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Nervous System- Brianna Mayorga p.6 - Coggle Diagram
Nervous System- Brianna Mayorga p.6
Major Functions of the NS
1. Sensory Input
- information gathered by sensory receptors about internal and external changes
2. Integration
- processing and interpretation of sensory input
3. Motor Output
- activation of effector organs (muscle & glands) produces a response
Major Divisions & Subdivisions of NS
Peripheral Nervous System
: contains brain and spinal cord of dorsal body cavity
Sensory ( afferent)
conducts impulses from receptors to the CNS
Motor ( efferent)
transmits impulses from the CNS to effector organs
Somatic Nervous System
: mobilize body systems during activity; voluntary
Automonic System
: regulates smooth muscles, cardiac, and glands; involuntary
Parasympathetic
: conserves energy
Sympathetic
: mobilizes body during activities
Central Nervous System
: nervous system outside of CNS consisting of mainly spinal & cranial nerves
Limbic System
Reticular Formation
Connective Tissue Coverings
Meninges
Dura Mater
: strongest and most durable; creamy/milky appearance; top layer
Pia Mater
: thin/transparent; deepest layer; delicate connective tissue
Arachnoid
: spiderweb-like meninge; in between pia & dura
Nerve Wrappings
Epineurium
: tough fibrous sheath
Perineurium
: connective tissue that bundles fibers
Endoneouronium
: loose connective tissue which encloses axons
Classification of neurons
Structural classification
: 3 types
1. Multipolar
: 3 or more processes ( 1 axon, others dendrites); most common & major neuron type in CNS
2. Bipolar
: 2 processes ( 1 axon, 1 dendrite); rare
3. Unipolar
: 1 T-like process ( 2 axons); known as pseudounipolar
Functional classification
: 3 types
1. Sensory
: transmits impulses to sensory receptors; almost all unipolar;
2. Motor
: carries impulses from CNS to effectors; multipolar
3. Interneurons
: associative neurons; between sensory & motor neurons; 99% of body's neurons
Tissues
Nervous tissue consists of 2 principal cell types
Neuroglia ( glial cells)
small cells that surround and wrap delicate neurons
4 Main Neuroglia that supports the CNS
1. Astrocytes
: most abundant and highly branched; support & brace neurons
2. Microglial
: small, ovid cells; migrate toward injured neurons
3. Ependymal cells
: squamous to columnar & may be ciliated; lines central cavities of brain and spinal column
4. Oligodendrocytes
: branched cells; processes wrap CNS nerve fibers
Neuroglia of the PNS
Satellite cells
: surround neuron cell bodies in pns
Schwann cells
: surrounds all peripheral nerve fibers
Neurons ( nerve cells)
: excitable cells that transmit electrical signals
Extreme longevity, high metabolic rates which requires high and continuous supply of oxygen and glucose
Neuron Cell Body
: biosynthetic center of the neuron, contains nucleus ( synthesizes proteins & chemicals); most neuron cell bodies are located in CNS
Neuron Processes
: In CNS it contains both neuron cell bodies & their processes, in PNS it contains chiefly neuron processes;
tracts
( bundles of neuron processes),
nerves
( bundles of neuron processes in CNS)
Major parts & functions of brain
Fissures/Sulci
Longitudinal fissure, transverse fissure, central sulcus, & lateral sulcus
Cerebellum
Cerebrum
Frontal(logic,understanding), parietal(sensory), occipital(visual), temporal(auditory) lobe
Brainstem
Midbrain, pons, medulla oblangata
Diencephalon
Thalamus, hypothalamus, & epithalamus (coordination)
Ventricles
Lateral, third, & fourth ventricle
Major parts & functions of spinal cord
Central canal
runs length of cord; filled with CSF
Grey matter & spinal roots
Dorsal horns
receive somatic and visceral sensory input
Ventral horns
: somatic motor neurons
Lateral horns
: sympathetic neurons
Gray commissure
: bridge of gray matter
Ventral roots, dorsal roots, dorsal roots (ganglia), spinal nerves
White matter
is divided into 3 white columns
Dorsal, lateral, ventral
Action Potential & Nerve impulse
Principal way neurons send signals; occurs only in muscle cells; do not decay over distance as graded potentials do;
in neurons AKA NERVE IMPULSE
1. Resting state
: all gated Na+ & K+ channels are closed; maintains the resting membrane potential
2. Depolarization
: Na+ channels open; results in large action potential spike & membrane polarity jumps to +30 mV
3. Repolarization
: Na+ channels are inactivating, & K+ channels open up; membrane returns to resting membran potential
4. Hyperpolarization
: some K+ channels remain open, & Na+ channels reset
Cranial Nerves
12 pairs of cranial nerves associated with brain
Olfactory nerves
: sensoryy nerves of smell; olfactory function
Optic nerves
: arise from retinas; a brain tract; purely sensory (visual) function
Oculomotor nerves
: eye muscles; functions in raising eyelid, directing eyeball, etc..
Trochlear nerves
: directs eyeball
Trigeminal nerves
: largest cranial nerves; pons to face; for mastication
Abducens nerves
: fibers from inferior pons; primarily a motor, innervating lateral rectus muscle
Facial nerves
: motor functions include facial expression; sensory function (taste) 2/3 of tongue
Vestibulocochlear nerves
: small motor component; mostly sensory function; formerly auditory nerve
Glossopharyngeal nerves
: fibers from medulla; innervates part of tongue for swallowing
Vagus nerves
: only cranial nerves that extend beyond head & neck region; sensory fibers carry impulses from thoracic & abdominal viscera
Accessory nerves
: formed from ventral rootlets from C1 to C5; formerly spinal accessory nerve
Hypoglossal nerves
: fibers from medulla exit skull via hypoglossal canal; muscles of tongue that contribute to swallowing & speech
Spinal Nerves
31 pairs of spinal cord; supply all body parts except head & part of neck; each spinal nerve is connected to spinal cord via 2 roots
dorsal
and
ventral
roots
Ventral roots
contain motor (efferent) fibers from ventral horn motor neurons
Dorsal roots
contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia
Neurotransmitters
Major neurotransmitters of ANS are acetylcholine (ACh) & norepinephrine (NE)
Cholineric receptors
: 2 types of receptors bind to ACh
Nicotine & Muscarinic receptors
Adrenergic receptors
: 2 types that respond to NE
Alpha & Beta receptors
Compare & Contrast the ANS
Autonomic Nervous System
Both are regulated by the higher brain which regulates and coordinates both of them; most spinal & cranial nervous contain somatic & autonomic fibers
Keeps body energy low as possible; mobilizes body during activity; innervates smooth muscles, cardiac muscles, & glands;
Somatic Nervous System
Controls body movements via skeletal muscles; innervates skeletal muscles; somatic motor neurons realease ACh
Reflex Arc
(neural path)
1.Receptor
: site of stimulation action
2. Sensory Neuron
: transmits afferent impulses to CNS
3. Integration Center
: either monosynaptic or polysynaptic region within CNS
4. Motor Neuron
: conducts efferent impulses from integration center to effector organ
5. Effector
: muscle fiber or gland cell that responds to efferent impulses by contracting or secreting
Drugs
Heroine/Opioids
: interferes w/ inhibitory & dopamine neurotransmitters; causes a feeling of sedation & well-being
Ecstasy/MDMA/Methamphetamine
: interferes with serotonin neurotransmitters; affects sleep, perception, & appetite
Marijuana
: interferes w/ inhibitory & dopamine neurotransmitters; produces slower movements & feeling of relaxation
Alcohol
: interferes w/ GABA & glutamate neurotransmitters; affects decision-making & impulse control
Cocaine
: interferes with dopamine neurotransmitter; affects part of the brain in charge of controlling voluntary movement
LSD/Psychedelics
: interferes w/ serotonin neurotransmitters; causes excitement & hallucinations
Inhalents
: stimulant; common household objects consumed as drugs which cause hallucinations, confusions, & seizures
Nicotine/Cigarettes
: consists dangerous & harmful substances to nerves & heart; causes cancer, heart diseases, & chronic lung diseases
GHB & Rohypnol
: chemically made & similar to anti-panic attack medications; causes hallucinations, coma, & slow breathing
Dissociative drug
: anesthetic used on humans & animals; causes violent behavior, seizures, & coma
Disorders associated with Nervous System
Paralysis
occurs on the opposite side of the damage
Hypothalamic disturbances
can cause disorders like : obesity, dehydration, emotional imbalances, & sleep disturbances
Epileptic seizure
are torrents of electrical discharges by group of neurons
Meningitis
is inflammation in the meninges
Hydrocephalus
is the obstruction which blocks CSF circulation or drainage
Cerebral palsy
is a neuromuscular disability involving poorly controlled or paralyzed voluntary muscles
Spina bifida
is the incomplete formation of vertebral arches (typically involves lumbosacral region)
Phantom limb pain
is pain felt in limb that has been amputated
Autonomic neuropathy
: damage to autonomic nerves that is a common complication of diabetes mellitus
Hypertension
(high blood pressure)
Raynaud's disease
: treated w/ vasolidatos; exaggerated vasoconstriction
Autonomic dysreflexia
: blood pressure skyrockets, high risk of stroke