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Nervous System Imogen Ecal Period 1 - Coggle Diagram
Nervous System Imogen Ecal Period 1
Major Functions of the Nervous System
integration: processing and interpretation of sensory input
motor output: activation of effector organs (muscles & glands) = response
sensory input: info about internal and external changes gathered by sensory receptors
controls internal environment to maintain homeostasis
voluntary movement
Major Divisions & Subdivisions of the Nervous System
Peripheral Nervous System
motor (afferent) division
autonomic nervous system (involuntary)
sympathetic: mobilizes body during activity
parasympathetic: maintenance functions, conserves energy
innervation; visceral organs served by both divisions; dynamic antagonism
somatic nervous system (voluntary)
sensory (efferent) division
spinal nerves to and from spinal cord
cranial nerves to and from brain
Central Nervous System
brain
spinal cord
controls most functions of the body and mind
Tissues
Nervous Tissue
found in spinal cord, brain, and in nerves
Dendrite: receives input
Nucleus:
Axon: conducting region of neuron
Axon Terminal: region that secretes neurotransmitters
Schwann Cells: form myelin sheaths
Cell Body: genetic information, maintains the neuron's structure, and provides energy to drive activities
Nodes of Arnvier: in between axons
myelin sheath: composed of myelin and surrounds the axon to increase speed
gray matter
found in brain and spinal cord
short, nonmyelinated neurons and cell bodies
white matter
found in brain and spinal cord
myelinated axons
Classification of Neurons
Motor Neurons
impulses from CNS to receptors
Interneurons
lie between sensory and motor neurons
most abundant in body
Sensory Neurons
impulses from sensory receptors to CNS
unipolar; cell bodies located in ganglia in PNS
Neuroglia
neuroglia (glial cells): wrap and surround delicate neurons
neurons (nerve cells): transmit electrical signals
astrocytes: most abundant and versatile, supports neurons, plays a role in exchanges between capillaries and neurons
microglial cells: small cells with thorny processes that touch and monitor neurons
ependymal cells: range in shape (squamous to columnar) may be ciliated, lines central cavities of brain and spinal column
oligodendrocytes: branched cells, processes wrap CNS nerve fibers into myelin sheaths in thick nerve fibers
Connective Tissue Coverings
Meninges
Dura Mater: outermost layer; tough
Arachnoid Mater: string like; between dura mater and pia mater
Pia Mater: innermost layer; looks like saran wrap; clear and thin
Connective Tissue Coverings
perineurium: coarse connective tissue, bundles fibers into fascicles
epineurium: tough fibrous sheath around all fascicles to form nerve
endoneurium: loose connective tissue; encloses axons and myelin sheaths (schwann cells)
Major Parts & Functions of the Brain
Cerebellum: between cerebrum and brain stem; helps in coordination and movement related to motor skills
arbor vitae: white matter in cerebellum (tree shaped)
Pituitary Gland: controlling growth and development and the functioning of the other endocrine glands
Olfactory Bulbs: responsible for sense of smell
Optic Chiasma: aids in vision; X shape
Ventricles: empty spaces in brain filled with cerebral spinal fluid (CSF); lateral ventricle, fourth ventricle, third ventricle, cerebral aqueduct
Diencephalon:
Thalamus: relay station for information coming into cortex
Hypothalamus: main visceral control and regulating center; vital for homeostasis
Mamillary Body: recollective memory
Epithalamus: forms roof of 3rd ventricle and contains the pineal gland
Brain Stem
Pons: motor function, sensation, eye movement, hearing, taste
Medulla Oblongata: transmitting signals between the spinal cord
Midbrain: movements of the eye, and in auditory and visual processing
Cerebrum (Cerebral Hemispheres)
Frontal Lobe: front of the brain; attention, planning, decision making
Parietal Lobe: touch, taste, hearing
Temporal Lobe: memory processing, emotions
Occipital Lobe: back of the brain; aids in vision
Wernicke's Area: involved in understanding spoken and written words
Broca's Area: motor speech area; directs muscles of speech production
Pineal Gland: internal clock
corpus callosum: ensures both sides of the brain can communicate and send signals to each other
fornix: cognition and episodic memory recall
Major Parts & Functions the Spinal Cord
Cross Sectional Anatomy
ventral (anterior) median fissure
dorsal (posterior) median fissure
central canal: runs down length of spinal cord, filled with cerebral spinal fluid (CSF)
gray matter located in core and white matter located outside
dorsal horns: interneurons that receive somatic and visceral sensory input
ventral horns: some interneurons; somatic motor neurons
lateral horns: sympathetic neurons
Gross Anatomy
Epidural space: cushion of fat & veins in the space between vertebrae and spinal dura mater
Filum terminate: fibrous extention of conus covered with pia mater & anchors to spinal cord
Denticulate ligaments: extensions of pia mater that secure cord to dura mater
spinal nerves: attach to spinal cord by 31 paired roots
Cauda Equina: collection of nerve roots at inferior end of vertebral column
2 way communication to and from the brain
Action Potential & the Nerve Impulse
Generated
depolarization: Na+ channels open
resting state: gated Na+ & K+ channels closed
repolarization (returns to resting membrane potential): Na+ channels inactivate, K+ channels open
hyperpolarization: some Ka+ channels open & Na+ channels reset
AP happens all or none
Depolarization doesn't guarantee generation of AP
Propagation allows AP to be transmitted from origin down entire axon length toward terminals
refractory period: neurons cannot trigger AP
Cranial Nerves
V. Trigeminal Nerves: largest nerve, motor & sensory function
VI. Abducens Nerves: Helps move the rectus muscle; eye movement
IV. Trochlear Nerves: responsible for movement of the eye
VII. Facial Nerves: has both motor & sensory functions
III. Oculomotor Nerves: responsible for muscle movement in the eyes
VIII. Vestibulocochlear: responsible for balance
IX. Glossophangeal Nerves: both motor and sensory functions
X.Vagus Nerves: motor, sensory, and parasympathetic functions
II. Optic Nerves: responsible for vision
XI. Accessory Nerves: provides motor function to some muscles in the neck
XII. Hypoglossal Nerves: supplies tongue muscles
I. Olfactory Nerves: responsible for a person's sense of smell
Neurotransmitters
classified by chemical structure & function
language of the nervous system
Information transfer across synaptic cleft
the entry of Ca2+ causes synaptic vesicles to release neurotransmitters
neurotransmitters diffuse across synaptic cleft and binds to specific receptors on postsynaptic membrane
graded potential is made when neurotransmitters bind to ion channels
neurotransmitter effects terminated
voltage-gated Ca2+ channels open, Ca2+ enters axon terminal
AP arrives at axon terminal of presynaptic neuron
Compare & Contrast Autonomic Nervous System
Parasympathetic Division: maintenance functions & conserves energy
preganglionic nerves long
fibers originate from brain stem
Rest-and-Digest System
postganglionic fibers short
ganglia near visceral effector organs
Sympathetic Division: Mobilizes body during activities
Fight-or-Flight System
fibers originate in thoracis & lumbar region
preganglionic nerves short
preganglionic fibers long
ganglia close to spinal cord
more complex & innervates more organs
Dual Innervation: all visceral organs served by both divisions
Reflex Arc
Integration Center: monosynaptic or polysynaptic
Motor Neuron: conducts efferent impulses from integration center to effector organ
Sensory Neuron: transmits afferent impulses to CNS
Effector: muscle fiber or gland; responds to efferent impulses by contracting or secreting
Receptor: site of stimulus action
Response: ex. muscle contraction
Stimulus: ex. stimulus on skin
Disorders Associated with Nervous System
Huntington's Disease: inherited disorder that causes neurons in parts of the brain to gradually break down and die; affects both men and women around the ages 30-50, but can start earlier
Parkinson's Disease: progressive nervous system disorder that affects movements, present in both men & women, 50% more present in women
Multiple Sclerosis: autoimmune disease; myelin sheaths in CNS destroyed by immune system, makes them hard. Those affected will have a hard time moving, the feeling of weakness, and loss of muscle control; drugs that modify the immune system will help.
Alzheimer's Disease: results in dementia (key proteins misfolded and malfunctioned; caused by brain cells dying which makes the brain shrink
Hemiplegia: paralysis of one side of the body; results in speech and sensory deficits
Meningitis: inflammation of the meninges
Epileptic seizure: flood of electrical discharges by groups of neurons, prevents other messages from getting through
Hydrocephalus: water on brain; increased pressure from CSF being blocked from circulating and being drained
Contusion: permanent brain damage
Concussion: temporary brain damage
Subdural or subarachnoid hemorrhage: pressure from blood may force brain stem through foramen magnum = death
cerebral edema: swelling of brain from traumatic head injury
stroke: caused by interruption of blood flow to brain
Ischemia: inadequate blood supply = death of tissue
(ALS) Lou Gehrig's Disease: destruction of ventral horn motor neurons and fibers of pyramidal tract;
loss of ability to speak, swallow, and breathe
Cerebral Palsy: neuromuscular disability involving poorly controlled or paralyzed voluntary muscles
Anencephaly: cerebrum and parts of the brain never develop; death after birth
Spina Bifida: incomplete formation of vertebral arches; caused by lack of folic acid
hypertension: high blood pressure; heart works harder; more prone to wear and tear
Raynaud's disease: fingers turn pale; painful in toes and fingers
Autonomic dysreflexia: life threatening; blood pressure rises which increases risk of stroke
Drugs
MDMA: AKA ecstasy, causes increase of energy and distortion of perception; feeling of euphoria; interferes with body temperature regulation; when taken in large amounts, they can cause panic attacks
Nicotine: Cigars, cigarettes, vaping; highly addictive but is bad for the body; can be taken through smoking, nicotine patches; stimulant, can be relaxing to users
Inhalents: Not drugs, they're household products; it can cause hallucinations, brain damage, and impair coordination
Psychedelics: Hallucinogen; causes hallucinations and distortions; causes users to sense things that are not there, intensifies emotions and senses
Dissociative Drug: Feeling of detachment; causes hallucinations and distortions; lose touch with reality for users
Opioids: Used for pain relief; same category as morphine; when injected, they can cause pinpoint pupils and which is followed by a period of drowsiness and clouded thinking
Ecstasy: Mimics serotonin and can lead to addiction
Heroine: Binds to opiate receptors; feeling of sedation and well being
Marijuana: Users feel relaxed and calm from slowed down movements
Methamphetamine: Mimics dopamine and is highly addictive; works with the brain's reward pathway
Alcohol: Causes users to be disoriented and make bad decisions
Cocaine: Users are fidgety; also works in the brain's reward pathway and is addictive
LSD: Users are more aware and easily startled
Spinal Nerves
31 paired roots
5 lumbar nerves
5 sacral nerves
12 thoracic nerves
1 coccygeal nerves
8 cervical nerves
Part of the parasympathetic nervous system