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What are the two main structural divisions of the nervous system?
Central Nervous System (CNS): Brain and spinal cord.
Peripheral Nervous System (PNS): Cranial nerves, spinal nerves, and ganglia.
What are the three main functional divisions of the nervous system?
Sensory Input: Detects stimuli inside and outside the body.
Integration: Processes and interprets sensory input.
Motor Output: Activates effector organs (muscles/glands) to produce a response.
What is the structure of a neuron?
Dendrites: Receive signals from other neurons.
Cell Body (Soma): Contains the nucleus and organelles.
Axon: Transmits impulses away from the cell body.
Axon Terminals: Release neurotransmitters into the synapse.
What is the function of a neuron?
conduct electrical impulses (action potentials)
transmit info throughout the nervous system.
What is the role of a synapse?
where neurons communicate
typically through chemical messengers (neurotransmitters)
presynaptic neuron (transmits toward the synapse)
postsynaptic neuron (transmits away from the synapse).
What is the structure of myelin sheaths?
Composed of lipoprotein myelin
surround thicker axons
formed by Schwann cells in the PNS
oligodendrocytes in the CNS.
What is the function of myelin sheaths?
insulate axons
prevent current leakage
increase the speed of nerve impulse conduction
What is the difference between gray matter and white matter in the CNS?
Gray Matter: Contains neuron cell bodies, dendrites, short nonmyelinated neurons, and neuroglia. It is the site of synapses
White Matter: Contains myelinated axons that connect different regions of the CNS
What is a nerve?
cable-like organ in the PNS
composed of many axons wrapped in connective tissue
can be sensory, motor, or mixed.
What are the structural components of a nerve?
Axons: Transmit nerve impulses
Connective Tissue: Wraps around axons
Myelin Sheath: Insulates axons (if myelinated)
Blood Vessels: Supply nutrients
What is a reflex?
rapid, automatic motor response to a stimulus
mediated by a reflex arc
What are the components of a reflex arc?
Receptor: Detects the stimulus
Sensory Neuron: Transmits afferent impulses to the CNS
Integration Center: Processes the information (in the CNS)
Motor Neuron: Sends efferent impulses to the effector
Effector: Muscle or gland that responds
What is the role of interneurons in the CNS?
association neurons located between sensory and motor neurons
receive sensory input,
direct info to different regions of the CNS
initiate motor responses.
What is the difference between a monosynaptic and polysynaptic reflex?
Monosynaptic Reflex: Involves only one synapse (e.g., knee-jerk reflex).
Polysynaptic Reflex: Involves one or more interneurons (e.g., withdrawal reflex).
What are the two types of myelin sheaths and where are they found?
PNS Myelin Sheaths: Formed by Schwann cells, which wrap around axons
CNS Myelin Sheaths: Formed by oligodendrocytes, which coil around multiple axons
What is the function of interneurons in the CNS?
integrate sensory info
coordinate motor responses by relaying signals b/w sensory and motor neurons.
What is the difference between afferent and efferent nerves?
Afferent Nerves: Carry sensory signals from receptors to the CNS.
Efferent Nerves: Carry motor signals from the CNS to muscles and glands.
What is the role of the integration center in a reflex arc?
processes sensory input
determines the appropriate motor response
often involving one or more synapses in the CNS.
What is the function of the nodes of Ranvier?
gaps along myelinated axons where action potentials are regenerated
allows for faster conduction of nerve impulses.
What is the difference between somatic and visceral motor divisions?
Somatic Motor: Controls voluntary movement of skeletal muscles.
Visceral Motor (Autonomic Nervous System): Controls involuntary regulation of smooth muscle, cardiac muscle, and glands.
