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Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
Nervous system
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Nervous system


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    • is the master controlling and communicating system of the body; works with other organ system;
    • electrical impulses which act as signaling device and as a means of communicating with body cells are specific and cause an immediate response;
    • three overlapping functions:
        • monitor changes occurring both inside and outside the body (stimuli); the gathered input is called SENSORY INPUT;
        • it process and interprets the sensory input and decides on the input (INTEGRATION)
        • it effects a response by activating muscles or glands (MOTOR OUTPUT)
  • 3.
    • Structural Classifications:
      • Central Nervous System (CNS) – consists of the brain and spinal cord;
      • Peripheral Nervous System (PNS) – outside the CNS; consists of the spinal nerves and cranial nerves
    • Functional Classification: (concerned only with PNS structures)
      • Sensory or Afferent division – consists of nerves that convey impulses to the CNS from sensory receptors located in various parts of the body;
        • Sensory fibers delivering impulses from the skin, skeletal muscles, and joints are called SOMATIC SENSORY FIBERS;
  • 4.
        • Sensory fibers transmitting impulses from the visceral organs are called VISCERAL SENSORY FIBERS;
      • 2. Motor or Efferent division – carries impulses from the CNS to the effector organs, the muscles and glands;
        • Somatic Nervous System – allows conscious or voluntary control of our movements;
        • Autonomic Nervous System – regulates events that are involuntary; such as the activity of smooth and cardiac muscles and glands;
            • Sympathetic NS
            • Parasympathetic NS
  • 5.
      • the nervous system is made up of two principal types of cells:
          • Supporting Cells
          • Neurons
      • these cells in the CNS are lumped together as NEUROGLIA ;
      • generally made up of cells that support, insulate, and protect the delicate neurons;
      • types of neuroglia:
        • Astrocytes – most abundant; form a living barrier between capillaries and neurons; play a role in making exchanges between the capillaries and neurons;
  • 6.
        • 2. Microglia – are phagocytes that dispose of debris (dead brain cells, bacteria, etc.)
        • 3. Ependymal cells – line the cavities of the brain and spinal cord; their beating cilia helps circulate CSF and forms a protective cushion around the CNS;
        • 4. Oligodendrocytes – forms myelin sheath around the nerve fibers in the CNS ;
    • Supporting Cells in the PNS comes in two major forms:
        • Schwann Cells – form myelin sheath around the nerve fibers in the PNS ;
        • Satellite Cells – act as protective, cushioning cells;
  • 7.
      • also called nerve cells ;
      • are the functional unit of the nervous system;
      • are highly specialized to transmit nerve impulses from one part of the body to another;
      • parts:
        • Cell Body – contains the nucleus and is the metabolic center of the cell;
        • Dendrites – neuron processes that conduct nerve impulses toward the cell body;
        • Axons – processes that conduct nerve impulses away from the cell body;
  • 8.
      • most long nerve fibers are covered with a whitish, fatty material, called MYELIN;
          • also protects and insulates the fibers and increases the transmission rate of nerve impulses;
          • most axons are wrapped with myelin called MYELIN SHEATH;
    • Clusters of neuron cell bodies in the CNS are called NUCLEI;
    • Small collections of cell bodies in the PNS are called GANGLIA;
  • 9.
    • Functional Classification of a Neuron:
      • Sensory / Afferent Neurons – carrying impulses from the sensory receptors to the CNS;
      • Motor / Efferent Neurons – carrying impulses from the CNS to the viscera and/or muscles and glands;
      • Interneurons – connect the motor and sensory neurons;
  • 10.
    • Structural Classification of Neurons (based on the no. of processes)
      • Multipolar Neurons – several processes; most common structural type;
      • Bipolar Neurons – contain two processes, an axon and a dendrite;
      • Unipolar Neurons – contain a single neuronal process;
    • Neurons have two major functional properties:
      • Irritability – ability to respond to a stimulus and convert it to a nerve impulse;
      • Conductivity – ability to transmit the impulse to other neurons, muscles, or glands;
  • 11.
    • REFLEXES – are rapid, predictable, and involuntary response to stimuli;
        • Occur over neural pathways called REFLEX ARC (a complete circuit consisting of a sensory neuron ending in the spinal cord, connecting neuron within the cord, and a motor neuron to a muscle );
        • Autonomic Reflexes regulate the activity of smooth muscles, the heart, and glands; ex. Salivary and Pupillary reflex
        • Somatic Reflexes includes all reflexes that stimulate the skeletal muscles;
  • 12.
      • originates in the NEURAL TUBE ;
      • is the part enclosed by bone or the cranium;
      • it includes the BRAIN and the SPINAL CORD;
      • the chambers of the brain are called VENTRICLES (filled with cerebrospinal fluid )
      • Four Major Parts:
        • Cerebrum
        • Diencephalon
        • Brainstem
        • Cerebellum
  • 13.
    • Anatomy of the Brain
      • the brain is the largest and most complex mass of nervous tissue in the body;
    • Four major regions of the brain:
    • Cerebral Hemispheres (cerebrum)
      • are paired superior part of the brain;
      • enclose and obscure most of the brain stem;
      • Gyri – elevated ridges of tissue on the surface of the cerebral hemispheres;
      • Sulci – hollow grooves that separates the gyri;
      • The cerebral hemispheres are separated by a single deep fissure called the LONGITUDINAL FISSURE;
  • 14.
    • Lobes of the brain:
      • Parietal Lobe – area for somatic sensory;
      • Frontal Lobe – area for motor movement;
      • Occipital Lobe – area for vision;
      • Temporal Lobe – auditory and olfactory area;
  • 15.
    • A specialized area that is involved in our ability to speak is called BROCA’S AREA;
    • Areas involved in higher intellectual reasoning and language comprehension is called WERNICKE’S AREA;
    • Layers of cell bodies of Neurons:
      • Gray Matter – outermost layer; functional area;
      • White Matter – deeper layer; composed of fibers tracts carrying impulses to or from the cortex; form tracts or bundles that connect two parts of the cerebrum to other parts of the brain.
    • The cerebral hemispheres are connected by one large fiber tract called CORPUS CALLOSUM;
  • 16.
    • 2. Diencephalon
      • Or interbrain;
      • Sits atop the brainstem and is enclosed by the cerebral hemispheres;
      • Major structures:
          • Thalamus – encloses the third ventricle , is a relay station for sensory impulses passing upward to the sensory cortex;
          • Hypothalamus – forms the floor of the third ventricle; is an important autonomic NS center because it plays a role in regulation of body temperature, water balance, and metabolism; also secretes oxytocin and ADH;
  • 17.
    • 3. Brainstem
      • Is found on the lower part of the brain hidden by the cerebral hemispheres;
      • Provides a pathway for ascending and descending tracts;
      • Their nuclei form the cranial nerves and control vital activities such as breathing and BP;
      • RETICULAR FORMATION – is a diffuse mass that extends in the entire length of the brainstem;
  • 18.
    • Parts of Brainstem:
    • Midbrain – contains the cerebral aqueduct of Sylvius;
      • contains nuclei that act as reflex centers involved with vision and hearing;
  • 19.
    • Parts of Brainstem…..
    • 2. Pons – rounded structure that protrudes below the midbrain;
      • contains many fiber tracts;
      • involved in control of breathing;
      • also contains nuclei of several cranial nerves;
  • 20.
    • Parts of Brainstem…
    • 3. Medulla Oblongata – is the most inferior part of the brainstem;
      • also an important fiber tract area;
      • Also contains nuclei that regulate vital visceral functions;
      • Contains centers that control heart rate, BP, breathing, swallowing, and vomiting;
  • 21.
    • 4. Cerebellum
      • Is a large, cauliflowerlike structure that projects dorsally from under the occipital lobe of the cerebrum;
      • Provides the precise timing or good coordination of skeletal muscle activity and controls our balance, posture, and equilibrium;
      • Ataxia means clumsy, disorganized movements when the cerebellum is injured;
    • because of the delicate nature of the neurons, the body provides many protective structures to protect them:
        • Skull
        • Vertebral Column
        • Meninges – this are three connective tissue membranes that covers and protect the CNS;
            • The outermost layer (DURA MATER) is a double-layered membrane that surrounds the brain;
            • The middle meningeal layer is the weblike ARACHNOID MATER;
            • The innermost layer is the PIA MATER which clings tightly to the surface of the brain and spinal cord;
  • 23.
    • The FALX CEREBRI is the fold of dura mater that passes transversely across the upper end of the posterior cranial fossa in the transverse fissure;
      • also separates the occipital lobe of the cerebrum from the upper surface of the cerebellum;
    • The SUBARACHNOID SPACE is filled with CSF;
    • ARACHNOID VILLI absorb CSF into the venous blood;
    • MENINGITIS – inflammation of the meninges;
    • ENCEPHALITIS – inflammation of the brain;
  • 24.
        • 4. Cerebrospinal Fluid (CSF)
          • Is a watery broth similar to blood plasma;
          • Formed by the CHOROID PLEXUS;
          • Is found in and around the brain and spinal cord which forms a watery cushion that protects these fragile structures against blows and trauma;
    • EPIDURAL SPACE – is the interval between the dura mater and cranial bones ; in the SPINE, it is the space between the dura mater and the vertebral canal;
    • SUBDURAL SPACE – is the interval between the arachnoid and dura mater of the brain or the spinal cord;
  • 25.
    • SUBARACHNOID SPACE (space between the arachnoid and pia mater)
  • 26.
      • the brain is very dependent on a constant environment;
      • separates the neurons from blood-borne substances;
      • composed of least permeable capillaries in the body;
      • water-soluble substances like water, glucose, and essential amino acids pass easily;
      • is virtually useless against fats, respiratory gases, and other fat-soluble molecules that diffuse easily thru all the plasma membranes;
  • 27.
      • is a glistening white continuation of the brainstem;
      • provides a two-way conduction pathway to and from the brain;
      • enclosed within the vertebral or spinal column;
      • extends from the FORAMEN MAGNUM of the skull to the 1st or 2nd lumbar vertebra;
      • it is protected and cushioned by meninges;
  • 28.
    • In humans, 31 pairs of spinal nerves arise from the cord;
    • Collection of spinal nerves at the inferior end of the vertebral canal is called CAUDA EQUINA;
  • 29.
    • the gray matter of the spinal cord is H-shaped and is found more interior;
    • the two posterior projections are the DORSAL or POSTERIOR HORNS for sensory functions;
    • the two anterior projections are the VENTRAL or ANTERIOR HORNS for motor function of the somatic nervous system (voluntary);
    • the LATERAL HORN is a bulge on each limb of gray substance in the thoracic and upper lumbar segments;
    • the gray matter surrounds the central canal of the cord which contains the CSF;
  • 30.
      • Cervical Plexus – on each side of the body is made up of the ventral divisions of the C1-C4;
            • Supplies the skin and muscles of the scalp, neck, and part of the face;
            • The PHRENIC NERVE originates from this plexus;
      • Brachial Plexus – formed by C5-T1; lies posterior to the clavicle;
            • Supplies the shoulder and upper limb;
      • Lumbar Plexus – formed by L1-L4; lies in the posterior abdomen in the area of the psoas muscle; supplies the FEMORAL NERVE;
      • Sacral Plexus – formed by L4-S3; located within the pelvis on the posterolateral wall; the largest branch is the SCIATIC NERVE;
  • 31.
      • consists of nerves and scattered groups of neuronal cell bodies found outside the CNS;
    • A. NERVES
      • Is a bundle of neuron fibers found outside the CNS;
        • Afferent / Sensory Nerve
        • Efferent / Motor Nerve
      • arise directly from the base of the brain (brainstem), and are not associated with the spinal cord;
      • The 12 pairs primarily serve the head and neck except for the CN X (vagus) which extends to the thoracic and abdominal cavities;
      • most cranial nerves are mixed (both motor and sensory function);
  • 32.
    • CN I – olfactory n. II – optic n.
    • III – oculomotor n. IV – trochlear n.
    • V – trigeminal n.
    • VI – abducens n. VII – facial n.
    • VIII – auditory n.
    • IX – glossopharyngeal n X – vagus n.
    • XI – spinal
    • accessory n.
    • XII – hypoglossal n.
    “ Pls. read your book!”
  • 33.
      • is the motor subdivision of the PNS that controls body activities automatically;
      • regulates cardiac muscle activity, smooth muscle contraction, and secretion of exocrine glands;
      • has a chain of two motor neurons:
        • Preganglionic axons – axons before the ganglion; leaves the CNS to synapse with the second motor neuron in a ganglion outside the CNS;
        • Postganglionic axons – the axon extends to the organ it serves;
  • 34.
    • two divisions (usually they are antagonistic)
        • Sympathetic NS (thoracolumbar division) – is often called the “fight-or-flight” system;
          • Controls body functions that are essential for survival;
          • Effects:
            • Increases heart rate
            • Increases BP
            • Bronchial dilation
            • Decreases peristalsis
            • Dilated pupils
  • 35.
          • Parasympathetic NS (craniosacral division)
            • is most active when the body is at rest and not threatened in any way;
            • Concerned with normal body functions, usually opposite the SNS;
  • 36.
      • the brain is supplied by a specialized form of blood vessels called the CIRCLE OF WILLIS;
      • Arteries that supply the brain:
        • internal carotid artery – branch of the common carotid artery;
        • vertebral artery – branch of the subclavian artery;
        • middle meningeal artery – branch of the external carotid artery;
  • 37.