Nervous system

• Somatic Nervous System: The system you can control, like most skeletal muscular movements (though even some of these can be under autonomous control, like reflexes).
• Autonomic Nervous System: The system you cannot control, like most of the smooth muscles in your digestive tract, the cardiac muscle in your heart, the muscles in your pupils which constrict or dilate your pupil, your breathing rate, ...
• Parasympathetic (paralyzed infront of TV) Nervous system: returns body to rest conditions. A part of Autonomic nervous system.

  -Heart rate decreases to normal.

  -Breathing rate decreases

  -Digestive enzymes can be made.
• Sympathetic Nervous System: “fight or flight”. Prepares your body for action. A part of autonomic nervous system.

  -Heart rate increases

  -Breathing increases

  -Bronchi dilate

  -Pupils dilate

  -Digestion slows, enzymes stop production
• CNS: Central Nervous System, consists of the brain and spinal cord, and neurons in these parts.
• PNS: Peripheral Nervous System: All other neurons outside CNS. Sensory neurons bring information into CNS from sensory receptors, motor neurons carry signals out of CNS to effector organs such as muscles and glands.
• Neurotransmitter: Chemical released by one cell that binds to another cell's receptor protein causing an electrical signal to occur within the second cell.
• Acetylcholine is a neurotransmitter found at all synapses between nerve cells and some synapses between nerves and muscles. It causes depolarization when it binds to its receptor on the postsynaptic membrane. It cause the muscle to contract
• Neuron: a specialized cell transmitting nerve impulses. Parts: cell body with nucleus, dendrites, axon, myelin sheath and schwann cells inside, nodes of Ranvier, axon terminal (motor end plate, synaptic knobs)
• Synapse: junction between two neurons or between a neuron and muscle cell. Neurotransmitter diffuses across gap called synaptic gap or synapse. Binds to receptor glycoprotein on postsynaptic membrane. If enough neurotransmitter molecules are bound, postsynaptic membrane becomes more permeable to sodium ions. This results in depolarization of postsynaptic membrane.
• Saltatory conduction: rapid conduction of action potentials along the axon of a neuron with myelin sheath, which helps the current jump on the nodes of Ranvier
• Chemical communication of nerve cells is called neurotransmission. in this process, chemicals are released from one cell to another. Electrical communication of nerve cells is called action potential. in this process, electrical impulses are passed along the axon of a neuron.
• Myeline sheaths help to insulate the axon and prevent it from becoming damaged by the environment and makes the current faster.
• Depolarization: The process of a neuron becoming more positive inside, causing the sodium channels to open and the potassium channels to close. Trapping Na+ and K+ inside the neuron.
• Repolarization: The restoration of the membrane potential to its resting value -70 mV. K+ channels open and Na+ channels close. So Na+ is inside and K+ outside.
• Hyper-polarization: the state of a neuron in which the membrane potential is so high that it is no longer conducting an action potential, -90mV.
• Action Potential: the electrical signal or nerve impulse that travels down the axon of a neuron, reaching a +35mV at peak.
• Threshold: The minimum amount of a stimulus that is required to trigger an electrical signal, it has to reach more than -55mV to reach past the threshold and start an action potential.