Week 1- Prenatal Development Flashcards
What was a development in the 19th century for Prenatal development
Improvements in optics showed that embryonic development did not involve simple processes of growth, but also substantial differentiation
What does Scala Naturae mean
- Great chain of being
- Species are fixed and arranged hierarchically
- The idea that humans were the top of an evolutionary ladder
What is Recalculation theory
The stages of development for an animal embryo are the same as other animals’ adult stages or forms
Stages of prenatal development
- The germinal period (conception to implantation)
- The period of the embryo (implantation to 2 months)
- The period of the Fetus (2 months to birth)
What can be seen of an embryo at 3 weeks
- Eye is apparent
- Heart and liver forming
- Buds where arms and legs will be
- Brain is beginning to bulge
What can be seen of an embryo at 7 weeks
- Individual toes and fingers are now apparent
- Developing bulge in the gut
What can be seen of an embryo at 2 months
- Limbs are now well formed
- The brain has expanded
What can be seen of an embryo at 4 months
- Ears are taking final form
- Eyelids are well advanced
- Fetuses are capable of movement and can react to touch and sound
- Hearing 250-500 Hz
What can be seen of an embryo at 8 months
-Genitalia are now fully formed
Origins of congenital aberrations are unknown in how many cases
50%
What are examples of genetic reasons for birth defects
- Cystic fibrosis
- Sickle cell anemia
- Various chromosomal disorders
What are examples of environmental reasons for birth defects
-Toxins Alcohol Pesticides Radiation Thalidomide -Nutrition
What does aneuploidy
The condition of having fewer than usual or more than the usual number of chromosomes
The three classes of aneuploidy
Trisomy 21
Trisomy 18
Trisomy13
The three classes of aneuploidy are associated with
Significant developmental problems in various organ systems plus learning difficulties
What is trisomy 21 displayed as
Down’s syndrome
What is trisomy 18 displayed as
Edwards syndrome
What is trisomy 13 displayed as
Patau syndrome
Humans have how many sex chromosomes
A variable number, not all of these lead to variations
The Central Nervous System is vulnerable when
Prenatal development
External genitalia is vulnerable when
After the embryonic period
What’s the thalidomide tragedy
- Thalidomide developed in 1954 to treat headaches and morning sickness
- 20,000 children in 46 different countries were born with severely misshapen limbs
What’s Feral Alcohol Syndrome
- Microcephaly
- Problems with vision and hearing
- Very wide upper nose and absence of a philtrum
What’s vestigial reflexes
Partially or wholly lost their original function
E.g. gripping mums fur, no fur
