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Nervous System

Nervous System. 3 Functions of the Nervous System. 1. Monitor changes inside and outside the body. Changes are stimuli and the gathered information is the sensory input.

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Nervous System

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  1. Nervous System

  2. 3 Functions of the Nervous System • 1. Monitor changes inside and outside the body. • Changes are stimuli and the gathered information is the sensory input. • 2. Processes and interprets the sensory input and makes decisions about what should be done at each moment this is integration. • 3. It then effects a response by activation muscles or glands this is called motor output.

  3. Structural Classification • Central Nervous System-(CNS)- brain and spinal cord • Interpret incoming sensory information and issue instructions based on past experience and current conditions. • Peripheral Nervous System-(PNS)- nerves that extend from the brain and spinal cord. • Carry impulse to and from the brain.

  4. Functional Classification • Functional Classification has to only with the PNS structures. • Sensory division-(afferent)- convey impulses to the CNS • Somatic sensory fibers- transmit impulses from the skin, skeletal muscles and joints. • Visceral sensory fibers- transmit impulses from the visceral organs. • Motor division-(efferent)- carries impulse from the CNS to effector organs, muscles and glands. Bring about motor response.

  5. Functional Classification • Motor division has two subdivisions • Somatic nervous system- allows us to consciously, or voluntarily, control our skeletal muscles. • Voluntary Nervous System • Autonomic Nervous System- regulates events that are automatic or involuntary. • Involuntary Nervous System

  6. Structure and Function • Neuroglia- supporting cells in the CNS are lumped together. Literally meaning “nerve glue” • Astrocytes-star-shaped cells that account for nearly half of the neural tissue. These cells protect by picking up excess ions and recapturing released neurotransmitters. • Microglia- spiderlike phagocytes that dispose of debris, including dead cells and bacteria

  7. Cont. • Ependymal- line the cavities of the brain and the spinal cord. Helps circulate cerebrospinal fluid that fills those cavities that cushion the brain. • Oligodendrocytes- glia that wrap their flat extensions tightly around the nerve fibers, producing fatty insulating coverings called myelin sheaths. • Glia cannot transmit nerve impulses • This is what most tumors are formed from in the brain. • In the PNS support cells are: • Schwann cells – form myelin sheath • Satellite cells- act as protective cushioning cells

  8. Neurons Anatomy • Neuron- nerve cell that transmit messages from one part of the body to another. • All have: • Cell bodythat contains a nucleus • One or more slender processes extending from the cell body. • Cell body- metabolic center of the neuron. • Have all organelles except centrioles • Nissl substance- rough ER • Neurofibrils- intermediate filaments that are important in maintaining cell shape

  9. Neuron Anatomy • Fibers- vary in length from microscopic to 3-4 feet long • Dendrites- convey incoming messages toward the cell body. • Branch like projections off of the cell body but not long arms. • Axons- generate nerve impulses and typically conduct them away from the cell body. • Long arm like projection from the cell body.

  10. Neuron Anatomy • Axonal Terminal- contain little sacs that have neurotransmitters in them that send and receive nerve impulses. • Synaptic cleft- tiny gas • Neurons never actually touch each other. • Myelin- covers axons and is a white fatty material. Increases nerve impulse speed. • CNS nerves are called tracts • PNS nerves are called nerves • White matter is mylinated and Grey matter has no myelin.

  11. Classification • MultipolarNeuron-Many processes coming off of the cell body • Bipolar Neuron- two processes coming off of the cell body • UnipolarNeuron- one processes coming off of the cell body

  12. PhysiologyNerve Impulse

  13. Central Nervous System • In the embryonic development the CNS first appears as a tube (Neural Tube). • Then it expands to four regions of the brain to form chambers called ventricles.

  14. Functional Anatomy of the Brain • Weighs a little over 3 lbs. • Four Regions- • Cerebral hemisphere • Diencephalon • Brain stem • cerebellum

  15. Cerebral Hemisphere • Most superior part of the brain • Largest region of the brain • Gyri- covers the entire surface of the cerebral hemispheres exhibits elevated ridges of tissue. • Sulci- shallow grooves • Fissures- deeper grooves

  16. Lobes • Parietal lobe- recognize pain, coldness, or a light touch. • Most sensitive areas are the lips and the fingertips. • Occipital lobe- visual area • Temperal lobe- auditory area • Deep inside the temporal lobe is the olfactory area

  17. Lobes • Frontal lobe- primary motor area • Allows us to move and have motor control • Broca’s area- ability to speak • Speech area- located on the temporal, parietal, and occipital • Corpus Callosum-connects the cerebral hemispheres. Allows the hemispheres to communicate.

  18. Diencephalon • Sits atop the brain stem and is enclosed by the cerebral hemispheres. • Major structures- • Thalamus-sensory impulses • Hypothalamus- regulation of body temp., water balance, and metabolism. Thirst, appetite, sex, and pain. Regulates the pituitary gland. • Pituitary gland- anterior floor by a slender stalk. • Epithalamus- roof of 3rd ventricle. Pineal body and the choroid plexus.

  19. Brain Stem • Size of your thumb in diameter. • Structures are the midbrain, pons, and medulla oblongata. • Controls breating and blood pressure. • Midbrain- reflex centers involved with vision and hearing. • Pons- control of breathing. • Medulla Oblongata- vital visceral activities. Heart rate, breathing, swallowing, and vomiting. • Reticular Formation- motor control of visceral organs. • RAS- plays a role in consciousness and the awake/sleep cycles. Damage to this area can result in coma.

  20. Cerebellum • Large cauliflowerlike • Skeletal muscle activity • Equilibrium apparatus of the inner ear, eye • Compared to the auto pilot. • If damaged movement becomes clumsy like a drunk person

  21. Brain Injuries • Concussion- slight brain injury • Dizzy, loss of consciousness briefly, no permanent damage • Contusion- marked tissue destruction. • Cerebral edema- swelling of the brain due to injury.

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