Neurological System Overview

Neurological System

• The nervous system comprises the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS includes the brain and spinal cord.
• The PNS includes nerves and sensory organs.
• The brain is divided into the cerebrum, diencephalon, cerebellum and brainstem.
• The brainstem includes the midbrain, pons, and medulla oblongata.
• Each part of the brain has specific functions including sensory information processing, voluntary movement control, and involuntary functions.
• The spinal cord transmits signals between the brain and the body.
• The peripheral nervous system includes cranial nerves (12 pairs), spinal nerves (31 pairs), ganglia, and sensory organs.
• Neurons are specialized nerve cells.
• A neuron comprises a cell body, dendrites, and axon.
• Dendrites receive signals from other neurons.
• Axons transmit signals to other neurons.
• Neurotransmitters carry signals across synapses.
• Common neurotransmitters include acetylcholine, norepinephrine, and dopamine.
• There are different types of nerve pathways for the body (e.g., reflex arc and other nerve pathways).
• The nervous system is sensitive to injury and requires careful assessment and support during care.

Definitions of Key Terms

• Accommodation: ability of the ocular lens to focus on objects at varying distances.
• Afferent: carries impulses toward the central nervous system (CNS).
• Aphasia: loss of the ability to communicate through speech, writing, or signs.
• Babinski Reflex: reflex action characterized by dorsiflexion of the big toe and flaring of other toes.
• Clonus: involuntary muscular contractions characterized by a rhythmic, alternating pattern.
• Calculi: hard deposits of mineral salts in the urinary tract or other organs.
• Cerebrovascular accident (CVA) or stroke: disruption of blood flow to the brain.
• Delirium: state of confusion and disorientation, usually temporary.
• Decerebrate posturing: rigid extension of the arms and legs.
• Dysphagia: difficulty swallowing.
• Efferent: carries impulses away from the CNS.
• Extensor posturing: rigid extension of the arms and legs.
• Flexor posturing: flexion of the arms and legs at the joints.
• Hemiparesis: weakness on one side of the body.
• Hemiplegia: paralysis on one side of the body.
• Nystagmus: involuntary, rapid eye movement.
• Quadriplegia: paralysis of all four extremities.
• Synapse: the junction between two neurons.
• Tetraplegia: paralysis of all four extremities.

Anatomy and Physiology

• The brain is divided into different lobes (e.g., frontal, parietal, occipital, temporal).
• Each lobe has specific functions concerning different brain activities.
• The diencephalon consists of the thalamus and hypothalamus.

Anatomy and Physiology of the CNS

• The cerebrum is the center of intellect and consciousness.
• The cerebellum coordinates movement, posture, and balance.

Anatomy and Physiology of the Brainstem

• The midbrain controls visual and auditory processing and cranial nerves III and IV.
• The pons relays messages and helps regulate respiration.
• The medulla oblongata regulates heartbeat, respiration, and blood pressure.

Anatomy and Physiology of the Spinal Cord

• The spinal cord extends from the medulla to the lumbar vertebra.
• It acts as a conduction pathway for sensory and motor impulses.
• It also functions as a reflex center.
• Pyramidal tracts control voluntary movement.
• Extrapyramidal tracts control involuntary movement.

Anatomy and Physiology of the Peripheral Nervous System

• Sensory receptors detect and relay information to the brain.
• Cranial nerves connect the brain with structures in the head and neck.
• Spinal nerves connect the spinal cord with the rest of the body.
• Ganglia are clusters of nerve cell bodies.
• Nuclei are clusters of nerve cell bodies in the CNS.
• Dermatomes are areas of skin innervated by specific spinal nerves.

Conduction of an Impulse

• Neurons have a polarized state (inside negative, outside positive).
• A stimulus changes the permeability of the neuronal membrane.
• Neurotransmitters carry impulses across synapses from the axons to the dendrites.
• Different neurotransmitters function in distinct parts of the body.

Assessment of the Neurological System

• Neurological assessment evaluates the body's ability to perform motor and sensory functions.
• It normally includes evaluations of mental status, cranial nerves, motor system, reflexes, and sensory system.

Protective Mechanisms of the CNS

• The skull and vertebral column protect the brain and spinal cord.
• Meninges are layers that protect the brain and spinal cord.
• Cerebrospinal fluid (CSF) cushions these structures.

Blood Flow to the CNS

• The brain requires a constant supply of oxygen (O2).
• The Circle of Willis is a major arterial network supplying the brain.
• Increased intracranial pressure (ICP) can be a sign of various problems.

Age-Related Changes

• Various changes occur in the nervous system with age.
• Some changes include a reduction in the number of neurons, slower nerve conduction, and decreased blood flow.

Causative Factors of Neurological Disorders

• Genetic factors (e.g., cerebral palsy, muscular dystrophy) and acquired conditions (e.g., head injury, inflammation).
• Vascular disorders (e.g., stroke, aneurysms) and degenerative diseases (e.g., Parkinson's disease, Alzheimer's disease).
• Infections and tumors also contribute.

Diagnostic Studies

• Specific tests are used to assess neurological functioning.
• Various diagnostic methods examine the cerebral state.

Nursing Implications

• Assessment and management of neurological issues require various nursing protocols.
• Interventions must be tailored to the specific condition.
• Proper nursing care includes protecting the patient from injury.

Cranial Nerves

• Cranial nerves connect the brain to structures in the head.
• They are numbered I to XII.
• Some are primarily sensory; others motor, and some are both.
• Different cranial nerves perform different functions.

Prevention Methods

• Prevention of neurological complications is crucial.
• Protective gear, preventing head injuries, and controlling vascular risk factors (e.g., high blood pressure) can reduce the risk of neurological disorders.