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    2. 2.  Stimulus – a change in the external or internal environment that is detected by a receptor and brings about a response. Response – change in an organism due to a stimulus. Reflex – a rapid and “unconscious” response  Require a precise pathway – at least 3 synapses  Include 6 parts: >>>>>>>>>>>>>>>>>>> REFLEXES and REFLEX ARCS
    3. 3.  Receptor – detects stimulus, transforms into an impulse Sensory Neurons –  part of the PNS  connects receptor to CNS thru dorsal nerve root  Impulse travels freely along the axon Relay Neuron –  receives messages from sensory neurons across synapses - passes them to motor neurons  Within gray matter of spinal cord
    4. 4.  Motor Neurons –  Part of the PNS  Carries impulse from CNS (relay neuron) to effector (muscle)  Leaves thru ventral root of SC  Cell body is in gray matter SC Gray Matter – region of synaptic connection in the SC Effector – carries out response
    5. 5.  The mechanism of evolution- requires:  Variations in phenotypes  Genetic basis for variation  Change in the environment Examples: 2 related to global warming:  Sylvia atricapilla – Black Cap - migration  Parus major – Great tit - breeding
    6. 6.  MIGRATION PATTERNS  Normal breeding – early summer across central and northern Europe.  Then migrates to warmer areas before winter.  Patterns show normal migratory pattern – Germany to Spain  Recent studies – 10% migrating to the UK Experiments show that direction of migration is genetically inherited.
    7. 7.  Breed in spring/early summer through Europe.  Timing of egg laying is genetically programmed  Day length determines time of year.  Recent studies have shown that egg laying time is becoming earlier.  Have greater reproductive success  due to earlier opening of leaves on trees & biomass that feeds on the leaves –  Biomass – food for the great tit!
    8. 8. Types of ReceptorsMechanoreceptor – pressure, texture, vibrations (ear)Chemoreceptors – chemical solutes and vaporsPhotoreceptors – react to lightThermoreceptors – change in temperature
    9. 9.  Choroid – light absorbing pigment; stray light Retina – receptors for vision; rod cells Fovea – densely packed cone cells; acute vision Optic nerve – carries nerve impulses to brain Optic disk – blind spot Vitreous humor – supports eye; transparent Lens – focuses light Aqueous humor - supports eye; transparent Pupil – light enters here Iris – regulate size of pupil Cornea – outer layer; fixed focusing Sclera and conjunctiva – white; protects and supports Rod cells – black and white sensors; dark light Cone – color sensors; bright light
    10. 10. The Perception of Light
    11. 11.   Rod cells Cone cells Light brightness Diversity of cellsWavelength sensitivityImpulse: neuron ratio distribution
    12. 12. Edge Enhancement – precentral nervous system;carried out on the retinaitself.
    13. 13.  Gray areas – peripheral vision; fewer light sensitive cells Focused attention on any gray area – use center of the retina.
    14. 14. Contralateral Processing – is the way the brain collects and integrates information to create the perception of seeing.
    15. 15. Both eyes send information and sends to both sides of the brain.n Optic chiasm – where information crosses to the other side of the braine Both eyes are responsible for processing information from both eyes.
    17. 17. 1. Eardrum – pressure waves causes the eardrum to vibrate2. Hammer, Anvil, Stirrup – eardrum pushes on bones of the middle ear; magnifies 20x.3. Oval Window – middle ear bones push on membrane ; causes cochlea to move4. Cochlea – pressure wave travels through fluid r Sensory cilia in cochlea move Causes the release of neurotransmitters between receptor and auditory nerve.s Auditory nerve – generates an impulse. Impulse is carried to the brain for translation________________________________________________ Semicircular canals – responsible for balance Eustachian Tube – functions to equalize air pressure and drains mucus Hearing Test
    18. 18. Learned Behavior Innate Behavior Experience  Instinctive Modified by trial and  Genetically based error  Not modified Variation within  Uniform throughout population population Affected by environment  Unaffected by Capacity to learn may environment product of natural  Beneficial behaviors selection rather than product of natural specific behaviors selection Learned or Innate??
    19. 19. INNATE LEARNED Sucking instinct Emotional expressions  Training animals Birds hatching  Walking Migratory patterns  Learning to drive Hunting instinct  Tying shoes Not breathing underwater Courtship and sexual behavior in species Reflexes – all Instincts
    20. 20.  A directional response to a stimulus: Positive or Negative  Chemotaxis – response to chemicals  Phototaxis – response to light  Gravitaxis – response to gravity  Rheotaxis – response to water current  Thigmotaxis – response to touch Paramecium
    21. 21.  Response to a non directional stimulus: Humidity – a non directional stimulus  Orthokinesis – speed of movement altered  Klinokinesis – rate of turning
    22. 22. Allows an organism tochange or adapt inresponse to theenvironment which givesan increased chance ofsurvival
    23. 23. Non-associative Associative Habituation – repeated stimulus  Imprinting – learned early in brings about decreased life – very receptive response. No reward or  Forms instant bond with one punishment who provides the essential skills Sensitization – increased for survival response to a stimulus after a  Conditioning – reward or punishing stimulus punishment  Classical – PavlovianCrow Response  Operant – behave to win award or avoid punishment  Training  A good example
    24. 24. Pavlovian Conditioning You Tube Pavlov
    25. 25. 1. Unconditioned Response – automatic to the stimulus (food elicits salivation)2. Neutral Stimulus – no response (bell ringing)3. Conditioning – neutral and unconditioned combined (dog associates bell with food and salivates)4. Conditioned Stimulus and Response (dog will salivate when bell rings – even without food)Example Example
    26. 26.  Watch the video: To what extent do cowbirds learn their sons socially and how much is innate? Birdsong and Culture Birdsong  Strong indicator of reproductive fitness  Females select males based on RF  Exaggerates traits - Lyre
    27. 27.  How do neurons talk to each other?Through the SYNAPSE.Most are chemical. 2 main types:  Excitatory – normal synapse.  Neurotransmitter released by presynaptic neuron (axon)  Causes positive ions to enter the post synaptic neuron (dendrite)  Acetylcholine and dopamine  Inhibitory  Opposite effect – carry negative ions – Chloride - - into the post synaptic neuron. Increases polarization – hyperpolarization.  Makes it difficult to produce an action potential  Dopamine and GABA
    28. 28.  Important Points:  Axons of many neurons feed into the dendrite of the post synaptic neuron.  Each axon contributes to a membrane potential.  The effects of each can be excitatory or inhibitory.  The effect is summative---- and if it reaches Threshold, an AP is propagated. Effects of excitatory neurotransmitters can be cancelled by inhibitory neurons. AP at postsynaptic neuron is determined by summation of messages.HOW IT WORKS!
    29. 29. Psychoactive DrugsAffect the brain and personality by either increasing or decreasing post-synaptic transmission.
    30. 30. Cholinergic vs. Adrenergic Cholinergic –  Synapses using acetylcholine as the neuroT  Acetylcholine – parasympathetic of PNS  Importance in keeping “normalcy”  Response = relaxing  inhibitory Adrenergic –  Synapses using noradrenalin as the neuroT  Noradrenalin – sympathetic of PNS  Importance for “alertness,” increased energy, & euphoria  stimulant
    31. 31. Excitatory Drugs Nicotine –  similar to acetylcholine --- fits in receptor  Mimic excitatory neurotransmitters/ block inhibitor  Is not broken down by enzymes - remains
    32. 32. Excitatory DrugsAmphetamines –  stimulate release of noradrenalin and dopamine  Moves directly into pre-synaptic neuron vesicle.  Results increased awareness and energy
    33. 33. Excitatory DrugsCOCAINE –Normal  Dopamine and adrenaline act as excitatory neurotransmitters  Both usually taken back up at the pre synaptic axon or enzyme.With Cocaine  Blocks receptors on the re-uptake pump  NT/hormone remains and more is released  Increases post-synaptic transmission Changes –  Dopamine is a pleasure NT  Euphoria, increased energy, alertness  Highly addictive – body produces less natural dopamine
    34. 34. Inhibitory Drugs BENZODIAZAPINES (gamma-Aminobutyric acid) main inhibitory NT  Enhance the effect of GABA (main inhibitory NT)  Combines with and slows down GABA receptors on post-synaptic neurons  Slows down brain activity.
    35. 35. Inhibitory DrugsAlcohol  Initially acts as a stimulant  Release of dopamine  As level of BAC raises – has a sedative effect  Increases binding of GABA  Acts as an anesthetic
    36. 36. Inhibitory DrugsTetrahydrocannabinol  Cannabis –Normal Dopamine and GABA proceed when neededWith THC THC inhibits GABA release GABA cannot inhibit dopamine Mood and Behavior  Increased feelings of pleasure  Intoxicated, hunger, memory loss,  Used to treat nausea in cancer patients.
    37. 37. ADDICTION (Mouse Party) A chronic neurological disorder with: Genetic characteristics Psychosocial characteristics Environmental characteristics Changes in the brain result in compulsive desire to use a drug
    38. 38. General Causes of Addiction Genetic – not fully understood  Different allele for a receptor?  Carry modified versions of genes linked to drug metabolism  Susceptibility does not mean inevitability. Psychosocial/ Environmental  Peer pressure  Timing  Availability  Legality/Religion  Community  Family  Mental health
    39. 39. END
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