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Justin Cabrera P.6 Nervous system - Coggle Diagram
Justin Cabrera P.6
Nervous system
Major functions of the nervous system
Integration
Processing and interpretation of sensory input
Motor output
Activation of effector organs (muscles and glands) produces a response
Sensory input
information gathered by sensory receptors about internal and external changes
master controlling and communicating system of body
Cells communicate via electrical and chemical signals
CNS
Integration and control center: Interprets sensory input and dictates motor output
PNS
Spinal nerves to and from spinal cord
Cranial nerves to and from brain
Functional Divisions
sensory (afferent) division
Visceral sensory fibers: convey impulses from visceral organs to CNS
Somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints
to CNS
Motor (efferent) division
Transmits impulses from CNS to effector organs
Autonomic nervous system (involuntary)
Consists of visceral motor nerve fibers
Regulates smooth muscle, cardiac muscle, and glands
Somatic nervous system (voluntary)
Conscious control of skeletal muscles
conduct impulses from CNS to skeletal
muscle
Major divisions and subdivisions of the nervous system
Central Nervous system(CNS)
Spinal Cord
Cephalization
Increased number of neurons
Highest level reached in human brain
Evolutionary development of rostral (anterior) portion
Brain
Ventricles
Fourth ventricle
Location: hindbrain
Third ventricle
Location: Diencephalon
Lateral Ventricle
Location: deep in each hemisphere
Description: C shaped chambers
Matter Type
Gray Matter: short, nonmyelinated neurons and cell bodies
White Matter: Myelinated and nonmyelinated axons
Cerebellum
Brain Stem
Midbrain
Medulla
Pons
Diencephalon
Cerebral Hemispheres
Peripheral Nervous System(PNS)
Transmission Lines: Nerves and their Structure and Repair
Motor Endings and Motor Activity
Reflex Activity
Sensory Receptors
Awareness of stimulus and interpretation of meaning of stimulus occur in brain
Classification of neurons
Structural
2.Bipolar: two processes
one axon, 1one dendrite
Location: retina and olfactory mucosa
3.Unipolar(pseudounipolar): one T-like process
two axons
1.Multipolar: three or more processes
Most common and major neuron type in CNS
1 axon, others dendrites
Functional
Motor
Multipolar
located in CNS
Function: Carry impulses from CNS to effectors
3.Interneurons(association neurons)
Function: Shuttle signals through CNS pathways
Location: Most are entirely within CNS
between motor and sensory neurons
99% of body’s neurons are interneurons
Sensory
Almost all are unipolar
Location: ganglia in PNS
Function: Transmit impulses from sensory receptors toward CNS
Tissues
Neuroglia (glial cells):small cells that surround and wrap delicate neurons
CNS
Astrocytes
Support and brace neurons
Guide migration of young neurons
Support and brace neurons
Control chemical environment around neurons
Location: Cling to neurons, synaptic endings, and capillaries
Respond to nerve impulses and neurotransmitters
Most abundant, versatile, and highly branched of glial cells
Influence neuronal functioning
Participate in information processing in brain
Microglial cells
Migrate toward injured neurons
Small, ovoid cells with thorny processes that touch and monitor neurons
Oligodendrocytes
Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers
Ependymal cells
Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue
fluid bathing CNS cells
Line the central cavities of the brain and spinal column
PNS
Schwann cells (neurolemmocytes)
Function similar to astrocytes of CNS
Location: Surround neuron cell bodies in PNS
Satellite cells
Similar function as oligodendrocytes
Vital to regeneration of damaged peripheral nerve fibers
Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers
Neurons (nerve cells):excitable cells that transmit electrical signals
structural units of nervous system
specialized cells that conduct impulses
Extreme longevity (lasts a person’s lifetime)
Amitotic, with few exceptions
High metabolic rate: requires continuous supply of oxygen and glucose
All have cell body and one or more processes
Major parts and functions of the spinal cord
Spinal Cord
Gross Anatomy and Protection
Epidural Space - cushion of fat and network of veins
Filum terminale extends to coccyx
Cervical and Lumbar enlargements - areas where nerves serving upper and lower limbs arise from spinal cords
Spinal Nerves
Cervical and Lumbosacral enlargements - nerves serving upper and lower limbs emerge here
Cauda Equina - collection of nerve roots
Cross- Sectional
Ventral (anterior): median fissure
Dorsal (posterior): median sulcus
Gray Matter and Spinal Roots
Dorsal Horns
interneurons that receive somatic and visceral sensory input
Ventral Horns
some interneurons
Lateral Horns
sympathetic neurons
Ventral roots
bundle of motor neuron that exit the spinal cord
Dorsal Roots
sensory input to cord
Dorsal root (spinal) ganglia
cell bodies of sensory neurons
Spinal nerves
formed by fusion of dorsal and ventral roots
White Matter
Description: Runs in Ascending, Descending, Transverse
Three White Columns
Dorsal
Lateral
Ventral
Major parts and functions of the brain
Cerebral hemispheres
Surface Markings:
Gyri - ridges
Sulci - shallow grooves
Major Sulci
Central Sulcus
Parieto-occipital sulcus
Lateral Sulcus
Fissures - deep groves
Longitundinal Fissue - separates two hemispheres
Transverse cerebral fissure - separates cerebrum and cerebellum
Lobes
Frontal
Parietal
Temporal
Occipital
Insula
Hemispheres has:
Cerebral Cortex
Awareness, Sensory Perception, Voluntary Motor Irritation, Communication, Memory Storage, Understanding
Motor Areas - control voluntary movement
located in frontal lobe
Premotor Cortex
Broca's Area
active in planning speech
Sensory Areas - Conscious awareness of sensation
Primary somatosensory Cortex
Somatosensory association cortex
Association Areas - inegrate diverse information
Multimodal Association Areas
Anterior Association Area
Posterior Association Area
Limbic Association Area
Lateralization of Cortical Functioning
Laterialization
Cerebral Domiance
Left Hemisphere - controls language, math, logic
Right Hemispheres - intuiotion, emotion, and artisitc and musical skills
White Matter
Basal Nuclei
Cerebral White Matter
Basal Nuclei (ganglia) - each hemisphere has a basal Nuclei
Functions:
Influence Muscle Movements
Play role in cognition and emotion
Regulate intensity of slow or stereotyped movements
Filter out incorrect reponses
Inhibit unnecessary movements
PARKINSON AND HUNTINGTON'S DISEASE ARE DISORDERS OF THE GANGLIA
Diencephalon
Thalamus
act as a relay station for information coming into cortex
mediate sensation, motor actives, cortical arousal, learning, and memory
Hypothalamus
main visceral control and regulating center that is vital to homeostasis
regulate body temp, hunger, thirst, and sleep cycles
DISORDERS: SEVERE BODY WASTING, OBESITY, SLEEP DISTURBANCES
Epithalamus
forms roof of third ventricle
contains pineal gland (body)
secretes melatonin that helps regulate sleep wake cycle
Cerebellum
processes input from cortex, brain stem, and sensory receptors to provide precise, coordinated movements of skeletal muscles
plays role in thinking, language, and emotoin
balance and emotion
Functional Brain Systems
EPILEPTIC SEIZURE - TORRENT OF ELECTRICAL DISCRHAGES BY A GROUP OF NEURONS
Reticular Formation
Regulate Visceral Motor Functions
Respiratory centers
Cardiac Centers
Vasomotor CEnters
helps control coarse limb movemnts
connections allow it to govern brain arousal
extends through central core of brain stem
Limbic System
fornix - fiber tract that links limbic system regions
puts emotional responses to odors
interacts with prefrontal lobes (react emotionally)
large part of emotional or affective brain
Meninges (cover and protect CNS)
Dura Mater
Strongest meninx
Arachnoid Mater
middle layer with spiderweb like extensions
Pia Mater
delicate connective tissue that clings tightly to brain
MENINGITIS - INFLAMMATION OF THE MENINGES
Action potential & the Nerve Impulse
Action potential
Propagation of an Action Potential
Propagation allows AP to be transmitted from origin down entire axon length toward terminals
Since Na+ channels closer to the AP origin are sitll inactivated, no new AP is generated there
MULTIPLE SCLEROSIS (MS) IS AN AUTOIMMUNE DISEASE THAT AFFECTS PRIMARILY YOUNG ADULTS
Generating an Action Potential
Depolarization - Na+ channels Open
Repolarization - Na+ channels are inactivating, and K+ channels open
Resting State - All gated Na+ and K+ channels are close
Hyperpolarization - Some K+ channels remain open, and Na+ channels reset
Nerve Impulse
Synapse
Presynaptic Neuron
neuron conducting impulses toward synapse (sends information)
Postsynaptic Neuron
Neuron transmitting electrical signal away from synapse (receives information)
Chemical Synapses
Ca2+ entry causes synaptic vesicles to release neurotransmitter
Neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane
Voltage-gated Ca2+ channels open, and Ca2+ enters axon terminal
Binding of neurotransmitters opens ion channels, creating graded potentials
AP arrives at axon terminal of presynaptic neuron
Neurotransmitter effects are terminated
Spinal nerves
Each spinal cord segment is designated by paired spinal nerves that arise from it
Cervical and lumbosacral enlargements
Nerves serving upper and lower limbs emerge here
Attach to spinal cord by 31 paired roots
Part of PNS
participate in dermatomes(Except for C1)
Compare & contrast the autonomic nervous system
Autonomic Nervous System
Visceral Sensory Neurons
sends info about chemical changes, stretch, temperature and irritation of viscera
receptors are free nerve endings widely scattered throughout viscera
VISCERAL REFLEXES
RECEPTOR IN VISCERA
INTEGRATION CENTER
STIMULUS
MOTOR NEURON
VISCERAL EFFECTOR
RESPONSE
AUTONOMIC NEUROPATHY - DAMAGE TO AUTONOMIC NERVES THAT IS A COMMON COMPLICATION OF DIABETES MELLITUS
ANS vs. Somatic Nervous System
SNS
innervates skeletal muscles
cell body is in CNS, thick myelinated group
all somatic motor neurons release acetylcholine
ANS
innervates cardiac muscle, smooth muscle, and glands
cell body in CNS, with thin myelinated axon extending to ganglion
release ACh
releases norepinephrine or ACh at effectors
BOTH
higher brain centers regulate and coordinate both systems
most spinal and many cranial nerves contain both somatic and autonomic fibers
Reflex arc
SPINAL REFLEX ARC
SENSORY NEURON
INTEGRATION CENTER
MOTOR NEURON
RECEPTOR
EFFECTOR
STIMULUS
RESPONSE
Disorders associated with Nervous System
Degenerative Brain Disorders
Alzheimer's Disease
progressive degenerative disease of brain that results in dementia
as brain cells die, brain shrinks
Parkinson's Disease
degereneration of dopamine relaseing neurons of suibstsantia nigra
Huntington's disease
fatal hereditary disorder caused by accumulation of protein huntingtin in brain cells
Methods to Check
CT, MRI, & PET allow for quick identification of tumors, lesions, plaque, or areas of infarct
Disorders of the ANS
Hypertension
overactive sympathetic vasoconstrictor response to stress
Raynaud's Disease
painful, exaggerated vasoconstriction in fingers and toes
Autonomic Dysreflexia
blood pressure skyrockets, posing increased risk for stroke
Neurotransmitters
Function: Language of nervous system
Division
Sympathetic Division
more complex and innervates more organs than parasympathetic
rest and digest
keeps body energy use as low as possible, even while carrying out maintenance activites
mobilizes body during activity
Parasympathetic Division
fibers originate from brain stem and scral regions or cord
promotes maintenance functions, conserves enery
Classification of Neurotransmitters
Chemical Structure
Acetylcholine
Released at neuromuscular junctions
Used by many ANS neurons and some CNS neurons
Amino Acids
Proven neurotransmitters
Difficult to prove which are
neurotransmitters
Purines
Effect in both CNS and PNS
Gases and Lippids
Peptides (neuropeptides)
Endorphins: Reduce pain perception
Endocannabinoids
Act at same receptors as THC
Biogenic amines
Catecholamines
Dopamine
Indolamines
Histamine
Serotonin
Function
Play roles in emotional behaviors and biological clock
Used by some ANS motor neurons
Imbalances are associated with mental illness
Function
EFFECTS: excitiary verse inhibitory
Neurotransmitter effects can be excitatory (depolarizing) and/or inhibitory (hyperpolarizing)
Effect determined by receptor to which it binds
ACTIONS: direct versus indirect
Indirect Action - Neurotransmitter acts through intracellular second messengers
Direct Action - neurotransmitters binds directly to and opens ion channels
Autonomic Nervous System
Acetylcholine
Norepinephrine
Cholinergic Receptors
Nicotinic Receptors
Muscarinic Receptors
Adrenergic Receptors
Alpha receptors
Beta receptors
Drugs
Methamphetamine
Description: interfere with dopamine
Function: makes the user feel intense pleasure and exhilaration
Alcohol
Description: interfere with GABA and glutamate
Function: affects the brain in areas involved in harmony formation, decision making and impulse control
Marijuana
Description: interfere with dopamine
slowing down movement, making us relaxed and calm
Cocaine
Description: interfere with dopamine
Function: affects the voluntary movement
user acts fidgety and unable to stay still
Ecstasy
Description: interfere with serotonin
affects serotonin pathways, responsible for mood, sleep, perception, and appetite
LSD
Description: interferes with serotonin
Function: responsible for feelings of wakefulness and evoking a startle response to unexpected stimulus.
Heroine
Description: interfere with dopamine
Function: responsible for transmissions of pain signals, stress response, and emotional attachment
Connective Tissue Coverings
Endoneurium
loose connective tissue that encloses axons
Perineurium
coarse connective tissue that bundles fibers into fascicles
Epineurium
tough fibrous sheath around all fascicles to form the nerve
Cranial Nerves
Olfactory Nerves
sensory nerves of smell
Optic Nerves
arise foo retinas; really a brain tract
Oculomotor Nerves
Functions in raising eyelid, directing eyeball,
Trochlear Nerves
primarily motor nerve that directs eyeball
trigeminal Nerves
convey sensory impulses from various areas of face
Abducens Nerves
primarily a motor, innervating lateral rectus muscle
Facial Nerves
Chief motor nerves of face with five major branches
VEstibulocochlear Nerves
auditory nerve
Glossopharyngeal Nerves
innervate part of tongue and pharynx for swallowing and provide parasympathetic fibers to parotid salivary glands
Vagus Nerve
cranial nerves that extend beyond head and neck region
Accessory Nerves
spinal accessory nerve
hypoglossal Nerve
intrinsic muscle of tongue that contribute to swallowing and speech