Lecture 16 Flashcards
What are the two main types of cells that make up the central nervous system (CNS), and what percentage of the brain do they each account for?
The two main types of cells in the CNS are neurons and glial cells. Neurons make up approximately 10% of brain cells, while glial cells account for about 90% of brain cells
How does cognition depend on both neurons and the transmission of information between neurons?
Cognition relies on neurons for their role as basic signaling units, transmitting information via electrical and chemical signals. However, the transmission of information between neurons is essential for cognitive processes, as it allows for the communication and integration of information in the brain.
Describe the structure of a neuron, including its main components.
Dendrites: Treelike processes that extend from the cell body and receive inputs from other neurons.
Soma (cell body): The central part of the neuron that contains metabolic machinery.
Axon: A long process that transmits electrical impulses to distant sites in the nervous system.
Axon terminals: Endings where communication with other neurons occurs.
Explain the role of dendrites in neuronal communication.
Dendrites are specialized structures that extend from the cell body of a neuron. They serve as input receivers, receiving signals and information from other neurons. Dendrites play a crucial role in integrating and processing incoming signals, which are then transmitted to the cell body for further processing.
What is the primary function of the soma in a neuron?
The soma, or cell body, of a neuron serves as the central part of the neuron. It contains the metabolic machinery necessary for maintaining the neuron’s functions, and this machinery is suspended in fluid and surrounded by the cell membrane.
Describe the role of an axon in neuronal communication.
The axon is responsible for transmitting electrical impulses to distant sites in the nervous system. It acts like a telegraph wire, carrying signals generated by the neuron to other neurons or target cells. Axons can vary in length, and some may be covered in myelin to speed up signal conduction.
What is myelin, and what role does it play in nerve impulses?
Myelin is a fatty substance that surrounds and insulates nerve fibers, particularly axons. Its main function is to facilitate the conduction of nerve impulses, which means it helps speed up the transmission of signals along the axon. Myelin appears white, and its importance is evident in conditions like multiple sclerosis (MS), where the destruction of myelin leads to impaired signal transmission.
How does the presence of myelin affect the speed of nerve impulse transmission?
Myelin significantly increases the speed of nerve impulse transmission. It acts as an insulating sheath around the axon, allowing for the rapid propagation of electrical signals by preventing signal leakage or decay. In the absence of myelin, nerve impulses would travel much more slowly.
What is the role of axon terminals?
Axon terminals transmit information between neurons or to target cells.
Define a synapse and its components.
A synapse is a junction between neurons or cells, comprising the presynaptic and postsynaptic sides.
How is information transmitted at a synapse?
Electrical impulses trigger neurotransmitter release, which crosses the synaptic gap and affects the postsynaptic cell.
What do neurotransmitters do in synaptic transmission?
Neurotransmitters are chemical messengers that bind to receptors, altering the postsynaptic cell’s activity.
Do all neurons use the same neurotransmitters?
No, neurotransmitter choice varies among neurons based on their functions and properties.
What are the main types of glial cells in the CNS?
The main types of glial cells in the CNS are astrocytes, oligodendrocytes, and microglia.
What is the role of astrocytes in the brain?
Astrocytes form the blood-brain barrier (BBB), protecting the CNS from certain substances in the bloodstream and providing support to neurons.
