Neurons - part 1

• The nervous system works in conjunction with the endocrine system to maintain homeostasis within the body.
• The nervous system responds to environmental change via electrochemical messages relayed from the brain.
• The endocrine system responds to environmental change via chemical messengers relayed through the bloodstream (hormones).
• Glial Cells are used for structural and nutritional support in the nervous system.
• Alcohol is believed to mimic GABA's effect in the brain, binding to GABA receptors and inhibiting neuronal signaling.
• Neurotransmitter Types include Inhibitory, Trigger, K+ channels to open, causing K+ to flow out and thus lowering the membrane potential, leading to hyperpolarization, making it more difficult to generate an action potential.
• GABA blocks or inhibits brain signals and decreases activity in the nervous system.
• Neurons conduct nerve impulses throughout the body and are supported by glial cells.
• Neurons are the basic unit of the nervous system.
• Dendrites are branches which accept nerve impulses from other neurons and carry them towards the cell body.
• Axons are longer branches which carry nerve impulses away from the cell body.
• A fatty myelin sheath surrounds each axon, insulating the neuron and speeding up the rate of impulse transmission.
• Schwann Cells, a type of glial cell, are responsible for producing the myelin around each axon.
• Gaps between Schwann cells are referred to as the nodes of Ranvier.
• Electrical impulses “jump” from node to node at the nodes of Ranvier.
• Once the electrical signal reaches the axon terminal, it is passed on to the dendrites of an adjoining neuron.
• The myelination of neurons is vital for proper signal transduction within the nervous systems.
• Myelinated Neurons and Unmyelinated Neurons make up the white matter of your brain, which is responsible for conducting nerve impulses.
• Myelinated Neurons and Unmyelinated Neurons make up the grey matter of your brain, which is responsible for processing information and generating nerve impulses.
• Neurons can regenerate after injury.
• Neurons cannot regenerate after injury.
• MS is a genetic disorder which causes hardened tissue to form on top of the myelin sheath, affecting nerve transmission.
• Symptoms of MS include numbness/tingling of limbs, muscle spasms, loss of balance and coordination.
• The more scar tissue that builds up along the nerve, the worse the symptoms become.
• MS gradually worsens with age.
• Types of Neurons include Sensory Neurons (afferent), Interneurons, and Motor Neurons (efferent).
• Sensory Neurons gather information from sensory receptors and transmit these impulses to the brain.
• Interneurons process and integrate incoming sensory info from sensory neurons and relay outgoing information to motor neurons.
• Motor Neurons transmit information from the brain to muscles, glands, and other organs.
• A reflex arc is a neural circuit that passes through interneurons in the spinal cord for immediate response.
• A nerve impulse or action potential has both a chemical and electrical component, hence the term electrochemical impulse.
• The four stages of a nerve impulse are Polarized/resting state, Depolarization, Repolarization, and Refractory Period.
• The difference in charge across the membrane of a resting neuron is called resting membrane potential.
• Inside the resting cell, there exists a higher concentration of potassium (K+) than sodium (Na+); outside the cell, the opposite is true.
• Increasing the stimulus strength does not increase the impulse strength; a neuron will either fire or not fire.
• An action potential is considered to be an “all-or-none” event because any stimulus that fails to achieve a membrane potential of at least -55 mV will have no effect.
• Neurotransmitters diffuse across the synaptic cleft to the post-synaptic membrane.
• The axon terminal is in close contact with the dendrites of another neuron.
• Neurotransmitter Binding induces or inhibits an action potential in the corresponding neuron.
• Neurotransmitter Release occurs when an action potential reaches the axon terminal, causing calcium channel “gates” within the axon terminal to open, causing calcium ions to flow into the cell and trigger the movement of neurotransmitter vesicles towards the presynaptic membrane.