Lesson 35 - The Nervous System

35: the nervous system Monday, April 22, 2024 12:52 PM generating and propagating signals • resting potential is formed by an electrochemical gradient across the cell membrane • depolarization beyond the membrane potential threshold leads to an action potential • action potential is due to a rapid flow of Na+ into the cell, then a rapid flow of K+ out of the cell • action potential is propagated down the axon nervous systems • sensory cells appeared billions of years ago • more organized nervous systems date back to the Cambrian explosion • nervous systems can be relatively simple • nerve net controls gastrovascular cavity • specific routes for information in sea star, but limited central processing • nervous systems become more specialized in bilaterians • cephalization: clustering of sensory neurons and interneurons in front of body • simple CNS: brain and nerve cords • more complex CNS: includes ganglia (clusters of neurons), regional specialization • more complex CNS: includes ganglia (clusters of neurons), regional specialization nervous systems are made of neurons • neurons for integration make up the central nervous system (CNS) ○ brain and spinal cord • neurons carrying information into CNS make up the peripheral nervous system (PNS) ○ nerves and ganglia • glia support neurons ○ insulate axons ○ nourish neurons vertebrate central nervous system • brain and spinal cord ○ develop form dorsal hollow nerve cord • grey matter: neuron cell bodies • white matter: bundled axons vertebrate central nervous system • brain and spinal cord ○ develop form dorsal hollow nerve cord • grey matter: neuron cell bodies • white matter: bundled axons • cerebrospinal fluid: ○ supplies CNS with nutrients and hormones ○ removes waste the dorsal hollow nerve cord develops into the brain and spinal cord. what derived trait of all chordates plays a key role in supporting the vertebrate CNS? a. vertebrae b. notochord c. pharyngeal gill slits d. post-anal tail cerebrospinal fluid also plays a key role in the regulation of what physiological process? a. digestion b. excretion c. gas exchange d. circulation peripheral nervous system • transmits information to and from CNS • regulates movement, internal environment d. circulation peripheral nervous system • transmits information to and from CNS • regulates movement, internal environment • afferent neurons: ○ PNS gives information to CNS • efferent neurons: ○ PNS gives information to muscles, glands, endocrine cells • motor system: ○ neurons carry info to skeletal muscles ○ voluntary or involuntary (reflex) • autonomic nervous system: ○ 3 divisions: sympathetic, parasympathetic, enteric ○ generally involuntary ○ controls digestive, cardiovascular, excretory, and endocrine organs • sympathetic division: fight or flight ○ usually antagonist function • parasympathetic division: rest and digest ○ usually antagonist function if i announced a pop quiz in class, the ______ system might become highly active. if i announced a pop quiz in class, the ______ system might become highly active. a. enteric nervous b. motor system c. parasympathetic nervous d. sympathetic nervous the brain • 3 major regions ○ forebrain: complex processing, smell, sleep, learning ○ midbrain: routing of sensory information ○ hindbrain: involuntary activities, motor activities • size of regions related to importance of function • cerebrum: ○ forebrain ○ center for learning, emotion, memory, perception ○ voluntary motor function • cerebellum: ○ hindbrain ○ movement, motor skills, visual, and auditory input • diencephalon: ○ forebrain ○ thalamus: sensory input to cerebrum ○ hypothalamus: internal regulation • brainstem: ○ midbrain and hindbrain ○ integrates hearing, visual reflexes ○ forebrain ○ thalamus: sensory input to cerebrum ○ hypothalamus: internal regulation • brainstem: ○ midbrain and hindbrain ○ integrates hearing, visual reflexes ○ medulla and pons: automatic functions, coordinated movement