S1W11Dev Flashcards

Question

Stem cells

Answer 1

Undifferentiated cells that differentiate into specialised cells or divide (mitosis) to produce more stem cells.

Answer 2

42 days gestation. Neural progenitor cells either: * Stay in choroid plexus. * Continue to divide into neurons and glial cells. Peak proliferation rate = 250k neurons/minute. 22 weeks gestation neurogenesis complete apart from olfactory bulb hippocampus.

Answer 3

Surround neurons and hold them in place. Supply oxygen and nutrients to neurons Destroy pathogens/dead neurons.

Answer 4

Neural progenitor cells migrate at different rates and directions, aiming to reach the target cell in up to four days. Migrate up to 2cm.

Answer 5

How do cells know where to go? Cut optic nerve of newts and rotate the eye 180 degrees. Axons grew back to original places but newts saw upside down. Axons are guided by gradient of proteins called neurotrophins. Numerous synapses made in target then synaptic pruning removes.

Answer 6

Neural progenitor cells take on characteristics of specific neuron. Formation of axon and dendrites. Acquisition of enzymes to produce neurotransmitters. Acquisition of receptors to receive synaptic transmissions.

Answer 7

Formation of synapses Lifelong but slows with age 1-2yo – peak synapse formation - twice as many connections as adults. Synaptic pruning

Answer 8

Grows first Tip of axon = growth cone (site of elongation and extension). Growth cones sample local environment for molecules that direct growth. Axons can grow whilst migrating.

Answer 9

Grows once neuron reaches target. Grows slower than axons.

Answer 10

Myelin surrounds axon forming insulating sheath Oligodendrocytes form myelin in CNS (Schwann cells in PNS). ``` Process: Spinal cord > Hindbrain > Midbrain > Forebrain • Takes years ```

Answer 11

Produce trophic factors that maintain axonal integrity and neuronal survival. Neuron/Oligodendrocyte interactions influence neuronal size and axon diameter.

Answer 12

``` Brain overproduces: o Neurons (peak at 7mo) o Synapses (peak at 1-2yo at 15,000) ``` Regression results in thinning of cortex associated with behavioural development. Apoptosis and Pruning.

Answer 13

Prenatal. Reduces neurons Results in loss of cell and all synapses Neuron dies Maximal during late prenatal stage (reduces 28bil to 23bil by birth) Triggered by lack of neurotrophins released from postsynaptic cell.

Answer 14

Postnatal Reduces synapses Neuron survives Three methods: o Axon degeneration o Axon retraction o Axon shedding All result in axon removal and deletion of synapse Triggered by hormones and neurotrophins.

Answer 15

What determines which synapses are pruned? States that the connections between two neurons might be strengthened if the neurons fire simultaneously.

Answer 16

Conception to week 8 gestation. Rudimentary structures of brain produced Major compartments of CNS and PNS defined Neuron production starts at week 6 gestation

Answer 17

Week 9 gestation to birth Characteristic pattern of gyral and sulci folding. Development of neocortex. Neurogenesis, migration and differentiation. Neuronal cell loss.

Answer 18

One quarter of adult size Spinal cord and brain stem well developed Limbic system and cerebral cortex still primitive

Answer 19

Synaptogenesis in cerebral cortex(exuberant period) At peak cerebral cortex creates 2 million synapses/second. Corresponds with mental milestones Myelination rapid in first 2 years. 2yo - brain 80% of its adult size

Answer 20

Too many synapses in cerebral cortex in childhood Synaptic pruning increases 4-6yo Brain 90% adult size by 6yo

Answer 21

Synaptic pruning until end of adolescence Grey matter decreases in volume Myelination continues especially in frontal cortex White matter increases in volume Prefrontal cortex matures later than limbic system Creates neural imbalance Theorised to be one reason for teen impulsiveness Brain adult weight

Answer 22

Brain peak power at 22yo for 5 years Then: Cortex becomes thinner Myelin sheath degrades Decrease in plasticity Decrease memory, reasoning, spatial skills and thought speed Changes minimal in healthy individuals

Answer 23

65+ years elderly for experiments Brain shrinks in size Myelin sheath degrades Blood flow to brain decrease Damage by free radicals increases Decrease in memory, ability to learn, attention, reasoning.

Answer 24

Vascular (20-30%) Lewy Bodies (10-25%) Frontotemporal (10-15%) Alzheimer’s (50-75%) Anatomically: Plaques (outside neuron) Tangles (inside neuron)

Answer 25

Nature: Genes guide brain set-up Provide information for cells and general connections Nurture: Experience responsible for fine tuning

Answer 26

Maternal diet important Low calories = decreased foetal neural development Low Omega 3 = poor infant neural development Severe maternal iodine deficiency = mental deficiency (cretinism)

Answer 27

Child’s own diet important Iron deficiency = poor STM encoding or retrieval Inadequate calories and protein = smaller brains due to reduced dendritic growth, myelination and glial cells