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The Synapse and Reflexes

The Synapse and Reflexes. Structure of a Synapses. Synapse: Is a junction where a axon interacts with another neuron Presynaptic Terminal : End of the axon Postsynaptic Membrane: Membrane of the dendrite Synaptic Cleft: Space between the presynaptic membrane and postsynaptic membrane

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The Synapse and Reflexes

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  1. The Synapse and Reflexes

  2. Structure of a Synapses Synapse: Is a junction where a axon interacts with another neuron Presynaptic Terminal: End of the axon Postsynaptic Membrane: Membrane of the dendrite Synaptic Cleft: Space between the presynaptic membrane and postsynaptic membrane Synaptic vesicles: Stores chemical neurotransmitters

  3. Neurotransmitters • Excitatory - increase membrane permeability, increases chance for threshold to be achieved to trigger an action potential • Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved to trigger an action potential

  4. Types of Neurotransmitters • Acetylcholine ACh - stimulates muscle contraction • Norepinephrine & Dopamine (sense of feeling good, low levels = probable cause to depression) • Serotonin (sleepiness) • Endorphins (reduce pain, inhibit receptors)

  5. Reflexes • Reflex: An involuntary reaction in response to a stimulus • Reflex Arch: Pathway in which a reflex occurs.

  6. Types of Nerves • Sensory Nerves - conduct impulses into the brain or spinal cord • Motor Nerves - carry impulses to muscles of glands from the brain and spinal cord • Mixed Nerves - contain both sensory and motor nerves

  7. Reflex Arch Pathway • 5 steps of Reflex Arch • Sensory Receptor • Afferent neuron • interneuron • Motor neuron • Effector organ

  8. Nerve Pathways • Reflex arc - only includes a few neurons • Reflex Behavior – automatic and subconscious responses • Stretch or Knee-jerk reflex – Muscles contract when applied force it put on them (patellar reflex) • Withdrawal reflex - avoidance of painful stimuli

  9. Neuronal Pathways • Converging Pathways: More than one neuron synapses converge on the same neuron. (more than one neuronal pathway) • Diverging Pathways: The axon from one neuron divides or diverges with one or more neurons. (one neuronal pathways can diverge into multiple pathways)

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