Neurons and Nervous System: Structure, Function, and Signal Transmission, Slides of Botany and Agronomy

Download Neurons and Nervous System: Structure, Function, and Signal Transmission 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 © 2011 Pearson Education, Inc. Docsity.com Some Neurotransmitters Neurotransmitter Location Some Functions Acetylcholine Neuron-to-muscle synapse Activates muscles Dopamine Mid-brain Control of movement Epinephrine Sympathetic system Stress response Serotonin Midbrain, pons, medulla Mood, sleep Endorphins Brain, spine Mood, pain reduction Nitric oxide Brain Memory storage Docsity.com During resting potential, which channels are closed? 1 2 3 4 25% 25%25%25% 1. Potassium 2. Sodium 3. All 4. None Docsity.com What determines the intensity of a neural signal? 1 2 3 4 25% 25%25%25%1. Speed of action potential. 2. Size of action potential. 3. Duration of action potential. 4. Frequency of action potentials. Docsity.com 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 • You’re probably all familiar with the knee- jerk reflex, which your doctor uses to test your reflexes. Sketch a reflex arc for the knee jerk reflex, beginning with whacking your knee with a hammer. Label the sensor and effector in your diagram. W O R K T O G E T H E R Docsity.com Organization 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 Docsity.com Brain: Structure • Hindbrain carries out the most basic functions. • Midbrain coordinates signals. • Forebrain processes signals, stores memories, creates thought. Docsity.com Peripheral nervous system • Nerves, neurons, and sensory organs outside the central nervous system • Functions: • Sends signals to the CNS • Receives and transmits motor signals from the CNS • Stimulates effectors 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 Parasympathetic Division • Portion of the autonomic nervous system that produces the “rest and ruminate” response: • Constricts pupils • Dilates blood vessels • Reduces heart and breathing rates. • Stimulates digestion. Docsity.com The central nervous system includes: 1 2 3 4 25% 25%25%25% 1. Brain only 2. Brain and spine 3. Brain, spine, and major nerves 4. Spine and major nerves Docsity.com Motor neurons carry signals which direction? 1 2 3 4 25% 25%25%25% 1. Sensory organs -> CNS 2. Muscles -> CNS 3. CNS -> sensory organs 4. CNS -> muscles Docsity.com