Neurological System

Neurological System



  • The cerebrum consists of the right and left hemispheres.
  • Each hemisphere receives sensory information from the opposite side of the body and controls the skeletal muscles of the opposite side.
  • The cerebrum governs sensory and motor activity and thought and learning.

Cerebral cortex

  • The cerebral cortex is the outer gray layer; it is divided into five lobes.
  • It is responsible for the conscious activities of the cerebrum.

Basal ganglia:

Cell bodies in white matter that help the cerebral cortex produce smooth voluntarymovements



  • Relays sensory impulses to the cortex
  • Provides a pain gate
  • Part of the reticular activating system


  • Regulates autonomic responses of the sympathetic and parasympathetic nervous systems
  • Regulates the stress response, sleep, appetite, body temperature, fluid balance, and emotions
  • Responsible for the production of hormones secreted by the pituitary gland and the hypothalamus



  • Responsible for motor coordination
  • Contains the visual reflex and auditory relay centers

Pons: Contains the respiratory centers and regulates breathing

Medulla oblongata

  • Contains all afferent and efferent tracts and cardiac, respiratory, vomiting, and vasomotor centers
  • Controls heart rate, respiration, blood vessel diameter, sneezing, swallowing, vomiting, and coughing

Cerebellum: Coordinates smooth muscle movement, posture, equilibrium, and muscle tone

Spinal cord

  • Provides neuron and synapse networks to produce involuntary responses to sensory stimulation
  • Controls body movement and regulates visceral function
  • Carries sensory information to and motor information from the brain
  • Extends from the first cervical to the second lumbar vertebra
  • Protected by the meninges; cerebrospinal fluid, and adipose tissue


  • Inner column of gray matter; contains two anterior and two posterior horns
  • Posterior horns connect with afferent (sensory) nerve fibers.
  • Anterior horns contain efferent (motor) nerve fibers.

Nerve tracts

  • White matter contains the nerve tract.
  • Ascending tracts (sensory pathway)
  • Descending tract (motor pathway)


  • Dura mater is the tough and fibrous membrane.
  • Arachnoid membrane is the delicate membrane and contains cerebrospinal fluid.
  • Pia mater is the vascular membrane.
  • Subarachnoid space is formed by the arachnoid membrane and the pia mater.

Cerebrospinal fluid (CSF)

  • Secreted in the ventricles; circulates in the subarachnoid space and through the ventricles to the subarachnoid layer of the meninges, where it is reabsorbed
  • Acts as a protective cushion; aids in the exchange of nutrients and wastes
  • Normal pressure is 50 to 175 mm H2O.
  • Normal volume is 125 to 150 mL.


  • Four ventricles
  • The ventricles communicate between the subarachnoid spaces and produce and circulate cerebrospinal fluid.

Cerebral Cortex

  • Frontal Lobe
  • Broca’s area for speech
  • Morals, emotions, reasoning and judgment, concentration,
  • and abstraction
  • Parietal Lobe
  • Interpretation of taste, pain, touch, temperature, and pressure
  • Spatial perception
  • Temporal Lobe
  • Auditory center
  • Wernicke’s area for sensory and speech
  • Occipital Lobe
  • Visual area
  • Limbic System
  • Emotional and visceral patterns for survival
  • Learning and memory

Blood supply

  • Right and left internal carotid arteries
  • Right and left vertebral arteries
  • These arteries supply the brain via an anastomosis at the base of the brain called the circle of Willis.


  • Acetylcholine
  • Norepinephrine
  • Dopamine
  • Serotonin
  • Amino acids
  • Polypeptides


  • The neuron consists of the cell body, axons, and dendrites.
  • The cell body contains the nucleus.
  • Neurons carrying impulses to the central nervous system (CNS) are called sensory neurons.
  • Neurons carrying impulses away from the CNS are called motor neurons.
  • Synapse is the chemical transmission of impulses from one neuron to another.

Axons and dendrites

  • The axon conducts impulses from the cell body.
  • The dendrites receive stimuli from the body and transmit them to the axon.
  • The neurons are protected and insulated by Schwann cells.
  • The Schwann cell sheath is called the neurolemma.
  • Neurons do not reproduce after the neonatal period.
  • If an axon or dendrite is damaged, it will die and be replaced slowly only if the neurolemma is intact and the cell body has not died.

Spinal nerves

  • There are 31 pairs of spinal nerves.
  • Mixed nerve fibers are formed by the joining of the anterior motor and posterior sensory roots.
  • Posterior roots contain afferent (sensory) nerve fibers.
  • Anterior roots contain efferent (motor) nerve fibers.

Autonomic nervous system

  • Sympathetic (adrenergic) fibers dilate pupils, increase heart rate and rhythm, contract blood vessels, and relax smooth muscles of the bronchi.
  • Parasympathetic (cholinergic) fibers produce the opposite effect.

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