bio 660 Neuro Flashcards
What is a neuron composed of?
Cell body, dendrites, axon
What are densely packed cell bodies in the CNS called?
Nuclei
What are densely packed cell bodies in the PNS called?
Ganglia
What are dendrites?
Receptive portions of the neuron; receives information
What do axons do?
Carry impulses away from the cell body
Is membrane potential about the inside or outside of the cell?
Inside of the cell
What is an electrochemical gradient?
Describes the forces affecting ion movement if allowed to become permeable a membrane
When does action potential start?
When a membrane is depolarized enough that it triggers voltage-gated ion channels
What is a graded potential?
Changes in membrane potential that decrease over distance
What is a refractory period?
A period immediately following stimulation that is unresponsive for some time; reduced sensitivity
What is myelin?
A segmented layer of lipid material; acts as insulation
What is myelin called in the PNS?
Schwann cells
What are the nodes of Ranvier?
Gaps/regular interruptions in the myelin sheath
What is saltatory conduction?
The flow of ions between segments of myelin rather than along the entire length of the axon
What is divergence?
The ability of branching axons to influence many neurons
What is convergence?
Branches of numerous neurons converging on one or a few neurons
What is the Central Nervous System (CNS) made up of?
Brain and spinal cord
What is the Peripheral Nervous System (PNS) made up of?
Cranial nerves and spinal nerves
What are afferent pathways?
Ascending
What are efferent pathways?
Descending
What does the somatic nervous system do?
Regulates voluntary motor control of the skeletal muscles
What does the autonomic nervous system do?
Regulates the body’s internal environment through involuntary control of organ systems
What is Wallerian degeneration?
Degeneration of a nerve fiber that has been separated by injury or disease
What is a synapse?
Gap between neurons
What is temporal summation?
Integration of stimuli occurring at different times
What is spatial summation?
Integration of stimuli occurring at different locations
What is the second messenger system?
Receptors may activate another molecule inside the cell to make changes
What is the reticular formation?
Network of connected nuclei that regulate vital reflexes, such as cardiovascular and respiratory function
What are the functions of the frontal lobe?
Primary motor area and limbic systems
What are the functions of the parietal lobe?
Somatic sensory input
What are the functions of the occipital lobe?
Primary visual cortex
What are the functions of the temporal lobe?
Primary auditory cortex
What is the basal ganglia?
A group of structures involved in the coordination of movement
What are the symptoms of upper motor neuron syndrome?
Hemiparesis or hemiplegia, diplegia, paraparesis or paraplegia, quadriparesis or quadriplegia
What are the symptoms of lower motor neuron syndrome?
Flaccid paralysis/paresis, hypotonia, hyporeflexia, fibrillation, muscle atrophy
What is Amyotrophic Lateral Sclerosis (ALS)?
A neurodegenerative disorder affecting upper and lower motor neurons
What does “flaccid” mean?
Damage to anterior horn cells or ventral root, resulting in no signals to the muscle
What does “spastic” mean?
Damage to upper motor neurons in the motor cortex, resulting in sporadic stimulation from spinal cord reflexes, with no voluntary control
What is paresthesia?
Loss of sensory function, characterized by tingling or numbness
How many spinal nerves are there?
31
How many cervical spinal nerves are there?
8
How many thoracic spinal nerves are there?
12
How many lumbar spinal nerves are there?
5
How many sacral spinal nerves are there?
5
How many coccygeal spinal nerves are there?
1
Where is cerebrospinal fluid produced?
Choroid plexus
How many vertebrae are there?
33 (7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal)
What is the blood-brain barrier (BBB)?
Cellular structures that selectively inhibit certain potentially harmful substances in the blood from entering the interstitial space of the brain or the CSF
What are vesicles?
Bundles of myelinated axons in the PNS
What is the autonomic nervous system responsible for?
Coordinating and maintaining the steady state among the visceral (internal) organs
What is a preganglionic neuron?
Myelinated neuron
What is a postganglionic neuron?
Unmyelinated neuron
What does the sympathetic nervous system do?
Initiates the “fight or flight” response, increasing blood pressure and heart rate while slowing digestion
What does the parasympathetic nervous system do?
Initiates the “rest and digest” response, decreasing blood pressure and heart rate while increasing digestion
How does the parasympathetic nervous system affect the heart?
Decreases rate; slows and steadies
How does the sympathetic nervous system affect the heart?
Increases rate and force of heartbeat
How does the parasympathetic nervous system affect the GI tract?
Increases motility, secretions, and opens sphincters
How does the sympathetic nervous system affect the GI tract?
Decreases motility, secretions, and opens sphincters
