Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Axon - Rochester Community Schools
Document related concepts
Transcript
37 Neurons, Synapses, and Signaling © 2014 Pearson Education, Inc. Overview: Lines of Communication • Neurons - nerve cells • Processing Centers • ganglia - simple clusters of neurons • brain - complex organization of neurons © 2014 Pearson Education, Inc. Figure 37.1 © 2014 Pearson Education, Inc. Figure 37.2 Dendrites Stimulus Axon hillock Nucleus Cell body Presynaptic cell Axon Signal direction Synapse Synaptic terminals Synaptic terminals Neurotransmitter © 2014 Pearson Education, Inc. Postsynaptic cell Neuron Structure and Function • cell body – contains most organelles • Dendrites - highly branched extensions, receive signals • Axon long extension, transmits signals to other cells © 2014 Pearson Education, Inc. Figure 37.2 Dendrites Stimulus Axon hillock Nucleus Cell body Presynaptic cell Axon Signal direction Synapse Synaptic terminals Synaptic terminals Neurotransmitter © 2014 Pearson Education, Inc. Postsynaptic cell • Synapse – junctions at ends of axons where neurotransmitters transmit chemical signals to other cells © 2014 Pearson Education, Inc. • glial cells – Nervous system support cells • In the mammalian brain, glia outnumber neurons 10- to 50-fold © 2014 Pearson Education, Inc. Figure 37.3 80 m Glia Cell bodies of neurons © 2014 Pearson Education, Inc. Information Processing • 3 stages of Nervous information processing – Sensory input – Integration – Motor output © 2014 Pearson Education, Inc. Figure 37.4 Sensory input Integration Sensor Motor output Processing center Effector © 2014 Pearson Education, Inc. • Sensory neurons transmit information from sensors • Interneurons in brain or ganglia integrate information • Other Neurons trigger activity (Ex. motor neurons) © 2014 Pearson Education, Inc. • Central nervous system (CNS) – Brain – Spinal cord • Peripheral nervous system – Nerves that thread through the body © 2014 Pearson Education, Inc. Figure 37.5 Dendrites Axon Cell body Portion of axon Sensory neuron © 2014 Pearson Education, Inc. Interneurons Motor neuron Resting Potential • -70millivolt Charge difference across membrane of neuron (Negative Inside) © 2014 Pearson Education, Inc. Ion Concentrations at Resting Potential • Potassium (K+) – Higher inside than outside • Sodium (Na+) – Higher outside than inside © 2014 Pearson Education, Inc. K+ Na + outside plasma membrane K + © 2014 Pearson Education, Inc. Na+ inside p.577 How Ions Move across Membrane Interstitial fluid Cytoplasm Passive transporters with open channels © 2014 Pearson Education, Inc. Passive transporters with voltage-sensitive gated channels Na+/K+ pump Active transporters Lipid bilayer of neuron membrane Figure 34.7 Page 577 Pumping and Leaking Na+ pumped out Interstitial fluid Na+ leaks out Plasma membrane Cytoplasm © 2014 Pearson Education, Inc. Na+ leaks in Na+ pumped in K+ leaks out Figure 34.7 Page 577 Figure 37.6 Key Na OUTSIDE OF CELL K Sodiumpotassium pump Potassium channel Sodium channel © 2014 Pearson Education, Inc. INSIDE OF CELL Action Potential • Temporary reversal in membrane potential • Voltage change causes voltage-gated channels to open • Inside neuron becomes more + than outside © 2014 Pearson Education, Inc. Figure 37.9 Ions Change in membrane potential (voltage) Ion channel (a) Gate closed: No ions flow across membrane. © 2014 Pearson Education, Inc. (b) Gate open: Ions flow through channel. Action Potential 1 Na+ Na+ K+ K+ K+ 2 Na+ K+ K+ K+ K+ Na+ © 2014 Pearson Education, Inc. Na+ Na+ Na+ 3 Na+ Na+ 4 Figure 34.8a-d Page 578-79 All or Nothing • All action potentials are same size • Stimulation below threshold level, no action potential • Above threshold level, always same size © 2014 Pearson Education, Inc. Repolarization • Pumping of Na+ out repolarizes cell back to resting potential © 2014 Pearson Education, Inc. Figure 37.10c (c) Action potential triggered by a depolarization that reaches the threshold Strong depolarizing stimulus Membrane potential (mV) 50 0 −50 −100 © 2014 Pearson Education, Inc. Action potential Threshold Resting potential 0 1 2 3 4 5 Time (msec) Figure 37.11 Key Na K 3 Rising phase of the action potential 4 Falling phase of the action potential Membrane potential (mV) 50 Action potential −50 2 INSIDE OF CELL Inactivation loop 1 Resting state © 2014 Pearson Education, Inc. 2 4 Threshold 1 1 5 Resting potential Depolarization OUTSIDE OF CELL 3 0 −100 Sodium channel Time Potassium channel 5 Undershoot Figure 37.12-1 Axon Action potential Plasma membrane 1 Na © 2014 Pearson Education, Inc. Cytosol Figure 37.12-2 Axon Plasma membrane Action potential 1 Na K Cytosol Action potential 2 Na K © 2014 Pearson Education, Inc. Figure 37.12-3 Axon Plasma membrane Action potential 1 Na K Cytosol Action potential 2 Na K K Action potential 3 Na K © 2014 Pearson Education, Inc. Evolutionary Adaptations of Axon Structure • Vertebrate axons insulated by a myelin sheath of Schwann cells • gaps in the myelin sheath are called nodes of Ranvier © 2014 Pearson Education, Inc. Figure 37.13 Node of Ranvier Layers of myelin Axon Schwann cell Axon Myelin sheath Nodes of Ranvier Schwann cell Nucleus of Schwann cell 0.1 m © 2014 Pearson Education, Inc. Figure 37.14 Schwann cell Depolarized region (node of Ranvier) Cell body Myelin sheath Axon © 2014 Pearson Education, Inc. Generation of Postsynaptic Potentials • neurotransmitters bind to ion channels in the postsynaptic cell which open, generating a postsynaptic potential © 2014 Pearson Education, Inc. Figure 37.15 Presynaptic cell Axon Postsynaptic cell Synaptic vesicle containing neurotransmitter 1 Synaptic cleft Postsynaptic membrane Presynaptic membrane 3 K 4 Ca2 2 Voltage-gated Ca2 channel © 2014 Pearson Education, Inc. Ligand-gated ion channels Na • Postsynaptic potentials may be… • Excitatory postsynaptic potentials (EPSPs) or… • Inhibitory postsynaptic potentials (IPSPs) © 2014 Pearson Education, Inc. 38 Nervous and Sensory Systems Nervous and Sensory Systems © 2014 Pearson Education, Inc. Figure 38.1 © 2014 Pearson Education, Inc. Figure 38.2 Eyespot Brain Nerve cords Nerve net Transverse nerve (a) Hydra (cnidarian) (b) Planarian (flatworm) Brain Brain Ventral nerve cord Spinal cord (dorsal nerve cord) Sensory ganglia Segmental ganglia (c) Insect (arthropod) © 2014 Pearson Education, Inc. (d) Salamander (vertebrate) • Multiple nerve cells bundled form nerves • Cephalization -clustering of sensory neurons and interneurons at the anterior © 2014 Pearson Education, Inc. Figure 38.3 CNS PNS Neuron VENTRICLE Cilia Oligodendrocyte Schwann cell Microglial cell Capillary Ependymal cell Astrocytes 50 m Intermingling of astrocytes with neurons (blue) © 2014 Pearson Education, Inc. LM Figure 38.4 Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Cranial nerves Ganglia outside CNS Spinal nerves © 2014 Pearson Education, Inc. The Peripheral Nervous System • afferent neurons transmit to the CNS • efferent neurons transmit away from the CNS © 2014 Pearson Education, Inc. Figure 38.5 Central Nervous System (information processing) Peripheral Nervous System Afferent neurons Efferent neurons Sensory receptors Autonomic nervous system Motor system Control of skeletal muscle Internal and external stimuli Sympathetic Parasympathetic division division Enteric division Control of smooth muscles, cardiac muscles, glands © 2014 Pearson Education, Inc. • 2 efferent PNS components: • The motor system controls skeletal muscles and (voluntary or involuntary) • The autonomic nervous system regulates smooth and cardiac muscles © 2014 Pearson Education, Inc. • The autonomic nervous system has sympathetic, parasympathetic, and enteric divisions • The enteric controls the digestive tract, pancreas, and gallbladder • Sympathetic regulates the “fight-or-flight” response • Parasympathetic promotes calming and “rest and digest” functions © 2014 Pearson Education, Inc. Figure 38.6a © 2014 Pearson Education, Inc. Figure 38.6b Brain structures in child and adult Embryonic brain regions Telencephalon Cerebrum (includes cerebral cortex, white matter, basal nuclei) Diencephalon Diencephalon (thalamus, hypothalamus, epithalamus) Mesencephalon Midbrain (part of brainstem) Metencephalon Pons (part of brainstem), cerebellum Myelencephalon Medulla oblongata (part of brainstem) Forebrain Midbrain Hindbrain Midbrain Hindbrain Mesencephalon Metencephalon Diencephalon Cerebrum Diencephalon Myelencephalon Midbrain Pons Forebrain Embryo at 1 month © 2014 Pearson Education, Inc. Telencephalon Medulla oblongata Cerebellum Spinal cord Spinal cord Embryo at 5 weeks Child Figure 38.6c Left cerebral hemisphere Right cerebral hemisphere Cerebral cortex Corpus callosum Cerebrum Basal nuclei Cerebellum Adult brain viewed from the rear © 2014 Pearson Education, Inc. Figure 38.6d Diencephalon Thalamus Pineal gland Hypothalamus Pituitary gland Brainstem Midbrain Pons Medulla oblongata Spinal cord © 2014 Pearson Education, Inc. Figure 38.10 Nucleus accumbens Happy music © 2014 Pearson Education, Inc. Amygdala Sad music Figure 38.11 Motor cortex (control of skeletal muscles) Frontal lobe Somatosensory cortex (sense of touch) Parietal lobe Prefrontal cortex (decision making, planning) Broca’s area (forming speech) Temporal lobe Auditory cortex (hearing) Cerebellum Wernicke’s area (comprehending language) © 2014 Pearson Education, Inc. Sensory association cortex (integration of sensory information) Visual association cortex (combining images and object recognition) Occipital lobe Visual cortex (processing visual stimuli and pattern recognition) Figure 38.16 Gentle pressure Sensory receptor Low frequency of action potentials More pressure High frequency of action potentials © 2014 Pearson Education, Inc. Perception • Perception is the brain’s construction of stimuli • Sensory adaptation is a decrease in responsiveness to continued stimulation © 2014 Pearson Education, Inc. Types of Sensory Receptors • Based on energy transduced, sensory receptors fall into five categories – Mechanoreceptors – Electromagnetic receptors – Thermoreceptors – Pain receptors (nociceptors) – Chemoreceptors © 2014 Pearson Education, Inc. Figure 38.17a Eye Infrared receptor (a) Rattlesnake © 2014 Pearson Education, Inc. • types of mammal taste receptors: sweet, sour, salty, bitter, and umami © 2014 Pearson Education, Inc. Figure 38.18 Papilla Tongue Papillae Taste buds Taste bud Key Sweet Salty Sour Bitter Umami Taste pore Sensory neuron © 2014 Pearson Education, Inc. Food molecules Sensory receptor cells Sensing of Gravity and Sound in Invertebrates • Most invertebrates maintain equilibrium using statocysts • contain mechanoreceptors that detect the movement of statoliths Ciliated receptor cells Cilia Statolith Sensory nerve fibers (axons) © 2014 Pearson Education, Inc. Figure 38.20 Middle ear Outer ear Skull bone Inner ear Stapes Incus Malleus Semicircular canals Cochlear duct Auditory nerve to brain Bone Auditory nerve Vestibular canal Tympanic canal Cochlea Pinna Oval Auditory window canal Tympanic Round membrane window Eustachian tube Organ of Corti 1 m Tectorial membrane Bundled hairs projecting from a hair cell (SEM) © 2014 Pearson Education, Inc. Basilar Hair membrane cells Axons of sensory neurons To auditory nerve Figure 38.20b Cochlear duct Bone Auditory nerve Vestibular canal Tympanic canal Organ of Corti © 2014 Pearson Education, Inc. Figure 38.20c Tectorial membrane Basilar membrane © 2014 Pearson Education, Inc. Hair cells Axons of sensory neurons To auditory nerve 1 m Figure 38.20d Bundled hairs projecting from a hair cell (SEM) © 2014 Pearson Education, Inc. Hearing • tympanic membrane vibrates in response to vibrations in air • bones of middle ear transmit vibrations to the oval window on the cochlea • This creates pressure waves in the fluid in the cochlea that travel through the vestibular canal • These cause hair cells to vibrate creating action potentials © 2014 Pearson Education, Inc. Figure 38.21 More neurotransmitter Less neurotransmitter 0 −70 Time (sec) (a) Bending of hairs in one direction Membrane potential (mV) −70 0 1 2 3 4 5 6 7 © 2014 Pearson Education, Inc. −50 Signal Membrane potential (mV) Signal Receptor −50 potential Receptor potential −70 0 −70 0 1 2 3 4 5 6 7 Time (sec) (b) Bending of hairs in other direction Equilibrium • Detecting movement, position, and balance – The inner ear contains granules called otoliths that allow us to perceive position relative to gravity or linear movement – Three semicircular canals contain fluid and can detect angular movement in any direction © 2014 Pearson Education, Inc. Figure 38.22 Semicircular canals PERILYMPH Cupula Vestibular nerve Fluid flow Hairs Hair cell Vestibule Utricle Saccule © 2014 Pearson Education, Inc. Nerve fibers Body movement Figure 38.23 LIGHT DARK Photoreceptor Ocellus Visual pigment Ocellus © 2014 Pearson Education, Inc. Nerve to brain Screening pigment Compound Eyes • Insects and crustaceans have compound eyes, made of segments called ommatidia • Compound eyes are very effective at detecting movement © 2014 Pearson Education, Inc. Figure 38.24 2 mm © 2014 Pearson Education, Inc. Invertebrate Eyes Limpet ocellus ommatidium cuticle epidermis lens Compound eye of a deerfly sensory neuron © 2014 Pearson Education, Inc. Land snail eye Figures 35.13 & 35.14 Pages 608 & 609 Invertebrate Eyes © 2014 Pearson Education, Inc. Fig. 35-13d, p.608 Invertebrate Eyes © 2014 Pearson Education, Inc. Fig. 35-1,e, p.608 vitreous body lens cornea © 2014 Pearson Education, Inc. retina optic tract Fig. 35-15, p.609 © 2014 Pearson Education, Inc. Fig. 35-16, p.610 Figure 38.25aa Sclera Suspensory ligament Choroid Retina Fovea Cornea Iris Optic nerve Pupil Aqueous humor Lens Vitreous humor © 2014 Pearson Education, Inc. Optic disk Central artery and vein of the retina Single-Lens Eyes • iris changes pupil diameter • Muscles change the shape of the lens (Visual Accommodation) to focus image on retina • photons stimulate rods and cones • However, it is the brain that “sees” © 2014 Pearson Education, Inc. Pattern of Stimulation © 2014 Pearson Education, Inc. Figure 35.18a Page 611 a Light rays from an object converge on the retina, form an inverted, reversed image. muscle contracted b When a ciliary muscle contracts, the lens bulges, bending the light rays from a close object so that they become focused on the retina. close object slack fibers muscle relaxed c When the muscle relaxes, the lens flattens, focusing light rays from a distant object on the retina. © 2014 Pearson Education, Inc. distant object taut fibers Fig. 35-18, p.611 Figure 38.25ab Retina Photoreceptors Neurons Optic nerve fibers © 2014 Pearson Education, Inc. Rod Ganglion Bipolar Horizontal cell cell cell Amacrine cell Cone Pigmented epithelium The Photoreceptors • Rods – Contain the pigment rhodopsin – Detects dim light, changes in intensity • Cones – Three kinds; detect red, blue, or green – Provide color sense © 2014 Pearson Education, Inc. Figure 38.25ba Rod Synaptic terminal Cone Rod Cone © 2014 Pearson Education, Inc. Cell body Outer Disks segment Color Vision • Among vertebrates, most fish, amphibians, and reptiles, including birds, have very good color vision • Humans and other primates are among the minority of mammals with the ability to see color well • Mammals that are nocturnal usually have a high proportion of rods in the retina © 2014 Pearson Education, Inc. Fovea and Optic Nerve fovea start of an optic nerve in back of the eyeball © 2014 Pearson Education, Inc. Fig. 35-22, p.613 Retina to Brain optic retina nerve © 2014 Pearson Education, Inc. lateral geniculate nucleus visual cortex Figure 35.23 Page 613 (focal point) distant object © 2014 Pearson Education, Inc. Nearsighted Vs Farsighted Fig. 35-24a, p.614 (focal point) close object © 2014 Pearson Education, Inc. Nearsighted Vs Farsighted Fig. 35-24b, p.614 BEHAVIOR!! © 2014 Pearson Education, Inc. Pheromones • Many animals communicate through chemical substances called pheromones © 2014 Pearson Education, Inc. Animal Behavior - Types 2 Types of Behavior Innate (Nature): instinct and genes determine behavior Learned (Nurture): experience and learning influence behavior © 2014 Pearson Education, Inc. Animal Behavior - Types - Innate Components of Innate Behavior Fixed action pattern all or none response - once started must be performed to completion Sign stimulus (Releaser) - stimulus that causes release of FAP © 2014 Pearson Education, Inc. Figure 39.15 (a) (b) © 2014 Pearson Education, Inc. Figure 39.16a (a) Worker bees © 2014 Pearson Education, Inc. Figure 39.16c (c) Waggle dance (food distant) A 30 C B Beehive Location A © 2014 Pearson Education, Inc. Location B Location C Learned Behavior – – – – – Habituation classical conditioning operant conditioning insight learning Imprinting © 2014 Pearson Education, Inc. Figure 39.UN03 Imprinting Learning and problem solving Cognition Associative learning © 2014 Pearson Education, Inc. Spatial learning Social learning Habituation The animal decreases or stops response to a repetitive stimulus that neither rewards nor harms it. Example - a worm may stop responding a to shadow if it neither hurts nor helps it © 2014 Pearson Education, Inc. Classical/Pavlovian Conditioning The animal makes a mental connection between a stimulus and some kind of reward or punishment. © 2014 Pearson Education, Inc. Classical/Pavlovian Conditioning • © 2014 Pearson Education, Inc. Classical/Pavlovian Conditioning © 2014 Pearson Education, Inc. Classical/Pavlovian Conditioning © 2014 Pearson Education, Inc. Figure 39.19a © 2014 Pearson Education, Inc. Figure 39.19b © 2014 Pearson Education, Inc. Figure 39.19c © 2014 Pearson Education, Inc. Spatial Learning and Cognitive Maps • Spatial learning learning the environment • Niko Tinbergen showed how digger wasps use landmarks to find nest entrances © 2014 Pearson Education, Inc. Figure 39.18 Experiment Nest Pinecone Results Nest © 2014 Pearson Education, Inc. No nest Operant Conditioning The animal learns to behave in a certain way through repeated practice, in order to receive a reward or avoid punishment. also called trial-and-error learning. First described by B. F. Skinner. Know about Skinner and the “Skinner box.” © 2014 Pearson Education, Inc. Insight learning Also called reasoning. The animal applies prior knowledge to a new situation, without trial and error. • common in humans and other primates. © 2014 Pearson Education, Inc. Imprinting learning during a critical period during development Once imprinting occurs, the behavior cannot be changed. © 2014 Pearson Education, Inc. Figure 39.17 (a) Konrad Lorenz and geese © 2014 Pearson Education, Inc. (b) Pilot and cranes © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Imprinting Examples Many Birds learn that the first things they see move are their parents salmon learn their home stream’s scent as they swim downstream birds learn their song during a short critical period (if a bird does not hear the proper song during this time it will never learn it correctly) © 2014 Pearson Education, Inc. Imprinting Sexual imprinting - Learning to recognize members of one`s own species - sometimes individuals raised by another species will attempt to mate with foster species as adult © 2014 Pearson Education, Inc. Figure 39.22 © 2014 Pearson Education, Inc. Figure 39.23 © 2014 Pearson Education, Inc.
