BBB - Overview of the Nervous System Lesson

Learning Target:

• Describe the nervous system and its subdivisions and functions.

AP psychology course and exam description, effective fall 2020. (n.d.). https://apcentral.collegeboard.org/media/pdf/ap-psychology-course-and-exam-description.pdf

Nervous System

The nervous system is a complex and organized communication network that responds to internal and external stimuli. Information is received, interpreted, and responded to through the nervous system. It is made up of the brain, spinal cord, nerves, and sense organs, and is divided into two parts. However, for behavior to occur the two must function as one.

Central Nervous System

The central nervous system is made up of the brain and spinal cord and is responsible for our thoughts, feelings, and actions. Acting as a command center, the brain commands and the spinal cord is responsible for ingoing and outgoing messages. The spinal cord utilizes two neural tracks to communicate messages from the body to the brain and the brain to the body. Sensory messages traveling to the brain are called ascending and those traveling from the brain are called descending. This system is so critical that it is entirely encased in bone. Every thought, feeling, and action is processed through it.

The spinal cord also produces reflexes. Reflexes are simple automatic behaviors that occur without any brain involvement. In a spinal reflex, sensory neurons send information to the spinal cord and interneurons relay the information to motor neurons who then signal the reflex. The brain receives the information last. Reflexes are our body's way of minimizing injury. By skipping the brain our reaction times to injury or pain is much faster and prevents further damage.

Peripheral Nervous System

The peripheral nervous system is made up of the sensory and motor nerves that connect the CNS to the rest of the body. They play a key role in communication through the entire body. Like the nervous system, the peripheral nervous system has two divisions.

The first division of the PNS is the somatic system. It controls all voluntary movements. The somatic system has two jobs: 1) take sensory information to the CNS; 2) carry information from the CNS to your muscles. The autonomic system oversees regulating involuntary functions such as heartbeat, blood pressure, and digestion. There is little or no conscious effort involved in activating the autonomic system. The autonomic system is also further divided into two divisions: the sympathetic and parasympathetic systems.

The sympathetic and parasympathetic systems work to control most of the same organs but in the opposite way. The sympathetic nervous system is your body's emergency system and activates your "fight or flight responses." Threats and emergencies are met head-on, or you flee the situation. Bodily responses when the sympathetic nervous system is activated include accelerated breathing, faster heart rate, digestion slows down, pupil dilatation, and perspiration. 

The parasympathetic nervous system calms you down after an emergency. All your bodily functions return to normal. Heart rate and breathing settle, pupils constrict, and digestion resumes. It is important to note that they work together to keep the body in balance.

Complete the Divisions in the Nervous System activity below.

 

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