Questions and Answers
What are the two main divisions of the nervous system?
The spinal cord is part of the Peripheral Nervous System.
False
What fills the spaces within the meninges?
Cerebrospinal fluid
Match the following parts of neurons with their functions:
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The __________ nervous system controls internal organs and is not consciously controlled.
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Sympathetic nervous system responses promote calming of the nerves.
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What is the shape of grey matter in the spinal cord?
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Which type of neuron relays information to the effectors?
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The __________ layer of the meninges closely adheres to the brain and spinal cord.
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Study Notes
Importance of the Nervous System
- Facilitates response to environmental changes through electrochemical messages and hormones.
Central Nervous System (CNS)
- Composed of the brain and spinal cord.
- Surrounded by meninges, a protective series of three membranes.
- Meninges consist of:
- Dura Layer: Thick outermost layer, acts as a drainage system for blood and cerebrospinal fluid.
- Arachnoid Layer: Middle layer, avascular with a spider-web appearance, contains cerebrospinal fluid.
- Pia Layer: Innermost vascular layer that closely adheres to the brain and spinal cord.
Peripheral Nervous System (PNS)
- Connects organs to the CNS.
- Divided into:
- Somatic Nervous System: Controls skeletal muscles and is consciously managed.
- Autonomic Nervous System: Regulates internal organs, not consciously controlled; includes sympathetic and parasympathetic systems.
Spinal Cord Structure
- Extends from the skull's base into the spine.
- Central canal filled with cerebrospinal fluid; contains white matter and grey matter.
- Cerebrospinal Fluid: Cushions and protects the CNS.
- White Matter: Contains myelinated neurons; organized into ascending (to the brain) and descending (from the brain) tracts.
- Grey Matter: Contains non-myelinated neurons; shaped like an "H," includes sensory, motor, and interneurons.
Autonomic Nervous System Functions
- Sympathetic Nervous System: Initiates "fight-or-flight" response; increases heart rate, breathing, and energy availability during stress.
- Parasympathetic Nervous System: Reverses sympathetic effects; promotes calmness, reduces heart and breathing rates, and enhances digestion.
Neuron Anatomy
- Basic functional unit of the nervous system, consisting of sensory, interneurons, and motor neurons.
- Dendrites: Receive information and carry impulses to the cell body.
- Axon: Transmits impulses away from the cell body to other neurons or effectors.
- Myelin Sheath: Insulates axons and increases impulse transmission speed, formed by Schwann cells.
- Nodes of Ranvier: Gaps in the myelin sheath that allow for saltatory conduction, enhancing transmission speed.
Types of Neurons
- Sensory Neurons (Afferent): Relay information from the environment to the CNS.
- Motor Neurons (Efferent): Transmit signals from the CNS to effectors (muscles, glands).
- Interneurons: Connect sensory and motor neurons, processing information within the CNS.
Neural Circuits & Reflexes
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Reflex Arc: A simple neural pathway; consists of:
- Stimulus → Receptor → Sensory neuron → Interneuron (in spinal cord) → Motor neuron → Effector.
- Reflex actions are involuntary and occur without conscious thought.
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Description
Explore the essential functions of the nervous system in this quiz, focusing on both the central and peripheral components. Understand the roles of electrochemical messages and the protective membranes surrounding the central nervous system. Dive into the mechanics of how the body responds to changes through various nerve systems.
