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Questions and Answers
What is the primary function of neurotransmitters in synapses?
What is the primary function of neurotransmitters in synapses?
Which phase of the action potential involves K+ channels opening and K+ ions leaving the cell?
Which phase of the action potential involves K+ channels opening and K+ ions leaving the cell?
What type of synapse primarily involves the release of neurotransmitters?
What type of synapse primarily involves the release of neurotransmitters?
At the resting membrane potential (RMP), what is the typical voltage value for neurons?
At the resting membrane potential (RMP), what is the typical voltage value for neurons?
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What occurs after the peak of the action potential?
What occurs after the peak of the action potential?
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In a synapse, what term describes the tiny gap between neurons?
In a synapse, what term describes the tiny gap between neurons?
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What is the effect of continuous K+ ion efflux during the hyperpolarization phase?
What is the effect of continuous K+ ion efflux during the hyperpolarization phase?
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How do neurons primarily transmit information across a synapse?
How do neurons primarily transmit information across a synapse?
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What is the function of astrocytes in the central nervous system?
What is the function of astrocytes in the central nervous system?
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Which type of glial cell is responsible for producing myelin in the central nervous system?
Which type of glial cell is responsible for producing myelin in the central nervous system?
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During which phase of membrane potential does the neuron become more negatively charged than the resting membrane potential?
During which phase of membrane potential does the neuron become more negatively charged than the resting membrane potential?
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What describes the process by which a nerve impulse travels along an axon?
What describes the process by which a nerve impulse travels along an axon?
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What occurs when a neuron 'fires'?
What occurs when a neuron 'fires'?
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Which statement best describes resting membrane potential?
Which statement best describes resting membrane potential?
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What type of synapse involves neurotransmitters crossing a gap to transmit signals?
What type of synapse involves neurotransmitters crossing a gap to transmit signals?
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What role do microglia play in the central nervous system?
What role do microglia play in the central nervous system?
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What triggers the release of neurotransmitters at a chemical synapse?
What triggers the release of neurotransmitters at a chemical synapse?
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Which statement is true regarding electrical synapses?
Which statement is true regarding electrical synapses?
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What is the typical resting membrane potential of a neuron?
What is the typical resting membrane potential of a neuron?
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During the initial phase of an action potential, which ion first enters the neuron?
During the initial phase of an action potential, which ion first enters the neuron?
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What function do neurotransmitters serve at a synapse?
What function do neurotransmitters serve at a synapse?
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Which characteristic distinguishes chemical synapses from electrical synapses?
Which characteristic distinguishes chemical synapses from electrical synapses?
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What allows synaptic vesicles to release neurotransmitters into the synaptic cleft?
What allows synaptic vesicles to release neurotransmitters into the synaptic cleft?
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What is the primary function of gap junctions in electrical synapses?
What is the primary function of gap junctions in electrical synapses?
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Study Notes
Nervous System Overview
- The nervous system comprises two main components:
- Central Nervous System (CNS): Brain and spinal cord.
- Peripheral Nervous System (PNS): Nerves transmitting info to and from the CNS.
Nervous Tissue Composition
- Primarily composed of two cell types:
- Neurons: Excitable nerve cells transmitting electrical signals.
- Neuroglia (glia): Supporting cells, meaning "nerve glue".
Neuron Structure and Function
- Dendrites: Receive signals from other neurons.
- Cell body: Organizes and maintains cell function.
- Nucleus: Controls entire neuron function.
- Axon hillock: Generates nerve impulses.
- Axon: Carries impulses away from the cell body.
- Axon terminals: Forms junctions with other cells, or organs.
- Schwann cell: Produces myelin sheath.
- Myelin sheath: Increases impulse speed.
- Node of Ranvier: Gaps in myelin, allowing impulse "jumps".
Neuron Classes
- Afferent neurons (sensory neurons): Transmit sensory signals to the CNS.
- Efferent neurons (motor neurons): Transmit signals from CNS to muscles and glands.
- Interneurons: Connect sensory and motor neurons, forming complex CNS pathways.
Neuroglia (CNS Glial Cells)
- Astrocytes: The most numerous, involved in metabolism and synapse formation.
- Microglia: Phagocytes, protecting the body by ingesting foreign particles.
- Ependymal cells: Line cavities of CNS and spinal cord, and assist in the formation of cerebrospinal fluid.
- Oligodendrocytes: Produce myelin sheaths in the CNS
Neuroglia (PNS Glial Cells)
- Satellite cells: Surround neuron cell bodies in ganglia.
- Schwann cells: Form myelin sheaths in the PNS.
Nerves
- Bundles of neurons.
- Some nerves contain few neurons others contain hundreds or thousands..
- Myelin sheath insulates axons.
- Nodes of Ranvier are gaps in the myelin sheath.
- Impulses "jump" across these gaps, increasing speed.
Nerve Impulse Route
- Signals travel from dendrite to cell body, to axon hillock, to axon, to axon terminals.
Nerve Impulse
- Electrical signal traveling along an axon.
- Electrical difference exists between the axon's inside and surroundings.
Action Potential
- Brief changes in electrical conditions at a neuron's membrane.
- Occurs when a neural signal arrives in the neuron and "triggers" the impulse to occur.
Polarized
- Cell membrane has a potential difference.
- When potential becomes more positive than resting potential the membrane becomes depolarized.
- When potential becomes more negative than resting potential the membrane becomes hyperpolarized.
Resting Membrane Potential (RMP)
- Electrical charge inside the cell is negative relative to the outside.
- Usually around -70 mV.
Formation of an Action Potential
- Step 1: Sensory cell or neuron stimulus causes depolarization toward threshold potential.
- Step 2: If excitation threshold is met, Na channels open.
- Step 3: At peak action potential, K channels open and K ions leave the cell.
- Step 4: Membrane becomes hyperpolarized as K+ ions continue to leave the cell.
- Step 5: Na+/K+ transporters restore the resting potential.
Synapses
- Junction between neurons.
- Information passed usually chemically.
- Presynaptic (towards synapse) and postsynaptic (away from synapse).
- Synaptic cleft is a small space between neurons.
- Neurotransmitters leave presynaptic, diffuse across cleft, bind to receptors, influencing postsynaptic activity.
Chemical Synapses
- Action potential triggers Ca2+ channels and releases neurotransmitters across synapse.
Electrical Synapses
- Direct physical connection between neurons; allowing ions to flow directly between cells.
- Faster and more reliable than chemical synapses.
Task
- (Diagram labels) These labels should accompany a diagram of a neuron for easier understanding and assignment.
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Description
This quiz covers the essential components of the nervous system, including the central and peripheral nervous systems. It also delves into neuron structure, functions, and types, highlighting key terms and functions associated with neurons and supporting cells.
