings from scientists

Question 11

What are the 3 stages?

Answer 11

Geminal Period
Period of the embryo
Period of the foetus

Question 12

What is the geminal period?

Answer 12

Conception to implantation
Conception begins when sperm fertilises the egg in the Fallopian tube, the zygote moves down into uterus, this multiples and turns into morula. in the first few stages, morula gets smaller and smaller and turns into stem cells. then takes a new shape - blastocyst

Question 13

What is the period of the embryo?

Answer 13

Implantation to 2 weeks
Cell differentiation at 2 weeks - different organ systems in the body develop such as the ectoderm, mesoderm and endoderm
At 3 weeks - different tissues develop
At 7 weeks - area of rapid growth in digestive tract, brain expands

Question 14

What is the period of the foetus?

Answer 14

2 months to birth
Further development and growth occurs here
4 months - organism can respond to sound at 250-500hZ
Touch forming, capable of moving, ears/eyes develop
8 months - reflex is strong, maintains a preferred position in the womb, has a sense of where it is

Question 15

What is a zygote?

Answer 15

A fertilised egg

Question 16

What are the variations from typical development?

Answer 16

WHO states that 50% or cases are unknown 50% of the time
Genes
Environment

Question 17

Genetic factors affecting development

Answer 17

Mitosis vs mieosis - function of this is to produce a series of gametes that only have half chromosomes from mum, half from dad
Chromosomal variations - usually have 23 pairs, males have XY, females have XX
Can have different chromosomal variations which aren’t always incapable with life, there is a huge range
some lead to birth deficits, some to pubertal deficits

Question 18

What are the types of chromosomal variations?

Answer 18

Trisomy 21 - Down syndrome
Trisomy 18 - Edwards syndrome
Trisomy 13 - Patau syndrome
90% die in first year

Question 19

What are chromosomal variations called?

Answer 19

Aneuploidy - having more or less

Question 20

Environmental factors affecting development

Answer 20

Taratogens

Fetal alcohol syndrome

Question 21

Taratogens

Answer 21

Substances than cause deficits at birth
Till the zygote is in the uterate wall, it is free from influences as not sharing the blood at mum, but once implantation occurs, substances effect them
The central nervous system is vulnerable throughout all trimesters, limbs only vulnerable in some

Question 22

Thalidomide tragedy

Answer 22

Developed in 1954 to treat headaches, morning sickness. By 1961, 20,000 children in 46 countries were born with misshapen limbs. thought it was caused by atomic bombs. In Us, it was never approved on Dr Frances Kelsey refused it - HERO as only 40 cases in US.
these were prescribed in last trimester, when limbs are most vulnerable

Question 23

Fetal alcohol syndrome

Answer 23

Effects the CNS (vulnerable the whole way)
Causes brain problems, vision, hearing, learning difficulties
Children survive but have problems

Question 24

Fetal learning

Answer 24

DeCasper and Spence - Training: read 2 stories per day. Testing: 2.5 days after birth, 8 babies hear familiar story, associated with faster sucking, shows they prefer familiarity
Hepper - mothers who watched neighbours, when played there were significant differences in the movements of babies 2 days after