What attributes of genes e g heterozygous vs homozygous dominant vs recessive determines what type of protein and thus trait will be expressed o Homozygous genes on each chromosome are identical o Heterozygous genes on each chromosome are different o Dominant expressed trait will show through in either homozygous or heterozygous condition Rr RR o Recessive expressed trait will only show through in homozygous condition rr What types of natural and experimental procedures can be used to differentiate between genetic and environmental influences on behavior o Studies using genetically modified animals i e knockout mice o Twin studies Monozygotic identical genetic code Dizygotic fraternal as genetically similar as typical siblings o Neurons are cells specialized to receive and transmit information o They are individual entities but work as a group with the help of glial cells to make o Adoption studies o Gene association studies What are neurons specialized to do up the nervous system Name the parts of neurons that enable this specialization cell o Have cell body soma just like any other o Branching extensions specialized to receive and transmit signals Dendrites receive information May be equipped with spines to increase surface area Axon sends information May be coated in a myelin sheath so information can be conducted faster Spaces between myelin called nodes of Ranvier Presynaptic terminals end of axon where electrical action turns chemical What forces act on what types of ions to affect their distribution inside and outside the cell for example why does Na want to go into the cell but why can t it o The composition of the cell membrane makes it semi permeable Non charged particles ex O2 can diffuse through Charged particles ex ions need help from a channel Big charged particles ex proteins can t pass at all o Concentration gradient Particles in solution don t stay clustered together with chemicals of the same type they diffuse and distribute equally in the solution Example food coloring moves through a plant s stem up to the flowers Ions on the outside of the cell membrane want to mix with ions on the inside of the cell but the semi permeable nature of the membrane prevents that Particles with opposite charges attract one another and particles with like o Electrical gradient charges repel each other Example magnets Positive ions on the outside of the cell membrane are drawn to the negative ions on the inside of the cell but their movement is blocked by the semi permeable nature of the membrane o Ions are subject to both electrical and concentration gradients Example sodium Na and potassium K ions want to mix because of their different chemical nature but repel one another due to their similar electrical natures What protein complex on the cell membrane actively restores and maintains this distribution and how o Changing the membrane potential If the charge differs on either side of the membrane the membrane is said to be polarized If it becomes more polarized i e the charge of the inside of the cell gets even more different from the outside the cell is said to be hyperpolarized If it becomes less polarized i e the charge of the inside of the cell gets closer to that of the outside the cell is said to be depolarized The neuron responds to anything that changes the permeability of the membrane i e opens channels and or changes the concentration of ions or charge across the membrane Electrical current artificial stimulation with an electrode Environmental energy light pressure sensory systems Chemical energy neurotransmitters drugs What must happen for a neuron to reach its threshold of excitation and what happens when it does o Depolarization past a neuron s threshold opens voltage gated Na and K channels o A neuron can take only so much depolarization Its limit is called its threshold of excitation o The threshold is based on what voltage it takes to open voltage gated ion channels Describe how two neurons communicate across a chemical synapse how does this differ from electrical synapses o Though each neuron is an independent unit they do not exist in isolation Groups of neurons are linked together in a circuit like fashion to get info from one area of the body to another o An electrical signal cannot jump from one separate neuron to another o The message must be reconfigured into a form that can move across the space between neurons This space between individual neurons is referred to as a synaptic cleft o Chemicals released by the presynaptic cell can diffuse across the gap to the postsynaptic cell This functional area between o Neurotransmitters o Order of events at chemical synapses Synthesis and storage Release Activation of receptors Elimination two neurons is referred to as a synapse hence pre and postsynaptic Chemicals that are released into the synapse at the axon of a presynaptic cell after a single action potential and based on activity at a receptor have an effect on the membrane potential of the postsynaptic cell What ion is directly responsible for the movement of neurotransmitters into the synaptic cleft o Depolarization from action potential opens voltage gated calcium Ca channels in presynaptic terminal presynaptic terminal o Calcium influx results in exocytosis of vesicles neurotransmitter bursts out of end of o Neurotransmitter diffuses across synapse Define and give examples of temporal and spatial summation o Temporal summation recurrent small stimulation to the same place o Spatial summation small stimulation to multiple areas What effect do EPSPs and IPSPs have on the membrane potential of a neuron o Excitatory postsynaptic potential EPSP Graded depolarization Results from an influx of sodium ions Increases probability of an action potential o Inhibitory postsynaptic potential IPSP Graded hyperpolarization Results from influx of chloride ions or efflux of potassium Decreases probability of an action potential Describe in what ways drugs can act at receptors in order to mimic or block natural neurotransmitter action e g serve as agonists or antagonists be prepared for examples o Agonist increases enhances facilitates or mimics natural action of receptor o Antagonist decreases blocks or opposes natural action of receptor What neurotransmitter system does all abused drugs as well as natural rewards act upon o Both abused drugs and natural rewards activate dopamine receptors in the brain Differentiate between the actions of stimulants depressants and
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