BackIntroduction to the Nervous System and Nervous Tissue
Study Guide - Smart Notes
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Nervous System Overview
Definition and Components
The nervous system is a complex network responsible for coordinating the body's activities by receiving, processing, and transmitting information. It includes the brain, spinal cord, and nerves.
Central Nervous System (CNS): Consists of the brain and spinal cord. It serves as the main control center for processing information.
Peripheral Nervous System (PNS): Composed of nerves that branch throughout the body, including 31 pairs of spinal nerves and 12 pairs of cranial nerves.
Divisions of the Nervous System
Central Nervous System (CNS)
The CNS integrates sensory information and coordinates bodily responses. It is protected by the skull and vertebral column.
Brain: The center for thought, memory, emotion, and sensory processing.
Spinal Cord: Transmits signals between the brain and the rest of the body.
Peripheral Nervous System (PNS)
The PNS connects the CNS to limbs and organs, facilitating communication between the body and the brain.
Spinal Nerves: 31 pairs, responsible for transmitting signals to and from the spinal cord.
Cranial Nerves: 12 pairs, primarily associated with the head and neck.
Functions of the Nervous System
Basic Functions
The nervous system maintains homeostasis by regulating and integrating bodily functions.
Sensory Input: Receives information from sensory receptors (e.g., touch, sight, sound).
Integration: Processes and interprets sensory input in the CNS to make decisions.
Motor Output: Sends signals to muscles and glands to elicit responses.
Types of Neurons
Sensory Neurons: Gather information from receptors in the body and transmit it to the CNS.
Interneurons: Located in the CNS; process information and determine responses.
Motor Neurons: Carry signals from the CNS to muscles and glands, causing them to respond.
Functional Divisions
Somatic Nervous System
The somatic nervous system controls voluntary movements by innervating skeletal muscles.
Responsible for conscious control of muscle activity.
Autonomic Nervous System
The autonomic nervous system regulates involuntary functions by controlling smooth muscle, cardiac muscle, and glands.
Operates without conscious control.
Divided into two main branches:
Sympathetic Division
Prepares the body for "fight or flight" responses.
Increases heart rate, dilates pupils, inhibits digestive activity, and stimulates glucose release.
Parasympathetic Division
Promotes "rest and digest" activities.
Stimulates digestion, slows heart rate, and conserves energy.
Summary Table: Divisions and Functions of the Nervous System
Division | Main Components | Function |
|---|---|---|
Central Nervous System (CNS) | Brain, Spinal Cord | Integration and processing of information |
Peripheral Nervous System (PNS) | Spinal Nerves, Cranial Nerves | Communication between CNS and body |
Somatic Nervous System | Skeletal Muscles | Voluntary movement |
Autonomic Nervous System | Cardiac Muscle, Smooth Muscle, Glands | Involuntary control |
Sympathetic Division | Various organs | "Fight or flight" response |
Parasympathetic Division | Various organs | "Rest and digest" response |
Example
When you touch a hot object, sensory neurons transmit the signal to the CNS, which processes the information and sends a motor output to withdraw your hand.
Additional info: The nervous system is essential for rapid communication and coordination of body functions, and its divisions allow for both voluntary and involuntary control of physiological processes.
