Nervous System: Major Divisions Quiz

Nervous System: Major Divisions

The human nervous system is responsible for controlling all bodily functions through complex communication networks involving various cells, tissues, organs, and systems. It consists of two major divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). Each division has specific roles in maintaining homeostasis, which is essential for survival.

Central Nervous System (CNS)

Definition and Functions

The CNS includes the brain and spinal cord. Its primary function is processing and interpreting information from the environment and within the body, integrating responses to maintain balance with the external and internal worlds. This function allows us to interact with our surroundings, respond appropriately to threats, and perform voluntary actions.

Brain Structure and Functioning

The brain is divided into three parts: the cerebrum, diencephalon, and brainstem. Key structures within these regions include:

• Cerebellum: Located at the back of the brain, responsible for coordination of voluntary movements and balance.
• Cerebral Cortex: The outermost layer of the cerebrum, involved in perception, thought, awareness, emotion, language, judgment, decision making, and consciousness.
• Limbic System: Consists of various structures within the hemispheres of the brain, responsible for emotions like fear, happiness, love, anger, and desire.
• Brainstem: Connected to the spinal cord and plays a role in automatic functions such as breathing and heart rate regulation.

Peripheral Nervous System (PNS)

Definition and Functions

The PNS consists of nerves outside the brain and spinal cord, including the cranial and spinal nerves. Its primary function is transmitting sensory information from receptors throughout the body to the CNS and carrying motor commands from the CNS to effector cells like muscles and glands. This system allows for coordination between the body's internal environment and its external surroundings.

Cranial Nerves

There are twelve cranial nerves that originate from the brain itself:

1. Olfactory: Responsible for the sense of smell.
2. Optic: Involved in vision.
3. Oculomotor, Trochlear, Abducens, Trigeminal, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal: Each of these nerves controls specific eye movements or facial expressions, as well as sensations.

Spinal Nerves

The PNS also includes thirty one pairs of spinal nerves that exit the vertebral column through various openings called foramina. These nerves carry motor commands to effector cells and sensory information from receptors in their respective regions to the CNS.

Now that we have covered the major divisions of the nervous system, let's explore how these systems work together to maintain homeostasis and ensure our survival. The CNS processes information from the PNS, integrating responses to maintain balance within the body. For example, if you touch a hot stove, sensory receptors send information through spinal nerves to the brain, which interprets this as pain and sends motor commands to withdraw your hand. This complex communication network allows for rapid and appropriate reactions to external stimuli, ensuring our safety and wellbeing.