NS Function and Divisions
What are the functions of the NS?
Sensation, integration, response
What are the divisions and subdivisions of the NS?
CNS and PNS (in PNS: somatic sensory, visceral sensory, somatic motor, and the autonomic nervous system which has the parasympathetic and sympathetic nervous systems)
What are the characteristics of neurons?
1. Highly specialized to conduct nerve impulses 2. Long lived 3. Don't divide 4. High metabolic rate (takes a lot of energy)
What are the structures of neurons?
Neurosoma (cell body), dendrites (receivers), axons (senders)
Describe sensory neurons
bring info to the CNS
integrate information IN THE CNS
Describe motor neurons
responses leaving the CNS
What is the most common neuronal variety throughout the body?
What are the 6 types of neuroglia?
CNS: Astrocytes, microglial, ependymal cells, and oligodendrocytes PNS: Satellite cells and schwann cells
What is the function of astrocytes?
Support, control ionic environment, nourishment, communication, it has many varied in functionality
What is the function of microglial cells?
Phagocytosis- remove debris, immune function
What is the function of ependymal cells?
Involved in the production and circulation of cerebrospinal fluid
What is the function of oligodendrocytes?
Form the myelination in the CNS for insulation
What is the function of satellite cells?
Support and environmental regulation (surround neurosomas)
What is the function of schwann cells?
For myelination in the PNS for insulation
What is myelin?
A plasma membrane of water, lipids, and proteins that insulates axons
What is the function/benefit of myelin?
Increases the speed of conduction (gaps are necessary)
What influences conduction speed?
The diameter of the nerve fiber and myelin
General NS Organization
What is the difference between gray and white matter?
Gray matter lacks myelin
Where is gray/white matter in the spinal cord?
Gray: inner portion White: outer portion
Where is gray/white matter located in the brain?
Gray: Cortex (cerebrum and cerebellum), superficial White: tracts, deep to cortex Brain Nuclei: deep clusters of gray matter embedded in white matter
Spinal Cord Structure
What are the functions of the spinal cord?
1. Conduction- carry impulses up and down 2. Neural Integration- decision making 3. Locomotion- simple patterns like walking 4. Reflexes- quick reaction without brain
What are the major structures of the spinal cord?
Cervical enlargement, lumbar enlargement, conus medullaris (end of the spinal cord), cauda equina (horse tail), and terminal filum (anchors conus medullaris)
What are the regions of the spinal cord?
Cervical, thoracic, lumbar, sacral
Describe the posterior (dorsal) horn
Sensory processing (sensory neurons)
Describe the anterior (ventral) horn
Send motor signals (motor neurons)
Describe the gray commisure
connects the right and left side of the spinal cord and allows for side to side information transfer
Describe the lateral horn
ONLY in thoracic and lumbar region of SC, for autonomic nervous system (specifically the sympathetic division)
Describe the dorsal (posterior) funiculus
ascending tracts (sensory info up to the brain)
Describe the ventral (anterior) funiculus
descending tracts (motor commands down from the brain) and a little ascending
Describe the lateral funiculus
ascending and descending tracts
What is the function of commissural fibers in white matter of the spinal cord?
carry information from side to side
Protection of the Spinal Cord
What protects the spinal cord?
1. Vertebral column 2. Meninges 3. Cerebrospinal fluid (CSF)
What are meninges?
What are the functions of the meninges?
1. Cover and protect the CNS 2. Separate soft tissue from bone
What are the layers of the meninges?
1. Dura mater 2. Arachnoid Mater 3. Pia Mater
What are the structures associated with the dura mater?
Dural sheath and the epidural space (fat filled [cushions])
What are the structures associated with the arachnoid mater?
Subarachnoid space (CSF and blood vessels)
What are the structures associated with the Pia Mater?
What is the function of the dura mater?
What is the function of the arachnoid mater?
Middle layer- subdural space
What is the function of the pia mater?
Internal layer- thin membrane that is clingy and well vascularized (nourishing)
What are the functions of CSF?
Cushion/floats CNS, removes waste, and circulates nutrients
What is a nerve?
Bundles of axons
What structures make up nerves?
Epineurium (outer covering), perineurium (surrounds nerve fascicles), and endoneurium (surrounds individual nerve fiber
What are ganglia?
clusters of cell bodies NOT in CNS
What are spinal nerves?
31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
What are the general structures of spinal nerves?
Rootlets, ventral root, dorsal root, and dorsal root ganglion
What is a nerve plexus?
network/web of nerves
What are the major plexuses?
Cervical plexus (C1-C4), Brachial plexus (C5-T1), Lumbar plexus (L1-L5), Sacral plexus (L4-S4)
What are the major nerves of the cervical plexus?
What are the major nerves of the brachial plexus?
Axillary, radial, median, and ulnar
What are the major nerves of the lumbar plexus?
Femoral and obturator
What are the major nerves of the sacral plexus?
Sciatic nerve (tibial, fibular)
What does the cervical plexus innervate?
Skin and muscles of the neck
What does the brachial plexus innervate?
Neck, axilla, and the arm
What does the lumbar plexus innervate?
Anterior and medial thigh
What does the sacral plexus innervate?
Posterior thigh and the lower limb
What is a reflex?
a response to a stimulation
What are the characteristics of a reflex and how does it work?
1. Stimulation (requires) 2. Fast (spinal cord and back) 3. Involuntary 4. Stereotyped (every time you do it, you get the same response)
What are the main functions of the brain?
1. Initiates voluntary and involuntary movement 2. Interprets and integrates sensory stimulation 3. Consciousness and cognitive function 4. Controls basic life sustaining activities
How is the brain organized?
Cerebrum, Cerebellum, Diencephalon, and Brain Stem
Describe the layers of protection for the brain
1. Skull 2. Meninges 3. CSF 4. Blood Brain Barrier
What are ventricles?
open chambers in the brain
List the order of the circulation through the ventricles
Starts in lateral ventricles, continues to the third ventricle, continues into the fourth ventricle, and goes into central canal of the spinal cord
Where is the brainstem located?
at the base of the brain
What structures make up the brain stem?
Pons, medulla oblongata, and midbrain
What structures make up the medulla oblongata and where is it located?
Nuclei and tracts, located continuous with the spinal cord (caudal to stem)
What is the function of the medulla oblongata?
Relay info, cardiac center, vasomotor center, respiratory center, and convey info. Has cranial nerves IX-XII
What structures make up the pons and where is it located?
Bulge, cerebellar peduncles, tracts, and nuclei. Located between medulla and midbrain
What is the function of the pons?
Carry signals up and down brainstem and connect right and left cerebellar hemispheres. Has cranial nerves V-VII
What structures makeup the midbrain and where is it located?
Nuclei, tectum (roof), cerebral aqueduct, tegmentum (floor), cerebral crura. Located in the rostral portion of the brainstem
What is the function of the midbrain?
Visual reflexes/integration, process/relay auditory signals, fine motor control, voluntary movement. Contains cranial nerves III and IV
Where is the diencephalon located?
Deep to the cerebrum, superior to the brainstem, and surrounds the third ventricle
What structures makeup the diencephalon?
Thalamus, hypothalamus, and epithalamus
What is the function of the thalamus?
Gateway to cortex: filter/relay sensory info (all but smell), motor control (relay info between cerebrum and cerebellum), and memory and emotional
What is the function of the hypothalamus?
Main control center of ANS: regulates homeostasis (hormone secretion, thermoregulation, food/water intake, sleep/circadian rhythms, emotion and sexual responses), memory (involved in memory formation)
What is the function fo the epithalamus?
Sleep-wake cycle (circadian/seasonal cycles) and relay
Where is the cerebellum located?
Inferior/posterior to cerebrum, dorsal to pons
What structures make up the cerebellum?
Cerebellar hemispheres, cortex, folia (folds), arbor vitae (white matter), deep nuclei, cerebellar peduncles
What is the function of the cerebellum?
Subconscious evaluation of sensory input, coordinate and smooth movements, maintain posture and equilibrium, some cognitive skills (muscle memory)
What are the major structures that make up the cerebrum?
Cerebral cortex, cerebral white matter, nuclei, right and left hemispheres (separated by the longitudinal fissure and connected by the corpus callosum) and the transverse fissure (separates the cerebrum and cerebellum)
Describe the association tracts
one part of a hemisphere to another
The limbic system is...
the major emotion and learning center
What are functional areas of the cerebral cortex
Localization of specific functions
What are the two specific functional areas of the cerebral cortex?
The primary cortex (sensory and motor) and the association cortex
What are cranial nerves?
Nerves that arise directly from the brain (primarily base)
What are the different types of cranial nerves?
Motor: III, IV, VI, XI, XII Sensory: I, II, VIII and Mixed: V, VII, IX, X
Functional Areas Image
LOOK AT NOTES FOR IN DEPTH DESCRIPTION OF FUNCTIONAL AREAS
Autonomic Nervous System
What are the functions of the ANS?
Homeostasis aka regulation
What are the divisions of the ANS?
Sympathetic and Parasympathetic nervous systems
What is the function of the sympathetic nervous system?
Fight or flight
What is the function of the parasympathetic nervous system?
Rest and digest (homeostasis)
What structures are associated with the sympathetic NS?
Smooth muscle in blood vessels, skin (raises hairs), sweat glands, and adrenal glands (epinephrine and norepinephrine secretion)
What structures are associated with the parasympathetic NS?
head/neck/thorax/abdomen and the digestive tract & pelvic organs
How do the sympathetic and parasympathetic divisions differ?
Sympathetic division has short preganglionic fibers and long postganglionic fibers while the parasympathetic division has long preganglionic fibers and short postganglionic fibers
How does the sympathetic and parasympathetic divisions differ from the somatic motor division?
The somatic motor division only has one ganglionic fiber
What is dual innervation?
sympathetic and parasympathetic divisions have antagonistic effects in working together
What is the enteric nervous system?
Nerve plexuses embedded in the wall of the digestive tract
What is the function of the enteric nervous system?
Motility and secretion of enzymes/acids
Somatic Neural Pathway
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Sympathetic Neural Pathway
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Parasympathetic Neural Pathway
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