a&p test 4

Neuron

Excitable cell that transmits electrical signals within the nervous system.

Dendrites

Receptive regions that receive incoming signals from other neurons.

Axon

Conductive region that carries action potentials away from the cell body.

Axon Hillock

Region where graded potentials are summed to initiate an action potential.

Synapse

Junction where a neuron communicates with another cell via neurotransmitters.

Astrocytes

Support neurons, regulate the extracellular environment, and help form the blood-brain barrier.

Oligodendrocytes

Produce myelin in the CNS to increase conduction speed.

Neurolemmocytes (Schwann Cells)

Produce myelin in the PNS.

Microglia

Phagocytic cells that protect the CNS.

Ependymal Cells

Line ventricles and help produce and circulate cerebrospinal fluid.

Resting Membrane Potential

Baseline electrical charge of a neuron (about -70 mV).

Na+/K+ Pump

Maintains ion gradients by pumping 3 Na+ out and 2 K+ into the cell.

Leak Channels

Allow passive movement of ions across the membrane.

Voltage-Gated Channels

Open in response to changes in membrane potential.

Ligand-Gated Channels

Open when a neurotransmitter binds.

Mechanically-Gated Channels

Open in response to physical deformation.

Graded Potential

Local signal that varies in strength and decreases over distance.

Excitatory Postsynaptic Potential (EPSP)

Depolarization that brings the membrane closer to threshold.

Inhibitory Postsynaptic Potential (IPSP)

Hyperpolarization that moves the membrane further from threshold.

Temporal Summation

Summation of signals from one neuron over time.

Spatial Summation

Summation of signals from multiple neurons simultaneously.

Action Potential

All-or-none electrical signal that travels along the axon.

Depolarization

Opening of Na+ channels causing Na+ influx.

Repolarization

Opening of K+ channels causing K+ efflux.

Hyperpolarization

Membrane becomes more negative than resting potential.

Absolute Refractory Period

Time when no second action potential can occur.

Relative Refractory Period

Stronger stimulus required to generate another action potential.

Rate Coding

Stimulus intensity encoded by frequency of action potentials.

Central Nervous System (CNS)

Brain and spinal cord.

Peripheral Nervous System (PNS)

All nerves and ganglia outside the CNS.

Gray Matter

Region containing neuron cell bodies.

White Matter

Region containing myelinated axons.

Nuclei

Clusters of neuron cell bodies in the CNS.

Ganglia

Clusters of neuron cell bodies in the PNS.

Tracts

Bundles of axons in the CNS.

Nerves

Bundles of axons in the PNS.

Meninges

Protective membranes covering the brain and spinal cord.

Dura Mater

Outer tough layer of the meninges.

Arachnoid Mater

Middle web-like layer of the meninges.

Pia Mater

Inner delicate layer of the meninges.

Blood-Brain Barrier

Protective barrier that regulates substances entering the brain.

Cerebral Cortex

Outer layer of the brain responsible for conscious thought.

Gyri

Raised ridges of the brain.

Sulci

Grooves of the brain.

Association Fibers

Connect regions within the same hemisphere.

Commissural Fibers

Connect the two hemispheres.

Projection Fibers

Connect the cerebrum to lower CNS regions.

Thalamus

Sensory relay center.

Hypothalamus

Regulates homeostasis including temperature, hunger, and hormones.

Limbic System

Involved in emotion and behavior.

Reticular Formation

Network that regulates alertness and consciousness.

Olfactory (I)

Sense of smell.

Optic (II)

Vision.

Oculomotor (III)

Eye movement and pupil constriction.

Trochlear (IV)

Eye movement (intorsion).

Trigeminal (V)

Facial sensation and chewing.

Abducens (VI)

Eye abduction.

Facial (VII)

Facial expression and taste (anterior tongue).

Vestibulocochlear (VIII)

Hearing and balance.

Glossopharyngeal (IX)

Taste (posterior tongue) and swallowing.

Vagus (X)

Parasympathetic control of the heart and organs.

Accessory (XI)

Neck muscle movement.

Hypoglossal (XII)

Tongue movement.

somatosensory cortex

Primary motor cortex

Primary auditory cortex

Primary olfactory cortex

Primary gustatory cortex

Cerebral nuclei

Internal capsule

Corpus callosum

Inner white matter

Cerebral cortex