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BIOL110s05-39 - BIOL 110 Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 39, F 5/6/05 http://www.smccd.net/accounts/staplesn/biol110/ • Quiz #7 (Last Quiz!): up by Monday. – http://smcwebtest.smccd.net/accounts/staplesn/index.tpx http://smcwebtest.smccd.net/accounts/staplesn/index.tpx • Extra Credit: Stanford Talk, and 2nd Journal Article due next Wed, 5/11. NO Late E.C. will be accepted!!! • Week 15 Field Trip: Edgewood Park (@ 280 & Edgewood Road) Edgewood – Grade for participation & Worksheet!!! (Replace 1 quiz!!!) – Bring: Good shoes/boots, light-colored clothing/pants, notepad light& worksheet, binoculars?, hat, sunblock, water, snack? worksheet – Mon.: Meet at Old Stage Camp entrance, 1:10pm. We leave up the Sylvan Trail at 1:20pm. – Wed.: Meet at 8:10am, leave at 8:20am. DON’T BE LATE! DON’ • Maps, info: www.friendsofedgewood.org • Next: Ch. 25, 23, 29 & 30, (31, 32). 1 REVIEW: • Ch. 25: Nervous System [& Senses] – Neuron Structure – dentrites/body, trigger zone, dentrites/body, axon, axon termini – Sensory conduction – resting potential, action potential (depolarization), repolarization input TODAY: trigger conducting output • Ch. 25: Nervous System [& Senses] – Nerve synapse, neurotransmitters – Reflex arcs – Central and peripheral nervous systems • Ch. 23: Immunity II. Chemical Synapse • Gap between the terminal ending of an axon and the input zone of another cell neurotransmitter molecule in synaptic cleft receptor for the neurotransmitter on gated channel protein in plasma membrane of postsynapic cell ions that affect membrane excitability plasma membrane of axon ending of presynapic cell synaptic vesicle plasma membrane of postsynapic cell synaptic cleft membrane receptor 2 Postsynaptic Membrane: Ion Gates Open neurotransmitter ions receptor for neurotransmitter gated channel protein slice from spinal chord slice stimulus (input) receptors sensory neurons integrators interneurons of brain, spinal cord motor neurons effectors muscles, glands response (output) motor neuron axons in a nerve leading from spinal chord muscle neuromuscular junction 3 Synaptic Transmission 1. Action potential in axon ending of presynaptic cell causes voltage-gated calcium channels to open 2. Flow of calcium into presynaptic cell causes release of neurotransmitter into synaptic cleft 3. Neurotransmitter diffuses across cleft and binds to receptors on membrane of postsynaptic cell to 4. Binding of neurotransmitter to receptors opens ion channels in the membrane of postsynaptic cell ion Synaptic Transmission Click to view animation. animation 4 Synaptic Integration • Many signals reach a neuron at the same time • Signals may suppress or reinforce one another • Whether or not an action potential occurs depends on the sum of the signals the neuron is receiving Information Flow sensory neuron interneuron motor neuron Cleaning Up • Presence of neurotransmitter in synaptic cleft is normally brief • Molecules diffuse away, are reabsorbed, or broken down – Drugs, such as ecstasy and cocaine, interfere with the reuptake of neurotransmitters 5 III. Nerves • A nerve is a bundle of nerve axons enclosed within a connective tissue sheath • Permit long-distance communication between the brain or spinal cord and the rest of the body axon myelin sheath A. Myelin Sheath • • • A series of Schwann cells Sheath blocks ion movements Action potential must “jump” from node to node (SALTATORY CONDUCTION) • Greatly enhances speed of transmission 6 unsheathed node axon “Jellyrolled” Schwann cells Jellyrolled” of an axon’s myelin sheath axon’ Na+ nodes action potential resting potential resting potential K+ Na+ Saltatory Conduction resting potential resting potential restored action potential Multiple Sclerosis • A condition in which nerve fibers lose their myelin • This slows conduction in these fibers • Symptoms include visual problems, numbness, muscle weakness, and fatigue 7 B. Reflexes • Automatic movements made in response to stimuli • In the simplest reflex arcs, sensory neurons sensory synapse directly on motor neurons • Most reflexes involve an interneuron interneuron Stretch Reflex STIMULUS Biceps stretches. Response Biceps contracts. 8 IV. Central and Peripheral Nervous Systems 1. Central nervous system (CNS) – – Brain Spinal cord 2. Peripheral nervous system – Nerves that thread through the body Peripheral Nervous System Peripheral 1. Somatic nerves – – Motor functions Carry signals to and from skeletal muscle, tendons, and skin Visceral functions Carry signals to and from internal organs and glands • • Sympathetic Parasympathetic 2. Autonomic nerves – – 9 Two Types of Autonomic Nerves a. Sympathetic nerves • Ganglia are near the spinal cord CENTRAL NERVOUS SYSTEM brain spinal cord sensory nerves axons of motor nerves • Promote responses that prepare the body for stress or prepare physical activity – (fight-or-flight response) (fight- or- b. Parasympathetic nerves • Ganglia are in walls of organs • Promote housekeeping housekeeping responses, such as digestion somatic subdivision (motor functions) These nerves carry signals to and from skeletal muscles, tendons, and skin. – Most organs receive input from both – Usually have opposite effects on organ autonomic subdivision (visceral functions) These nerves carry signals to and from internal organs (gut, heart, glands, etc.). parasympathetic sympathetic nerves nerves PERIPHERAL NERVOUS SYSTEM Both Systems Are Usually Active • Most organs are continually receiving both sympathetic and parasympathetic stimulation – EG: sympathetic nerves signal heart to speed up and parasympathetic stimulate it to slow down • Which dominates depends on situation 10 Immunity Chapter 23 Macrophage HIV-infected T-cell HIVT- Edward Jenner’s Experiment • Injected material from a cowpox sore into arm of healthy boy • Six weeks later, injected material from smallpox sores • Boy remained healthy • French called Jenner’s procedure vaccination vaccination – means “encowment” 11 ...
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