Ch 6 Neurogenetics

Cell membrane

Semipermeable barrier that surrounds the cell and regulates what enters and leaves

Selective permeability

Property of the membrane that allows some substances to pass while blocking others

Cytoplasm

Fluid inside the cell that contains organelles

Organelles

Specialized structures within a cell that perform specific functions

Nucleus

Contains DNA and controls cell activity

Rough endoplasmic reticulum (RER)

Synthesizes proteins (has ribosomes attached)

Smooth endoplasmic reticulum (SER)

Synthesizes lipids and detoxifies substances

Golgi apparatus

Modifies, packages, and ships proteins

Mitochondria

Produces energy for the cell in the form of ATP

Adenosine triphosphate (ATP)

Primary energy currency of the cell

Lysosomes

Contain enzymes that break down waste materials

Neuron

A specialized cell that transmits information through electrical and chemical signals

Cell body (soma)

Contains nucleus and maintains cell functions

Dendrites

Branch-like structures that receive signals from other neurons

Axon

Long projection that transmits signals away from the cell body

Axon hillock

Region where action potential is initiated

Axon terminal

End of axon that releases neurotransmitters

Synapse

Gap between neurons where communication occurs

Neurotransmitters

Chemical messengers that transmit signals across synapses

Receptors

Proteins that bind neurotransmitters

Ionotropic receptors

Receptors that directly control ion channels

Metabotropic receptors

Receptors that activate signaling pathways

Ions

Charged particles (e.g., Na+, K+) involved in electrical signaling

Resting potential

Stable negative charge of a neuron when not firing

Sodium-potassium pump

Protein that maintains ion balance by moving Na+ out and K+ in

Diffusion

Movement of particles from high to low concentration

Depolarization

Reduction of membrane potential (more positive)

Hyperpolarization

Increase in membrane potential (more negative)

Threshold

Level of stimulation required to trigger an action potential

Action potential

Rapid electrical signal traveling down the axon

All-or-none phenomenon

Action potential either fires completely or not at all

Refractory period

Time after firing when neuron cannot fire again

Vesicles

Membrane-bound sacs that store neurotransmitters

Neurotransmitter release

Release of chemicals into synapse when action potential reaches terminal

Reuptake

Process of neurotransmitters being taken back into presynaptic neuron

Transporters

Proteins that move neurotransmitters back into neuron

Raphe nuclei

Group of neurons in brainstem that produce and distribute serotonin

Serotonin

A neurotransmitter involved in mood, behavior, and regulation

Tryptophan

Amino acid precursor to serotonin

Tryptophan hydroxylase

Enzyme that converts tryptophan in serotonin synthesis

Aromatic amino acid decarboxylase

Enzyme that helps produce serotonin

Monoamine oxidase A (MAOA)

Enzyme that breaks down serotonin

Aldehyde dehydrogenase

Enzyme involved in serotonin metabolism

Monoamine

Neurotransmitter with one amino group (e.g., serotonin)

Zygote

Fertilized egg (single diploid cell)

Blastocyst

Early stage of development with inner and outer cell layers

Embryo

Weeks 3–8 of development where major structures form

Fetus

Weeks 9–birth where growth and maturation occur

Neurexins

Presynaptic proteins that help form synaptic connections

Neuroligins

Postsynaptic proteins that connect with neurexins

Synapse formation

Process of building connections between neurons

Synapse maintenance

Process of preserving neuronal connections

Serotonin transporter (SERT)

Protein that reabsorbs serotonin into presynaptic neuron

Neural activation

Pattern of neuron firing in response to stimuli

Neuroimaging

Techniques used to measure brain structure and function

Positron emission tomography (PET)

Imaging using radioactive tracers to measure brain activity and receptors

Magnetic resonance imaging (MRI)

Imaging technique showing brain structure

Functional MRI (fMRI)

Imaging that measures brain activity based on blood flow

Psychopharmacology

Study of how drugs affect behavior and mental processes

Pharmacodynamics

How drugs affect the body and brain

Pharmacokinetics

How drugs are absorbed, distributed, and eliminated

Pharmacogenetics

How genetic variation influences drug response

Monoamine oxidase inhibitors (MAOIs)

Drugs that block MAOA, increasing serotonin levels

Selective serotonin reuptake inhibitors (SSRIs)

Drugs that block serotonin reuptake, increasing availability in synapse

Drug mechanism

Drugs alter neurotransmitter systems to change neural activity

5-HTTLPR

Genetic variation in serotonin transporter gene affecting serotonin regulation

Individual drug response differences

Genetic differences cause variability in how people respond to drugs