Nervous System
Maria Chuc Garcia
P.1
Major Function Of N.S
Major Division and Subdivisions of N.S
Tissues (Structure & Function
of neurons & neuroglia)
Action Potential &
Nerve Impulses
Major parts and functions
of the brain
Major Parts and Functions of the Spinal Cord
Classification of neurons
Connective Tissue Coverings
Cranial Nerves
Spinal Nerves
Neurotransmitters
Compare and Contrast
the Autonomic System
Reflex Arcs( Major Functions and Parts)
Disorders associated with N.S
Drugs (Drugs of Abuse & Mouse Party)
Neurons
- Large, highly specialized cells, conduct impulses
All have a CELL BODY and one or more processes - Extreme longevity( forever), and HIGH metabolic rate; needs A LOT of oxygen
- 8 pairs of Cervical Nerves (C1- C8)
- 12 pairs of throcic nerves( T1- T12)
- 5 pairs of lumbaral( L1- L5)
- 5 pairs of sacral nerves ( S1-S5
- 1 pair of tiny coccygcal nerves (C0)
Spinal Cord Function
- Encloses in vertebral column
- 2-way communication to & from brain/body
- MAJOR reflex center; initiated and completed
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- Action Potential(APs) don't DECAY over distance as graded potential
- ONLY happens in muscle cells and axon neurons
- In NEURONS, aka NERVE IMPULSES
Meninges
- 3 layers of it to protect the brain
- Dura mater - Strongest meninx
- Arachnoid- Middle layer with spider web-like
sepratedfrom dura mater by subdural space - Pia Mater- Delicate C.T thatis stuck together
- many tiny blood vessels
1. Olfactory: Sensory nerves of smell
- Optic; Arise from retinas, really a brain tract, through optic chaisma
3. Oculomotor; Fibers extend from ventral midbrain through superior ociptal fissure. - Trachlear; Fibers from dorsal midbrain enter orbits via superior.
- Trigeminal: Largest cranial nerve, fibers extend from pons to face
6. Abudcens; Fibers from inferior pons or bits via superior orbital tissues
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Automatic System
- Consist of MOTOR Neurons
- Smooth muscle, cardiac, and glands
- Makes adjustments for optimal support for activities
- Ex; adjust heart rate, blood pressure, blood to areas, etc
Called Involuntary N.S & or general visceral motor system
- Sensory
- Transmit impulses from sensory receptors toward CNS
- Almost unipolar
- Cells bodies located in ganglia in PNS
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Components & functions :
1. Receptor: Site of the stimulus action
2. Sensory Neuron: Transmit afferent impulses to CNS
3. Integration Center: Mono-synaptic or postsynaptic region within CNS
4. Motor Neuron: Conducts efferent impulses from integration center to effector organ
5. Effector: Muscle fiber/gland cell responds to EFFECTOR impulses causing CONTRACTING or SECRETING
- Cerebral Hemispheres: Form superior part of the brain, consist of gyri, sulci, & fissures
- Diennephalon; 3 pair gray-matter structures Thalamus, hypothalamus, and epithalamus. All 3 enclose 3rd ventricle,
- Language of N.S
- 50+ have been identified
- Most neurons make 2+ neurotransmitters
- Classified by; Chemical Structure & Function
Meningitis
Cerebrovascular Accidents
Parkinson Disease
Traumatic Brian Injuries
Alzheimer Disease (AD)
- Dementia
- Memory loss, confusion, short attention span
- Neurofibrillary tangle with the neurons causing them to kill it
- Neurons dying, brain shrinks.
- Degeneration of Dopamine
- Lack of dopamine cause the basal nuclei to overattentive leading to tremors
- Mitochondrial abnormalities and degeneration pathways
- Inflammation of the meninges
- Spread to CNS, causing inflammation of brain called ENCEPHALITIS
- Strokes
- Tissue with not blood supply leading to death of brain tissue
Cause; blockage of cerebral artery - Hemipleyia ( Paralysis of one side or speech/ sensory deficits
Marijuana
Methamphetamine
Ecstasy(MDMA)
Alcohol
Heroine(Opioids)
LSD(Psychedelics)
Cocaine
Inhalants
Nicotine(tobacco)
GHB & Rohypnol
Dissociative Drug
- Hallucinogen( Cause Hallucinations)
- Seizures, death, & panic attacks
- Swallowing, snorting, injections, & smoking
- Sedative
- Memory loss, unconscious, overdose, & death
- Concussion: temporary alteration to function
- Contusion: Permanent damage
- Subdural & Subarachnoid Hemorrhage:
Pressure from blood, forcing brain stem through foreman magnum= DEATH
- Cigarettes & e-cigarettes( stimulant in tobacco plants
- Can cause cancer, lung disease, stroke & heart disease
- Dopamine Neurotransmitter
- Fidget & can'y stay still
- Inhibitory Neurotransmitters & Dopamine Neurotransmitters
- Pain relief, sedation
- Cause pin-point pupils, nausea, a rush of warmth pleasure
- Pill, patches, injecting, snorting, & smoking
- For increase of energy, feeling "fuel"
- Stimulant and hallucinogen
- Cause panic attacks and seizures
- Swallowing & snorting
- Inhibitory Neurotransmitter & Dopamine transmitter
- Makes people fell relax, slow & calm
- Dopamine Neurotransmitters
- Intense pleasure and exhilaration
- GABA Inhibitory Neurotransmitters & Glutamate Neurotransmitter
- Affects areas of the brain especially memory. Decision making & impulse control
- Serotonin Neurotransmitter
- Hallucinogens
- Mood swings, increasing heart rate, & panic
- Swallowing , snorting, injecting, or smoking
- Solvents, toxic chemicals, can also be household items
- Impair condition, speech, and judgement
- Affects brain, cause hallucination, confusion, and brain damage
Generating an Action Potential
1. Resting state: All gated Na+ & K+ channels are closed
2. Depolarization: Na+ channels open
3. Repolarization: Na+ channels are inactivating, K+ channels open
4. Hyperpolarization: Some K+ channels remain open, & K+ channels RESET
Propagation of an Action Potential
- Allows AP to transmit from origin down entire axon length toward terminals
- Once initiated, AP is self-propagating
- Na+ channels closer to AP origin are inactivate, NO new AP generated
Threshold & the ALL-or-NONE phenomenon
- NOT all depolarization events produce APs
- For axon to "fire", depolarization must reach threshold voltage to trigger AP
-ALL OR NONE= AP happens completely or doesn't happen
ANS vs. Somatic N.S
- Efffectors
ANS- Cardiac muscle, smooth, gland
SNS- Skeletal Muscle
- Efferent Pathways and Ganglia
SNS- Single, thick myelinated group, axon extend in spinal/cranial nerves directly yo SKELETAL muscle
ANS- pathways uses two-neuron chain;
- preganglionic Neuron- Cell body in CNS, light myelinated, preganglionic axon extended to ganglion
- Postganglionic Neuron- cell body synapse with preganglionic axon in autonomic ganglion with nonmyelinated postganglionic axon
- There are 31 pairs of spinal nerves
- All are mixed nerves named from pint of issue to spinal cord
- Supply all EXCEPT head and part of neck
- Every spinal nerve connected to spinal cord VIA 2 roots
Ventral Roots
Dorsal Roots - Ventral and dorsal branched ROOTLESS
- Acetylcholine(ACh), First identified and best understood, released at neuromuscualr junction
- Biogenic Amines
- Catecholamines: Dopamine, norepinephrine (NE), & epinephrine
- Indolamine: serotonin, made from amino acid
Histamine: made from histidine
- Amino Acids: Make up all proteins; difficult to prove which ones's are neurotransmitters.
- Purines; Monomers of nucleic acids that have effect in CONS and PNS
- Facial: Fibers from pons travele through internal acustic and enlarge
8. Vestibulocochlear: Afferent Fibers from hearing receptors. Mostly sensory function, small motor component - Glossopharyngal: Fibers from medulla have skull viajuglar. Motor function; inneravate part of tongue.
- Vagus: Only cranial nerves that extend beyond head and neck region.
- Accessory Nerves: Formed from ventral rootless. Rootlkess pass into cranion to each foreman magnum
12. Hyoglossal: Fibers from medulla exit still via hypeglossal canal
- Protected by bone, meninga s , CSF
-Epidural Space; Fat & network of veins in between vertebrae and & spinal dura mater - Spinal C. terminates in cone-shaped structure ( conus medullaris)
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- Brain Stem( Midbrain, Pons, Medulla); Control automotic behaviors for survival. Has white nuclei in white matter
- Cerebellum- Imput from c0rtex, brain stem, and sensory receptors provide coordinated mov. of skeletal muscle. THINKING, LANGAUGE, & EMOTION. Balance and COORDINATION
Central Nervous System( CNS)
- Brain and spinal cord of dorsal cavity
- Integration & control center; Intercept sensory input and dictate motor output
- the spinal cord, the medulla, the pons, the cerebellum, the midbrain, the diencephalon, and the cerebral hemispheres
Peripheral N.S( PNS)
- Portion of N.S outside CNS
- Nerves that extend from brain & spinal Cord
2 Functional Division - Somatic (afferent) division; Convey impulses from skin
- Motor( efferent) division; convey impulses from visceral organs to CNS
- Somatic .>S (voluntary)
- Autonomic N.S (involuntary)
- Motor
- Carry Impulses from CNS to effectors
-Multipolar - Cell bodies located in CNS( expect some autonomic neurons)
- Interneurons
-Called Association Neurons
- Life between motor and sensory neurons
- Shuttle signals through CNS pathways
Neuroglia
- 4 main support CNS Neurons
- Astrocytes, microglial cells, ependymal ells, and oligodendrocytes
- Satellite cells surround neuron cell bodies