Topic 7

Question 1

Fertilization

Answer 1

Sperm penetrates an egg creating the zygote
24 hours
Zygote = end of fertilization
Totipotent - develop into any class of cell

Question 2

Prenatal stages

Answer 2

Zygote - fertilization to 2 weeks
Embryo - 2 to 8 weeks
Fetus - 9 weeks to birth

Question 3

Gastrulation

Answer 3

Day 4 - Morula
- solid ball of cells
Day 6 - early blastocyst
- hollow ball of cells with fluid filled cavity
Day 10 - late blastocyst
- pre embryo
- embryonic disk
- 2 layers of cells
Day 16 - Gastrula
- embryo with 3 primary germ layers
- ectoderm
- mesoderm
- endoderm

Question 4

Elements of germ layers

Answer 4

Endoderm
- lung cells
- thyroid cells
- digestive cells
Mesoderm
- cardiac muscle
- skeletal muscle
- tubule cells in kidney
- red blood cells
- smooth muscle
Ectoderm
- skin cells
- neurons of the brain and nervous system
- pigment cells

Question 5

Development of nervous system

Answer 5

Neural plate - 3 weeks
- thickened region of ectodermal layer
- leads to neural tube
Neural groove
- neural plate folds itself
Neural tube
- groove closes to form tube
- brain (cranial and anterior) and spinal cord (caudal and posterior) develop

Question 6

_____ , ______, and _____ are visible by week 4

Answer 6

Forebrain
Midbrain
Hindbrain

Question 7

Stages of brain development

Answer 7

1.Cellbirth
- neurogenesis
- gliogenesis
2. Neuronal migration
3. Neuronal differentiation
4. Neuronal maturation
- dendrite and axongrowth
5. Synaptogenesis
- formation of synapses
6. Cell death and synaptic pruning
7. Myelogenesis
- formation of myelin

Question 8

Cell birth

Answer 8

Neurogenesis
Gliogenesis
10 billion cells form the cortex that blankets one hemisphere
Hippocampus makes cells throughout life

Question 9

Neuronal migration

Answer 9

Cell division occurs at ventricular zone and cells migrate away
Radial
- makes paths for cells to follow
Tangential
- on the perimeter
Migrate from inner to outer layers
Somal
- moving cell

Question 10

Neuronal differentiation

Answer 10

Neuroblasts to specific neurons
Begins after migration starts
Completed and birth
Depends on genetic instructions, timing, and signals

Question 11

Neuronal maturation

Answer 11

Happens after migration
Mature through
Dendritic growth
- growth of dendrites and spines
Axonal growth
- extends axons to appropriate targets
- growth cone (tip of the axon)
- filopod targets substances in the intracellular environment

Forms synaptic connections

Dendritic fields become more complex until 2 years

Question 12

Synaptogenesis

Answer 12

Formation of synapses
- genetic programming and environmental signals
5 months - simple connections
7 months - development of deep cortical neurons
After birth - development increases for first year

Question 13

Cell death and synaptic pruning

Answer 13

Born with more neurons and SC than needed
Neural Darwinism
- outcome of competition among neurons for connections and metabolic resources
Apoptosis
- recycling of cellular constituents
Unused synaptic connections prune away

Question 14

Glial development

Answer 14

Formation of astrocytes and oligodendrocytes starts after neurogenesis and continues through life
Last myelination happens at 25 in the prefrontal cortex

Question 15

Myelination

Answer 15

Speeds up transmission
Sensory and motor areas - first months
Behaviour emerges after neural machinery has developed
Simpler function = early myelintation
Frontal lobe development correlates with adult intelligence

Question 16

Prenatal brain development stages

Answer 16

Week 7 - resembles mini person
Week 8 - sexual differentiation
7 months - gyri and sulci form
9 months - brain looks like adult brain

Question 17

Motor behaviours

Answer 17

Motor cortex axons myelinate during reaching and grasping (2-4 months)

Neurons controlling finger movements myelinate during pincer grasping (10 months)

Question 18

Language development

Answer 18

1-2 years
Cell division and migration are complete in the language zones
2-12 years
Increased neuronal connectivity
Increased myelination
New SCs formed

Question 19

Donald hebb

Answer 19

Cognitively stimulating environments maximize intellectual development

House rats are smarter than caged rats

More dendrites
More and larger synapses
More and larger astrocytes

Question 20

Critical periods

Answer 20

Developmental window which some event has a long lasting influence on the brain

Neurons are not activated and die

Question 21

Developmental disorders

Answer 21

Impaired cognitive functioning due to abnormal brain development
- genetic
- exposure to infection
- exposure to toxins
- birth trauma
- malnutrition
- environmental

Environmental abnormalities have opposite effects of cognitively stimulating environments

Question 22

Stress in early life

Answer 22

Increased and more active amygdala
Decreased and less active hippocampus
More likely to develop depression and anxiety

Question 23

Frontal lobe development

Answer 23

Extra sensitive to epigenetics
ACEs
Passed by either parent

Question 24

Anencephaly

Answer 24

Cranial end of neural tube doesn’t close
Forebrain doesn’t develop
Die soon after birth

Question 25

Spina bifida

Answer 25

Caudal end of neural tube doesn’t close
Spinal abnormalities
Serious motor problems

Question 26

Autism spectrum disorders

Answer 26

Neurodevelopmental disorder
- most prevelant
- intellectual disability
- difficult to treat
- 75% male
- emerges at 3 and stabilizes

Genetic factors
Cerebellum, amygdala, and frontal cortex are affected
Abnormal reaction to faces
Reduced social ability
Repetitive patterns interests and activities
Cognitive artistic abilities

Question 27

Williams syndrome

Answer 27

Intellectual disability
Heterogeneous pattern of ability and disability
Social empathetic and talkative
Good language
Good facial recognition
Perfect pitch
Sense of rhythm
Attention issues
Anxiety
Poor spatial ability
Difficulty drawing