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Nervous System Genesis Dominguez period: 3 - Coggle Diagram
Nervous System
Genesis Dominguez
period: 3
Nervous Tissue (Neurons & Neuroglia)
NEURONS
Structure
Soma: Cell body
Dendrites: Receive signals
Axon: Sends impulses
Myelin sheath: Insulation
Nodes of Ranvier: Speed up impulses
Axon terminals: Release neurotransmitters
Functions
: Communication, signal transmission.
NEUROGLIA
CNS Glial Cells
Astrocytes: Support, blood-brain barrier
Oligodendrocytes: Myelin in CNS
Microglia: Immune defense
Ependymal cells: Cerebrospinal fluid (CSF)
PNS Glial Cells
Schwann cells: Myelin in PNS
Satellite cells: Support neuron cell bodies
Divisions & Subdivisions of the Nervous System
Peripheral Nervous System (PNS)
Definition: The PNS includes all the nerves outside the brain and spinal cord.
Purpose: It connects the body to the CNS by carrying sensory information to the brain and sending motor commands back to muscles and organs.
Motor (Efferent) Division (PNS)
Somatic NS: Voluntary skeletal muscles
Autonomic NS (ANS): Involuntary control
Sympathetic: Fight or flight
Parasympathetic: Rest and digest
Enteric: Digestive tract network
Sensory (Afferent) Division (PNS)
Somatic sensory: Skin, muscles, joints
Visceral sensory: Organs
Central Nervous System (CNS)
Define: The CNS is the part of the nervous system that includes the brain and spinal cord.
Purpose: It processes information, makes decisions, and sends out instructions to the body.
Brain (CNS)
Cerebrum
Diencephalon
Brainstem
Cerebellum
Spinal Cord (CNS)
Cervical, thoracic, lumbar, sacral regions
Reflex centers
Spinal Cord & Nerves
Spinal Cord Regions
Cervical: 8 pairs
Thoracic: 12 pairs
Lumbar: 5 pairs
Sacral: 5 pairs
Coccygeal: 1 pair
SPINAL NERVES
Components
Dorsal root: Sensory input
Ventral root: Motor output
Dorsal root ganglion: Cell bodies of sensory neurons
Functions
Carry sensory information to CNS
Carry motor commands to muscles
Functions
Conduction pathways: To/from brain
Reflex center: Automatic responses
Structure
Gray matter: Interneurons
White matter: Myelinated axons
Central canal: Contains CSF
Major Functions of the Nervous System
Integrative Function
Definition: CNS interprets sensory information.
Processes: Decision-making, memory, learning.
Cell type: Interneurons.
Motor Function
Definition: Sends commands from CNS to effectors.
Effectors: Muscles & glands.
Pathway: Motor neuron → Effector
Examples: Movement, sweating, hormone release.
Sensory Function
Definition: Detects internal & external changes.
Receptors: Specialized cells that sense stimuli.
Pathway: Receptor → Sensory neuron → CNS
Examples: Touch, temperature, pain, sight, sound.
Homeostasis
Maintains: Temperature, pH, hydration.
Uses: Feedback loops.
Action Potential & Nerve Impulse
Nerve Impulse Propagation
Impulse travels along axon → terminals → neurotransmitter release.
Terms
Ion channels: Protein gates for ions
Refractory period: Neuron can’t fire again
Saltatory conduction: Jumping of impulse on myelin
Synapse: Junction between neurons
Steps
Resting potential (−70 mV; Na⁺ outside, K⁺ inside)
Threshold reached
Depolarization (Na⁺ channels open, Na⁺ enters)
Repolarization (K⁺ channels open, K⁺ exits)
Hyperpolarization (briefly more negative)
Return to resting potential
Connective Tissue Coverings (Nerve Structure)
Additional Terms
Fascicle: Bundle of axons
Mixed nerve: Contains sensory + motor neurons
Layers
Endoneurium: Surrounds each axon
Perineurium: Surrounds fascicle (bundle)
Epineurium: Surrounds entire nerve
Major Parts & Functions of the Brain
CEREBRUM
Lobes & Functions
Frontal — reasoning, movement
Parietal — sensory processing
Temporal — hearing, memory
Occipital — vision
Cortex: Outer gray matter
Basal nuclei: Movement control
DIENCEPHALON
Thalamus: Relay station
Hypothalamus: Homeostasis, hormones
Pineal gland: Sleep/wake cycles
BRAIN STEM
Midbrain: Visual/auditory reflexes
Pons: Breathing control
Medulla oblongata: Heart rate, blood pressure, reflexes (coughing, swallowing)
CEREBELLUM
Balance, posture, coordination
Fine-tunes movement
Classification of Neurons
By Structure
Unipolar: One extension; sensory.
Bipolar: Two extensions; eyes & nose.
-Multipolar: Many extensions; motor & interneurons.
By Function
Sensory (afferent): To CNS
Motor (efferent): Away from CNS
Interneurons: Connect neurons in CNS
Cranial Nerves
XII – Hypoglossal
Function: Tongue movement
XI – Accessory
Function: Controls neck and shoulder muscles
X – Vagus
Function: Controls heart, lungs, digestion; speech
IX – Glossopharyngeal
Function: Taste (back of tongue), swallowing, saliva production
VIII – Vestibulocochlear
Function: Hearing and balance
VII – Facial
Function: Facial expressions, taste (front of tongue), saliva & tear production
VI – Abducens
Function: Eye movement (lateral rectus muscle)
V – Trigeminal
Function: Facial sensation, chewing
IV – Trochlear
Function: Eye movement (superior oblique muscle)
III – Oculomotor
Function: Eye movement, eyelid movement, pupil constriction
II – Optic
Function: Vision
I – Olfactory
Function: Smell
Neurotransmitters
Specific Neurotransmitters
Dopamine: Reward, movement
Serotonin: Mood
Acetylcholine: Muscle contraction
Norepinephrine: Alertness, stress response
Synaptic Steps
Impulse reaches terminal
Ca²⁺ enters terminal
Neurotransmitter released
Binds to receptors on next neuron
Signal continues or stops
Types
Excitatory: Increase chance of firing
ex: Glutamate
Inhibitory: Decrease chance of firing
ex: GABA
Reflex Arc
Types of Reflexes
Somatic reflex: Skeletal muscles
Autonomic reflex: Organ
Key Features
Fast
Involuntary
Protect the body
Parts
Receptor: Detects stimulus
neuron: Sends message to CNS
Interneuron: Processes info
Motor neuron: Sends command
Effector: Muscle/gland responds
Autonomic Nervous System (Comparison)
Sympathetic Division
Function: Fight or flight
Effects: ↑heart rate
↑ breathing
Dilated pupils
Slows digestion
Neurotransmitters: Norepinephrine
Parasympathetic
Division
Function: Rest and digest
Effects: ↓ heart rate
↑ digestion
Constricts pupils
Neurotransmitter: Acetylcholine
Same
Involuntary
Motor division of PNS
Control smooth and cardiac muscle
Disorders/Diseases/Drugs of abuse (Mouse Party
Autism
Brain disorder that makes it difficult to communicate.
Causes: family history, hereditary
Symptoms: delay in learning to talk, anxiety, repeated behaviors
Treatments: medication, coping skills, specialized therapy
Marijuana
Effects on the nervous system:Alters perception (time, space, colors), Mild euphoria / relaxation, Impairs memory, attention, coordination
Risks / long-term effects:Short-term memory problems
Slowed reaction time
Alzheimer Disease
A form of dementia associated with age.
Causes: Hereditary, family history, age over 60
Symptoms: memory loss, confusion, confusion
Treatments:no cure
Alcohol
Type: Depressant
Effects on the nervous system
Slows brain activity
Reduces inhibition
Depresses respiratory centers in high doses