Download Understanding the Nervous System & Senses: Neurons, Events, Synapses, & Processing and more Slides Botany and Agronomy in PDF only on Docsity! Nervous System and Senses Docsity.com Neural Activity Docsity.com Resting potential • Using active transport, the neuron moves N+ ions to the outside of the cell and K+ ions to the inside of the cell. • Large molecules in the cell maintain a negative charge. Docsity.com Action potential • On receiving a stimulus, sodium gates and potassium channels open briefly, allowing these ions to diffuse. • The gates close, and active transport restores the resting potential. Docsity.com Traveling Potentials
An action potential jumps
from node to node, greatly
speeding up conduction
down the axon
Schwann cell
myelin
sheath
axon
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Information Processing Docsity.com Why a CNS? • Neurons control movement. The brain (or spine) interprets sensory signals and determines the appropriate movements (that is, behavior). • Appropriate movement is critical to the survival of most animal species. • Selection has favored a central nervous system to control responses. Docsity.com Four basic operations • Determine type of stimulus • Signal the intensity of a stimulus • Integrate responses from many sources • Initiate and direct operations Docsity.com Integration of stimuli • Convergence = Signals may arrive through many neurons, but may all pass their signal to a single connecting neuron. • Such cells may be “decision-making” association neurons that may determine an appropriate output. Docsity.com Directing operations • Neural pathways consist of: • Sensory neurons • Association neurons, which receive signals from many sources • Motor neurons • Effectors: muscles, glands Docsity.com Reflexes • The simplest neural pathway is the reflex arc. • This involves one or more sensory neurons, association neurons in the spine, and motor neurons, which carry out the reflex entirely before the brain is aware of the response. Docsity.com Neural organization
Peripheral Nervous System (PNS)
transmits signals between the CNS
and the rest of the body
—
Motor Neurons Sensory Neurons
carry signals from the carry signals to
CNS that control the the CNS from
activities of muscles sensory organs
and glands
al
Somatic Nervous System Autonomic Nervous System
controls voluntary controls involuntary responses
movements by activating by influencing organs, glands,
skeletal muscles and smooth muscle
es
Sympathetic Division Parasympathetic Division
B prepares the body for dominates during times of
stressful or energetic “rest and rumination’;
activity; “fight or flight" directs maintenance activities
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Central Nervous System • Consists of brain and spine • Functions: • Receives sensory signals and determines appropriate response • Stores memory • Carries out thought Docsity.com Spine: structure • The spinal cord is protected by the vertebrae. • Gray matter contains cell bodies; white matter contains myelinated fibers. • PNS nerves extend outside of the vertebrae. Docsity.com Somatic nervous system • Motor neurons that control voluntary movements by activating skeletal muscles. • Also involved in what we perceive as involuntary movements, such as reflexes (though voluntary control of the muscles involved, such as tensing them, can reduce the response). Docsity.com Autonomic Nervous System • Motor neurons that control involuntary responses involving the organs, glands, and smooth muscles. Docsity.com Sympathetic division • Portion of the autonomic nervous system that produces the “fight or flight” response: • Dilation of pupils • Increased heart and breathing rates • Constriction of blood vessels • Inhibits digestion Docsity.com
