By Mr. Danilo Villar Rogayan Jr.

Transcription

1 The Nervous System By Mr. Danilo Villar Rogayan Jr. Instructor I, Department of Natural Sciences College of Agriculture & Veterinary Medicine RMTU San Marcelino

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3 Introduction Highly complex system of two parts Central nervous system (CNS) Peripheral nervous system (PNS) Controls all other organ systems and is important for maintaining balance within those systems Disorders are numerous and often difficult to diagnose and treat 29-3

4 General Functions of the NS CNS Brain Spinal cord PNS Peripheral nerves Two sections Somatic nervous system (SNS) Skeletal or voluntary muscles Autonomic nervous system (ANS) Automatic functions 29-4

5 General Functions (cont.) Three types of neurons Afferent or sensory nerves Sensory information from environment or inside body to CNS for interpretation Efferent or motor nerves Impulses from CNS to PNS to allow for movement or action Interneruons Interpretive neurons between afferent and efferent nerves in the CNS 29-5

6 29-6 Neuron Structure Functional cells of NS Transmit electrochemical messages called nerve impulses to Other neurons Effectors (muscles or glands)

7 Neuron Structure (cont.) Neurons lose their ability to divide If destroyed, not replaced Neuralgia Support cells for neurons that can divide Astrocytes anchor blood vessels to nerves Microglia act as phagocytes Oligodendrocytes assist with production of myelin sheath 29-7

8 Neuron Structure (cont.) Neurons have cell body processes called nerve fibers that extend from the cell body. Dendrites short Receive nerve impulses for the neuron Axons long Send nerve impulses away from the cell body 29-8

9 29-9 Neuron Structure (cont.) Schwann cells Axon Dendrites White matter axons with myelin sheath Schwann cells neurological cells Wrap around some axons Cell membranes contain myelin Myelin insulates axons and enables axons to send nerve impulses more quickly Gray matter axons without myelin sheath

10 Central Nervous System Includes the spinal cord and brain Blood-brain barrier Protects layers of the membranes of the CNS Formed by tight capillaries Prevents unwanted substances from entering the CNS tissues Inflammation can make more permeable 29-10

11 29-11 CNS (cont.) Meninges protect brain and spinal cord Dura mater Tough outer layer Arachnoid mater Middle layer (web-like) Pia mater Innermost and most delicate Directly on top of brain and spinal cord Holds blood vessels on the surface of these structures

12 29-12 CNS: Spinal Cord Slender structure continuous with the brain Descends into the vertebral canal and ends around the level of the first or second lumbar vertebra 31 spinal segments: 8 cervical segments 12 thoracic segments 5 lumbar segments 5 sacral segments 1 coccygeal segment

13 29-13 CNS: Brain Four sections Cerebrum Diencephalons Brain stem Cerebellum

14 CNS: Brain Cerebrum Largest section Two cerebral hemispheres Connected by a thick bundle of nerve fibers called the corpus callosum Longitudinal fissure between hemispheres Sulci grooves on surface Gyri or convolutions bumps of brain matter between sulci Brain 29-14

15 29-15 CNS: Brain Cerebrum (cont.) Lobes Frontal Motor areas for voluntary body movements Parietal Somatosensory interprets sensations Temporal Auditory interprets sounds Occipital Interprets what a person sees Frontal Temporal Parietal Occipital

16 CNS: Brain Brain Stem Connects the cerebrum to the spinal cord Midbrain Just beneath diencephalon Controls both visual and auditory reflexes Pons Rounded bulge on underside of brain stem Between midbrain and medulla oblongata Regulates respiration Medulla oblongata Inferior portion of brain stem Directly connected to spinal cord Controls many vital activities, such as heart rate, blood pressure, and breathing Brain 29-16

17 CNS: Brain Cerebellum Location Inferior to the occipital lobes of the cerebrum Posterior to the pons and medulla oblongata Coordinates Complex skeletal muscle contractions that are needed for body movements Fine movements Brain 29-17

18 29-18 Previous slide

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20 Left and Right Brain Left Brain Good at remembering names Likes to do things one at a time Likes to keep feelings to himself/herself Is not a risk-taker, careful, does not like to make mistakes Fairly long attention span, good listener Will ask many questions before making a decision Right Brain Good at remembering faces Likes to do several things at once Likes to let people know how he/she feels Is good at thinking up funny things to say and do High tolerance for clutter, disorganized Short attention span, daydreamer Likes to guess at the answer in problem solving situations

21 29-21 Peripheral Nervous System Nerves that branch off the CNS Peripheral nerves Two types: Cranial nerves Spinal nerves

22 PNS: Spinal Nerves Peripheral nerves originating from the spinal cord 31 pairs of spinal nerves 8 pairs of cervical nerves (C1 through C8) 12 pairs of thoracic nerves (T1 through T12) 5 pairs of lumbar nerves (L1 through L5) 5 pairs of sacral nerves (S1 through S5) 1 pair of coccygeal nerves (C0) Spinal Nerves 29-22

23 29-23 Previous slide

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25 29-25 Common Diseases and Disorders Disease/Disorder Alzheimer s disease Amyotrophic lateral sclerosis (ALS) Bell s palsy Description Progressive, degenerative disease of the brain Lou Gehrig s disease Degeneration of neurons in the spinal cord and brain Weak or paralyzed facial muscles

26 29-26 Common Diseases and Disorders (cont.) Disease/Disorder Brain tumors and cancers Epilepsy and seizures Guillain-Barré Syndrome Description Abnormal growths Can be primary or secondary tumors Most common gliomas Occurs as a result of bursts of electrical signals that disrupt normal brain functioning Body s immune system attacks the PNS

27 29-27 Common Diseases and Disorders (cont.) Disease/Disorder Description Headaches Tension Migraines Cluster Meningitis Multiple sclerosis (MS) Episodic or chronic With aura/without aura Form of migraines; occurs in groups Inflammation of meninges Chronic disease of CNS Myelin is destroyed

28 29-28 Common Diseases and Disorders (cont.) Disease/Disorder Description Neuralgias Parkinson s disease Sciatica Stroke Disorders causing nerve pain Progressive and degenerative motor system disorder Damage to sciatic nerve Brain cells die because of an inadequate blood flow; brain attack

29 In Summary Functions of the nervous system Detecting and interpreting sensory information Making decision about that information Responding to and carrying out motor functions Neurons are responsible for functions Divisions CNS brain and spinal cord PNS cranial and spinal nerves Knowledge of this system is essential when assisting the physician during a neurologic exam 29-29

30 Activity of the nervous system improves the capacity for activity, just as exercising a muscle makes it stronger. ~ Dr. Ralph Gerard 29-30

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32 Lakô hã salamát! Maraming salamat!