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Weird body facts fly larvae helps to heal wounds quicker long ago, some doctors noticed soldiers that had maggots on their wounds healed quicker than those without maggots. maggots eat the dead skin cells and bacteria. maggot therapy (also known as maggot debridement therapy (mdt), larval therapy, larva therapy, or larvae therapy) is the intentional introduction of live, disinfected maggots or fly larvae into non-healing skin or soft tissue wounds of a human or other animal. this practice was widely used before the discovery of antibiotics, as it serves to clean the dead tissue within a wound in order to promote healing. ? Sulci -fissures between convolutions of brain ORGANIZATION OF THE NERVOUS SYSTEM The Nervous System Central Nervous System Brain Spinal Cord Peripheral Nervous System Somatic Autonomic Parasympathetic Sensory Motor Sympathetic VERTEBRATE NERVOUS SYSTEM Two divisions: Central nervous system (CNS)- act as a coordinating centre (brain & spinal cord) Peripheral nervous system (PNS)- effectors, carry information to and from the CNS. Further divided into Somatic – control skeletal muscle, bones & skin Autonomic – control internal organs of body Sympathetic Parasympathetic ANATOMY OF A NERVE CELL ANATOMY OF NERVE CELLS Two different types of cells Glial (neurological cells; non-conducting, offer structural support and metabolism of nerve cells) Neurons (functional units of nervous system) Three groups Sensory Neurons Interneurons Motor Neurons http://www.youtube.com/watch?v=FZ3401XVYww&feature=related THREE TYPES OF NEURONS Sensory (Afferent) Neurons Interneurons INPUT – from sensory organs to brain and spinal cord Sense and relay information from environment to CNS Located in clusters called ganglia PROCESSING Link neurons within body Integrate and interpret sensory information and connect neurons to outgoing motor neurons Motor (Efferent) Neurons OUTPUT Relay information to effectors, (muscles, organs, glands; effectors as they produce responses) away from the CNS RELAYING THE SIGNAL Messages move from dendrite, through the nerve cell body, to the axon Axons are covered with a myelin sheath (insulation), made by Schwann cells which prevent loss of charged ions from nerve cells Areas between sections of myelin are called nodes of Ranvier; nerve impulses jump from one node to another, speeding up messages All nerve fibres found within peripheral nervous system contain a thin membrane called neurilemma which surrounds axon Neurilemma promotes regeneration of damaged axons Not all nerve cells contain neurilemma and a myelin sheath Nerves containing mylenated fibres and neurilemma called white matter due to whitish appearance Grey matter lack myelin sheath and neurilemma and do not regenerate after injury MULTIPLE SCLEROSIS – MYELIN SHEATH DESTRUCTION THE REFLEX ARC The simplest neural circuit is the reflex arc. Reflexes are involuntary. No brain coordination is used. 5 essential components: Receptor Sensory neuron Interneuron (in spinal cord) Motor neuron Effector REFLEX ARC http://www.youtube.com/watch?v=Y5nj3ZfeYDQ HOMEWORK Complete Move Fast! Poster lab write-up Read pg 354-360 Q’s #7, 9, & 10 ELECTROCHEMICAL IMPULSE The Electrocardiogram (ECG) is used to diagnose heart problems. The Electroencephalograph (EEG) is used to measure brain-wave activity Action Potential – the voltage difference across a nerve cell membrane when the nerve is excited Resting Potential – voltage difference across a nerve cell membrane during the resting stage (usually negative) Unlike most cells, neurons have a rich supply of positive and negative ions inside and outside the cell A sodiumpotassium pump maintains resting membrane potential after ions “leak” down their concentration gradient - 3 Na+ ions are actively pumped out while 2 K+ ions are pumped in. ACTION POTENTIAL • action potentials – the movement of an electrical impulse along the plasma membrane of an axon. • • that are abrupt, pulse-like changes in the membrane potential that last a few ten thousandths of a second. • Action potentials can be divided into three phases: the resting or polarized state, depolarization, and repolarization • The amplitude of an action potential is nearly constant and is not related to the size of the stimulus, so action potentials are all-or-nothing events. Depolarization must be completed and the nerve repolarized before the next action potential can be conducted as nerves conducting an impulse cannot be activated until the condition of the resting membrane is restored This time is called the refractory period (usually 1-10 ms) Action Potential ION GATES CONTROL THE MOVEMENT OF IONS ACROSS THE CELL MEMBRANE. The separation of electrical charges by the “polarized membrane” has the ability to do work, expressed in millivolts (mV). Upon excitation, nerve cell membrane becomes more permeable to Na than K Na ions rush into cell causing depolarization Once voltage inside cell is +ve, then Na gates close The sodium-potassium pump located in cell membrane restores condition of resting membrane by transporting Na+ ions out of the neuron while moving potassium ions inside the neuron in a ration of 3 Na+: 2K+ ions ATP fuels the pump Saltatory Conduction ALL OR NONE RESPONSE A nerve or muscle fibre responds completely or not to a stimulus. Nerves have a threshold level…minimum level of a stimulus required to produce a response. HOMEWORK • Watch Nerve Impulse Animation and make notes • Synapses - Mouse Party Task: Due Friday June 3rd Go to:http://learn.genetics.utah.edu/content/addiction/dr ugs/mouse.html – Explore the effects of any three of the following drugs on brain function in mice: • • – Heroine, ecstasy, marijuana, methamphetamine, alcohol, cocaine, LSD In your own words, explain how the drug affects brain function and draw a labeled diagram of the synapse depicting the effects for each drug Terminology • Synapse – Region at which neurons come nearly together to communicate. (neuron or effector organ) • Synaptic Cleft – Gap between neurons (at a synapse) – Impulses can not propagate across a cleft • Synaptic Vesicle – Packets of neurotransmitter in presynaptic neuron • Presynaptic Neuron – Neuron sending a signal (before the synapse) • Postsynaptic Neuron – Neuron receiving a signal (after the synapse) Neurotransmitters 5 general criteria: 1) synthesized and released by neurons 2) released at the nerve terminal in a 'chemically identifiable' form 3) the chemical should reproduce the activity of the presynaptic neuron 4) can be blocked by competitive antagonist based on concentration 5) active mechanisms to stop the function of the neurotransmitter Classical transmitters are small molecules (often amino acid based) Non-classical transmitters can be peptides or even gasses 5 Steps of Neurotransmission 1) synthesis of the neurotransmitter precursors and enzymes should be in the correct place 2) storage of neurotransmitter OR precursor often stored in presynaptic vesicles 5 Steps of Neurotransmission 3) release of the neurotransmitter generally by vesicle fusion 4) binding to target receptor ionotropic receptors open ion channels metabotropic receptors modulate other signals 5 Steps of Neurotransmission 5) termination of the signal active termination caused by reuptake or chemical breakdown *For e.g. acetylcholine is broken down by . . . passive termination uses diffusion Types of Neurotransmitters Acetylcholine + muscles, learning, memory Serotonin (a derivative of tryptophan) Norepinephrine (aka noradrenaline) Dopamine Endorphins + sleep, relaxation, self esteem, too little = depression, perception + stress and fight/flight response, sympathetic NS:+BP & heart rate + prolactin (milk production), involved in pleasure, movement (-) pain, involved in pleasure GABA (gamma aminobutyric acid) Glutamate (-) anxiety, too little in parts of brain can lead to epilepsy Most common NT, memory, toxic “FLIGHT OR FIGHT RESPONSE” Sympathetic component prepares body for stress [neurotransmitter used=norepinephrine] •Diverts blood from internal organs to skeletal muscles, heart & brain Parasympathetic brings things back to normal [neurotransmitter used=acetylcholine] •Work in conjunction/opposition to each other –Ex. “on” / “off” switches You come across a bear on your walk to school…what happens? • • • • • • Sympathetic nervous system does what? Increases heart rate Increases breathing rate Dilates bronchioles Dilates pupils Inhibits digestion Acetylcholine – make post-synaptic membrane permeable to Na+ Cholinesterase (enzyme)…breaks down Acetyltcholine...prevents constant depolarization CENTRAL NERVOUS SYSTEM concentrated in the anterior portion of most animals brain is covered by meninges three-layer protective membrane forms the blood/brain barrier cerebrospinal fluid surrounds brain and spinal cord acts as a shock absorber and a transportation medium of materials determines which chemicals will reach the brain carries nutrients to brain cells relays wastes from cells to blood THE SPINAL CORD carries sensory nerve messages from receptors of brain and relays motor nerve messages to muscles organs glands interneurons are organized into nerve tracts which connect the spinal cord with the brain dorsal nerve tract brings sensory info into spinal cord ventral nerve tract carries motor info from spinal cord to peripheral muscles, organs, and glands THE BRAIN comprised of three main regions forebrain midbrain Hindbrain FOREBRAIN contains paired olfactory lobes thalamus (below the cerebrum) relay, consciousness, pain hypothalamus (below thalamus) (temperature, water, hunger, thirst, sex drive); receive info about smells direct connection between hypothalamus and pituitary connects nervous system with endocrine system cerebrum (2 hemispheres connected by the corpus callosum, surrounded by cerebral cortex and divided into 4 lobes: frontal- voluntary muscles, walking, speech, personality, intellect parietal- touch, temperature awareness, emotion, interpreting speech occipital- vision and interpreting visual information temporal – vision, hearing, memory, interpretation of sensory information THE BRAIN http://www.youtube.com/watch?v=YpAe3mk 1koQ&feature=related MIDBRAIN relays information to sensory areas (connective) temporal- vision and hearing, linked to memory Associative cortex: conceptualization, planning, contemplation, memory. Motor cortex: voluntary movement of skeletal muscles. Sensory cortex: vision, hearing, smell. HINDBRAIN Primitive, controls breathing, heart rate, blood pressure. Main regions of hindbrain cerebellum, pons, and medulla oblongata Cerebellum located immediately beneath two cerebral hemispheres largest section of hindbrain deals with coordination and muscle control. Pons acts as a bridge. Passes information between two regions of cerebellum and between cerebellum and medulla Medulla oblongata Acts as connection between peripheral and central nervous system controls involuntary muscle action diaphragm, heart rate, blood vessel dilation etc. also acts as coordinating centre for autonomic nervous system. AUTONOMIC NERVOUS SYSTEM Sympathetic NS – prepares body for stress Parasympathetic NS – return body to normal Check out table NATURAL PAINKILLERS Endorphins bond to sites on pain receptor ganglia (Substania Ganglia…SG). Opiates simulate natural endorphins (p. 437) Heroin, codeine, morphine etc…must continue to take in order to keep working (addiction!) HOMEWORK Case Study Quick quiz Quizzes on a range of bio topics :) Another good quiz A virtual body