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Leidy Esquivel Per:2 Nervous System - Coggle Diagram
Leidy Esquivel Per:2 Nervous System
Major functions of the nervous system
Sensory input- information gathered by sensory receptors about internal and external changes
Integration- Processing and interpretation of sensory input
Motor output- Activation of effector organs produces a respond
Major divisions and subdivisions
Divisions
Somatic Nervous system (voluntary)
Conscious control of skeletal muscles
Somatic motor nerves conduct impulses from CNS to skeletal msucle
Autonomic Nervous system (involuntary)
Regulates smooth muscle, cardiac muscles, and glands
Consists of visceral motor fibers
Subdivisions
Peripheral Nervous system (PNS)
Consists mainly of nerves that extend from brain and spinal cord
Portion of nervous system outside CNS
Sensory (afferent) - convey impulses from skin, skeletal muscles, and joints
to CNS
Motor (efferent) - Transmits impulses from CNS to effector organs
Central Nervous system(CNS)
Integration and control center: Interprets sensory input and dictates motor output
Brain and spinal cord of dorsal body cavity
Tissues
Neuroglia (glia cells)
small cells that surround and wrap delicate neurons
PNS
Satellite cells
Surround neuron cell bodies in PNS
Function similar to astrocytes of CNS
Schwann cells
Vital to regeneration of damaged peripheral nerve fibers
Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve
fibers
CNS
Microglial cells
Migrate toward injured neurons
Can transform to phagocytize microorganisms and neuronal debris
Small, ovoid cells with thorny processes that touch and monitor neurons
Ependymal Cells
Line the central cavities of the brain and spinal column
Form permeable barrier between cerebrospinal fluid in cavities and tissue
fluid bathing CNS cells
Range in shape from squamous to columnar
Astrocytes
Most abundant, versatile, and highly branched of glial cells
Cling to neurons, synaptic endings, and capillaries
Support and brace neurons, Respond to nerve impulses and neurotransmitters ect.
Oligodendrocytes
Branched cells
Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker
nerve fibers
Neurons (nerve cells)
excitable cells that transmit electrical signals
Structural units of nervous system
Extreme longevity
Amitotic, with few exceptions
High metabolic rate: requires continuous supply of oxygen and glucose
Nuclei: clusters of neuron cell bodies in CNS
Ganglia: clusters of neuron cell bodies in PNS
Classification of neurons
Functional classification of neurons
Motor
Carry impulses from CNS to effectors
Multipolar
Most cell bodies are located in CNS
Interneurons
Lie between motor and sensory neurons
Shuttle signals through CNS pathways
Most are entirely within CNS
99% of body’s neurons are interneurons
Sensory
Almost all are unipolar
Cell bodies are located in ganglia in PNS
Transmit impulses from sensory receptors toward CNS
Structural classification
Bipolar
Rare
Two processes
Unipolar
One T-like process
Also called pseudounipolar
Multipolar
Three or more processes
Most common and major neuron type in CNS
Connective Tissue Coverings
Perineurium
Coarse CT that bundles fibers into fascicles
Epineurium
Tough fibrous sheath around all fascicles to form the nerve
Endoneurium
Loose CT that encloses axons & their myelin sheaths (Schwann cells)
Major parts and functions of the brain
Cerebral hemispheres (cerebrum)
maintains your balance, posture, coordination and fine motor skills
Brainstem
Pons
Located between midbrain and medulla onblongata
Medulla onblongata
Blends into spinal cord at foramen magnum
Midbrain
located between diencephalon and pons
Diencephalon
Hypothalamus
Forms cap over brain stem and forms inferolateral walls of third ventricle
Epithalamus
Forms roof of third ventricle
Thalamus
Main thalamic function is to act as relay station for information coming to cortex
Cerebellum
Interprets sights, sounds and touches. It also regulates emotions, reasoning and learning
Major parts and functions of the spinal cord
Epidural space
Cushion of fat and network of veins in space between vertebrae and spinal dura
mater
Denticulate ligaments
Extensions of pia mater that secure cord to dura mater
Filum terminale
Fibrous extension of conus covered with pia mater
Anchors spinal cord
Spinal nerves
Part of PNS
Each spinal cord segment is designated by paired spinal nerves that arise from it
Attach to spinal cord by 31 paired roots
Cauda equina
Collection of nerve roots at inferior end of vertebral
Action potential & the Nerve Impulse
Depolarization
Na+channels open
Depolarizing local currents open voltage-gated Na+channels, and Na+rushes
into cell
Na+influx causes more depolarization, which opens more Na+channels
Repolarization
Na+channel inactivation gates close
Membrane permeability to Na+declines to resting state
Na+ channels are inactivating, and K+ channels open
Resting state
All gated Na+ and K+ channels are closed
Only leakage channels for Na+and K+are open
Maintains the resting membrane potential
Hyperpolarization
Some K+channels remain open, allowing excessive K+efflux
Inside of membrane becomes more negative than in resting state
Some K+ channels remain open, and Na+ channels reset
Cranial nerves
Abducens nerves
Fibers from inferior pons enter orbits via superior orbital fissures
Primarily a motor, innervating lateral rectus muscle
Facial nerves
Chief motor nerves of face with five major branches
Motor functions include facial expression, parasympathetic impulses to lacrimal
and salivary glands
Fibers from pons travel through internal acoustic meatuses and emerge through
stylomastoid foramina to lateral aspect of face
Trigeminal nerves
Convey sensory impulses from various areas of face (
Supply motor fibers (V3) for mastication
Largest cranial nerves; fibers extend from pons to face
Vestibulocochlear nerves
Formerly auditory nerve
Mostly sensory function; small motor component for adjustment of sensitivity of
receptors
Trochlear nerves
Fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate
superior oblique muscle
Primarily motor nerve that directs eyeball
Glossopharyngeal nerves
Fibers from medulla leave skull via jugular foramen and run to throat
Motor functions: innervate part of tongue and pharynx for swallowing and provide
parasympathetic fibers to parotid salivary glands
Oculomotor nerves
Function in raising eyelid, directing eyeball, constricting iris, and
controlling lens shape
Fibers extend from ventral midbrain through superior orbital fissures to four of six
extrinsic eye muscles
Vagus nerves
Only cranial nerves that extend beyond head and neck region
Fibers from medulla exit skull via jugular foramen
Optic nerves
Pass through optic canals, converge, and partially cross over at optic chiasma
Optic tracts continue to thalamus, where they synapse
Arise from retinas; really a brain tract
Accessory nerves
Rootlets pass into cranium via each foramen magnum
Formerly spinal accessory nerve
Formed from ventral rootlets from C1 to C5 region of spinal cord
Olfactory nerves
Fibers synapse in olfactory bulbs
Pathway terminates in primary olfactory cortex
Sensory nerves of smell
Hypoglossal nerves
Innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing
and speech
Fibers from medulla exit skull via hypoglossal canal
Spinal nerves
Cervical nerves (C1-C8)
Cervical plexus
Brachial plexus
Thoracic nerves (T1-T12)
Intercostal nerves
Lumbar enlargement
Lumbar nerves (L1-L5)
Lumbar plexus
Cauda esquina
Sacral nerves (S1-S5)
Sacral plexus
Coccygeal nerve Co1
Ventral roots - Contain motor fibers from ventral horn motor neurons that innervate
skeletal muscles
Dorsal roots - Contain sensoryfibers from sensory neurons in dorsal root ganglia
that conduct impulses from peripheral receptors
Neurotransmitters
Acetylcholine ( Ach)
Released at neuromuscular junctions
Degraded by enzyme acetylcholinesterase
Synthesized from acetic acid and choline by enzyme choline acetyltransferase
Dopamine, norepinephrine, epinephrine
made from the amino acid
tyrosine
Serotin
made from the amino acid tryptophan
Histamine
made from the amino acid histidine
Amino acids
Amino acids make up all proteins: therefore, it is difficult to prove which are
neurotransmitters
Peptides
Strings of amino acids that have diverse functions
Purines
Monomers of nucleic acids that have an effect in both CNS and PNS
Compare & contrast the autonomic nervous system
Autonomic Nervous System
Effector
Innervate smooth muscle, cardiac muscle, and glands
Preganglionic fibers release Ach
Postganglionnic fibers release norepinephrine or Ach at effectors
Parasympathetic division
promotes maintenance functions,
conserves energy
Sympathetic division
mobilizes body during activity
Somatic Nervous system
Innervates skeletal muscles
Release acetylcholine
Both
Have motor fibers
Higher brain centers regulate and coordinate both systems
Most spinal and mainly cranial nerves contain both somatic and autonomic fibers
Reflex arc (major parts & functions)
Integration center
either monosynaptic or polysynaptic region within CNS
Motor neuron
conducts efferent impulses from integration center to effector
organ
Sensory neuron
transmits afferent impulses to CNS
Effector
Receptor
site of stimulus action
Disorders/Diseases
Alzheimer's Disease
Hereditary, past head traumas, Age: over 60
Memory loss, confusion & disorientation, unfounded suspicions
A form of dementia associated with age
Uncurable, stem cells, medication
Spinal Cord Injury
Damage to the spinal cord
Direct injury or disease, assault, fall, accident, weakened vertebral column
weakness, paralysis, spastic muscles
Surgery, bed rest, physical therapy
Autism
Past medical issues, family history, mostly males
Anxiety, repeated behaviors, depression
Brain disorder that makes it difficult to communicate
Medication, behavioral management, anxiety management
Meningitis
Infection in the meninges surrounding the brain
Drug allergies, fungi or parasites, tumors
Nausea & vomiting, fever & chills, severe headache
Antibiotics, Medication for symptoms, prevention with vaccination
Cerebrovascular Accident (Stroke)
Blood vessels burts, Diabetes, High cholesterol
Loss coordination & balance, Confusion or memory loss, Muscle weakness
Occurs when blood flow to a portion of the brain is halted
Blood thinners, surgery to open blood vessels, Hospitalization
Multiple Sclerosis
Hereditary, possibly viral infection, environmental factors
Muscle weakness, spams, tremors, constipation, vision & hearing loss
Autoimmune disease, that damages the myelin sheath
Steroid treatments, assistive devices, physical therapy
Drugs of abuse (Mouse Party)
Methamphetamine
Interfere with dopamine neurotransmitters
Meth mimics dopamine, inside cell, meth enters the dopamine vesicles forcing the dopamine molecules out.
A person on this drug feels intense pleasure and exhilaration
Alcohol
Interfere with GABA neurotransmitters
It delivers a double sedative punch. interacts with GABA receptors to make them more inhibitory.
Person on this drug involved in memory, decision making, and impulse control.
Marijuana
Interfere with inhibitory/dopamine neurotransmitters
When body activates, cannabinoid receptors turn off the release of inhibitory neurotransmitters
Makes a person feel relaxed and calm when they are on the drug
Cocaine
Interfere with dopamine neurotransmitters
The drug blocks the transporters, leaving dopamine trapped in the synaptic cleft.
Person on the drug feel fidgety and unable to be still
Ecstasy
mimics serotin and is taken up by serotin transporters. The transporter becomes confused and does its job in reverse.
The person on this drug feels sleepy, and affects perception and appetite
Interfere with serotin neurotransmitters
LSD
Interfere with serotin neurotransmitters
The drug chemically resembles serotin and elicits its affected by binding to serotin receptors
Person on this drug feels wakefulness and evoking a startle response to unexpected stimulus.
Heroine
The release of neurotransmitters is shut down because opiates activate opiate receptors
The person on this drug feels well and feelings of sedation
The drug interfere with dopamine neurotransmitters