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Nervous system

Terms in this set (73)

What are the structures of the nervous system?
brain, spinal cord, cranial nerves, ganglia
What is the ganglia?
Small masses of nervous tissue that are located outside the brain
What are enteric plexuses?
extensive networks of neurons that regulate the digestive system
What are sensory receptors?
Monitor changes in the internal or external environment
What are the functions of the nervous system?
Sensory function to detect internal and external changes
Integrative functions to analyze and store sensory information and makes decisions for appropriate responses to that info
Motor functions to respond to integration decisions
What are sensory neurons?
Neurons that carry information from cranial or spinal nerves to the brain and spinal cord
What are motor or efferent neurons?
Neurons that carry information from brain and spinal cord to the cranial or spinal nerves
What are effectors?
Cells and organs contacted by motor neurons
What is the central nervous system?
brain and spinal cord
What is the function of the central nervous system?
Integrate and correlate sensory information
Source of thoughts, emotions, and memories
What is the peripheral nervous system?
Cranial nerves and their branches, spinal nerves and their branches, ganglia, and sensory receptors
What is the somatic nervous system?
Consists of somatic sensory neurons from the head, body wall, and limbs as well as for the special senses
Motor neurons from the CNS to the skeletal muscles only
What is the autonomic nervous system?
Sensory neurons from receptors in visceral organs to the CNS
Motor neurons from CNS to smooth muscle, cardiac muscle and glands
Action is involuntary
Consists of sympathetic division and parasympathetic division
What is the enteric nervous system?
Brain of the gut
Involuntary
Neurons extend the entire length of the GI tract
What are neurons?
Nerve cells that provide unique functions such as sensing, thinking, remembering, muscle activity, and gland secretions
What are neuroglia?
Support, nourish, and protect neurons and maintains interstitial fluid that surrounds them
What are the structures of a neuron?
A cell body, dendrites, axon
What is a cell body?
A nucleus surrounded by cytoplasm with typical organelles
What are dendrites?
Little trees that receive or input portion of a neuron and is receptive to other neurons
What is an axon?
Carries nerve impulses to other neurons, a muscle fiber or a gland cell
What are astrocytes?
Supports neurons with microfilaments
Creates a blood-brain barrier to prevent harmful substances from being transferred fro the blood to the interstitial fluid of the CNS
Regulates the growth, migration, and interconnection between neurons in the brain of an embryo
Maintain the correct chemical environment for the generation of nerve impulse
What are oligodendrocytes?
Form and maintain the myelin sheath around CNS axons
What is microglia?
Function in phagocytosis by removing debris, microbes, and damaged tissues
What are ependymal cells?
Possess microvilli and cilia
line the ventricles of the brain and central canal of the spinal cord
Produce, monitor and assist in the circulation of cerebrospinal fluid
What are Schwann cells?
Encircle PNS axons
Form the myelin sheath around axons
Participate in axon regeneration
What are satellite cells?
Surround PNS ganglia
Protection and support
What does the myelin sheath do?
Electrically insulates an axon of a neuron and speeds up the conduction of nerve impulses
What is the neurolemma?
Outer nucleated layer of a schwann cell covering a myelinated or unmyelinated axon and is found only in PNS and aids in regeneration of axons
What is demyelination?
loss or destruction of the myelin sheath
what is white matter
myelinated axons
what is gray matter
non myelinated anxos, dendrites, synapses, and cell bodies
What is a nerve impulse
Begins and travels due to the movement of ions between interstitial fluid and the inside of a neuron and travels rapidly and at a constant strength (all or none response)
What is resting potential?
Inactive and polarized- relatively negative on the inside and positive on the outside
excess Na+ outside and excess K+ inside
What happens when a neuron is stimulated?
Sodium channels open and sodium ions rush in causing depolarization
As sodium level rises, potassium ions leave which then re-polarizes the neuron
The change in polarity is action potential and is propagated the entire length of the axon
What happens after the change in polarity when the neuron is stimulated?
The membrane channels close and Na+/K+ pumps both ions back to their original location
This restores the original charge and thus the axon returns to its resting potential
What are disorders preventing the nerve impulse?
Tetrodotoxin (puffer fish poisoning)
Paralytic shellfish poisoning (Plugs up sodium channels)
What is a presynaptic neuron?
a nerve cell that carries the impulse towards a synapse
What is a postsynaptic neuron?
a nerve cell or effector that carries a nerve impulse away from a synapse
What is a neurotransmitter?
molecules released from a synaptic vesicle that excites postsynaptic neurons, muscle fibers, or gland cells
What is acetylcholine?
excitatory neurotransmitter between a motor neuron and a muscle fiber and may also be an inhibitory neurotransmitter
What is norepinephrine?
role in arousal, dreaming, and regulating mood
What is dopamine?
active during emotional responses, addictive behaviors, and pleasurable experiences
what is serotonin
sensory perception, temperature regulation, control of mood and appetite and the onset of sleep
What are meninges?
three connective tissue membranes that encircle the spinal cord and brain
What is the dura mater?
outer layer that forms a sac from the level of the foramen magnum to the 2nd sacral vertebra
What is the arachnoid mater?
middle layer
What is the subdural space?
space between dura mater and arachnoid mater that contains interstitial fluid
What is the pia mater?
inner layer that adheres to the surface of spinal cord and brain with many blood vessels
What is the subarachnoid space?
between arachnoid mater and pia mater that contains CSF
What is the cervical enlargement?
nerves of shoulders and upper limbs
what is the lumbar enlargment
nerves to and from lower limbs
what is the conus medullaris
ends in filum terminale
What are the functions of the spinal cord?
Promotes homeostasis by conducting nerve impulses along tracts and integrates the information
Motor output to skeletal muscle travels down two types of pathways
What is direct pathway?
destined to cause precise movements
what is indirect pathway
convey impulses from brain to govern automatic movements and coordinate body movements with visual stimulus
What are spinal reflexes?
reflex occurring in the gray mater of spinal cord (knee jerk)
what are cranial reflexes
reflex occurring in the brain stem (eye movement during reading)
what are somatic reflexes
involved contraction of skeletal muscle
What are autonomic reflexes?
involve automatic responses of smooth muscle, cardiac muscle and glands
What is the brain stem
This attaches to the spinal cord. There are three parts of the brain stem. (medulla, midbrain, and pons)
What is the cerebellum?
At the back, responsible for muscle contraction & balance (little brain)
evaluates how well movements initiated by the cerebrum are being carried out
What is the diencephalon?
thalamus and hypothalamus
What is the cerebrum?
largest portion of the brain that is supported by the brain stem and diencephalon
What is the falx cerebri?
separates the two hemispheres of the cerebrum
what is the falx cerebelli
separates the two hemispheres of the cerebellum
What is the tentorium cerebelli?
separates the cerebrum from the cerebellum
What is the medulla oblongata?
the posterior part of the brain that controls the rate of breathing and other autonomic functions
what are pyramids?
white matter bulges formed by large motor tracts that pass to the spinal cord
what are pons
a bridge that connects parts of the brain with one another
what is midbrain
cerebral aqueduct passes through the midbrain connecting the 3rd and 4th ventricles
what is the thalamus
relay station and contributes to motor functions by transmitting information from the cerebellum to the primary motor area of the cerebral cortex
What is the hypothalamus?
controls body activities and regulates homeostasis
connects to the pituitary gland and produces several hormones
control of the ANS
regulation of eating and drinking
controls body temp
What is the epithalamus?
involved in hormonal secretions from pineal gland and olfaction (sense of smell and emotional responses to them) from the habenular nuclei
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