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Audrina Hernandez Period 3 Nervous System - Coggle Diagram
Audrina Hernandez
Period 3
Nervous System
Major Functions of The Nervous System
Integration
Processing the information of sensory input
Motor output
Activation of effector organs producing a response
Sensory Input
Information gathered by sensory receptors
Major Divisions/Subdivisions
CNS
Brian & Spinal Cord
PNS - cranial & spinal nerves
Motor (efferent) division - motor nerve fibers; conducts impulses from CNS to effectors (muscles/glands)
Somatic nervous system - somatic voluntary motor nerve fibers; conducts impulses from CNS to skeletal muscles
Autonomic nervous system (ANS) - visceral involuntary motor nerve fibers; conducts impulses from CNS to cardiac muscle, smooth muscle, and glands
Sympathetic division - mobilizes body systems during activity
Parasympathetic division - conserves energy; promotes house-keeping functions during rest
Sensory (afferent) division - somatic & visceral sensory\; donducts impulses from receptors to CNS
Tissues
Neurons - transmit electrical signals
CNS
Nuclei - Clusters of neuron cell bodies
Tracts - Bundles of neuron processes
Myelin Sheaths - formed by Schwann cells; wraps around axon; one cell is one segment of sheath; gaps in between are called Nodes of Ranvier; nonmyelinated sheaths can wrap around multiple fibers
PNS
Ganglia - Clusters of neuron call bodies
Nerves - Bundles of neuron processes
Myelin Sheaths - formed by oligodendrocytes; can wrap around up to 60 at once; involves white matter and grey matter
Dendrites (both PNS & CNS) - motor neurons; branched processes; convey message towards cell body as graded potentials (short distance signals); receptive region of neuron
Neuroglia - surround and wrap delicate neurons
CNS
Astrocytes - most abundant; support and brace neurons; guide migration of young neurons; involved in brain processing information; respond to nerve impulses/neurotransmitters
Microglial Cells - small, go toward hurt neurons
Ependymal Cells - line central cavities of brain/spinal column; form a permeable barrier between CSF in cavities/tissue
Obligodendrocytes - branched cells; processes wrap CNS nerve fibers
PNS
Satellite Cells - surround neuron call bodies in PNS; function similar to astrocytes in CNS
Schwann Cells (neurolemmocytes) - surround all PNS fibers; similar function to oblogodendrocytes; vital to regeneration PNS
Reflex Arc
Sensory neuron - transmits afferent impulses to CNS
Integration center - monosynaptic or polysynaptic region within CNS
Receptor - Site of stimulus action
Motor neuron - conducts efferent impulses from integration center to effector organ
Effector - muscle fiber/gland cell responding to efferent impulses by contracting or secreting
Somatic reflexes - Activate skeletal muscle
Autonomic (visceral) reflexes - activate visceral effectors (smooth or cardiac muscle or glands)
Drugs of Abuse
Methamphetamine - Interferes with dopamine, goes into dopamine vesicles and forces them out, going into synapse; an addictive drug, feelings of intense pleasure/exhilaration
Cocaine - Interferes with dopamine; blocks dopamine transporters and binds to receptor multiple times; overstimulates cell
Marijuana - Interferes with inhibitory neurotransmitters; turn off inhibitory transmitters and dopamine is released into synapse; slows down movements and makes people feel calm/relaxed
Alcohol - Interferes with GABA inhibitory neurotransmitters; makes GABA receptors more inhibitory, prevents glutamate from exciting cell; affects memory formation, decision making, & impulse control
Ecstasy - Interferes with serotonin neurotransmitters; makes serotonin go out of cell instead of in cell, affects persons mood, sleep, & appetite
LSD - interferes with serotonin receptors; may inhibit or excite receptors; feelings of wakefulness & evokes startle response
Heroine - Interferes with inhibitory neurotransmitters; causes dopamine to flood synapse (causes "high" feeling); affect persons stress response, pan signals, & emotional attachment
Disorders/Diseases
Alzheimer's - degeneration of brain leading to dementia; results in memory loss, short attention span, disorientation, eventual language loss, confusion, hallucinations, etc.
Parkinson's Disease - the degeneration of dopamine releasing neurons of the substantia nigra; causes tremors
Huntington's Disease - fatal disorder cause by an accumulation of the protein huntingtin in brain cells; degeneration of the basal nuclei and cerebral cortex, causes wild, jerky "flapping" movements
Cerebrovascular Accidents/Strokes - occurs when brain tissue is deprived of blood supply; can cause sensory and speech deficits
Meningitis - Inflammation of meninges, may lead to inflammation of the brain (encephalitis)
Hydrocsephalus - obstruction blocks the circulation of CSF, increasing pressure, in adults nervous tissue is crushes; newborns heads enlarge because of unfused skull bones
Cerebral Palsy - neuromuscular disability; poorly controlled voluntary muscles; results from brain damage or lack of oxygen during birth; Symptoms: spasms, speech difficulties, motor impairments; some patients have seizures, deafness and visual impairment
MS - autoimmune disease; immune system destroys myelin sheaths in CNS; hardened lesions (sclerosis) slows down and stops impulse conduction; Symptoms: weakness, moss of muscular control, speech disturbances, visual interference
Autonomic Dysreflexia - uncontrolled activation of autonomic neurons; in people with spinal injuries above T6
Raynaud's Disease - exaggerated vasoconstriction in fingers and toes; turns pale then cyanotic
Autonomic Neuropathy - damage to autonomic nerves; Symptoms: dizziness, impaired sweating, urinary incontinence
Cranial Nerves (12)
Abducens Nerves - motor; innervates lateral rectus muscle
Facial Nerves - Chief motor nerves of face
Trigeminal Nerves - largest cranial nerve; sensory impulses from face; motor fibers for mastication
Vestibulocochlear Nerves - mostly sensory; afferent fibers for hearing and equilibrum
Trochlear Nerves - primarily motor; directs eyeball
Glossopharyngeal Nerves - motor for swallowing; postsympathetic to salivary glands; sensory for taste
Oculomotor Nerves - motor; raise eyelids, directs eyeball; constricts iris, controls lens shape
Vagus Nerves - Only cranial nerve extending beyond head/neck
Optic Nerves - vision
Accessory Nerves - motor; innervates trapezius & sternocleidomastoid muscles
Olfactory Nerves - purely sensory; sense of smell
Hypoglossal Nerves - Motor; innervates exrinsic and intrinsic muscles of tongue; contributes to speech/swallowing
Spinal Nerves (31)
5 pairs of sacral nerves - (S1-S5)
1 pair of tiny coccygeal nerve (C0)
5 Pairs of lumbar nerves (L1-L5)
Each spinal nerve is connected to spinal cord
Ventral root - contain motor fibers
Dorsal root - contain sensory fibers
12 pairs of thoracic nerves (T2-T12)
8 pairs of cervical nerves (C1-C8)
Compare and Contrast The Autonomic Nervous System
Sympathetic Division
"fight or flight"
uses short preganglionic fibers & long postganglionic fibers
release Norepinephrine (NE)
Parasympathetic Division
"rest & digest"
uses long preganglionic fibers & short postganglionic fibers
release Acetylcholine (ACh)
Connective Tissue Coverings
Endoneurium: loose connective tissue;encloses each individual axon & myelin sheath
Perineurium: coarse connective tissue; groups fibers into bundles (fascicles)
Epineurium: tough fibrous sheath; wraps around fascicles
Dura mater: the strongest outer layer
Arachnoid mater: the middle layer; spiderweb-like extentions
Pia mater:the delicate innermost layer; clings tightly to brain
Classifications of Neurons
Structural
Bipolar - 2 processes (1 axon, 1 dendrite); rare
Unipolar - 1 T-like process (2 axons); also called pseudounipolar
Multipolar - 3 or more processes (1 axon, others dendrites); most common and major type in CNS
Functional
Sensory - transmit impulses from sensory toward CNS; almost all are unipolar
Motor - carry impulses from CNS to effectors; multipolar
Interneurons - also calles association neurons; in between sensort and motor neurons; shuttle signals through CNS pathways; most are in CNS; 99% of bodies neurons
Parts of Brain
Diencephalon - include thalamus, hypothalamus, and epithalamus
Brain stem - Midbrain, Pons, and medulla oblongata; controls automatic behaviors necessary for survival
Cerebral Hemispheres (Cerebrum):site of the conscious mind, awareness, communication, memory storage, and understanding
Cerebellum - 11% of brain mass; processes input from the cerebral cortex, brain stem, and sensory receptors