NS Function and Divisions
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What are the functions of the NS? Sensation, integration, response
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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)
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Nervous Tissue
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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)
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What are the structures of neurons? Neurosoma (cell body), dendrites (receivers), axons (senders)
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Describe sensory neurons bring info to the CNS
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Describe interneurons integrate information IN THE CNS
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Describe motor neurons responses leaving the CNS
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What is the most common neuronal variety throughout the body? Multipolar neurons
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Neuroglia
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What are the 6 types of neuroglia? CNS: Astrocytes, microglial, ependymal cells, and oligodendrocytes PNS: Satellite cells and schwann cells
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What is the function of astrocytes? Support, control ionic environment, nourishment, communication, it has many varied in functionality
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What is the function of microglial cells? Phagocytosis- remove debris, immune function
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What is the function of ependymal cells? Involved in the production and circulation of cerebrospinal fluid
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What is the function of oligodendrocytes? Form the myelination in the CNS for insulation
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What is the function of satellite cells? Support and environmental regulation (surround neurosomas)
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What is the function of schwann cells? For myelination in the PNS for insulation
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What is myelin? A plasma membrane of water, lipids, and proteins that insulates axons
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What is the function/benefit of myelin? Increases the speed of conduction (gaps are necessary)
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What influences conduction speed? The diameter of the nerve fiber and myelin
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General NS Organization
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What is the difference between gray and white matter? Gray matter lacks myelin
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Where is gray/white matter in the spinal cord? Gray: inner portion White: outer portion
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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
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Spinal Cord Structure
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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
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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)
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What are the regions of the spinal cord? Cervical, thoracic, lumbar, sacral
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Describe the posterior (dorsal) horn Sensory processing (sensory neurons)
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Describe the anterior (ventral) horn Send motor signals (motor neurons)
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Describe the gray commisure connects the right and left side of the spinal cord and allows for side to side information transfer
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Describe the lateral horn ONLY in thoracic and lumbar region of SC, for autonomic nervous system (specifically the sympathetic division)
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Describe the dorsal (posterior) funiculus ascending tracts (sensory info up to the brain)
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Describe the ventral (anterior) funiculus descending tracts (motor commands down from the brain) and a little ascending
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Describe the lateral funiculus ascending and descending tracts
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What is the function of commissural fibers in white matter of the spinal cord? carry information from side to side
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Protection of the Spinal Cord
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What protects the spinal cord? 1. Vertebral column 2. Meninges 3. Cerebrospinal fluid (CSF)
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What are meninges? protective membranes
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What are the functions of the meninges? 1. Cover and protect the CNS 2. Separate soft tissue from bone
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What are the layers of the meninges? 1. Dura mater 2. Arachnoid Mater 3. Pia Mater
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What are the structures associated with the dura mater? Dural sheath and the epidural space (fat filled [cushions])
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What are the structures associated with the arachnoid mater? Subarachnoid space (CSF and blood vessels)
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What are the structures associated with the Pia Mater? Terminal filum
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What is the function of the dura mater? Outer covering-protection
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What is the function of the arachnoid mater? Middle layer- subdural space
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What is the function of the pia mater? Internal layer- thin membrane that is clingy and well vascularized (nourishing)
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What are the functions of CSF? Cushion/floats CNS, removes waste, and circulates nutrients
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Nervous/Spinal Nerves
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What is a nerve? Bundles of axons
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What structures make up nerves? Epineurium (outer covering), perineurium (surrounds nerve fascicles), and endoneurium (surrounds individual nerve fiber
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What are ganglia? clusters of cell bodies NOT in CNS
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What are spinal nerves? 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
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What are the general structures of spinal nerves? Rootlets, ventral root, dorsal root, and dorsal root ganglion
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What is a nerve plexus? network/web of nerves
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What are the major plexuses? Cervical plexus (C1-C4), Brachial plexus (C5-T1), Lumbar plexus (L1-L5), Sacral plexus (L4-S4)
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What are the major nerves of the cervical plexus? Phrenic nerve-diaphragm
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What are the major nerves of the brachial plexus? Axillary, radial, median, and ulnar
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What are the major nerves of the lumbar plexus? Femoral and obturator
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What are the major nerves of the sacral plexus? Sciatic nerve (tibial, fibular)
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What does the cervical plexus innervate? Skin and muscles of the neck
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What does the brachial plexus innervate? Neck, axilla, and the arm
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What does the lumbar plexus innervate? Anterior and medial thigh
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What does the sacral plexus innervate? Posterior thigh and the lower limb
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What is a reflex? a response to a stimulation
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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)
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The Brain
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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
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How is the brain organized? Cerebrum, Cerebellum, Diencephalon, and Brain Stem
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Describe the layers of protection for the brain 1. Skull 2. Meninges 3. CSF 4. Blood Brain Barrier
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What are ventricles? open chambers in the brain
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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
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The Brainstem
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Where is the brainstem located? at the base of the brain
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What structures make up the brain stem? Pons, medulla oblongata, and midbrain
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What structures make up the medulla oblongata and where is it located? Nuclei and tracts, located continuous with the spinal cord (caudal to stem)
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What is the function of the medulla oblongata? Relay info, cardiac center, vasomotor center, respiratory center, and convey info. Has cranial nerves IX-XII
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What structures make up the pons and where is it located? Bulge, cerebellar peduncles, tracts, and nuclei. Located between medulla and midbrain
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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
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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
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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
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The Diencephalon
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Where is the diencephalon located? Deep to the cerebrum, superior to the brainstem, and surrounds the third ventricle
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What structures makeup the diencephalon? Thalamus, hypothalamus, and epithalamus
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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
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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)
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What is the function fo the epithalamus? Sleep-wake cycle (circadian/seasonal cycles) and relay
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The Cerebellum
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Where is the cerebellum located? Inferior/posterior to cerebrum, dorsal to pons
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What structures make up the cerebellum? Cerebellar hemispheres, cortex, folia (folds), arbor vitae (white matter), deep nuclei, cerebellar peduncles
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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)
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The Cerebrum
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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)
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Describe the association tracts one part of a hemisphere to another
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The limbic system is... the major emotion and learning center
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What are functional areas of the cerebral cortex Localization of specific functions
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What are the two specific functional areas of the cerebral cortex? The primary cortex (sensory and motor) and the association cortex
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What are cranial nerves? Nerves that arise directly from the brain (primarily base)
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What are the different types of cranial nerves? Motor: III, IV, VI, XI, XII Sensory: I, II, VIII and Mixed: V, VII, IX, X
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Functional Areas Image
LOOK AT NOTES FOR IN DEPTH DESCRIPTION OF FUNCTIONAL AREAS
Autonomic Nervous System
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What are the functions of the ANS? Homeostasis aka regulation
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What are the divisions of the ANS? Sympathetic and Parasympathetic nervous systems
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What is the function of the sympathetic nervous system? Fight or flight
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What is the function of the parasympathetic nervous system? Rest and digest (homeostasis)
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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)
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What structures are associated with the parasympathetic NS? head/neck/thorax/abdomen and the digestive tract & pelvic organs
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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
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How does the sympathetic and parasympathetic divisions differ from the somatic motor division? The somatic motor division only has one ganglionic fiber
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What is dual innervation? sympathetic and parasympathetic divisions have antagonistic effects in working together
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What is the enteric nervous system? Nerve plexuses embedded in the wall of the digestive tract
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What is the function of the enteric nervous system? Motility and secretion of enzymes/acids
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Somatic Neural Pathway
Use this and following images to describe the differences with somatic motor and autonomic systems
Sympathetic Neural Pathway
Use previous image and following image to contrast differences
Parasympathetic Neural Pathway
Use previous images to contrast
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