What are the two main divisions of the human nervous system?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
What structures make up the CNS?
The brain and spinal cord
What is the primary function of the CNS?
The CNS processes and integrates information received from the nerves.
What structures make up the PNS?
Nerves.
What is the primary function of the PNS?
The PNS transmits information to and from the CNS.
What is the overall pathway of information through the nervous system?
Receptors ->Sensory neurons-> CNS integrative neurons ->Motor neurons -> Effectors
What converts environmental stimuli (like light or sound) into electrical signals?
Sensory receptors. These electrical signals are called action potentials
What is another name for ascending sensory pathways, and what is their direction of travel?
They are called afferent pathways, and they transmit information up the spinal cord to the brain.
Through which root does sensory information enter the spinal cord?
The dorsal root.
What is another name for descending motor pathways, and what is their direction of travel?
They are called efferent pathways, and they send responding motor signals down the spinal cord from the brain
Through which root do signals leave the spinal cord to reach muscles or glands?
The ventral root.
What are the target organs (muscles or glands) that carry out a response called?
Effectors
Which nervous system division controls voluntary muscle reactions?
The Somatic Nervous System.
Which nervous system division controls involuntary responses?
The Autonomic Nervous System.
What types of tissues are controlled by the Autonomic Nervous System?
Smooth and cardiac muscles, and glands (like sweat glands).
What forms the lighter-colored white matter in the nervous system?
Myelinated axons.
What forms the darker-colored gray matter?
Unmyelinated axons.
Which specific cells form the myelin sheath in the CNS?
Oligodendrocytes
Which specific cells form the myelin sheath in the PNS?
Schwann cells.
How do action potentials travel in a myelinated axon, and what is the benefit?
By saltatory conduction, where the signal jumps quickly from Node of Ranvier to node. This speeds up transmission and requires less energy/ATP.
How do action potentials travel in an unmyelinated axon?
By continuous propagation, causing a wave of depolarization followed by repolarization along the axon’s length.
What condition results from the loss of myelin, decreasing axon transmission efficiency?
Multiple sclerosis
What membrane system must nutrients and wastes pass through to enter/leave the brain?
The blood-brain barrier (BBB)
What glial cells primarily form the BBB?
Astrocytes (star-shaped)
