Chapter 11 - Neural Tissue Flashcards
PNS
Includes all the neural tissue outside of cns. Has two divisions: sensory and motor.
Motor division of PNS
Carries motor commands from cns to peripheral tissues. Includes two systems: somatic and autonomic.
Sensory division of PNS
Brings information to the cns from receptors in peripheral tissues and organs.
Somatic nervous system
Controls skeletal muscle contractions.
Autonomic nervous system
Automatically regulates smooth muscle, cardiac muscle, glands, and adipose tissue.
Somatic sensory receptors
Provide position, touch, pressure, pain, and temperature sensations.
Special sensory receptors
Provide sensations of smell, taste, vision, balance, and hearing.
Visceral sensory receptors
Monitor internal organs
Dendrites
Receive stimuli from the environment or from other neurons. Highly branched.
Cell body
Contains nucleus and other organelles.
Axon
Carries information toward other cells.
Axon hillock
Origin of the axon from main cell body of a neuron.
Initial segment of axon
Where and action potential is initiated.
Telodenria
Series of fine extensions from the end of the axon trunk.
Synaptic terminals
Where the neuron communicates with other cells.
Anaxonic neurons
Small and lack anatomical features that distinguish dendrites from axons.
Bipolar neurons
Have two distinct processes - one dendritic process that branches extensively at its distal tip, and one axon - with the cell body between the two.
Unipolar neurons
Dendrites and axon are continuous and the cell body lies off to one side.
Multipolar neurons
Two or more dendrites and a single axon. Most common.
CNS
Consists of brain and spinal cord. Integrating and processing sensory data and motor commands.
Ganglion
Collection of neuron cell bodies in the PNS.
Neuralgia
“Glial cells” support and protect neurons in the PNS and CNS. Abundant and diverse, make up about half the volume of the nervous system.
Ependymal cells
Form a simple cuboidal to columnar epithelium known as the ependyma. Assist in producing and monitoring CSF.
Ependyma
Lines a fluid filled passageway within the spinal cord and brain.
Cerebrospinal fluid
Fills central canal of spine and surrounds the brain.
Microglia
Removes cellular debris, wastes, and pathogens in the neural tissues.
Astrocytes
Maintain the blood-brain barrier that isolates the CNS from the chemicals and hormones circulating in the blood.
Oligodendrytes
Provide structural framework in CNS by stabilizing the positions of axons.
Schwann cells
Only found in PNS. Form a sheath around peripheral axons. Outer membrane called neurolemma.
Satellite cells
Surround neuron cell bodies in PNS. Regulate environment around neurons.
Wallerian degeneration
Repair process of damaged axons in the PNS; often fails to restore full function.
Membrane potential
Inside of plasma membrane has a slight negative charge with respect to the outside. Due to excess of positively charged ions outside the membrane and a slight excess of negatively charged ions and proteins inside the membrane.
Graded potential
Temporary, localized change in resting potential produced by a stimulus. Change decreases with distance away from the stimulus.
Action potential
An electrical event that involves one location on the membrane. Spreads along the surface of an axon toward terminals.
Synaptic activity
Produces graded potentials in the plasma membrane of postsynaptic cells. Involves release of neurotransmitters such as ACh.
Local current
Movement of positive charges parallel the the inner and outer membranes during a graded potential.
Action potentials
Propagated changes in membrane potential that, once initiated, affect an entire excitable membrane.
Threshold
Membrane potential at which voltage-gated sodium channels are opened in response to a powerful enough graded depolarization.
Continuous propagation
Occurs along unmyelinated axons. Action potential appears to move along axolemma in tiny steps.
Saltatory propagation
Occurs in myelinated axons. Local current skips the internode of an axon and depolarizes the closest node.
Chemical synapses
Rely on neurotransmitter release. Depolarization of axon terminal is stimulus for neurotransmitter release.
