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Yuridia Sigala Period 3 Nervous System - Coggle Diagram
Yuridia Sigala Period 3 Nervous System
Major Functions of the Nervous System
Sensory input: detects changes inside/outside body
Integration: processes and interprets signals
Motor output: responds by activating muscles/glands
Maintains homeostasis
Higher functions: thinking, memory, emotions
Major Divisions
CNS (Central Nervous System)
Brain
Spinal cord
PNS (Peripheral Nervous System)
Sensory (Afferent) Division
Motor (Efferent) Division
Somatic NS → voluntary (skeletal muscles)
Autonomic NS → involuntary (organs)
Sympathetic (“fight or flight”)
Parasympathetic (“rest & digest”)
Tissues
Neurons
Structure: cell body, dendrites, axon, axon terminals
Function: transmit impulses
Neuroglia (Glial Cells)
Support, protect, nourish neurons
Examples: astrocytes, oligodendrocytes, Schwann cells, microglia
Classification of Neurons
By structure: unipolar, bipolar, multipolar
By function:
Sensory neurons → to CNS
Motor neurons → from CNS
Interneurons → inside CNS (connect neurons)
Connective Tissue Coverings
Surrounding nerves:
Endoneurium: around each axon
Perineurium: around fascicle (bundle)
Epineurium: around whole nerve
Major Parts & Functions of the Brain
Cerebrum: thinking, memory, senses, voluntary movement
Cerebellum: balance, coordination
Brainstem: breathing, heart rate
Midbrain, pons, medulla oblongata
Diencephalon:
Thalamus (relay station)
Hypothalamus (homeostasis, hormones)
Spinal Cord
Pathway for nerve impulses to/from brain
Reflex center (fast responses)
31 spinal nerve pairs
Action Potential & Nerve Impulse
Resting potential: neuron polarized
Threshold reached → action potential fires
Depolarization → Na⁺ rushes in
Repolarization → K⁺ leaves
Myelin speeds conduction (saltatory conduction)
Cranial Nerves
12 pairs
Control senses (vision, smell, taste, hearing), face movement, organs
Spinal Nerves
31 pairs from spinal cord
Mixed nerves: sensory + motor fibers
Innervate body from neck downward
Neurotransmitters
Chemical messengers between neurons
Examples:
Acetylcholine (muscles)
Dopamine (movement, reward)
Serotonin (mood)
Norepinephrine (alertness)
Reflex Arc
Rapid, automatic response
Parts:
Receptor → Sensory neuron → Interneuron (CNS) → Motor neuron → Effector (muscle/gland)
Sympathetic
Fight or Flight, increase heart rate, pupils dilate, uses adrenaline
Parasympathetic
Rest & digest, decrease in heart rate, Pupils constrict, Uses acetylcholine
Disorders/Diseases
Cerebrovascular Accident (Stroke), Autism, Alzheimer's Disease, Spinal Cord Injury, Meningitis,multiple Sclerosis,
Drugs
Meth, Alcohol,Cocaine,LSD,Heroine, Ecstasy, Marijuana