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Alanna Vargas Period 3 Nervous System - Coggle Diagram
Alanna Vargas Period 3 Nervous System
Reflex arc
Receptor
Sensory neuron
Integration center (spinal cord or brain)
Motor neuron
Effector (muscle or gland)
Example: knee jerk = monosynaptic
Example: touching something hot = polysynaptic
Action potential & the Nerve Impulse
Resting potential: about –70 mV
Na+/K+ pump: keeps inside more negative
Threshold: around –55 mV to trigger AP
Phases
Depolarization: Na+ rushes in
Repolarization: K+ rushes out
Hyperpolarization: cell dips more negative
Two types of conduction
Continuous: slow (no myelin)
Saltatory: fast (jumps at nodes of Ranvier)
Synapse: connection where neurotransmitters are released.
Major functions of the nervous system
Sensory input
Your body picks up info from inside and outside using receptors.
Examples:
Photoreceptors (light, eyes)
Mechanoreceptors (touch/pressure)
Chemoreceptors (chemicals, smell, taste)
Integration
Happens in the CNS (brain + spinal cord).
Info is sorted out, compared to memories, and a “decision” is made.
Motor output
Sending commands to effectors like muscles and glands.
Examples: moving your arm, releasing saliva, speeding up heartbeat.
detect-think-respond.
Neurotransmitters
ACh: muscle movement, memory
Dopamine: reward, movement
Serotonin: mood, sleep
Norepinephrine: alertness, stress
GABA: main inhibitory
Glutamate: main excitatory
Endorphins: natural pain relief
Spinal nerves
31 pairs
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
Plexuses:
Cervical
Brachial
Lumbar
Sacral
Major parts and functions of the brain
Frontal lobe: planning, personality, decision making, motor control
Parietal lobe: touch, temperature, spatial awareness
Temporal lobe: hearing, language, memory
Occipital lobe: vision
Thalamus: directs sensory info to correct brain area
Hypothalamus: hunger, thirst, body temp, hormone control
Pons/Medulla: breathing, heart rate, blood pressure
Cerebellum: smooth movements and balance
Limbic system: emotions and memory (amygdala + hippocampus)
Drugs of abuse
Cocaine: blocks dopamine reuptake → intense “high”
Meth: huge dopamine release → brain damage long term
Alcohol: boosts GABA → slow reaction/poor balance
Heroin: binds opioid receptors → pain relief, addiction
LSD/psychedelics: change serotonin → hallucinations
Marijuana/THC: affects memory, mood, appetite
Compare & contrast the autonomic nervous system
Sympathetic = fight or flight (higher heart rate, pupil dilation, stops digestion, uses NE mostly).
• Parasympathetic = rest and digest (slower heart rate, more digestion,Constricts pupils, Uses ACh mostly).
Tissues
Neurons (main nerve cells)
Cell body – holds nucleus
Dendrites – receive signals
Axon – sends signal away
Myelin – insulation, speeds signal
Axon terminals – release neurotransmitters to next cell
Main jobs: respond to a stimulus, send an electrical message, release chemicals.
Neuroglia (support cells)
CNS:
Astrocytes: clean up chemicals, help make the blood-brain barrier
Oligodendrocytes: make myelin in CNS
Microglia: defense cells, destroy bacteria
Ependymal cells: make cerebrospinal fluid (CSF)
PNS:
Schwann cells: make myelin in PNS
Satellite cells: protect neuron cell bodies in ganglia
Cranial nerves
I — Olfactory — smell
II — Optic — vision
III — Oculomotor — eye movement
IV — Trochlear — eye muscle (superior oblique)
V — Trigeminal — face sensation, chewing
VI — Abducens — eye movement outward (lateral rectus)
VII — Facial — facial expressions, taste
VIII — Vestibulocochlear — hearing/balance
IX — Glossopharyngeal — swallowing, taste
X — Vagus — major parasympathetic nerve (heart, lungs, digestion)
XI — Accessory — neck/shoulder movement
XII — Hypoglossal — tongue movement
Major parts and functions of the spinal cord
Gray matter: decision-making for reflexes
Dorsal horn: sensory
Ventral horn: motor
White matter: bundles of nerves up and down
Ascending = sensory info to brain
Descending = motor commands to body
Reflex center: some responses never go to the brain first
Disorders/Diseases
Alzheimer’s: memory loss, brain tissue shrinking
Parkinson’s: low dopamine, shaky movements
Multiple sclerosis: myelin destroyed
Stroke: blood flow problem in brain
Epilepsy: sudden electrical brain activity
Meningitis: infection of meninges
Major divisions and subdivisions of the nervous system
CNS (Central Nervous System)
Brain
Cerebrum – thinking, memory, voluntary movement
Diencephalon – thalamus (relay station), hypothalamus (homeostasis)
Brainstem – life-support functions
Midbrain, pons, medulla oblongata
Cerebellum – balance and coordination
Spinal Cord
Connects brain to body, handles reflexes
Segments: cervical, thoracic, lumbar, sacral
PNS (Peripheral Nervous System)
Somatic nervous system (voluntary)
Movement of skeletal muscles, sensory from skin/joints
Autonomic nervous system (automatic)
Sympathetic: fight/flight
Parasympathetic: rest/digest
Enteric (optional)
“Brain of the gut,” controls digestion without thinking
Nerves
Cranial nerves (12 pairs)
Spinal nerves (31 pairs)
Classification of neurons
By structure
Multipolar: many dendrites, one axon (most common)
Bipolar: one dendrite + one axon (eye, nose)
Unipolar: sensory neurons in ganglia
By function
Sensory (afferent) – carry info to CNS
Motor (efferent) – carry commands from CNS
Interneurons – connect neurons inside CNS (most common overall)
Connective Tissue Coverings
Endoneurium: wraps one axon
Perineurium: wraps a bundle of axons (fascicle)
Epineurium: wraps the whole nerve
Meninges (CNS covering):
Dura mater (tough)
Arachnoid mater (web-like)
Pia mater (thin, stuck to brain/spinal cord)