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Questions and Answers
What is the main function of the Central Nervous System (CNS)?
Which division of the Peripheral Nervous System is responsible for conveying sensory information from the special senses to the CNS?
What is the function of the Sympathetic Division of the Autonomic Nervous System?
What is the term for the sensory neurons that convey information from visceral organs to the CNS?
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Which of the following is an example of an involuntary action regulated by the Autonomic Nervous System?
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What is the main difference between the Somatic Nervous System and the Autonomic Nervous System?
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What is the function of sensory neurons in the Enteric Nervous System?
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What is the main function of motor neurons in the Enteric Nervous System?
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What is the main function of interneurons in the nervous system?
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What is the function of neuroglia in the nervous system?
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What type of neurons transmit nerve impulses towards the CNS?
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What is the function of the myelin sheath?
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What is the typical resting membrane potential of a cell?
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What is the function of the sodium-potassium pump in a cell?
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What is the name of the disease characterized by demyelination of nerve fibers?
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What type of matter contains neuronal cell bodies and neuroglia?
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What is the main function of ion channels in the membrane?
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What type of ion channels are found in auditory receptors and internal organ stretch receptors?
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What is the result of graded potentials in neurons?
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What is the characteristic of action potentials according to the all-or-nothing principle?
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What is the site of communication between two neurons or between a neuron and an effector cell?
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What type of synapses are closest to the axon hillock?
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What causes the chemically-gated channels to open in chemical synapses?
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What is the function of Ca2+ in chemical synapses?
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What is the duration of the synaptic delay in chemical synapses?
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What is the result of the binding of neurotransmitters with the membrane of the postsynaptic neuron?
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Study Notes
Nervous System Overview
- The nervous system is the master communicator of the body, working with the endocrine system to maintain homeostasis.
- The nervous system is divided into the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
Central Nervous System (CNS)
- The CNS consists of the brain and spinal cord, which serve as the integration and command center of the body.
- The CNS receives, interprets, and responds to sensory information from the body.
Peripheral Nervous System (PNS)
- The PNS consists of sensory (afferent) and motor (efferent) neurons that transmit information to and from the CNS.
- The PNS includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.
- The PNS can be divided into three subsystems: Somatic Nervous System, Autonomic Nervous System, and Enteric Nervous System.
Somatic Nervous System
- The Somatic Nervous System is responsible for voluntary movements and sensations.
- It consists of sensory neurons that convey information to the CNS and motor neurons that conduct impulses from the CNS to skeletal muscles.
Autonomic Nervous System
- The Autonomic Nervous System is responsible for involuntary movements and responses, such as regulating heart rate and digestion.
- It consists of sensory neurons that monitor visceral organs and motor neurons that control cardiac, smooth muscle, and glandular functions.
- The Autonomic Nervous System has two main divisions: Sympathetic and Parasympathetic.
Enteric Nervous System
- The Enteric Nervous System is responsible for controlling the digestive system.
- It consists of sensory neurons that monitor chemical changes and stretching in the GI tract and motor neurons that control contractions and secretions.
Nervous System Function
- The nervous system has three main functions: sensory, integration, and motor.
- Sensory function involves monitoring changes from inside and outside the body and retrieving sensory input.
- Integration function involves interpreting sensory information and making decisions.
- Motor function involves generating a response and activating effectors (muscles or glands).
Histology of Nervous Tissue
- Nervous tissue consists of two main types of cells: neurons and neuroglia.
- Neurons generate and propagate nerve impulses, while neuroglia provide support, nourishment, and protection to neurons.
- Neuroglia are smaller and more plentiful than neurons, and they can continually divide throughout life.
Neurons
- Neurons have three main parts: cell body, dendrites, and axon.
- The cell body contains the nucleus and is responsible for receiving and integrating sensory information.
- Dendrites are multiple "little trees" that receive or input sensory information.
- Axon propagates nerve impulses to another neuron, muscle, or gland.
Functional Classification of Neurons
- Neurons can be classified into three main categories based on the direction of nerve impulses:
- Sensory neurons (afferent neurons) transmit nerve impulses towards the CNS.
- Motor neurons (efferent neurons) transmit nerve impulses away from the CNS.
- Interneurons are found within the CNS and are responsible for integrating sensory information.
Neuroglia
- Neuroglia provide support, nourishment, and protection to neurons.
- There are six types of neuroglia: astrocytes, oligodendrocytes, microglia, ependymal cells, Schwann cells, and satellite cells.
Myelin Sheath
- The myelin sheath is a protective layer of fatty cells that surrounds axons.
- The myelin sheath is found in both the CNS and PNS and is responsible for increasing the transmission rate of nerve impulses.
- In the CNS, the myelin sheath is produced by oligodendrocytes, while in the PNS, it is produced by Schwann cells.
Nodes of Ranvier
- Nodes of Ranvier are small gaps in the myelin sheath where the axon is exposed.
- The electrical impulse "jumps" from node to node, allowing the nerve impulse to travel quickly along the axon.
Collections of Nervous Tissue
- Nervous tissue can be grouped into collections of neurons called ganglia or nuclei.
- Axons are bundled together to form nerves in the PNS and tracts in the CNS.
Gray Matter and White Matter
- Gray matter is composed of neuronal cell bodies and neuroglia and is found in the CNS.
- White matter is composed of myelinated axons and is found in the PNS and CNS.
- Gray matter appears gray because it lacks a myelin sheath, while white matter appears white because it contains a myelin sheath.
Resting Membrane Potential
- The resting membrane potential is the build-up of negative charges inside the cell membrane and positive charges outside the membrane.
- The resting membrane potential is typically around -70 mV and is maintained by the sodium-potassium pump.
Ion Channels
- Ion channels are openings in the cell membrane that allow specific ions to move across according to the electrochemical gradient.
- There are four types of ion channels: leak channels, chemically-gated channels, mechanically-gated channels, and voltage-gated channels.
Electrical Signals in Neurons
- Neurons communicate with each other using two types of electrical signals: graded potentials and action potentials.
- Graded potentials are small deviations from the resting membrane potential that can cause the cell to be more or less polarized.
- Action potentials are rapid sequences of events that decrease and reverse the membrane potential and then restore it back to normal.
Action Potentials
- Action potentials can travel long distances without losing strength and are an all-or-nothing response.
- Action potentials have a depolarizing phase, where sodium channels open, and a repolarizing phase, where potassium channels open.
- The threshold level of stimulation is required to trigger an action potential.
Synapse
- The synapse is the site of communication between two neurons or between a neuron and an effector cell.
- There are two types of synapses: chemical and electrical.
- Chemical synapses are the most common type and involve the release of neurotransmitters from the presynaptic neuron, which bind to receptors on the postsynaptic neuron.
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Description
Test your knowledge of the nervous system, its divisions, and its role in maintaining homeostasis. Learn about the central and peripheral nervous systems, and how they interact with the endocrine system. This quiz covers key concepts from anatomy and physiology.
