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Nervous System Pre Ib

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  • Every time you move a muscle & every time you think a thought, your nerve cells are hard at work. They are processing information: receiving signals, deciding what to do with them, & dispatching new messages off to their neighbors. Some nerve cells communicate directly with muscle cells, sending them the signal to contract. Other nerve cells are involved solely in the bureaucracy of information, spending their lives communicating only with other nerve cells. But unlike our human bureaucracies, this processing of information must be fast in order to keep up with the ever-changing demands of life.
  • This is an imbalanced condition. The positively + charged ions repel each other as do the negatively - charged ions. They “want” to flow down their electrical gradient and mix together evenly. This means that there is energy stored here, like a dammed up river. Voltage is a measurement of stored electrical energy. Like “Danger High Voltage” = lots of energy (lethal).
  • Voltage = measures the difference in concentration of charges. The positives are the “hole” you leave behind when you move an electron. Original experiments on giant squid neurons!
  • Opening gates in succession = - same strength - same speed - same duration
  • K+ gates open more slowly than Na+ gates
  • Na+ channel closed when nerve isn’t doing anything.
  • Dominoes set back up again. Na/K pumps are one of the main drains on ATP production in your body. Your brain is a very expensive organ to run!
  • Calcium is a very important ion throughout your body. It will come up again and again involved in many processes.
  • Nerves communicate with one another and with muscle cells by using neurotransmitters. These are small molecules that are released from the nerve cell and rapidly diffuse to neighboring cells, stimulating a response once they arrive. Many different neurotransmitters are used for different jobs: glutamate excites nerves into action; GABA inhibits the passing of information; dopamine and serotonin are involved in the subtle messages of thought and cognition. The main job of the neurotransmitter acetylcholine is to carry the signal from nerve cells to muscle cells. When a motor nerve cell gets the proper signal from the nervous system, it releases acetylcholine into its synapses with muscle cells. There, acetylcholine opens receptors on the muscle cells, triggering the process of contraction. Of course, once the message is passed, the neurotransmitter must be destroyed, otherwise later signals would get mixed up in a jumble of obsolete neurotransmitter molecules. The cleanup of old acetylcholine is the job of the enzyme acetylcholinesterase.
  • Selective serotonin reuptake inhibitor
  • Since acetylcholinesterase has an essential function, it is a potential weak point in our nervous system. Poisons and toxins that attack the enzyme cause acetylcholine to accumulate in the nerve synapse, paralyzing the muscle. Over the years, acetylcholinesterase has been attacked in many ways by natural enemies. For instance, some snake toxins attack acetylcholinesterase. Acetylcholinesterase is found in the synapse between nerve cells and muscle cells. It waits patiently and springs into action soon after a signal is passed, breaking down the acetylcholine into its two component parts, acetic acid and choline. This effectively stops the signal, allowing the pieces to be recycled and rebuilt into new neurotransmitters for the next message. Acetylcholinesterase has one of the fastest reaction rates of any of our enzymes, breaking up each molecule in about 80 microseconds. Is the acetylcholinesterase toxin a competitive or non-competitive inhibitor?
  • Corpus callosum is how the left and right lobes communicate. Often cut to treat epilepsy. Left lobe is for right side of body and vise-versa.
  • Medulla oblongata: lowest part of the brain,
  • As indicated previously, the membranous utricle extends from the vestibule through each of the semicircular canals. * At the base of each semicircular canal is an expanded area, the ampulla, which contains receptors for rotational movements. *
  • As there is a semicircular canal in each ear that corresponds to each of the three planes of the body, the semicircular canals provide information about rotational movements or dynamic equilibrium. *
  • Any turning motion * or change in rotational velocity sufficient to cause fluid movement sufficient to depress the cupula of the Christa ampularis in one or more of the semicircular canals will initiate nerve impulses to the brain concerning dynamic equilibrium. * This, in concert with information from the maculae and visual stimuli enables us to maintain a sense of balance and orientation. *
  • Transcript

    • 1. Nervous System
    • 2. Nervous System
      • Recognizes and coordinates the body’s response to changes in its internal and external environments .
      • General Functions of the Nervous System
        • Sensory input – vision, hearing, balance, smell, taste, and touch
        • Motor output – muscle contraction and movement
        • Memory and integration of information
    • 3. Organization of the Nervous System
      • 3 divisions:
        • Central Nervous System
          • The brain + the spinal cord
        • Peripheral Nervous System
          • The nervous system outside of the brain and spinal cord
    • 4.
      • 3. Neurons (Nerve Cells)
        • Specialized cells that carry electrical signals called impulses
        • 3 Types of Neurons :
          • Sensory – carry impulses from the sense organs to the spinal cord and brain
          • Motor – carry impulses from brain and spinal cord to muscles and glands
          • Interneurons – Connect sensory and motor neurons and carry impulses between them
    • 5. 3 Types of neurons dendrites sensory neuron cell body axon cell body interneuron cell body motor neuron dendrites “ associative”
    • 6. Nerve cells dendrites cell body axon synaptic terminal
        • Nerve cell (neuron)
      • Structure fits function
        • many entry points for signal
        • one path out
        • transmits signal
      signal direction signal direction dendrite  cell body  axon synapse myelin sheath
    • 7.
      • Five parts to a nerve cell
      • Are thin, branched processes whose main function is to receive incoming signals.
      • They increase the surface area of a neuron to increase its ability to communicate with other neurons.
      A. Dendrites
    • 8.
      • Site of originate for the dendrites and axon.
      • Transmit signals between the dendrites and axon.
      • Contains the nucleus of the cell.
      B. Cell Body
    • 9. C. Axons
      • Designed to convey info away from the cell body Surrounded by a myelin sheath , a wrapping of lipid which:
        • Protects the axon and electrically isolates it
        • Increases the rate of transmission
    • 10. signal direction
        • insulates axon
        • Increases speeds of signal. As an example thick MS travels at 150 m/sec or 330mph vs. thin MS traveling at 5 m/sec or 11 mph.
      myelin sheath D. Myelin sheath
    • 11. myelin axon Na + Na + + + + + + – – action potential saltatory conduction
      • Multiple Sclerosis
        • immune system (T cells) attack myelin sheath
        • loss of signal
    • 12. D.
      • At the end of each terminal contains a synaptic knob
      • These synaptic knobs contains synaptic vesicles. Which contains a membranous bags of Neurotransmitters. Used to communicate with the next nerve cell.
      E. Axon Terminal
    • 13. Fun facts about neurons
      • Most specialized cell in animals
      • Longest cell
        • blue whale neuron
          • 10-30 meters
        • giraffe axon
          • 5 meters
        • human neuron
          • 1-2 meters
      Nervous system allows for 1 millisecond response time
    • 14. Transmission of a signal from nerve cell to nerve cell
      • Think dominoes!
        • start the signal
          • knock down line of dominoes by tipping 1 st one
          •  trigger the signal
        • propagate the signal
          • do dominoes move down the line?
          •  no, just a wave through them!
        • re-set the system
          • before you can do it again, have to set up dominoes again
          •  reset the axon
    • 15. Transmission of a nerve signal
      • Neuron has similar system
        • protein channels are set up
        • once first one is opened, the rest open in succession
          • all or nothing response
        • a “wave” action travels along neuron
        • have to re-set channels so neuron can react again
    • 16. Cells: surrounded by charged ions
      • Cells live in a sea of charged ions
        • anions (negative)
          • more concentrated within the cell
          • Cl - , charged amino acids (aa - )
        • cations (positive)
          • more concentrated in the extracellular fluid
          • Na +
      K + K + channel leaks K + + – Na + Na + Na + Na + Na + Na + Na + Na + Na + K + Na + Na + Cl - K + Cl - Cl - Cl - K + aa - K + Cl - Cl - aa - aa - aa - aa - aa -
    • 17. Cells have voltage!
      • Opposite charges on opposite sides of cell membrane
        • membrane is polarized
          • negative inside; positive outside
          • charge gradient
          • stored energy (like a battery)
      + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – – – – – – – – – – – – – – – – – –
    • 18. Resting Potential
      • Neurons are also highly polarized (at about –70mV) due to:
              • Differential membrane permeability to K + and Na +
              • The electrogenic nature of the Na + /K + pump
              • The presence of intracellular impermeable anions
      1
    • 19. Measuring cell voltage unstimulated neuron = resting potential of -70mV
    • 20. How does a nerve impulse travel?
      • Stimulus : nerve is stimulated
        • reaches threshold potential
          • open Na + channels in cell membrane
          • Na + ions diffuse into cell
        • charges reverse at that point on neuron
          • positive inside; negative outside
          • cell becomes depolarized
      The 1st domino goes down ! – + + + + + + + + + + + + + + – + + + + + + + + + + + + + + + – – – – – – – – – – – – – – + – – – – – – – – – – – – – – Na +
    • 21.
      • Changes in V M allow for the generation of action potentials and thus informative intercellular communication.
      Threshold Potential/ Depolarization 2 3
    • 22. How does a nerve impulse travel?
      • Wave : nerve impulse travels down neuron
        • change in charge opens next Na + gates down the line
          • “ voltage-gated” channels
        • Na + ions continue to diffuse into cell
        • “ wave” moves down neuron = action potential
      The rest of the dominoes fall ! – – + + + + + + – + + + + + + – – + + + + + + – + + + + + + + + – – – – – – + – – – – – – + + – – – – – – + – – – – – – Na + wave 
    • 23. How does a nerve impulse travel?
      • Re-set : 2nd wave travels down neuron
        • K + channels open
          • K + channels open up more slowly than Na + channels
        • K + ions diffuse out of cell
        • charges reverse back at that point
          • negative inside; positive outside
      Set dominoes back up quickly ! + – – + + + + + – – + + + + + + – – + + + + + – – + + + + + – + + – – – – – + + – – – – – – + + – – – – – + + – – – – – Na + K + wave 
    • 24. How does a nerve impulse travel?
      • Combined waves travel down neuron
        • wave of opening ion channels moves down neuron
        • signal moves in one direction     
          • flow of K + out of cell stops activation of Na + channels in wrong direction
      + + – – + + + + + – – + + + + + + – – + + + + + – – + + + + – – + + – – – – – + + – – – – – – + + – – – – – + + – – – – Na + wave  K +
    • 25. How does a nerve impulse travel?
      • Action potential propagates
        • wave = nerve impulse , or action potential
        • brain  finger tips in milliseconds !
      + + + + – – + + + + + – – + + + + + + – – + + + + + – – + + – – – – + + – – – – – + + – – – – – – + + – – – – – + + – – Na + K + wave 
    • 26. Voltage-gated channels
      • Ion channels open & close in response to changes in charge across membrane
        • Na + channels open quickly in response to depolarization & close slowly
        • K + channels open slowly in response to depolarization & close slowly
      + + + + + – + + + + + + – – + + + + + + – + + + + + + – – + – – – – – + – – – – – – + + – – – – – – + – – – – – – + + – Na + K + wave 
    • 27. How does the nerve re-set itself?
      • After firing a neuron has to re-set itself
        • Na + needs to move back out
        • K + needs to move back in
        • both are moving against concentration gradients
          • need a pump!!
      + + + + + – – + + + + + + – – + + + + + – – + + + + + + – – – – – – – + + – – – – – – + + – – – – – + + – – – – – – + + Na + Na + Na + Na + Na + Na + K + K + K + K + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + K + K + K + K + K + K + K + K + wave  K + Na +
    • 28. Repolarization 4 5
    • 29. How does the nerve re-set itself?
      • Sodium-Potassium pump
        • active transport protein in membrane
          • requires ATP
        • 3 Na + pumped out
        • 2 K + pumped in
        • re-sets charge across membrane
      ATP
    • 30. Neuron is ready to fire again resting potential Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + Na + K + K + K + K + K + K + aa - K + K + K + aa - aa - aa - aa - aa - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
    • 31.
      • Resting potential
      • Stimulus reaches threshold potential
      • Depolarization Na + channels open; K + channels closed
      • Na + channels close; K + channels open
      • Repolarization reset charge gradient
      • Undershoot K + channels close slowly
      Action potential graph – 70 mV – 60 mV – 80 mV – 50 mV – 40 mV – 30 mV – 20 mV – 10 mV 0 mV 10 mV Depolarization Na + flows in 20 mV 30 mV 40 mV Repolarization K + flows out Threshold Hyperpolarization (undershoot) Resting potential Resting 1 2 3 4 5 6 Membrane potential
    • 32. Synapse
      • Impulse has to jump the synapse !
        • junction between neurons
        • has to jump quickly from one cell to next
      What happens at the end of the axon?
    • 33. Chemical synapse axon terminal synaptic vesicles muscle cell (fiber) neurotransmitter acetylcholine (ACh) receptor protein Ca ++ synapse action potential
      • Events at synapse
        • action potential depolarizes membrane
        • opens Ca +2 channels
        • neurotransmitter vesicles fuse with membrane
        • release neurotransmitter to synapse  diffusion
        • neurotransmitter binds with protein receptor
          • ion-gated channels open
        • neurotransmitter degraded or reabsorbed
    • 34. Nerve impulse in next neuron
      • Post-synaptic neuron
        • triggers nerve impulse in next nerve cell
          • chemical signal opens ion-gated channels
          • Na + diffuses into cell
          • K + diffuses out of cell
            • switch back to voltage-gated channel
      K + Here we go again ! – + + + + + + + + + + + + + + – + + + + + + + + + + + + + + + – – – – – – – – – – – – – – + – – – – – – – – – – – – – – Na + K + K + Na + Na + Na + ion channel binding site ACh
    • 35. Neurotransmitters
      • Acetylcholine
        • transmit signal to skeletal muscle
      • Epinephrine (adrenaline) & norepinephrine
        • fight-or-flight response
      • Dopamine
        • widespread in brain
        • affects sleep, mood, attention & learning
        • lack of dopamine in brain associated with Parkinson’s disease
        • excessive dopamine linked to schizophrenia
      • Serotonin
        • widespread in brain
        • affects sleep, mood, attention & learning
    • 36. Neurotransmitters
      • Weak point of nervous system
        • any substance that affects neurotransmitters or mimics them affects nerve function
          • gases: nitrous oxide, carbon monoxide
          • mood altering drugs:
            • stimulants
              • amphetamines, caffeine, nicotine
            • depressants
              • quaaludes, barbiturates
          • hallucinogenic drugs: LSD, peyote
          • SSRIs: Prozac, Zoloft, Paxil
          • poisons
    • 37. Acetylcholinesterase
      • Enzyme which breaks down acetylcholine neurotransmitter
        • acetylcholinesterase inhibitors = neurotoxins
          • snake venom, sarin, insecticides
      snake toxin blocking acetylcholinesterase active site acetylcholinesterase active site in red neurotoxin in green
    • 38. Simplest Nerve Circuit
      • Reflex , or automatic response
      • rapid response
        • automated
      • signal only goes to spinal cord
        • no higher level processing
      • adaptive value
        • essential actions
        • don’t need to think or make decisions about
          • blinking
          • balance
          • pupil dilation
          • startle
    • 39. Eye Blink or Pain Withdrawal Reflex Effector (muscle) Spinal cord Interneuron Gray matter White matter Motor neuron Sensory neuron Receptor in skin Stimulus
    • 40. Organization of the NS
      • Central N.S .
      • 1. Brain
      • 2. Spinal Cord
      • B. Peripheral N.S.
        • Motor Neurons
        • I Somatic
        • II. Autonomic
        • 1. Sympathetic
        • 2. Parasympathetic
        • 2. Sensory Neurons
    • 41.
      • Nervous System Flow Chart
      Nervous System Central NS Peripheral NS Brain Spinal chord Sensory Division Motor Division Autonomic NS (Involuntary) Somatic NS (Voluntary) Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)
    • 42.
      • Nervous System Flow Chart
      Nervous System Central NS Brain Spinal chord
    • 43.
      • Division of Labor
        • Central Nervous System (CNS)
        • Control center of the body that relays messages, and processes and analyzes information
          • Brain
            • Cerebrum – largest region; right and left hemispheres that are connected by corpus callosum; voluntary activities and higher brain functions
            • Cerebellum – located at the lower back part of brain; coordination and balance
      Nervous System
    • 44.
        • Brain stem – connects the brain and spinal chord; two regions: pons and medulla oblongata , control breathing, heart rate and swallowing
        • Thalamus and hypothalamus - between brain stem and cerebrum
        • Thalamus : relay station for sensory info
        • Hypothalamus : most important homeostatic site; hormones, body’s thermostat, fight or flight, thirst, hunger, reproduction
      Nervous System
    • 45. Pons Pituitary gland Hypothalamus Cerebrum Medulla oblongata Spinal cord Cerebellum Pineal gland Thalamus The Brain
    • 46. Cephalization = Brain evolution Simplest nervous system no control of complex actions More organization but still based on nerve nets; supports more complex movement
      • Cephalization = clustering of neurons in “brain” at front (anterior) end of bilaterally symmetrical animals
      Simplest, defined central nervous system more complex muscle control  where sense organs are Cnidarian nerve net Flatworm Platyhelminthes nerve cords associative neurons Echinoderm radial nerve nerve ribs
    • 47. Brain evolution Further brain development ganglia = neuron clusters along CNS
      • increase in interneurons in brain region
      More complex brains clusters of neurons known as ganglia connected to all other parts of body by peripheral nerves More complex brains in predators most sophisticated invertebrate nervous system Mollusk brain giant axon brain ventral nerve cords Arthropod Earthworm central nervous system peripheral nerves
    • 48. Evolution of vertebrate brain hindbrain  forebrain  forebrain  forebrain dominant cerebrum Shark Frog Cat Bird Human Spinal cord Hind: Medulla oblongata Optic tectum Hind: Cerebellum Midbrain Fore: Cerebrum Olfactory tract Crocodile
    • 49.
        • Spinal Cord
        • Two main functions:
          • Processing of simple responses to certain stimuli ( reflexes )
          • Carries info to and from brain to body
      Nervous System
    • 50.
      • Peripheral Nervous System (PNS)
      • Receives information from the environment and relays to and from CNS and sensory, motor and gland cells
    • 51.
      • Nervous System Flow Chart
      Nervous System Central NS Peripheral NS Brain Spinal chord Sensory Division Motor Division Autonomic NS (Involuntary) Somatic NS (Voluntary) Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)
    • 52.
      • Nervous System Flow Chart
      Nervous System Peripheral NS Sensory Division Motor Division Autonomic NS (Involuntary) Somatic NS (Voluntary) Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)
    • 53. Peripheral Nervous System (PNS)
      • Two division of nerves that connect the central nervous system to the rest of the body
      • Motor Division – impulses from CNS to muscles or glands
          • Two Parts:
            • Somatic Nervous System
            • Autonomic Nervous System
      • Sensory Division – transmits impulses from sense organs to CNS
    • 54.
      • Nervous System Flow Chart
      1. Motor Division Nervous System Peripheral NS Motor Division Autonomic NS (Involuntary) Somatic NS (Voluntary) Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)
    • 55. I. Somatic Nervous System
      • Responsible for voluntary, or conscious, movement.
      • The neurons only target the skeletal muscles responsible for body movement.
      • All of the neurons in the somatic system release acetylcholine , an excitatory neurotransmitter that causes skeletal muscles to contract
    • 56. II. Autonomic Nervous System
      • Controls involuntary actions
        • Subdivided into two system that have opposite effects on the same organs:
          • Parasympathetic ( rest & digest response )
            • Decreases heart rate
            • Controls internal organs during normal activity
          • Sympathetic (fight or flight response)
            • increases heart rate
            • Controls internal organs during high stress activity
    • 57.
            • These 2 systems are antagonistic.
            • Typically, we balance these 2 to keep ourselves in a state of dynamic balance.
    • 58.
      • Nervous System Flow Chart
      Nervous System Peripheral NS Sensory Division Motor Division Autonomic NS (Involuntary) Somatic NS (Voluntary) Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)
    • 59.
      • Nervous System Flow Chart
      Nervous System Sensory Division Mechanoreceptors Thermoreceptors Pain Chemoreceptors Photoreceptors 2. Sensory Division
    • 60. Sensory Receptors
      • 5 categories
      • 1. Pain Receptors
      • 2. Thermoreceptors
      • 3. Mechanoreceptors
              • Hearing
              • Balance
              • Touch
      • 4. Chemoreceptors
              • Smell
              • Taste
      • 5. Photoreceptors
              • Vision
    • 61. 1. Pain Receptors
      • Throughout body; except brain
      • Respond to chemical released by damaged cells
      • Important to recognize
        • Danger
        • Injury
        • Disease
    • 62. 2. Thermoreceptors
      • In skin, body core, hypothalamus
      • Detect variations in body temperature
    • 63. 3. Mechanoreceptors
      • Skin, skeletal muscle, and inner ears
      • Sensitive to
        • Touch
        • Pressure
        • Stretching of muscles
        • Sound
        • Motion
    • 64. Hearing and Balance
      • Ear
      • Two Functions
        • Hearing
        • Detecting Positional change to movement
    • 65. Hearing
      • Sound – air vibrations
      • Auditory canal – funnels air to tympanum (ear drum)
      • Tympanic membrane – vibrates
      • 3 bones in the ear ( Hammer, Anvil, Stirrup ) vibrate and transmit vibrations to the cochlea
      • Cochlea – filled with fluid and vibrations create pressure waves in the inner ear
      • Tiny hairs respond to waves and send messages to brain via the auditory (cochlea) nerve
    • 66. The Ear Auditory canal Tympanum Round window Eustachian tube Bone Cochlea Cochlear nerve Semicircular canals Oval window Stirrup Anvil Hammer
    • 67.
        • 3 Semi circular canals that form half circles
        • Filled with fluid and hairs that detect motion of head in relation to gravity
        • When the position of the head changes, the fluid inside the canals moves.
        • This information is transmitted to the brain along the vestibular nerve
      Balance
    • 68. Inner Ear Semicircular Canals
    • 69. Semicircular Canals
    • 70. Semicircular Canals Dynamic Equilibrium
    • 71. Touch and Related Senses
      • Largest sense organ?
        • SKIN
      • Sensory Receptors
        • Temperature
        • Touch
        • Pain
      • Greatest density of touch receptors
        • Fingers
        • Toes
        • Face
    • 72. 4. Chemoreceptors
      • Nose and Tongue
        • Chemical in external environment
    • 73. Smell and Taste
      • Chemoreceptors pick up chemical reception in nose and mouth and signal the brain using the olfactory nerve
      • Smell – olfactory bulb
      • T aste buds have four main sensations
        • Salty
        • Bitter
        • Sour
        • Sweet
    • 74. The Senses of Smell and Taste Cerebral cortex Nasal cavity Taste bud Smell sensory area Taste sensory area Thalamus Olfactory (smell) bulb Olfactory nerve Smell receptor Taste pore Taste receptor Sensory nerve fibers
    • 75. Location, Structure, and Taste Sensitivity of Taste Buds on the Tongue
    • 76. 5. Photoreceptors (rods and cones)
      • Rods and cones are part of the Eye
      • Sensitive to Light
        • Rods
          • Night (gray scale) vision
        • Cones
          • Daylight (color) vision
    • 77. Information travels along the optic nerve to the occipital lobe of the brain
    • 78. The Eye Choroid Retina Blood vessels Optic nerve Fovea Vitreous humor Sclera Ligaments Iris Pupil Cornea Aqueous humor Lens Muscle
    • 79. Pathway for Vision Reception
      • Light 
      • cornea 
      • iris and pupil 
      • lens 
      • Retina to photoreceptors 
        • Rods
        • Cones – Fovea
      • Optic Nerve 
      • Brain
    • 80. Nervous System Disorders
        • Migraine Headaches – caused by change in serotonin levels? (affected by caffeine, estrogen, certain foods)
        • Parkinson’s –caused by damage to dopamine transmitters; causes uncontrollable shaking, no cure
        • Tay-Sachs –lack enzyme to break down fatty deposits in the brain; neurological deterioration; death by age 4-5
        • Dementia - damaged brain cells caused by injury or disease (Alzheimer’s); memory loss and personality change.
    • 81. Drugs and the Nervous System
        • Stimulants
          • Accelerate HR, BP, and breathing rate
          • Increases the release of neurotransmitters; leads to release of energy and feeling of well-being
          • When effect wears off, brain’s supply is depleted
          • Caffeine
          • Cocaine
          • Methamphetamines
    • 82.
        • Depressants
          • Slow down HR, lower BP and breathing rate, relax muscles and relieves anxiety
          • Alcohol
          • Marijuana
          • Sleeping Pills
    • 83. Used to increase alertness, relieve fatigue Used to relieve anxiety, irritability, tension Used to relieve pain Stimulants Depressants Opiates Amphetamines Barbiturates Tranquilizers Morphine Codeine Increase heart and respiratory rates; elevate blood pressure; dilate pupils; decrease appetite Slow down the actions of the central nervous system; small amounts cause calmness and relaxation; larger amounts cause slurred speech and impaired judgement Act as a depressant; cause drowsiness, restlessness, nausea Drug Type Medical Use Examples Effects on the body Commonly Abused Drugs