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Anatomy Ch 10

Nervous system crap and other junk

QuestionAnswer
Neurons: react to changes, send nerve impulses for communication
Neuroglia surround and support neurons, nourish neurons, send and receive messages, help maintain blood brain barrier
CNS: Brain, spinal cord
PNS: Cranial nerves, spinal nerves (bring info or take away from all over body)
Somatic Nervous System: Motor division of PNS; skeletal muscles
Autonomic Nervous System: Motor division of PNS; Smooth muscles, cardiac muscles, glands
Sensory function of nervous system Nervous system receives info, Sensory receptors gather info by detecting changes, Info is carried to the cns
Integrative function of nervous system Nervous system coordinates sensory info to create sensations, memory, thoughts; Nervous system makes decisions on body’s response to sensory info
Motor functions of nervous system decisions are acted upon, Impulses are carried to effectors (muscles or glands)
Neurons vary in... size and shape; may differ in length and size of their axons and dendrites
Cell body (soma): contains nucleus, cytoplasm, organelles, neurofilaments, chromatophilic substance (Nissl bodies)
Dendrites: branched receptive surfaces; a neuron may have many
Axon: transmits impulses and releases neurotransmitters to another neuron or effector (another neuron, a muscle cell or a gland cell); a neuron may have only 1 axon
Schwann cells structures: PNS neuroglia that encase axons; myelin, myelin sheath
The speed of impulse conduction varies with... myelination
Axon diameter affects conduction speed; thick axons transmit faster than thin axons
Multipolar neurons: 99% of neurons,Many processes,Most neurons of CNS
Bipolar neurons: Two processes;Eyes, ears, nose
Unipolar neurons: One process,Cell bodies are in ganglia,Sensory
Sensory Neurons: Afferent neurons, Carry impulse to CNS, Most are unipolar, Some are bipolar
Interneurons: Association neurons, Link neurons, Multipolar, Located in CNS
Motor Neurons: Multipolar, efferent;Carry impulses away from CNS, Carry impulses to effectors
Synapse a site at which a neuron transmits a nerve impulse to another neuron
Presynaptic neuron sends impulse
Postsynaptic neuron receives impulse
Synaptic Transmission Impulse travels down axon presynaptic neuron to axon terminal;Impulse reaches synaptic knob cause influx of Ca+2 ions;Release of neurotransmitters from synaptic vesicles by exocytosis; Neurotrans exert excitatory/inhibitory effect postsynaptic neuron
Convergence: One neuron receives input from several neurons from different types of sensory receptors. Makes it possible for a neuron to sum impulses from different sources.
Divergence: One neuron sends impulses to several neurons via branching of its axon;Can amplify an impulse.;Impulse from a single neuron in CNS may activate several motor units in a skeletal muscle
Brain consists of: 2 cerebral hemispheres, diencephalon, brainstem, cerebellum
Both brain and spinal cord connect to... the peripheral nervous system (PNS) is by way of peripheral nerves
Meninges: membranes that protect brain and spinal cord; lie between bone and soft tissues of nervous system
3 layers of meninges: Dura matter, Arachnoid matter, Pia matter
Dura mater: Outer layer;Tough, dense connective tissue;Dural sinuses;Epidural space
Arachnoid mater: Middle layer; weblike;Subarachnoid space contains cerebrospinal fluid (CSF)
Pia mater: Inner layer; attached to surface of brain, spinal cord;Blood vessels & nerves;Nourishes CNS
CFS produced in... 4 ventricles
Ventricles: are continuous with the central canal of the spinal cord;They are filled with CSF
The 4 ventricles: 2 Lateral ventricles (called the first and second ventricles);Third ventricle;Fourth ventricle
Cerebrospinal Fluid (CSF) Secreted by the choroid plexuses,special capillaries.;Selective transfer of substances from the blood to form CSF;Nutritive and protective;After exchanging substances, CSF is absorbed by the arachnoid granulations
Major portions of the brain: Cerebrum, Diencephalon, Cerebellum, Brainstem
Largest part of brain Cerebrum
Cerebral hemispheres: 2 halves, separated by falx cerebri
Corpus callosum: Connects cerebral hemispheres
Gyri: Ridges or convolutions
Sulci: Shallow grooves in surface [Central sulcus ]
Fissures: Deep grooves in surface
Longitudinal fissure separates the cerebral hemispheres
Transverse fissure separates cerebrum from cerebellum
5 lobes of the cerebral hemispheres: Frontal lobe, Parietal lobe, Temporal lobe, Occipital lobe, Insula (Island of Reil) ; named for the bones they underlie
Cerebral cortex is responsible for higher mental functions: Interpreting impulses from sensory organs; Initiating voluntary movements; Storing information as memory; Retrieving stored information; Reasoning; Seat of intelligence and personality
Cutaneous sensory area: Parietal lobe;Interprets sensations on skin
Sensory speech area (Wernicke’s area): Temporal /parietal lobe;Usually left hemisphere;Understanding and formulating language
Visual area: Occipital lobe;Interprets vision
Auditory area Temporal lobe;interprets hearing
Sensory area for taste: Near base of the central sulcus; Includes part of insula
Sensory area for smell: Arises from centers deep within temporal lobes
Association Areas of the Cortex: Regions that are not primarily motor or sensory;Connect to each other and to other structures in the brain;Widespread throughout the cerebral cortex;Analyze and interpret sensory experiences;Provide memory, reasoning, verbalization, judgment, emotions
Primary motor areas: Frontal lobes;Control voluntary muscles;Most nerve fibers cross over in brainstem
Broca’s area: Anterior to primary motor cortex;Usually in left hemisphere; Controls muscles needed for speech
Frontal eye field: Above Broca’s area;Controls voluntary movements of eyes and eyelids
Dominant hemisphere controls: Language skills of speech, writing, reading;Verbal, analytical, and computational skills
Nondominant hemisphere controls: Nonverbal tasks;Motor tasks;Understanding and interpreting musical and visual patterns;Provides emotional and intuitive thought processes
2 types of memory: Short-term (working) memory, long-term memory
Short-term (working) memory: Neurons connected in a circuit;Circuit is stimulated over and over;When impulse flow ceases, memory does also unless it enters long-term memory via memory consolidation
Long-term memory: Holds more memory than short-term, lasts a lifetime ;Changes structure or function of neurons;Enhances synaptic transmission
Basal Nuclei: Sometimes called basal ganglia;Masses of gray matter deep within cerebral hemispheres;Consist of caudate nucleus, putamen, and globus pallidus;Produce dopamine;Help control voluntary movement
Diencephalon Between cerebral hemispheres and above the brainstem; Surrounds the third ventricle;Composed of gray matter
Diencephalon structures: Thalamus; Hypothalamus; Optic tracts; Optic chiasma; Infundibulum; Posterior pituitary; Mammillary bodies; Pineal gland
Brainstem consists of: Midbrain;Pons ;Medulla oblongata
Midbrain: Short section of brainstem;Lies between diencephalon and pons;Contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain
Pons: Rounded bulge on underside of brainstem;Between midbrain and medulla oblongata;Relays impulses from cerebrum to cerebellum
Medulla oblongata: Enlarged continuation of spinal cord;Conducts ascending and descending impulses between brain & spinal cord;Contains cardiac, vasomotor, respiratory control centers;Contains various nonvital reflex control centers (coughing, sneezing,ect)
Reticular Formation: Network of nerve fibers through brain stem;Extends in diencephalon;Connects to centers of hypothalamus, basal nuclei, cerebellum, cerebrum w/ascending&descending tracts;Filters sensory info;Arouses cerebral cortex into wakefulness;Decreased activity=Sleep
Non-rapid Eye Movement (Non-REM) Sleep: Slow wave sleep ;Person is tired;Decreasing activity of reticular formation;Restful and dreamless;Reduced blood pressure and respiratory rate;3 stages, ranging from light to heavy;Alternates with REM sleep
Rapid Eye Movement (REM) Sleep: Paradoxical sleep (because some areas of brain are active) ;Heart and respiratory rates irregular;Dreaming occurs
Cerebellum: Inferior to occipital lobes;Posterior to pons and medulla oblongata;Two hemispheres separated by falx cerebelli;Vermis connects hemispheres;Coordinates skeletal muscle activity;Maintains posture
Spinal Cord column of nervous tissue continuous w/ brain&brainstem;Extends down through vertebral canal;Begins at the foramen magnum & terminates at first& second lumbar vertebrae space;Consists of 31 segments; each gives rise to a pair of spinal nerves
Portions of the spinal cord(longitudinal section): Cervical enlargement;Lumbar enlargement;Conus medullaris;Filum terminale;Cauda equina
Structure of the spinal cord (cross section): White matter- Posterior Funiculus, Lateral funiculus, Anterior funiculus. ; Gray matter- Posterior Horn, Lateral horn, Anterior horn. Other- Central canal, Anterior median fissure, spinal nerve structures, gray commissure, posterior median suculus
2 main functions of the spinal cord: Center for spinal reflexes;Conduit (pathway) for impulses to and from the brain
Ascending tracts conduct sensory impulses to the brain
Descending tracts conduct motor impulses from the brain to motor neurons reaching muscles and glands
Tracts are composed of... axons
Reflex: Automatic, subconscious response to stimuli within or outside the body
Reflex arc: Neural pathway, consisting of a sensory receptor, 2 or more neurons, and an effector
Simple reflex arc contains only sensory and motor neurons;Most common reflex arc (sensory neuron, interneurons, motor neurons)
Monosynaptic (stretch) reflex: Consists of 2 neurons: sensory and motor; 1 synapse in spinal cord. [Example of a stretch reflex: the knee-jerk reflex]; Helps maintain an upright posture
Withdrawal Reflex: When person touches or steps on something painful; Prevents or limits tissue damage, by removing limb from painful stimulus•
Polysynaptic contains sensory neuron, interneuron, motor neuron•
Reciprocal innervation flexors contract, extensors are inhibited
Crossed Extensor Reflex: During withdrawal reflex, flexors on affected side contract, extensors are inhibited (ipsilateral);At same time, extensors on opposite side (contralateral)contract, flexors are inhibited;Also shifts body weight, so person remains upright
Major Ascending (Sensory) Spinal Cord Tracts Fasciculus gracilis and fasciculus cuneatus;Spinothalamic tracts;Spinocerebellar tracts
Major Descending (Motor)Spinal Cord Tracts: Corticospinal tracts;Reticulospinal tracts;Rubrospinal tract
Sensory nerves: Conduct impulses into brain or spinal cord
Motor nerves: Conduct impulses to muscles or glands
Mixed nerves: Contain both sensory and motor nerve fibers;Most nerves are mixed nerves;All spinal nerves are mixed nerves (except the first pair)
Cranial Nerves: 12 pairs on underside of brain;Most are mixed nerves ;Some are sensory, associated with special senses;Some are primarily motor, innervate muscles or glands;Most are attached to the brainstem, with 2 exceptions
2 cranial nerves not attached to brainstem: First pair has fibers that start in the nasal cavity; Second pair originates in eyes, fibers synapse in thalamus
Cranial Nerve I Olfactory Nerve (smell)
Cranial Nerve II Optic Nerve (vision)
Cranial Nerve III Oculomotor Nerve (motor nerve for eyes)
Cranial Nerve IV Trochlear Nerve (small cranial nerves for eyes)
Cranial Nerve V Trigeminal Nerve (mixed cranial nerve w/3 branches)
Cranial Nerve VI Abducens (motor impulses for eye movement)
Cranial Nerve VII Facial Nerve (mixed motor nerve to face expression, tears ect)
Cranial Nerve VIII Vestibulocochlear nerve (acoustic/auditory nerve)
Cranial Nerve IX Glossopharyngeal nerve (mixed nerve of tonsils, part of tongue, pharynx)
Cranial Nerve X Vagus Nerve (mixed ner
Cranial Nerve XI Accessory nerve
Cranial Nerve XII Hypoglossal nerve
Spinal Nerves are... All mixed nerves, except the first pair;Originate from spinal cord;31 pairs
31 pairs of spinal nerves: 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves , 5 sacral nerves, 1 coccygeal nerve (Co)
Cauda equina: Formed by descending roots of lumbar, sacral, and coccygeal nerves
Dorsal (posterior) root: Sensory root
Ventral (anterior) root: Motor root;Axons of motor neurons whose cell bodies are in the spinal cord
Dermatome: An area of skin innervated by the sensory nerve fibers of a particular spinal nerve
Spinal nerve: Union of ventral root and dorsal roots•Ventral + dorsal = “mixed” nerve
Branches of spinal nerves outside the spinal cord: Meningeal branch; Dorsal branch/ramus; Ventral branch/ramus; Visceral branch (only in thoracic and lumbar)
Nerve plexus: network formed by ventral rami of spinal nerves;Not in T2 -T12; instead, ventral rami become intercostal nerves;The fibers of various spinal nerves are sorted and recombined, so all fibers heading to same peripheral body part reach it in the same nerve
There are 3 nerve plexuses: Cervical, Brachial, Lumbosacral
Cervical plexus: Formed by ventral rami (branches) of C1-C4 spinal nerves;Lies deep in the neck;Supply muscles and skin of the neck;C3-C4-C5 nerve roots contribute to phrenic nerves, which transmit motor impulses to the diaphragm
Brachial plexus: Formed by ventral branches C5-T1;Lies deep within shoulders;There are 5 branches
Brachial plexus 5 branches: Musculocutaneous nerve, Ulnar nerve ,Median nerves, Radial nerve, Axillary nerve
Lumbosacral plexus: Formed by the anterior branches of L1-S4 roots;Extends from lumbar region into pelvic cavity;mObturator nerve, Femoral nerve, Sciatic nerve
Autonomic Nervous System (ANS) function: Part of the PNS; Functions without conscious effort;Controls visceral activities;Regulates smooth muscle, cardiac muscle, and glands;Helps maintain homeostasis;Helps body respond to stress;Prepares body for exercise, intense physical activity
Sensory (afferent) nerve fibers transmit signals from the viscera and skin to neural centers in CNS
Motor (efferent) impulses travel along 2 efferent nerve fibers which synapse in ganglia outside CNS
2 divisions of the autonomic nervous system: Sympathetic division, Parasympathetic division
Sympathetic division function: Prepares body for ‘fight or flight’ situations; speeds body up ;Most active under energy-requiring, stressful, emergency situations
Parasympathetic division function: Prepares body for ‘resting and digesting’ activities; slows body down;Most active under resting, non-stressful conditions
Autonomic Nerve Fibers All of the neurons are motor (efferent);Somatic motor pathways link CNS and a skeletal muscle fiber via 1 neuron;Autonomic motor pathways contain 2 neurons
Preganglionic fibers: Axons of preganglionic neurons; Neuron cell bodies are in CNS
Postganglionic fibers: Axons of postganglionic neurons; Neuron cell bodies in ganglia;Extend to visceral effector
Sympathetic Division: Thoracolumbar division;Preganglionic fibers originate in spinal cord, leave via ventral roots, leave spinal nerves through white rami &enter sympatheticchain (paravertebral) ganglia;
sympathetic trunks Sympathetic chain ganglia + fibers that connect them make up this
Parasympathetic division: Craniosacral division ;Preganglionic neurons originate in brainstem & S2–S4 spinal levels;Preganglionic fibers extend on cranial or sacral nerves to terminalganglia;Short postganglionic fibers continue to specific muscles or glands
Preganglionic fibers of the head included in oculomotor (III), facial (VII), and glossopharyngeal (IX) nerves
Preganglionic fibers of thorax and abdomen are parts of vagus (X) nerve, which contains ~75% of all parasympathetic fibers
Preganglionic fibers of sacral (S2 – S4) region of spinal cord carry impulses to pelvic viscera
Cholinergic neurons: Release acetylcholine;All preganglionic sympathetic and parasympathetic fibers;Postganglionic parasympathetic fibers
Adrenergic neurons: Release norepinephrine (noradrenaline);Most postganglionic sympathetic fibers
Control of Autonomic Activity Controlled largely by the hypothalamus;Control of the autonomic nervous system (ANS) is involuntary
Created by: Devtemrys