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17 Cards in this Set
- Front
- Back
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Nicotine in smokers |
• Nicotine structurally mimics acetylcholine • Reaches brain in 7 – 10 seconds • Able to bind to and stimulate acetylocholine receptors • Triggers short lived “feel good” feeling • Keep craving the feeling - why one cigarette is typically not enough • Also develop a tolerance so requires more to get same feeling |
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Caffeine |
• structurally mimics adenosine (ATP) • Adenosine is potent inhibitor of the brain • So if block adenosine from binding then stimulation occurs • Caffeine blocks brain adenosine receptors to function as a stimulant • Also addictive; suffer withdrawal symptoms • Build up tolerance so increase intake |
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“Crystal Meth” |
• Methamphetamine (snort/smoke/inject) –Artificially stimulates brain to release dopamine, false sense of happiness, energy & well being – Short-lived (last 6-8 hrs up to 24hr) –Meth destroys dopamine receptors so can’t feel pleasure – Highly addictive (1st use), |
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Functional groups of neurons |
– Integrate incoming information received from receptors or other neuronal pools – Forward processed information to other destinations |
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Simple neuronal pool |
– Single presynaptic fiber branches and synapses with several neurons in pool |
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– Discharge zone |
—neurons most closely associated with incoming fiber |
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– Facilitated zone |
—neurons farther away from incoming fiber |
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Circuits |
– Patterns of synaptic connections in neuronal pools |
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Four types of circuits |
– Diverging – Converging – Reverberating – Parallel after-discharge |
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Diverging circuit |
• One input, many outputs • An amplifying circuit • Example: A single neuron in the brain can activate 100 or more motor neurons in the spinal cord and thousands of skeletal muscle fibers |
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Converging circuit |
• Many inputs, one output • A concentrating circuit • Example: Different sensory stimuli Input 1 Input 2 Input 3 can all elicit the same memory |
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Reverberating circuit |
• Signal travels through a chain of neurons, each feeding back to previous neurons • An oscillating circuit • Controls rhythmic activity • Example: Involved in breathing, sleep-wake cycle, and repetitive motor activities such as walking |
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Parallel after-discharge circuit |
• Signal stimulates neurons arranged in parallel arrays that eventually converge on a single output cell • Impulses reach output cell at different times, causing a burst of impulses called an after-discharge • Example: May be involved in exacting mental processes such as mathematical calculations |
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Serial processing |
–Example: reflexes—rapid, automatic responses to stimuli that always cause the same response • Object approaching eye cause blink • Jerk hand away after touching hot object |
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Reflex arcs (pathways) have five essential components: |
1. receptor 2. sensory neuron 3. CNS integration center 4. motor neuron 5. effector |
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Axon & dendrites associated with neurilemma may undergo repair if: |
– cell body remains intact, – if Schwann cells are functional & – if scar tissue doesn’t occur too rapidly – If injure axons of a nerve in an upper limb, have a good chance of regaining nerve function unless the damage is quite severe |
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Most CNS nerve fibers never regenerate • Doesn’t matter if cell body remains intact, severed axon cannot be repaired • Why? |
“Bad environment” i.e., oligodendrocytes have lots of growth inhibiting proteins & astrocytes form scar tissue rich in substance that prevents axon regrowth • Brain or spinal cord injury is usually permanent |
