Chapter 2 Synapses

Synapse

Specialized junction for neuron communication.

Neurons

Cells transmitting information via electrical impulses.

Charles Sherrington

Pioneer who studied synapse properties through behavior.

Ramón y Cajal

Anatomically demonstrated neurons are separate.

Chemical Transmission

Neurons communicate using neurotransmitters at synapses.

Action Potential

Electrical impulse triggering neuron firing.

EPSP

Excitatory postsynaptic potential increasing action potential likelihood.

IPSP

Inhibitory postsynaptic potential decreasing action potential likelihood.

Reflex Arc

Circuit from sensory neuron to muscle response.

Motor Neuron

Neuron transmitting signals to muscles.

Sensory Neuron

Neuron detecting stimuli and transmitting signals.

Intrinsic Neuron

Neuron processing information within the central nervous system.

Neurotransmitters

Chemicals transmitting signals across synapses.

Neuropeptides

Small protein-like molecules influencing neuron communication.

Hormones

Chemical messengers regulating physiological processes.

Behavioral Observations

Method used by Sherrington to infer synapse properties.

Chemical Events

Sequence of neurotransmitter synthesis and receptor stimulation.

Drugs and Behavior

Substances altering synaptic events affecting behavior.

Cajal's Discovery

Demonstrated anatomical separation of neurons.

Sherrington's Reflex Study

Experiment showing reflexes involve synaptic communication.

Neuroscience Pioneers

Cajal and Sherrington, foundational figures in neuroscience.

Neurotransmitter Disposition

Process of neurotransmitter removal after signaling.

Stimulation of Receptors

Activation of receptors by neurotransmitters at synapses.

Synthesis of Neurotransmitters

Creation of neurotransmitters within neurons.

Electrical Impulses

Signals transmitted along axons to communicate.

Neuronal Communication

Process involving electrical and chemical signaling.

Scientific Reasoning

Using observations to infer scientific principles.

Reflexes

Automatic responses to stimuli involving synaptic transmission.

Neuroscience

Study of the nervous system and its functions.

Synapse

Junction where neurons communicate with each other.

Reflex Arc

Pathway of reflex action through the nervous system.

Sherrington

Neuroscientist who introduced the term synapse.

Temporal Summation

Cumulative effect of repeated stimuli over time.

Presynaptic Neuron

Neuron that sends signals to another neuron.

Postsynaptic Neuron

Neuron that receives signals from another neuron.

Reflex Delay

Time taken for reflex response due to synapse.

Action Potential Velocity

Speed of electrical impulse along axon, ~40 m/s.

Reflex Speed

Speed of reflex action, ~15 m/s or less.

Cumulative Effect

Increased response from multiple weak stimuli.

Threshold of Excitation

Minimum stimulus required for neuron activation.

Spinal Cord

Central pathway controlling reflex actions.

Flexion Reflex

Reflex action involving bending a limb.

Extension Reflex

Reflex action involving straightening a limb.

Neuronal Communication

Process of signal transmission between neurons.

Impulse Transmission

Movement of electrical signals through neurons.

Skin Receptor

Sensory receptor detecting stimuli on the skin.

Neuronal Delay

Time lag in signal transmission at synapse.

Stimulus Presentation

Delivery of sensory input to initiate reflex.

Weak Stimuli

Insufficient signals that do not evoke reflex.

Strong Reflex

Robust response resulting from adequate stimulation.

Sherrington's Observations

Findings that established principles of reflexes.

Reflex Properties

Characteristics observed in reflex actions.

Neural Junction

Site where two neurons connect.

Electrical Impulse

Signal transmitted along neurons.

Reflex Modulation

Adjustment of reflex strength by brain signals.

Neuronal Excitation

Activation of a neuron by incoming signals.

Subthreshold Excitation

Insufficient stimulation not reaching action potential.

Action Potential

Rapid change in membrane potential triggering neuron firing.

Postsynaptic Neuron

Neuron receiving signals from presynaptic neurons.

Microelectrodes

Devices used to measure electrical activity in neurons.

Depolarization

Reduction in membrane potential, making it less negative.

Graded Potential

Variable change in membrane potential, not all-or-nothing.

Excitatory Postsynaptic Potential (EPSP)

Graded depolarization caused by sodium ion influx.

Temporal Summation

Combining multiple EPSPs over time to reach threshold.

Spatial Summation

Combining EPSPs from different locations to reach threshold.

Threshold

Membrane potential level needed to trigger an action potential.

Hyperpolarization

Increase in membrane potential, making it more negative.

Sodium Ions (Na+)

Ions that flow into neurons during EPSPs.

Reflex

Automatic response to a stimulus, often involving spinal cord.

Neuronal Integration

Combining inputs from multiple neurons for complex responses.

Inhibitory Postsynaptic Potential (IPSP)

Graded hyperpolarization reducing likelihood of action potential.

Convergence

Multiple axons synapsing onto a single neuron.

Synaptic Activation

Process of neurotransmitter release and receptor binding.

Neural Complexity

Diverse responses generated from various neuronal inputs.

Neuronal Firing

Process by which neurons transmit signals through action potentials.

Reflex Arc

Pathway involved in reflex actions, including sensory and motor neurons.

Neurotransmitter

Chemical messenger facilitating communication between neurons.

Resting Potential

Stable membrane potential of a neuron at rest.

Sensory Neurons

Neurons that carry signals from sensory receptors.

Axon

Long projection of a neuron transmitting action potentials.

Neuronal Excitation

Increase in likelihood of neuron firing an action potential.

Neural Circuit

Network of interconnected neurons processing specific information.

Synapse

Junction between two neurons for signal transmission.

Neural Input

Signals received by a neuron from other neurons.

Synapse

Connection between neurons for signal transmission.

Dendrite

Branching structure receiving signals from other neurons.

Axon

Long projection transmitting signals away from neuron.

Depolarization

Reduction in membrane potential, increasing action potential likelihood.

Temporal Summation

Repeated stimulation at a single synapse over time.

Spatial Summation

Simultaneous stimulation at multiple synapses onto one neuron.

Inhibitory Synapse

Synapse that decreases likelihood of action potential.

Flexor Muscles

Muscles that draw extremities toward the body.

Extensor Muscles

Muscles that move extremities away from the body.

Interneuron

Neuron that connects sensory and motor neurons.

Inhibitory Postsynaptic Potential (IPSP)

Temporary hyperpolarization reducing action potential probability.

Excitatory Postsynaptic Potential (EPSP)

Temporary depolarization increasing action potential probability.

Hyperpolarization

Increase in membrane potential, moving away from threshold.

Action Potential

Rapid rise and fall in membrane potential.

Motor Neuron

Neuron transmitting signals to muscles for movement.

Sensory Neuron

Neuron transmitting sensory information to the central nervous system.