Ch2 Epigenesis Flashcards
Epigenesis
-Originally: emergence of specialized cells and systems of cells from same hereditary material -Now: set of processes by which factors outside of heredity material itself can influence how hereditary material functions
Gene-environment coaction
Process of coaction between genes & environment. Genes determine a lot about the cell specialization and the environment/chemicals. The chemicals (&/thus the environment) determine a lot about the genes, cell specialization. Heredity and environment are engaged from the very beginning in an intricate dance so that neither ever causes any outcome on its own
Gene regulation
The process by which noncoded genes either initiate or prevent the genes transcription (rather than producing protein
Atypical development: Effects of prenatal teratogens
- Environmental substances, agents that can harm developing fetus. “Monstrosity making”
- Cross the placental barrier
- Potential for harm impossible to determind with precision, depends on:
- Which stage of development
- Coactions of genes and environment-not all are equally susceptible/resistent
- Dosage/amount
- Number of risk factors
- Structural, prematurity, growth/size, metacognitive, learning/language/social, death
Atypical development: Nutritional influences
Teratogens are something in the fetal environment that should not be there, nutrition concerns things that should be there but are not.
Insufficient protein, essential viatmins, minerals affects physical, socioemotional, intellectual development; apigenetic alterations
Iron & anemia, Protein & play behavior, kwashiorkor
The developing brain: Fetal and infant brain development
- 2 week old forming neural tube/neurulation
- Cells start forming neurons inside neural tube
- Glial cells, neuron differentiation
- Early cells make hindbrain, midbrain, latest cells make cerebral cortext and forebrain
- 4th month, neurons fire spontaneously
- respond to experience
- Continue to develop neurons after birth until 12 months of age
- Develop adult neural stem cells throguhout life in SVZ, & hippocampus SGZ
- brain growth continues to do creation of synapses
The developing brain: Structure of the neuron and neural connections
- Nucleus
- Cell Body
- Dendrites: receive messages from other neurons
- Axon: long arm that needs to wire or connect
- Axon terminals with sacs of neurotransmitters, which communicate the messages
- released contents acrodss synaptic gap
- Myelin (myelination) glial cells wrap around axon to assist in conduction
- White matter: bundles of myelinated axons
- Grey matter: bundles of cell bodies, dendrites, unmyelinated cells
- Neurons joined via circuits, synaptic connections>systems
- projective neurons: axons extend far away from cell body
- interneurons: bran closer to local area
The developing brain: Pruning
- more neurons than necessary>pruning: neurons die off, synapses selectively discarded
- improper connection, misplaced neurons, rarely used,
The developing brain: How neurotransmitters function
- Neurotransmitter: chemical substances in nervous system.
- Commmunicate messages between neurons when released
- chemical message picked up by dendrite, cell body, axon of neighboring neuron, readby that cell as a message to “fire” or “stop firing”
The developing brain: Neuroplasticity and critical periods
Neuroplasticity: The malleability of human brain, its capacity to change, grow, especially in response to new environmental input. Includes capacity of neurons to shift functions to compensate for damage to other cells or because they have been transplanted to a different part of the brain.
Critical periods:
The developing brain: The limbic system
Collection of structures that regulate pleasure, pain, anger, sexuality, fear, affection
Referred to as the “emotional brain”, works with rest of brain
Includes: amygdala, hippocampus, septum, thalamus, hypothalamus
Stress and adaptation system: Allostasis
“Balance through adaption” Model of stress processes, CNS controls multiple interacting regulatory processes so that best balance for each specific challenge is found, rather than returning to fixed set point.
Stress and adaptation system: HPA (hypothalamic-pituitary-adrenal) axis/system
System involved in body’s physical response to stress. When a person experiences/anticipates stress, the AMYGDALA>detects danger, informs HYPOTHALAMUS>communicates danger to PITUITARY gland>Responds by releasing adrenocorticotropic hormone ACTH into blood, >causes ADRENAL glands to release epinephrine, norepinephrine, cortisol, travel back to brian, prepared body to resist the stressor.
Stress and adaptation system: Cortisol and glucocorticoids in stress response
- Cortisol is key glucocorticoid hormone
- travel back to brain, bind receptors on amygdala and hippocampus
- morning elevation, afternoon decline
epigenetic factors
Chemicals in cytoplasm Factors in the adjacent cells and tissues External factors, e.g., heat, light, social interaction
