nervous system
DESCRIPTION
Nervous System. AP Biology Ch. 48 Ms. Haut. Function of Nervous System. Sensory Input Conduction of signals from sensory receptors Integration Carried out by Central Nervous System (CNS) Brain and spinal cord Motor Output Carried out by Peripheral Nervous System (PNS) - PowerPoint PPT PresentationTRANSCRIPT
Nervous SystemNervous System
AP Biology
Ch. 48
Ms. Haut
Function of Nervous SystemFunction of Nervous System
Sensory Input– Conduction of signals from sensory receptors
Integration– Carried out by Central Nervous System (CNS)
Brain and spinal cord
Motor Output– Carried out by Peripheral Nervous System (PNS)– Conduction of signals to muscle or gland cells– Carry out body’s responses to stimuli
Animal Nerve Cells Animal Nerve Cells Nerves: rope-like bundles of extensions of
neurons, tightly wrapped in connective tissue
Neurons: functional unit of the nervous system
Functional Organization of Functional Organization of NeuronsNeurons
Sensory Neurons: relay information (stimuli) from the external and internal environments to CNS
Interneurons: integrate sensory input and motor output (carry stimuli in the brain and spinal cord)
Motor Neurons: convey impulses from CNS to effector cells in muscles or glands
Glial cells: support, protect, and nourish neurons
Structural Diversity of NeuronsStructural Diversity of Neurons
Overview of Vertebrate Nervous SystemOverview of Vertebrate Nervous System
Neuron CircuitryNeuron Circuitry
Simplest neural circuit involves synapses between 2 neurons, a sensory neuron and a motor neuron
Result is often an automatic response called a reflex
The Knee-jerk ReflexThe Knee-jerk Reflex
http://bio.rutgers.edu/~gb102/lab_5/103ar.html
Neural SignalsNeural Signals
Nerve impulse is an electrical signal that depends on the flow of ions across the plasma membrane of a neuron
Membrane Resting PotentialMembrane Resting Potential
Cell is said to be polarized
Action PotentialAction Potential
A nerve impulse is generated when the difference in electrical charge disappears
Occurs when a stimulus contacts the tip of a dendrite and increases the permeability of the cell membrane to Na+ ions
Cell is said to be depolarized
Graded PotentialsGraded Potentials
“All-or-none event”
Regulation of Action PotentialRegulation of Action Potential
Propagation Propagation of the Action of the Action
PotentialPotential After the wave
of depolarization has passed, the neuron reestablishes the difference in charges by pumping K+ out of the cytoplasm
Saltatory ConductionSaltatory Conduction
SynapsesSynapses
Nerve impulses pass down the dendrite, through the cell body, and down the axon.
At the end of the axon, the signal reaches a fluid-filled space (synapse) separating the end of the axon from the dendrite of the next neuron.
Neuromuscular junction: synapse located at the junction of a neuron and muscle fiber
Chemical SynapseChemical Synapse
MAJOR NEUROTRANSMITTERS AND THEIR EFFECTS
Acetylcholine (ACh)
Generally excitatory
Affects arousal, attention, memory, motivation, movement. Too much: spasms, tremors. Too little: paralysis, torpor.
Dopamine Inhibitory Inhibits wide range of behavior and emotions, including pleasure. Implicated in schizophrenia and Parkinson's disease.
Serotonin Inhibitory Inhibits virtually all activities. Important for sleep onset, mood, eating behavior.
Norepinephrine Generally excitatory
Affects arousal, wakefulness, learning, memory, mood.
Endorphins Inhibitory Inhibit transmission of pain messages.
Organizations of InvertebratesOrganizations of InvertebratesWithout CNS
CN
S
CN
S
(PNS)
Vertebrate Vertebrate Nervous Nervous SystemSystem
Autonomic Nervous SystemAutonomic Nervous System
Works on an involuntary basis2 subdivisions
Parasympathetic Sympathetic
Return body to normal after an emergency
Prepare body for emergency
Heart rate slows, pupils constrict, blood vessels dilate
Increase heart rate, constricted blood vessels, pupils dilate
Roles of Roles of Parasympathetic Parasympathetic and Sympathetic and Sympathetic Divisions of the Divisions of the Autonomic Autonomic Nervous SystemNervous System
Structure of BrainStructure of Brain
BrainstemBrainstem Medulla oblongata
– Contains centers that control visceral (autonomic, homeostatic) functions
Breathing, heart and blood vessel activity, swallowing, vomiting, and digestion
Pons – Have nuclei in the medulla that regulate breathing centers
Midbrain– Centers for receipt and integration of sensory information
Coordinates large-scale body movements such as walking
CerebellumCerebellum
Primary function is coordination of movement
Receives information about position from joints and length of muscles, as well as auditory and visual systems
Plays role in learning and remembering motor responses (hand-eye coordination)
Thalamus and Thalamus and HypothalamusHypothalamus Thalamus
– Main input center for sensory information going to cerebrum– Receives input from cerebrum to regulate emotion and
arousal Hypothalamus
– Source of posterior pituitary hormones and releasing hormones that act on anterior pituitary
– Regulates body temp, thirst, hunger, other basic survival mechanisms
– Plays role in sexual response and mating behaviors, fight-or-flight response, and pleasure
Structure and Function of Structure and Function of CerebrumCerebrum
Sleep and ArousalSleep and Arousal
Controlled by several centers in the cerebrum and brainstem
Reticular formation: neurons that pass through the brainstem– Reticular activating system--regulates sleep and arousal– Increased input to cortex, increases alertness
Medulla and pons– Nuclei stimulated induces sleep– Serotonin may activate sleep centers
Lateralization, Language, and Lateralization, Language, and SpeechSpeech
Association areas of cerebral cortex are lateralized (specialized functions)
Left hemisphere– Speech, language, calculation, and rapid serial
processing of details
Right hemisphere– Overall context, spatial perception, and creative
abilities
EmotionsEmotions
Limbic system-functional group of nuclei and interconnecting axon tracts in the CNS– Includes parts of the thalamus and hypothalamus, and
portions of the cerebral cortex– Linked to areas of cerebral cortex involved with
complex learning, reasoning, and personality
Amygdala-prominent component of limbic system– Major organizer of emotional information– Plays role in memory association