THE NERVOUS SYSTEM JOSE S. SANTIAGO M.D.
Nervous System CNS (central nervous system) Peripheral nervous system Spinal cord Brain Peripheral nervous system Sensory neurons Motor neurons
Functions of the Nervous System Sensory input – gathering information To monitor changes occurring inside and outside the body Changes = stimuli Integration To process and interpret sensory input and decide if action is needed
Functions of the Nervous System Motor output A response to integrated stimuli The response activates muscles or glands
Nerve Cells Neurons Cell body Axon Some have myelin sheath Dendrites
Neuron Anatomy Cell body Nucleus Large nucleolus Figure 7.4a
Neuron Anatomy Extensions outside the cell body Dendrites – conduct impulses toward the cell body Axons – conduct impulses away from the cell body Figure 7.4a
Nerve Cells Neuroglia Do not carry electrical impulses Protect the neurons by phagocytosis Provide nutrients
Synapses Synapse Electrical impulse transmission Gap between neuron and a muscle or between two neurons
Synapses Neurotransmitters of the peripheral nervous system Released from sac at end of neuron Acetylcholine and Norepinephrine
The Brain Part of the CNS Cerebrum Hemispheres divided by longitudinal fissure Corpus callosum connect the hemispheres Cerebral cortex
The Brain Cerebrum Gyri (convolutions) Lobes Sulci and fissures Frontal, parietal, temporal, and occipital
Cerebral Hemispheres (Cerebrum) The surface is made of ridges (gyri) and grooves (sulci) Figure 7.13a
Brain
Brain Thalamus Hypothalamus
Brain Brain stem Midbrain Pons Medulla oblongata Cerebellum
The Spinal Cord Part of the CNS Starts at the medulla oblongata and ends at the conus medullaris (level of body of L1 vertebra)
The Spinal Cord 31 pairs of nerves 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Spinal Cord Meninges - protective membranes Dura mater-tough, protective connective tissue; tightly bound to the skull; encases the cerebral veins
Spinal Cord Arachnoid mater- web-like strands of connective tissue Pia mater- thin permeable membrane
Spinal Cord Subdural space Subarachnoid space- contains CSF and arteries Cerebrospinal fluid- secreted by the choroid plexus Blood-brain barrier
Spinal Cord Blood-brain barrier- protection for the brain against undesirable blood substances
Peripheral Nervous System Cranial nerves 12 pairs Emerge bilaterally from base of the skull Spinal nerves 31 pairs Emerge bilaterally from the spinal cord
Spinal Nerves There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Spinal nerves are formed by the combination of the ventral and dorsal roots of the spinal cord Spinal nerves are named for the region from which they arise
Additional Word Parts – Roots Myelin/o myelin sheath
Roots Cerebell/o cerebellum
Roots Cerebr/o brain
Roots Cortic/o cortex; outer covering
Roots Dur/o dura mater
Prefixes Pachy- thick Pachymeninx- dura mater
Roots Encephal/o -brain Encephalitis-inflammation of the brain
Roots Magnet/o-magnet Magnetic Resonance Imaging (MRI)-produces picture of brain using magnetic waves
Roots Hydr/o -water Hydrocephalus-accumulation of fluid in the brain
Roots Ventricul/o- ventricles Ventricles-hollow cavities inside the brain
Roots Vertricul/o- ventricles Ventriculostomy-new opening in the ventricles; for treating hydrocephalus
Suffixes -oma -tumor Hematoma-accumulation of blood in a space Epidural hematoma-blood in the epidural space
Suffixes -oma -tumor Hematoma-accumulation of blood in a space Subdural hematoma-blood in the subdural space
Types of Brain Hematoma
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