Here are the definitions for each of the terms listed, based on AP Psychology concepts: 1. Nervous System: The network of nerve cells and fibers that transmits signals between different parts of the body, allowing communication and coordination. 2. Central Nervous System (CNS): The part of the nervous system consisting of the brain and spinal cord; it integrates sensory information and coordinates bodily functions. 3. Nerves: Bundles of fibers that transmit electrical signals between the brain, spinal cord, and the rest of the body. 4. Reflex: An automatic, rapid response to a stimulus that bypasses conscious thought, often to protect the body. 5. Autonomic Nervous System (ANS): The part of the peripheral nervous system responsible for controlling involuntary bodily functions like heart rate, digestion, and respiration. 6. Sympathetic Nervous System: A division of the ANS that prepares the body for stress-related activities, often referred to as the "fight-or-flight" system. 7. Peripheral Nervous System (PNS): All nerves outside the brain and spinal cord, connecting the CNS to limbs and organs. 8. Somatic Nervous System: A part of the PNS responsible for voluntary movements by controlling skeletal muscles. 9. Parasympathetic Nervous System: A division of the ANS that calms the body and conserves energy, often referred to as the "rest-and-digest" system. 10. Neurons: Specialized cells that transmit electrical signals in the nervous system. 11. Cell Body (Soma): The part of the neuron that contains the nucleus and is responsible for maintaining the life of the cell. 12. Dendrites: Branchlike extensions of the neuron that receive signals from other neurons and transmit them to the cell body. 13. Axon: A long, thin projection that transmits electrical impulses away from the neuron's cell body toward other neurons or muscles. 14. Myelin: A fatty substance that covers and insulates the axon, speeding up the transmission of nerve impulses. 15. Synapse: The gap between two neurons where neurotransmitters are released to transmit signals to the next neuron. 16. Glial Cells: Supportive cells in the nervous system that provide nutrients, protect neurons, and maintain the extracellular environment. 17. Reflex Arc: The neural pathway that mediates a reflex action, usually involving sensory neurons, interneurons, and motor neurons. 18. Sensory Neurons (Afferent Neurons): Neurons that carry incoming information from sensory receptors to the CNS. 19. Motor Neurons (Efferent Neurons): Neurons that carry outgoing information from the CNS to muscles and glands. 20. Interneurons: Neurons that communicate internally within the CNS, connecting sensory and motor neurons. 21. Action Potential: A brief electrical charge that travels down the axon when a neuron sends a signal, resulting from the movement of ions in and out of the neuron. 22. All-or-Nothing Principle: The concept that a neuron either fires at full strength or doesn't fire at all. 23. Depolarization: The process during an action potential when the neuron becomes less negative inside, allowing the transmission of a signal. 24. Reuptake: The process by which neurotransmitters are reabsorbed by the sending neuron after the signal has been transmitted. 25. Multiple Sclerosis (MS): A chronic illness where the immune system attacks the myelin sheath, leading to communication issues between the brain and body. 26. Neurotransmitters: Chemical messengers that cross the synapse to transmit signals from one neuron to another. 27. Excitatory Neurotransmitters: Neurotransmitters that increase the likelihood of the receiving neuron firing an action potential. 28. Dopamine: A neurotransmitter associated with reward, pleasure, and motor control; imbalances can be linked to conditions like Parkinson's and schizophrenia. 29. Hormones: Chemical messengers released by glands into the bloodstream that regulate bodily functions like growth, metabolism, and mood. 30. Leptin: A hormone that helps regulate body weight by signaling to the brain that the body has had enough to eat. 31. Melatonin: A hormone produced by the pineal gland that regulates sleep-wake cycles. 32. Refractory Period: The brief period after an action potential during which a neuron is unable to fire again. 33. Resting Potential: The state of a neuron when it is not firing a signal, characterized by a negative charge inside the cell. 34. Threshold: The level of stimulation required to trigger an action potential in a neuron. 35. Myasthenia Gravis: A chronic autoimmune disease that weakens muscles, caused by a breakdown in communication between nerves and muscles. 36. Inhibitory Neurotransmitters: Neurotransmitters that decrease the likelihood of the receiving neuron firing an action potential. 37. Serotonin: A neurotransmitter that regulates mood, appetite, and sleep; imbalances are linked to depression and anxiety.

Glutamate: The most common excitatory neurotransmitter in the CNS, playing a key role in learning and memory. 39. Endorphins: Neurotransmitters that act as natural painkillers and are also linked to feelings of pleasure or euphoria. 40. Acetylcholine: A neurotransmitter involved in muscle movement, attention, arousal, and memory. 41. Endocrine System: A network of glands that release hormones into the bloodstream to regulate bodily functions. 42. Adrenaline (Epinephrine): A hormone and neurotransmitter involved in the body’s fight-or-flight response. 43. Ghrelin: A hormone that stimulates hunger and increases food intake. 44. Oxytocin: A hormone involved in social bonding, reproduction, and childbirth. 45. Norepinephrine: A neurotransmitter and hormone involved in arousal, alertness, and the body’s stress response. 46. GABA (Gamma-Aminobutyric Acid): The primary inhibitory neurotransmitter in the brain, helping to calm neural activity and reduce anxiety. 47. Substance P: A neurotransmitter involved in the transmission of pain signals to the brain. 48. Agonist: A substance that mimics or enhances the effect of a neurotransmitter. 49. Antagonist: A substance that blocks or inhibits the effects of a neurotransmitter