Functional Organization of Nervous Tissue

Nervous System Functions

Controls body functions, processes information, coordinates responses.

Divisions of Nervous System

Central nervous system (CNS) and peripheral nervous system (PNS).

Neuron Structure

Composed of cell body, dendrites, and axon.

Neuron Components Functions

Dendrites receive signals; axon transmits impulses.

Neurons Classification by Structure

Types include unipolar, bipolar, and multipolar neurons.

Neurons Classification by Function

Includes sensory, motor, and interneurons.

CNS Glial Cells

Support neurons; include astrocytes, oligodendrocytes, microglia.

PNS Glial Cells

Support neurons; include Schwann cells and satellite cells.

Myelin Sheath Function

Insulates axons, speeds up action potential conduction.

Gray Matter Components

Contains neuron cell bodies, dendrites, and synapses.

White Matter Components

Consists of myelinated axons forming tracts.

Tracts

Bundles of axons in the CNS.

Nerves

Bundles of axons in the PNS.

Resting Membrane Potential

Electrical potential difference across a cell membrane at rest.

Ionic Differences at Rest

Higher Na+ outside, higher K+ inside the cell.

Graded Potential Characteristics

Variable strength signals that decay over distance.

Action Potential Creation

Rapid depolarization followed by repolarization of membrane.

All-or-None Principle

Action potentials occur fully or not at all.

Refractory Period

Time during which neuron cannot fire another action potential.

Action Potential Frequency Factors

Determined by stimulus strength and refractory period.

Saltatory Conduction

Action potential jumps between myelinated nodes.

Continuous Conduction

Action potential travels along unmyelinated axons.

Synapse Structure and Function

Site of communication between neurons.

Electrical Synapses

Direct ion flow between cells via gap junctions.

Chemical Synapses

Neurotransmitter release and binding to receptors.

Neurotransmitter Release

Triggered by action potentials; diffuses across synapse.

Neurotransmitter Removal

Reuptake or enzymatic degradation after signaling.

Neurotransmitter Effects

Binding alters postsynaptic membrane potential.

Excitatory Postsynaptic Potentials

Increase likelihood of action potential firing.

Inhibitory Postsynaptic Potentials

Decrease likelihood of action potential firing.

Spatial Summation

Multiple signals at different locations combine.

Temporal Summation

Multiple signals at the same location combine.

Types of Circuits

Includes diverging, converging, and reverberating circuits.