36 Questions
Which branch of medical science deals with the normal functioning and disorders of the nervous system?
Neurology
What is responsible for all our behaviors, memories, and movements?
Nervous system
Which neurons are responsible for sensing changes in the internal and external environment through sensory receptors?
Sensory (afferent) neurons
Which part of the nervous system includes the brain and spinal cord?
Central nervous system (CNS)
Which function of the nervous system involves analyzing sensory information, storing some aspects, and making decisions regarding appropriate behaviors?
Integrative function
Which type of neurons respond to stimuli by initiating action?
Motor (efferent) neurons
What maintains the resting membrane potential at -70 mV?
Changes in ion concentration or membrane permeability
What follows the depolarization phase of action potentials?
Repolarization
What plays a crucial role in the generation and propagation of action potentials?
Voltage-gated channels
What can affect the opening and closing of ion channels, influencing membrane potential?
Changes in extracellular ion concentrations, particularly Ca2+
What is crucial for the depolarization and repolarization of the membrane during action potentials?
Operation of voltage-gated Na+ and K+ channels
What is the fundamental process for the communication and function of the nervous system?
Generation and propagation of action potentials
What does the Peripheral Nervous System (PNS) consist of?
Sensory receptors, nerves, ganglia, enteric plexus, and sensory receptors
What is the function of the sensory division of the PNS?
Transmits action potentials from receptors to the CNS
What are sensory receptors in the PNS?
Specialized cells that monitor changes in the internal or external environment
Which divisions are included in the motor division of the PNS?
Somatic nervous system and autonomic nervous system (ANS)
What is the role of the autonomic nervous system (ANS) within the PNS?
Regulates subconscious or involuntary functions, with sympathetic and parasympathetic divisions
What do nerves in the PNS consist of?
Bundles of axons and their sheaths connecting the CNS to sensory receptors, muscles, and glands
What is the main factor responsible for establishing the resting membrane potential?
Unequal distribution of charged molecules and ions across the plasma membrane
What is the primary function of ligand-gated ion channels?
Open or close in response to a molecule binding to a receptor, changing the permeability of the cell membrane
What is the role of the sodium-potassium pump in maintaining ion concentration differences?
Pumping three Na+ out of the cell in exchange for two K+ into the cell
What is the consequence of altering the resting membrane potential through depolarization?
Changing the potential difference
What is the primary factor leading to more movement of K+ and Cl- at rest?
Leak channels for K+ and Cl- being more abundant than for Na+
What is the function of voltage-gated ion channels?
Respond to small voltage changes across the cell membrane
Which type of neuron has many dendrites and an axon?
Multipolar neuron
Which neuroglial cell forms myelin sheaths around portions of several axons in the central nervous system?
Oligodendrocyte
What is the function of microglia within the central nervous system?
Respond to inflammation and phagocytize foreign substances
What type of axon is protected and insulated by myelin, and has nodes of Ranvier?
Myelinated axon
What is the primary function of Schwann cells in the peripheral nervous system?
Wrap around portions of only one axon to form myelin sheath
Which part of the nervous tissue is composed of unmyelinated axons, cell bodies, dendrites, and neuroglia?
Gray matter
Which type of neuron has many dendrites and an axon?
Multipolar neuron
Which neuroglial cell forms myelin sheaths around portions of several axons in the central nervous system?
Oligodendrocyte
What is the function of microglia within the central nervous system?
Respond to inflammation and phagocytize foreign substances
What type of axon is protected and insulated by myelin, and has nodes of Ranvier?
Myelinated axon
What is the primary function of Schwann cells in the peripheral nervous system?
Wrap around portions of only one axon to form myelin sheath
Which part of the nervous tissue is composed of unmyelinated axons, cell bodies, dendrites, and neuroglia?
Gray matter
Study Notes
Ion Channels and Resting Membrane Potential
- Chloride ions (Cl-) are repelled by proteins and exit through always-open, nongated Cl- channels.
- Gated ion channels open and close in response to a stimulus, altering the cell membrane's permeability.
- Leak channels for K+ and Cl- are more abundant than for Na+, resulting in more movement of K+ and Cl- at rest.
- Ligand-gated ion channels open or close in response to a molecule binding to a receptor, changing the permeability of the cell membrane.
- Voltage-gated ion channels respond to small voltage changes across the cell membrane, with Na+, K+, and Ca2+ being important in different cell types.
- Other gated ion channels include those for touch and temperature receptors.
- The resting membrane potential is established by the unequal distribution of charged molecules and ions across the plasma membrane, resulting in a potential difference of -70 to -90 mV.
- Movement of K+ through leakage channels is due to attraction to trapped proteins, and the Na/K pump helps maintain ion concentration differences.
- The sodium-potassium pump maintains the differential levels of Na+ and K+ by pumping three Na+ out of the cell in exchange for two K+ into the cell.
- Changing the resting membrane potential can occur through depolarization or hyperpolarization, altering the potential difference.
- Alterations in K+ concentration gradient can lead to depolarization or hyperpolarization, affecting membrane permeability.
- Gated K+ channels in the membrane, if opened, can lead to more K+ diffusing out, opposed by the negative charge developing as K+ diffuses out.
Neuroglia and Neuron Structure and Function
- Neurons can be classified as multipolar, bipolar, or pseudo-unipolar based on their structure
- Astrocytes in the CNS regulate substances reaching the brain from the blood and maintain the blood-brain barrier
- Ependymal cells in the CNS line brain ventricles, secrete cerebrospinal fluid, and have cilia to move fluid in the brain
- Microglia in the CNS are specialized macrophages that respond to inflammation and foreign substances
- Oligodendrocytes in the CNS form myelin sheaths around axons
- Schwann cells in the PNS wrap around a single axon to form myelin sheaths and satellite cells provide support and nutrients
- Myelinated axons have myelin sheaths that protect and insulate them, while unmyelinated axons rest in invaginations of Schwann cells or oligodendrocytes
- Gray matter in nervous tissue consists of unmyelinated axons, cell bodies, dendrites, and neuroglia, while white matter consists of myelinated axons
- Nerve tracts in white matter propagate action potentials in the CNS
- Neurons produce electrical signals called action potentials to transfer information
- The electrical properties of neurons are a result of ionic concentration differences across the plasma membrane and membrane permeability
- The Na/K pump and membrane permeability result in differences in ion concentrations across the plasma membrane
Test your knowledge of ion channels and resting membrane potential with this quiz. Explore the roles of chloride, potassium, and sodium ions, as well as the mechanisms of gated and leak channels. Learn about the establishment and alteration of the resting membrane potential and the functions of various types of ion channels.
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