Brain, Body & Behavior: Lesson 3: Brain Communication

Nervous System: Brain Spinal Cord Nerves Remember: Science cannot yet regenerate nerves!

Neurology: NEUROLOGY: the branch of medicine that studies the disorders of the nervous system. NEUROLOGIST: a specialist in the study and treatment of the disorders of the nervous system. There are approximately 1000 disorders of the nervous system that are studied, researched and treated today. Jean-Martin Charcot : “father of neurology” known for his work on many neurological diseases, such as multiple sclerosis and ALS.

Neurons: What is a neuron? NEURON: a nerve cell. “Neuro” means nerve. We have about 100 billion neurons in the nervous system each having thousands of connections to other neurons in the nervous system … perhaps up to a thousand trillion connections!

Neurons: Electrochemical Communication: How does a neuron work? Neurons transmit electrical and chemical information throughout the brain and the body.

Neuron Comminucation: Neurons communicate with each other in two (2) ways: 1. ELECTRICAL NERVE IMPULSES: A nerve impulse occurs in the form of biological electricity. 2. CHEMICAL NERVE IMPULSES: A nerve impulse occurs when a neuron is stimulated to fire by chemicals called neurotransmitters.

Nerve Impulse: NERVE IMPULSE: an electrical and/or chemical message that travels down a neuron. These impulses travel at 120 yards (360 feet) per second. Response is almost immediate. Ex: movement, sensation.

Parts of a Neuron: A typical neuron looks like a tree with a roots, a trunk and branches.

Main Parts of a Neuron: The roots are dendrites (receive signals). The trunk of the neuron is called the axon. The branches are the axon terminals (send out signals).

Dendrites: Dendrite means “tree.” They look like roots of a tree. DENDRITES: Short fibers sticking out of a neuron that work as receptors (receivers) for messages. They receive messages from other nerve cells and send it through the neuron. The have DENDRITIC RECEPTORS on the ends: Receivers on the end of each dendrite which catch the chemicals as they jump from the previous neuron. They then send the message down the dendrites.

Dendritic Receptors

Soma: SOMA: cell body. Holds the NUCLEUS: the cell’s control center. The nucleus stores genetic material. The soma provides fuel, manufactures chemicals, and maintains the entire neuron in working order. Nucleus Soma

Axons: AXONS: long fibers that carry messages away from the soma to another neuron. AXON TERMINALS: At the end of each axon are axon terminals (a.k.a “terminal buttons”) sitting opposite the dendritic receptors of another neuron. The ends of axons which connect with other neurons and release neurotransmitters into the synapse. A message travels from a dendritic receptor, goes through the soma, and goes out the axon to another waiting neuron.

Axons

Axon Terminals

Synapse: Synapse means “junction point.” SYNAPSE: “junction point,” or space between two neurons. It is located between the axon terminal of one neuron and dendritic receptor of another. The junction point of two or more neurons where cell communication takes place. The axon terminal sends the nerve impulse and the dendritic receptor receives the nerve impulse.

Vesicles: VESICLES: Fluid filled bubble like containers (sacs) located at the end of axons that contain, burst, and release neurotransmitters.

Vesicles: When the nerve impulse reaches the axon terminal, the vesicles spill neurotransmitters into the synapse which connect with the dendritic receptor of another neuron.

Neurotransmitters: NEUROTRANSMITTERS: chemicals that transmit nerve information from one neuron to another. This procedure repeats from neuron to neuron. Sixty (60) known neurotransmitters??? Unknown???

Acetylcholine: ACETYLCHOLINE: Neurotransmitters that sends information from one neuron to another whenever we move a body part (makes muscles contract). It also works in memory. ALZHEIMERS DISEASE: Low levels of ACH negatively affect memory. Botulism toxin shuts off ACH causing paralysis. BOTULISM: a food poisoning that affects the nervous system caused by a bacteria. It can be fatal because it paralyzes the muscles used in breathing. BOTOX: injections used to relax facial muscles and improve the appearance of wrinkled skin.

Dopamine: DOPAMINE: neurotransmitter that sends information from one neuron to another to move a body part. Also involved with perception, attention and learning. Plays a role in addiction. All addictive drugs raise dopamine levels in the brain. PARKINSONS DISEASE: Low levels of dopamine. This disease affects the body’s ability to control movement. Characterized by shaking, tremors, rigidity of limbs, difficulty speaking, problems with balance, etc… SCHIZOPHRENIA: High levels amounts of dopamine. DELUSION: A false belief despite evidence to the contrary, usually a symptom of mental illness. HALLUCINATION: Sensing things that are not real.

Serotonin: A neurotransmitter that plays a part in sleep, arousal, aggression, sensitivity to pain, sex and the control of appetite and mood. Low levels are associated with depression.

Endorphins: Neurotransmitters that relieve pain and increase a person’s sense of well being. It is a natural form of morphine made by the body. Endo means “made by the body.” Orphin means “morphine.” Natural painkillers.

Reuptake: REUPTAKE: Neurotransmitters that are reabsorbed by the same cell that releases them. Ex: SSRI’s: Selective Serotonin Reuptake Inhibitors: Drugs that prevent the reuptake of serotonin, causing serotonin levels to increase in the brain, affecting mood. Paxil, Prozac, Zoloft, Wellbutrin, etc…

Effects of Drugs on Neurotransmitters: ECSTASY: (MDMA: methylenodioxymethamp hetamine) AMPHETAMINE: Stimulants that heighten awareness and intensify feelings of pleasure. It increases the heart rate, blood pressure and causes the mind to become more alert. Ecstasy stimulates the brain and increases the amount of serotonin released from an axon terminal across a synapse to a dendrite receptor. Ecstasy also inhibits the reuptake of serotonin back into the axon terminal that released it.

Effects of Drugs on Neurotransmitters: LSD: (Lysergic Acid Diethyl amide) a.k.a. “Acid” Hallucinogen: A substance that induces hallucinations. Resembles neurotransmitters in their chemical composition. It slows the reuptake of serotonin. Serotonin dendrite receptors become overstimulated. This causes a flood of sensory information that the brain sees as hallucinations.

The End