The Neuron Neuron: a cell that carries nerve impulses (action potential) Nerve: a bundle of nerve cells connected to each other to pass along action potentials Axon: transmits nerve impulses from the cell body to other neurons and muscles Cell Body: contains the nucleus and other organelles of the neuron cell Dendrite: receives nerve impulses from other neurons and transmits them to the cell body Myelin Sheath: fat substance that wraps around the axon, prevents the electrical impulse from leaving the axon (neurons can cross over each other) #1

signal direction myelin coating Myelin Sheath  Axon coated with insulation made of myelin cells  speeds signal  330 mph vs. 11 mph

Reflex Arc Sensory Neuron: send impulses from the sense organs (skin, nose, tongue, eye & ear) to the interneurons found in the spinal cord Interneuron: carries impulses from the sensory neurons to motor neurons Motor neuron: transmits impulses from the brain and spinal cord to muscles and glands, to cause a response (ex. contract vs. relax, sweat, tears, saliva, mucus). #2

Video Clips Simple Reflex Arc Brain Pop: Neuron

Simple Reflex Arc Action potentials (nerve impulses) can travel trillions of routes of neurons. Many impulses require transportation to the brain in order for the action potential to be interpreted and processed (for an appropriate response). The brain is NOT involved in a simple reflex arc. The nerve pathway consists of : stimulus  sensory neuron  interneuron (spinal cord)  muscle neuron  muscle/gland  response The brain will be informed of the stimulus, but is not involved in the reflex response. #3

Electrical signal: Changes + and – charges from one end of a neuron to another. Copyright © 2010 Ryan P. Murphy #4

Electrical signal: Changes + and – charges from one end of a neuron to another. Copyright © 2010 Ryan P. Murphy #4

Chemical signal: Chemicals allow signals to go from one neuron to another by “jumping the gap (synapse)”. Copyright © 2010 Ryan P. Murphy # 4

Copyright © 2010 Ryan P. Murphy

synapse SYNAPSE: gap between one neuron’s axon and another neuron’s dendrite # 4

NEUROTRANSMITTER: a chemical that diffuses across a synapse and binds to receptors on a neighboring neuron’s dendrite, causing the creation of a new action potential (impulse). # 5

Dopamine Neurotransmitter Affects ability to experience pleasure & pain (emotional response) # 6

Serotonin Neurotransmitter Plays a role in impulse control # 6

Endorphin Neurotransmitter Reduces perception of pain (natural pain killer) and leads to feelings of euphoria # 6

Epinephrine Neurotransmitter Helps body resist or avoid stress, fight or flight response (adrenaline) # 6

Melatonin Neurotransmitter Regulates sleep-wake cycle (circadian rhythm) # 6

Brain Anatomy The three main parts of the brain are the: brainstem, cerebellum and cerebrum Cerebrum Brain Stem Cerebellum Left Hemisphere Right Hemisphere # 7

The Amazing Story of Phineus Gage N9D4D4

CEREBRUM Functions: Carries out higher thought processes Divided into 4 lobes # 8

FRONTAL LOBE Functions: decision making planning, problem solving language processing Associated Cognitive Disorders: Mood changes Inability to express language Loss in social interaction PARIETAL LOBE Functions: Perception of sensory information (touch, pressure, temperature, pain) Spatial mapping Associated Cognitive Disorders: Alzheimer’s Disease ADHD Schizophrenia OCCIPITAL LOBE Function: Vision Associated Cognitive Disorders: Schizophrenia (hallucinations) Autism? Depression TEMPORAL LOBE Functions: Recognition Perception of hearing, smelling and vision Understanding language Learning and memory Associated Cognitive Disorders: Schizophrenia Alzheimer’s Disease PONS (Top Part of Brain Stem) Functions: Regulates breathing Associated Cognitive Disorders: Not known at this time MEDULLA OBLONGATA (Bottom Part of Brain Stem) Functions: Swallowing Vomiting Coughing Sneezing Associated Cognitive Disorders: Not known at this time # 8

HYPOTHALAMUS Function: Maintains homeostasis (Hunger, Thirst, Body Temperature, Sexual Activity) Associated Cognitive Disorders: Depression Bipolar disorder Schizophrenia # 8

CEREBELLUM Functions: Balance Motor-learning Reflex memory Posture Associated Cognitive Disorders: Autism Schizophrenia Dyslexia # 8

SPINAL CORD Functions: Reflexes Transmission of information to and from the brain Associated Cognitive Disorders: Paralysis Spinal Bifida # 8

The Nervous System Is Organized into Two Parts I. Central Nervous System (CNS) Includes the brain neurons & spinal chord neurons (interneurons) Processes information and analyzes responses II. Peripheral Nervous System (PNS) Includes motor nerves & sensory nerves (smell, sight, touch, taste, sound) Carries information gathered from the external environment to the CNS cerebrum cerebellum spinal cord cervical nerves thoracic nerves lumbar nerves femoral nerve sciatic nerve tibial nerve # 9