Nerves, The Brain and Spinal Cord Flashcards
What are the two main divisions of the nervous system?
Central Nervous System (CNS): Comprises the brain and spinal cord.
Peripheral Nervous System (PNS): Consists of all neural elements outside the CNS.
What are the four common characteristics of a neuron?
Cell Body (Soma): Contains the nucleus and organelles.
Axon: Transmits electrical impulses away from the cell body.
Dendrites: Receive signals from other neurons.
Synaptic Terminals: Release neurotransmitters to communicate with other neurons.
How many neurons are estimated to be in the human nervous system and the brain?
Nervous System: Approximately 7 trillion neurons.
Brain: About 86 billion neurons.
What is myelin, and which cells produce it in the CNS and PNS?
Myelin: A fatty substance that insulates axons, promoting efficient nerve impulse transmission.
CNS Myelin: Produced by oligodendrocytes.
PNS Myelin: Produced by Schwann cells.
What are the three types of neurons based on function?
Bipolar Neurons: Sensory neurons found in the nasal cavity, retina, and inner ear.
Pseudounipolar Neurons: Sensory neurons.
Multipolar Neurons: Motor neurons and interneurons; the most common type in the CNS.
Why is the multipolar neuron the most common within the nervous system?
Its structure, with multiple dendrites, allows it to receive and integrate a large amount of information simultaneously.
What are the subdivisions of motor neurons?
Upper Motor Neurons (UMN): Transmit information from the brain to lower motor neurons and interneurons in the brainstem and spinal cord; part of the CNS.
Lower Motor Neurons (LMN): Have cell bodies in the spinal cord or brainstem; their axons directly innervate skeletal muscles; part of the PNS.
What constitutes grey and white matter in the CNS?
Grey Matter: Contains neuron cell bodies; lacks myelin.
White Matter: Composed of myelinated axons; myelin gives it a white appearance.
What are the primary functions of the nervous system?
Sensory Input (PNS): Receiving and transmitting sensory information.
Integration (CNS): Processing sensory input and deciding on a response.
Motor Output (PNS): Executing the response by activating muscles or glands.
How is information transmitted along and between neurons?
Along Neurons: Via electrical impulses called action potentials.
Between Neurons: Through chemical signals involving neurotransmitters released at synapses.
