Q3 L01 - why study the brain and the nervous system
Why Study the Brain and The Nervous System?
<ul><li>It is what makes us feel – both emotionally and physically and remember </li></ul><ul><li>Explains disorders of the brain and nervous system including Alzheimer's, Parkinson's disease, strokes, etc with a biological base. </li></ul>
Nervous System and Neurons <ul><li>Neurons: Basic building blocks of the nervous system. Scientists estimate 100 billion neurons in the human brain </li></ul><ul><li>Nervous System: responsible for sending, receiving, and processing nerve impulses throughout the body. All the organs and muscles inside your body rely upon these nerve impulses to function. </li></ul>
Structure of a Neuron Dendrites: Branched fibers that extend outward from the main cell body and carry information into neuron.
Structure of a Neuron Soma: Receives information from dendrites. If there is enough stimulation, the message is passed onto the axon
Structure of a Neuron Nucleus: central region of the cell body, in which DNA is stored
Structure of a Neuron Myelin: A fatty insulation coating some types of neural axons, which speeds conduction of neural impulses.
Structure of a Neuron Axon: Conducts information from the cell body to the axon terminals in the form of an electric charge.
Structure of a Neuron Axon Terminal Buttons: forms junctions with other neurons through its synaptic vesicles and releases chemicals called neurotransmitters.
THE SYNAPSE <ul><li>Sending the message to other neurons and with the body… </li></ul><ul><li>Tip of each axon terminal has a little knob on it called the terminal button. </li></ul><ul><li>In it are little saclike structures called synaptic vesicles (Latin for ‘little blister’) </li></ul><ul><li>When the nerve impulse reaches the terminal button, it triggers the release of neurotransmitters from the synaptic vesicles. The molecules of the neurotransmitter crosses the synaptic gap to fit into the receptor sites that fit the shape of the molecule. </li></ul>
Neurotransmitters <ul><li>While the neurotransmitters from one cell cause the next cell to fire, it has to have a way to be turned off as well on. </li></ul><ul><li>Otherwise, pain will not stop until a burnt finger is completely healed. </li></ul><ul><li>There are at least 50 to 100 that researchers have identified. </li></ul><ul><li>Neurotransmitters that turn cells ON = excitatory </li></ul><ul><li>Neurotransmitters that turn cells OFF = inhibitory </li></ul>
Major Neurotransmitters Acetylcholine Found at synapses between neurons and muscle cells as well as in the hippocampus Controls muscle contractions. < acetylcholine = paralysis. > acetylcholine = convulsions and possible death. Dopamine Found in the brain. Voluntary movements, learning and memory, emotional arousal. < dopamine linked to Parkinson’s. > dopamine linked to Schizophrenia leading to hallucinations and emotional disturbances. GABA (Gamma-aminobutyric acid) Helps calm anxiety, eg, by binding to the same receptor sites that are affected by tranquilizing drugs and alcohol. Effect of alcohol is to stimulate release of excess GABA, which causes inhibition of the nervous system associated with getting drunk. Serotonin Found in the lower part of the brain. Involved in mood, appetite and sleep. < linked to anxiety, depression, mood disorders and insomnia. Endorphins Reduces perceptions of pain. Leads to feelings of euphoria, modulation of appetite, release of sex hormones, and enhancement of the immune response. As powerful as morphine.