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Nervous System Arianna Reyes P.1 - Coggle Diagram
Nervous System Arianna Reyes P.1
Major Functions
The nervous system send messages and signal throughout the body that informs of external and internal stimuli. It also is the center of mental activity such as learning, emotion, thought, and memory. The nervous system also plays a part in regulating homeostasis
Overlapping Functions
Integration
: processing and interpret of sensory input
Motor output
: activation of effector organs, which results in response
Sensory input
: info gathered by receptors about external and internal changes
Major Divisions & Subdivisions
Central Nervous System
Integration and control center
Peripheral Nervous System
Nerves that extend from brain and spinal cord
2 Functional Divisions
Sensory (afferent) Division
Somatic Sensory Fibers
: convey impulses from skin, skeletal muscles, and joints to CNS
Visceral Sensory Fibers
: convey impulses from visceral organ to CNS
Motor (efferent division)
: transmits impulses from CNS to effector organs
Autonomic Nervous System
: regulates smooth muscle, cardiac muscle, and glands
Sympathetic
Parasympathetic
Somatic Nervous System
: SM fibers conduct impulse from CNS to skeletal muscle
Tissues (Structure & Function)
Neurons
: makes up the main parts of the nervous system
Neuroglia
: provides rich support system
Connective Tissue Coverings
Perineurium: coarse connective tissue bundles fibers into fascicles
Epineurium: Tough sheaths around all fascicles to form nerve
Endoneurium: loose connective tissue encloses axons and their myelin sheaths
Major Parts & Functions of the Brain
Regions of the Brain
Cerebral Hemispheres, Diencephalan, Brain Stem, and Cerebellum
Diencephalan is paired with 3 gray matter structures
Hypothalamus
: forms cap over brain stem
Epithalamus
: Dorsal portion of diencephalon
Thalamus
: relay station for information coming to cortex
Gyri
: Ridges
Sucli
: shallow grooves
Fissures
: deep grooves
5 Lobes of the Brain
Frontal, Parietal, Temporal, Occipital, Insula
Cerebral Cortex
Site of conscious, memory, and understanding
3 Functional Areas
: motor, sensory, association
Brain Stem
3 Regions: midbrain, pons, and medulla oblongata
Midbrain
: contains two ventral bulges that contain pyramidal motor tracts. It also contains superior colliculi which manages visual reflex centers, and inferior colliculi which maintain auditory relay centers
Pons
: 4th ventricle separates pons from cerebellum
Medulla Oblongata
: Contains choroid plexus, a capillary rich membrance that forms cerebral spinal fluid
Functions: Cardiovascular and respiratory centers, as well as regulating vomiting, hiccuping, swallowing, etc.
Functional Brain Systems
Limbic
: structures on medial aspect of cerebral hemisphere
Reticular Formation
: through central core of brain stem
Meninges: The Protector of the Brain
Arachnoid Mater
: spiderweb like extensions and second most layer
Pia Mater
: delicate tissue that clings to the brain and the inner most layer
Dura Mater
: Strongest meninx and the outer most layer
Major Parts & Functions of Spinal Cord
Spinal cord is enclosed in vertebral column which begins and formen magnum and ends at L1 or L2 vertebra
The spinal cord is a 2-way communication to and from the brain and body
Major reflex center
Epidural Space
: cushion of fat and network of veins between vertebrate and spinal dura mater
Denticulate ligaments
Cervical and lumbar enlargement where nerves arise from spinal cord
Cuada equina
Collection of nerve roots at inferior end of vertebral canal
Spinal Cord Cross Section
Resembles a butterfly or the letter "H"
Contains 3 areas of gray matter
Dorsal Horns
: receives sensory input
Ventral Horns
: some interneironsis; somatic neurons
Lateral Horns
: sympathetic neurons (only in thoracic and superior lumbar regions)
Ventral roots
: bundle of motor neuron axons exit spinal cord
Dorsal roots
: sensory input to cord
Dorsal root ganglia (spinal)
: cell bodies of sensory neurons
Gray Commissure
Bridge of gray matter connects gray matter on either side; encloses central canal
Action Potential & Nerve Impulse
Generating Action Potential (4 Main Steps)
Resting state: All gated Na+ and K+ channels are closed
Depolarization: Na channels open
Repolarization: Na+ channels inactivating and K+ channels open (returns to resting)
Hyperpolarization: Some K+ channels remain open and Na+ channels reset
Refractory Periods
Time in which neuron cannot trigger another AP
Threshold and the All-Or-None Phenomenon
Depolarization must reach the threshold voltage to trigger AP
All-Or-None: AP either happens completely or not at all
Conduction Velocity
Continous Conduction: slow conduction occurs in nonmyelinated axons
Saltatory conduction: only in myelinated axons and 30x faster
Cranial Nerves
12 Pairs of Cranial Nerves
VII - Facial nerves
: fibers from pons travels through internal acoustic meatuses and emerge through stylomastoid foramina to lateral of face
VIII - Vestibulocochlear nerves
: afferent fibers from hearing receptors and equilibrium receptors pass from inner ear through internal acoustic and enter midbrain stem at pons- medulla border
VI - Abducens nerves
: fibers from inferior pons enters via superior orbital fissures
IX - Glossopharyngeal nerves
: fibers from medulla leave skull via jugular foramen and run to throat
V - Trigeminal nerves
: fibers from pons to face
X - Vagus nerves
: fibers from medulla exit skull via jugular foramen
XI - Acessory nerves
: rootlets pass into cranium via jugular foramen to innervate trapezius ans sternomastoid muscles
IV - Trochlear nerves
: fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate superior oblique muscle
III - Oculomotor nerves
: fibers from ventral midbrain through superior orbital fissures to 4 of 6 eye muscles
II - Optic nerves
: arise from retinas; brain tract
I - Olfactory nerves
: sensory nerves of smell
XII - Hypoglossal nerves
: fibers from medulla exit skull via hypoglossal canal
Spinal Nerves
31 Pairs of Spinal Nerves
12 thoracic nerves (T1-T12)
5 lumbar nerves (L1-L5)
8 cervical nerves (C1-C8)
5 sacral nerves (S1-S5)
1 coccygeal nerve (C0)
Each spinal nerve connected via two roots: dorsal and ventral
Neurotransmitters
Peptides (Neuropeptides)
Strings of amino acids that have diverse functions
Purines
Monomers of nucleic acids that effect both CNS and PNS
Amino acids
Make up all proteins
Gases and Lipids
Biogenic amines
Catecholamines
Dopamine, norepinphrine, and epinephrine made from the amino acid tyrosin
Indolamines
Histamine: made from histidine
Seratonin: made from tryptophan
Endocannabinoids
Act at same receptors as THC
Acetycholine (ACh)
Released at neuromuscular junction and degraded by enzyme acetcholinesterase (AChE)
Compare and Contrast of Autonomic nervous system
Compare: higher brain centers regulate both systems
Contrast: doesn't contain every neuron usually found in the nervous system
Reflex Arc
Components
Integration center
: monosynaptic or polysynaptic region within CNS
Motor neuron
: efferent impulses from integratoin center to effector organ
Sensory neuron
: transmits afferent impulses to CNS
Effector
: muscle fiber organ gland cell responds to efferent impulses by contracting or secreting
Receptor
: site of stimulus action
Classified as:
-Somatic
-Autonomic
The process in which a part of the body can react to stimulus
Disorders Associated with Nervous System
Anencephaly
Parts of brain stem never develop because neural fold fails to fuse
Spina bifida
Incomplete formation of vertebral arches; involves lumbosacral region
Cerebral Palsy
Poorly controlled or paralyzed voluntary muscles
Multiple Sclerosis
Autoimmune disease that affects primarily young adults which destroys myelin sheaths in CNS
Hypertension
High blood pressure
Autonomic neuropathy
Damage to autonomic nerves that is common complication if diabetes mellitus
Raynaud's Disease
Exaggerated vasoconstriction in fingers and toes
Autonomic Dysreflexia
Uncontrolled activation of autonomic neurons in quadriplegics
Drugs of Abuse
Ecstasy
Responsible for changing mood, sleep, perception, and appetite. It stimulates mild dopamine and creates a slight addictive property
Marijuana
Causes short term memory, slowed movement, and good feelings of being calm and relaxed
Heroine
The user is sent in immediate sedation and well being
Methamphetamine
The user feels intense pleasure and exhilaration. It is highly addictive because it works directly on the reward system
Alcohol
Affects decision making and impulse control
Cocaine
Causes fidgety behavior and focuses on the reward pathway, making it addictive
LSD
Causes wakefulness and startled responses to unexpected stimulus
Nicotine
AKA:
Cigarettes, E-Cigarettes, Cigars, Snuff, Pipe, Nicotine gum, and Patches
Increases nerve activity and heart rate. Withdrawal symptoms include: cravings, difficulty concentrating, irritability, and sleep disturbances
MDMA
Causes increase in energy or distortion in perception. It also causes feelings of euphoria, but also causes involuntary jaw clenching, muscle cramping, chills and sweating.
AKA:
Methylenedioxymethamphetomine, or Ecstasy
Inhalents
Can impair coordination, speech, and judgement. They can also cause hallucinations, confusion, seizures, brain damage, or sudden death
AKA:
Solvents, Aerosol Sprays, and Gases
Psychedelics
AKA:
LSD, Peyote Cactus, and Psilocybin Mushrooms
Causes hallucinations and spontaneous emotions as well as increase in body temperature, heart rate, blood pressure, loss of appetite, nausea, paranoia, panic, and sleeplessness
Opioids
AKA:
Morphine, Codeine, Hydrocodone, Fentanyl and Carfentanyl
Causes feelings of clouded thinking and drowsiness; high doses can lead to death
Dissociative Drug
AKA:
Ketamine, PCP, and Dextromethorphan
Causes distortions in perception and feelings of detachment from the body and its surroundings. It may also causes unpredictable behavior and in high doses can lead to coma, fever, or death
Classification of Neurons
Structural Classification
Bipolar
: 2 processes
Unipolar
: 1 T-like process
Multipolar
: 3 or more processes
Functional Classification
Motor
: carry to CNS effectors
Interneurons
: between motor and sensory neurons
Sensory
: transmit from sensory receptors to CNS