Nervous System
- Introduction
• The nervous system is the body’s control and communication network.
• It detects, processes, and responds to internal and external stimuli.
• It regulates body functions, including movement, sensation, cognition, and homeostasis. - Divisions of the Nervous System
A. Structural Divisions
• Central Nervous System (CNS): brain and spinal cord; the main control center.
• Peripheral Nervous System (PNS): all nerves outside CNS; connects CNS to the body.
B. Functional Divisions
• Sensory (Afferent) Division: carries impulses to the CNS from sensory receptors.
• Motor (Efferent) Division: carries impulses from the CNS to muscles and glands.
• Further divided into:
• Somatic Nervous System: voluntary control of skeletal muscles.
• Autonomic Nervous System (ANS): involuntary control of smooth muscles, cardiac muscles, and glands.
• Sympathetic division: prepares body for “fight or flight”.
• Parasympathetic division: promotes “rest and digest”. - Structure of Neurons and Supporting Cells
• Neurons: functional units that transmit electrical impulses.
• Composed of cell body, dendrites (receive signals), and axon (sends signals).
• Neuroglia (Glial cells): support, protect, and nourish neurons. - Brain and Spinal Cord
A. Brain
• Organized into several parts: cerebrum, cerebellum, brainstem (midbrain, pons, medulla).
• Controls consciousness, thought, memory, sensation, movement, and vital functions like breathing and heartbeat.
B. Spinal Cord
• Extends from brainstem down vertebral column.
• Conducts impulses between brain and body.
• Controls reflex actions. - Nerve Impulse Transmission
• Resting neurons have polarized membranes.
• Upon stimulus, rapid changes in membrane potential create an action potential.
• Nerve impulses travel along axons, jumping between nodes in myelinated neurons (saltatory conduction).
• Neurotransmitters transmit signals across synapses to next neuron or effector. - Autonomic Nervous System (ANS)
• Regulates involuntary body functions to maintain homeostasis.
• Sympathetic division: increases heart rate, dilates pupils, inhibits digestion.
• Parasympathetic division: decreases heart rate, constricts pupils, stimulates digestion.
• Both divisions balance body responses depending on needs. - Functions of the Nervous System
• Sensory Input: monitoring changes inside and outside the body.
• Integration: processing and interpreting sensory input.
• Motor Output: responding by activating muscles or glands.
• Mental Activity: controls consciousness, thinking, memory.
• Homeostasis: regulates internal environment by controlling bodily functions. - Common Disorders of the Nervous System
• Stroke, epilepsy, Parkinson’s disease, multiple sclerosis.
• Peripheral neuropathy, meningitis, Alzheimer’s disease.
• Trauma-related injuries to brain and spinal cord. - Nursing Care and Considerations
• Monitor neurological status (consciousness, reflexes, sensory/motor function).
• Assist with mobility and prevent complications from immobility.
• Manage symptoms such as pain, seizures, and muscle weakness.
• Provide support and education about neurological conditions.
• Administer medications safely and monitor for side effects. - Summary for Quick Review
The nervous system controls and coordinates all body activities through the CNS and PNS. Sensory input is gathered and processed in the brain and spinal cord, which send motor output to muscles and glands. The autonomic nervous system regulates involuntary functions, balancing sympathetic “fight or flight” and parasympathetic “rest and digest” responses. Nursing care focuses on monitoring neurological health, managing symptoms, and supporting patients with neurological disorders.