What are the two main divisions of the nervous system?	The central nervous system (CNS: brain and spinal cord) and the peripheral nervous system (PNS: cranial and spinal nerves connecting the CNS to the body).
What are the three main parts of a neuron?	Cell body (soma), dendrites (receive signals), and axon (transmits signals away from the cell body to other cells).
What is a myelin sheath and what is its function?	A fatty insulating layer around axons formed by Schwann cells (PNS) or oligodendrocytes (CNS). It speeds up nerve impulse conduction via saltatory conduction.
What are the three functional types of neurons?	Sensory (afferent) neurons carry signals to the CNS, motor (efferent) neurons carry signals from the CNS, and interneurons connect neurons within the CNS.
What is resting membrane potential?	The electrical charge difference across a neuron's membrane at rest, approximately -70 mV, maintained by the sodium-potassium pump (3 Na+ out, 2 K+ in).
What is an action potential?	A rapid, all-or-none reversal of membrane polarity that propagates along an axon. It involves depolarization (Na+ influx) followed by repolarization (K+ efflux).
What is the threshold potential?	The membrane voltage (about -55 mV) that must be reached for voltage-gated Na+ channels to open and trigger an action potential.
What is saltatory conduction?	The rapid jumping of action potentials from one node of Ranvier to the next along a myelinated axon, greatly increasing conduction speed.
What is a synapse?	The junction between two neurons (or a neuron and effector cell) where signals are transmitted, typically via neurotransmitters released across a synaptic cleft.
How does synaptic transmission occur?	An action potential triggers Ca2+ influx at the axon terminal, causing vesicles to release neurotransmitters into the synaptic cleft, which bind receptors on the postsynaptic cell.
Name four major neurotransmitters and their general functions.	Acetylcholine (muscle contraction, memory), dopamine (reward, motor control), serotonin (mood, sleep), GABA (inhibition of neural activity).
What is the difference between an EPSP and an IPSP?	An EPSP (excitatory postsynaptic potential) depolarizes the membrane, making firing more likely. An IPSP (inhibitory postsynaptic potential) hyperpolarizes it, making firing less likely.
What are the four major regions of the brain?	Cerebrum (higher thinking), cerebellum (coordination, balance), diencephalon (thalamus, hypothalamus), and brainstem (midbrain, pons, medulla oblongata).
What are the four lobes of the cerebrum and their primary functions?	Frontal (reasoning, motor), parietal (somatosensory), temporal (hearing, memory), and occipital (vision).
What is the function of the hypothalamus?	Regulates homeostasis including body temperature, hunger, thirst, circadian rhythms, and controls the pituitary gland to link the nervous and endocrine systems.
What is the function of the medulla oblongata?	Controls involuntary vital functions such as heart rate, blood pressure, and respiratory rhythm. It is located in the lower brainstem.
What is the function of the thalamus?	Acts as the brain's relay station, routing sensory information (except smell) to the appropriate areas of the cerebral cortex for processing.
What are the components of a reflex arc?	Receptor, sensory neuron, integration center (CNS interneuron or synapse), motor neuron, and effector (muscle or gland).
Why are reflexes faster than voluntary responses?	Reflex arcs are processed at the spinal cord level without requiring brain involvement, reducing the neural pathway and response time.
What are the two divisions of the autonomic nervous system?	Sympathetic ('fight or flight' — increases heart rate, dilates pupils) and parasympathetic ('rest and digest' — slows heart rate, stimulates digestion).
What neurotransmitters do sympathetic and parasympathetic neurons release?	Sympathetic postganglionic neurons release norepinephrine; parasympathetic postganglionic neurons release acetylcholine.
What is the blood-brain barrier?	A selective barrier formed by tight junctions between capillary endothelial cells in the brain. It protects the CNS by restricting passage of pathogens and large molecules.
What are neuroglia (glial cells) and what do they do?	Non-neuronal support cells of the nervous system. They insulate axons (Schwann cells, oligodendrocytes), provide structural support (astrocytes), and perform immune defense (microglia).
What is the role of the spinal cord?	It relays sensory and motor signals between the brain and body, and serves as an integration center for spinal reflexes.