Introduction
The nervous system is the control center of the human body. In AP Psychology, understanding the structure and functions of the nervous system is critical. The course divides the nervous system into subsystems—the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)—each with distinct roles. This unit examines how these systems interact to produce behavior and mental processes.
The Central Nervous System (CNS)
Definition and Components:
Brain:
The brain is the command center that processes information from the environment and coordinates responses. It is responsible for higher-order functions such as thought, memory, and emotion.Spinal Cord:
The spinal cord acts as a major pathway for transmitting signals between the brain and the rest of the body. It also manages simple reflexes independently of the brain.
Functions:
- Integration of sensory information
- Coordination of motor responses
- Regulation of higher mental functions such as learning, reasoning, and emotion
Example: When you touch a hot surface, sensory receptors send a signal to the spinal cord and brain. The brain processes the pain and sends back a signal to move your hand away.
The Peripheral Nervous System (PNS)
Definition and Overview:
- The PNS connects the CNS to limbs and organs, effectively relaying information between the brain/spinal cord and the rest of the body.
The PNS is divided into two major components: the Autonomic Nervous System (ANS) and the Somatic Nervous System.
Autonomic Nervous System (ANS)
Function:
- Governs involuntary physiological processes such as heart rate, digestion, and respiratory rate.
Subdivisions:
Sympathetic Nervous System
Role:
Prepares the body for “fight or flight” situations by increasing heart rate, dilating pupils, and redirecting blood flow to muscles.Example:
When you are startled, the sympathetic system causes a rapid increase in pulse and energy mobilization.
Parasympathetic Nervous System
Role:
Promotes “rest and digest” functions that conserve energy by slowing the heart rate and increasing intestinal and gland activity.Example:
After eating, the parasympathetic system helps facilitate digestion and relaxation.
Somatic Nervous System
Function:
Governs voluntary movements and sensory information processing. This system controls actions such as walking, grasping, and talking.
Components:
- Sensory (afferent) division: Transmits sensory information from the body to the CNS.
- Motor (efferent) division: Sends signals from the CNS to muscles to produce movement.
Example:
Deciding to pick up a book involves the somatic nervous system directing your skeletal muscles to contract in a coordinated way.
Key Concepts to Remember
Integration of Systems:
The CNS and PNS work together seamlessly. The CNS processes and integrates information, while the PNS delivers messages to and from various parts of the body.Involuntary vs. Voluntary Control:
The ANS (subdivided into sympathetic and parasympathetic) regulates involuntary actions, while the somatic system is responsible for voluntary movements.Interaction for Survival:
Quick reflexes (mediated by the spinal cord) and rapid responses (triggered by the sympathetic nervous system) work in tandem to protect the body.Real-World Examples:
Consider everyday scenarios (e.g., reacting to danger, digesting food, performing a deliberate task) to see these systems in action.
Sample Exam Question and Answer
Exam Question
Question:
Explain the structure and functions of the human nervous system by differentiating between the central and peripheral nervous systems. In your answer, describe the roles of the autonomic and somatic nervous systems and provide examples of how these systems interact to produce a behavioral response.
Model Answer
The human nervous system is composed of two primary subsystems: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord. The brain serves as the control center for processing sensory information, generating thoughts, and regulating emotions, while the spinal cord transmits messages between the brain and the rest of the body and also handles simple reflexes.
The PNS connects the CNS to the limbs and organs, thereby facilitating communication between the brain/spinal cord and other parts of the body. The PNS is divided into the autonomic and somatic nervous systems. The autonomic nervous system regulates involuntary processes such as heart rate and digestion and is further divided into the sympathetic nervous system, which prepares the body for “fight or flight” responses, and the parasympathetic nervous system, which promotes “rest and digest” functions. For example, when an individual is suddenly startled, the sympathetic nervous system triggers an increase in heart rate and energy mobilization.
In contrast, the somatic nervous system controls voluntary movements and transmits sensory information. It is responsible for actions like walking or picking up objects. An example of its function is when a person decides to pick up a book—the brain sends a signal via the somatic nervous system to the skeletal muscles, coordinating the movement.
Thus, the nervous system operates through an intricate interplay where the CNS processes information, the autonomic system manages involuntary responses, and the somatic system governs voluntary actions. This coordinated effort allows an individual to react quickly and appropriately to a wide range of environmental stimuli.
This answer demonstrates a clear understanding of the different components and their functions, highlighting the interactions that are fundamental to behavior and mental processes.
Study Tips for Exam Success
Review Definitions:
Ensure you understand and can differentiate terms such as CNS, PNS, ANS, sympathetic, parasympathetic, and somatic.Use Diagrams:
Draw and label diagrams of the nervous system to visualize the relationship between its parts.Practice Application:
Think of everyday examples that illustrate the functions of each system.Practice Writing Responses:
Use sample questions like the one provided to practice writing clear and concise exam responses within the allotted time.
Conclusion
Understanding the nervous system is fundamental to grasping the biological bases of behavior. The interaction between the central and peripheral nervous systems—and within the PNS itself between the autonomic and somatic divisions—illustrates how our body controls both involuntary and voluntary actions. By reviewing these detailed study notes and practicing with sample exam questions, you will be well-prepared to tackle related questions on the AP Psychology exam.