AP Biology Nervous System

Regents Biology Why do animals need a nervous system?  What characteristics do animals need in a nervous system?  fast  accurate  reset quickly Remember… think about the bunny… Poor bunny!

Regents Biology Nervous System  Central nervous system  brain & spinal chord  Peripheral nervous system  nerves from senses  nerves to muscles cerebrum cerebellum spinal cord cervical nerves thoracic nerves lumbar nerves femoral nerve sciatic nerve tibial nerve

Regents Biology Nervous system cells dendrites cell body axon synapse  Neuron  a nerve cell signal direction signal direction

Regents Biology Fun facts about neurons  Most specialized cell in animals  Longest cell  blue whale neuron  meters  giraffe axon  5 meters  human neuron  1-2 meters Nervous system allows for 1 millisecond response time

Regents Biology Myelin sheath signal direction  Axon coated with insulation made of myelin cells  speeds signal  signal hops from node to node  330 mph vs. 11 mph myelin sheath Multiple Sclerosis  immune system (T cells) attacks myelin sheath  loss of signal Multiple Sclerosis  immune system (T cells) attacks myelin sheath  loss of signal

Regents Biology Synapse Junction between nerve cells  1st cell releases chemical to trigger next cell  this is where drugs affect nervous system

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Regents Biology Types of neurons sensory neuron (from senses) interneuron (brain & spinal chord) motor neuron (to muscle)

Regents Biology Simplest Nerve Circuit  Reflex, or automatic response  rapid response  automated  signal only goes to spinal cord  no higher level processing  advantage  essential actions  don’t need to think or make decisions about  blinking  balance  pupil dilation  startle

Regents Biology Eye Blink or Pain Withdrawal Reflex Effector (muscle) Spinal cord Interneuron Gray matter White matter Motor neuron Sensory neuron Receptor in skin Stimulus

Regents Biology  Resting Potential = -70 millivolts  Many Na+ on the outside of the neuron  Many K+ on the inside of the neuron  Many large negatively charged ions

Regents Biology  Threshold voltage = -50 mV ( Na+ start rushing in) Action Potential = +30 mV  Na+ continue to rush in and the K + rush out  Wave of depolarization  Refractory period-no impulse can be sent  Na-K pump-reset resting potential

Regents Biology Divisions of the Peripheral Nervous System

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Regents Biology Blood Brain Barrier  blue dye  that tissues of the whole body EXCEPT the brain and spinal cord would turn blue  Functions  Protects the brain from "foreign substances" in the blood that may injure the brain.  Protects the brain from hormones and neurotransmitters in the rest of the body.  Maintains a constant environment for the brain

Regents Biology The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid

Regents Biology Central Canal

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Regents Biology White and Gray matter

Regents Biology Cranial Nerves

Regents Biology Spinal Nerves

Regents Biology Human brain

Regents Biology Primitive brain  The “lower brain”  medulla oblongata  pons  cerebellum  Functions  basic body functions  breathing, heart, digestion, swallowing, vomiting  homeostasis  coordination of movement

Regents Biology Higher brain  Cerebrum  hemispheres  left = right side of body  right = left side of body  Corpus callosum  major connection between 2 hemispheres

Regents Biology Division of Brain Function  Left hemisphere  “logic side”  language, math, logic operations, vision & hearing details  fine motor control  Right hemisphere  “creative side”  pattern recognition, spatial relationships, non-verbal ideas, emotional processing, parallel processing of information

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Regents Biology Cerebrum specialization  Regions of the cerebrum are specialized for different functions  Lobes  frontal  temporal  occipital  parietal

Regents Biology Limbic system Controls basic emotions (fear, anger), involved in emotional bonding, establishes emotional memory

Regents Biology  Reticular formation  Electroencephalogram EEG  Slow wave sleep  REM sleep

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Regents Biology  Short Term memory  Lasts only a few minutes  Long Term memory  Lasts for weeks or years  To move from short term to long term:  Rehearsal  Emotional state  Association with old data

Regents Biology Referred pain

Regents Biology Sensation vs perception Figure 29.1 p

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Regents Biology M/HEALTH/LASIK-EYE- SURGERY/MM ategoryID= changizi

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Regents Biology Muscle Contraction  Nerve releases acetylcholine which causes the sarcoplasmic reticulum to release Ca++.  Ca++ bond with troponin which causes tropomyosin to pull away from actin binding sites.  Myosin cross bridges go in and muscle contracts.

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