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The NERVOUS System

Explore the sensory, integrative, and motor functions of the nervous system and its central and peripheral divisions, including the autonomic and somatic systems. Learn about neurons, neuroglial cells, and the roles of white and gray matter in nervous tissue.

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The NERVOUS System

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  1. The NERVOUS System

  2. 7.01 The three broad functions of the nervous system: • Sensory • senses stimuli from both within the body and from the external environment • Integrative • analyzes, interprets, and stores information about the stimuli it has receives from the sensory portion of the nervous system • Motor • responds to stimuli by some type of action • muscular contraction • glandular secretion

  3. 7.02 Describe the general organization of the nervous system. • Central Nervous System (CNS) • Brain • Spinal Cord • Peripheral Nervous System (PNS) • Spinal Nerves (31 pairs) • Cranial Nerves (I-XII pairs) • Subdivisions • Autonomic Nervous System (ANS) - Involutary • Sympathetic • Parasympathetic • Somatic Nervous System - Voluntary

  4. 7.02 The Central Nervous System (CNS)Brain and Spinal Cord • CNS Function • Sorts incoming sensory information • Generates thoughts and emotions • Forms and stores memories • Stimulates muscle contractions • Stimulates glandular secretions

  5. 7.02 Peripheral Nervous System (PNS)Spinal and Cranial Nerves • Spinal Nerves (31 pairs) • Cranial Nerves (I-XII pairs) • Subdivisions • Autonomic Nervous System (ANS) - Involutary • Sympathetic • Parasympathetic • Somatic Nervous System - Voluntary CNS PNS

  6. CNS Green is the PNS

  7. 7.02 The Autonomic Nervous System (ANS) • Contains sensory neurons mainly from the viscera that convey information to the CNS • Contains the efferent neurons that conduct impulses to smooth muscle, cardiac muscle, and glands • Unconscious control • Two divisions of the ANS • Sympathetic Division - stimulatory effect • Parasympathetic Division - inhibitory effect

  8. Sympathetic Stimulatory. “Fight or Flight” Parasympathetic Inhibitory.

  9. 7.02 The Somatic Nervous System(SNS) • Made up of sensory neurons that convey information from the cutaneous and special sense receptors in the head, body wall, and extremities to the CNS • Also contains the motor neurons from the CNS that conduct impulses to the skeletal muscles

  10. 7.03 List the functions and structures of neurons. • The nerve cells responsible for the special functions of the nervous system • sensing - remembering - thinking • controlling muscle activity • controlling glandular secretions • Synapse - the functional relay points between two neurons or between a neuron and an effector organ • Neuromuscular Junction • Neuroglandular Junction

  11. 7.03 List the functions and structures of neurons. • Cell Body (Soma or Perikaryon) • nucleus, cytoplasm, organelles of a neuron • Dendrites - tapered, highly branched processes protruding from the cell body • usually very short • AFFERENT FUNCTION • Axons - long, thin, cylindrical process • usually myelinated • EFFERENT FUNCTION

  12. Neuron

  13. Neurons

  14. 7.03 List the functions and structures of neuroglialcells: • Nervous system cells that support, nurture and protect the neurons • Types of Neuroglia found in the CNS • Astrocytes • Oligodendrocytes • Microglia • Ependymal Cells • Types of Neuroglia found in the PNS • Neurolemmocytes (Schwann Cells) • Satellite Cells

  15. 7.03 Astrocytes (Astroglia) • Star-shaped cells with many processes • Forms the Blood Brain Barrier (BBB) • Forms the pia mater covering the brain and spinal cord. • Soaks up excess ions and toxins • Participate in brain development • Facilitates repair for CNS trauma

  16. 7.03 Astrocyte

  17. 7.03 Microglia • Small phagocytic cells that protect the central nervous system by engulfing and invading microbes • Clears away debris from dead cells

  18. 7.03 Oligodendrocytes(Oligodendroglia) • Oligo- small or few • Small glial cells with few processes • Form a supporting network around the neurons by twining around neurons and producing a lipid and protein wrapping around the neurons (myelin sheath)

  19. 6.03 Oligodendrocyte

  20. 7.03 Ependymal Cells • Neuroglia cells line the brain ventricles and the central canal of the spinal cord • Form and circulate cerebral spinal fluid (CSF)

  21. 7.03 Neuroglia of the PNS(Schwann and Satellite cells) • Schwann Cells - Neurolemmocytes • Cells responsible for producing the myelin sheaths around the PNS neurons • Satellite Cells • Similar to astrocytes • Structural support • soaks up excess ions and toxins

  22. 7.03 Schwann Cell Myelination

  23. 7.03 Myelination

  24. 7.03 Myelination • The process of developing or producing a Myelin Sheath • Insulates the axon of a neuron • Increases the speed of nerve impulse conduction • CNS - oligodendrocytes • PNS - neurolemmocytes (Schwann Cells) • Guillain-Barre syndrome and Multiple Sclerosis are involved the destruction of the myelin sheaths around the nerve

  25. 7.04 Contrast white and gray matter of nervous tissue. • White Matter - the aggregation of myelinated processes from many neurons • Visible upon freshly dissected brain or spinal tissue • White color is due to myelination • Gray Matter - unmyelinated nerve cell bodies, axons, dendrites, ganglia, and axon terminals • Appears gray because of lack of myelin

  26. 7.04 Gray and White Matter

  27. 7.05 Describe the location, and function of CSF.(ventricles, subarachnoid space) • Cavities within the brain • Lateral ventricles (2) - located within each hemisphere in the cerebrum • Third ventricle - a vertical slit between the lateral ventricles and inferior to the right and left halves of the thalamus • Fourth ventricle - space between the brainstem and the cerebellum

  28. 7.05 Describe the location, and function of CSF.(Choroid Plexus) • Network of capillaries in the walls of the ventricles • Covered with ependymal cells that form the cerebrospinal fluid • These ependymal cells are so close together they form the blood-brain barrier. • Selectively permeable barrier • Protects the brain and spinal cord from potentially harmful substances in the blood

  29. 7.05 Blood Supply to the Brain • One of the most metabolically active organs in the body • Makes up only 2-3% of body weight but uses about 20% of available O2 at rest • Well supplied with O2 and nutrients • Only nutritional source for brain metabolic activity is glucose • Capillaries in the brain are much less leaky than other capillaries in the body and form a blood brain barrier

  30. 7.05 Describe the function of CSF. • Mechanical Protection • Serves as a shock absorbing medium • Buoys the brain so it literally floats within the cranial cavity • Chemical Protection • Provides an optimal chemical environment for neural signaling • Circulation • Acts as a medium for exchange of nutrients and waste products between the blood and nervous tissue

  31. 7.05 Ventricles of the Brain

  32. 7.05Flow ofCerebro- SpinalFluid(CSF)

  33. 7.05Flow ofCerebro-Spinal Fluid

  34. Hydrocephalus Blocked Cerebral Aqueduct

  35. 7.06 Identify the structures responsible for the maintenance and protection of thecentral nervous system. • Protected by the cranial bones and the cranial meninges • Dura Mater - outer layer • Arachnoid - middle layer • Pia Mater - inner layer • Also protected by cerebrospinal fluid (CSF) • fluid that nourishes and protects the brain and spinal cord • continuously circulates through the subarachnoid space around the brain and throughout the cavities within the brain

  36. 7.06 Meninges • Connective tissue covering found around the brain and spinal cord • Three layered membrane • Dura Mater - outer most layer • dense irregular connective tissue • Arachnoid - middle layer • spider web arrangement of collagen fibers • Pia Mater - inner most meninges • very delicate layer of thin tissue

  37. 7.06 Meninges of the Brain

  38. 7.06Meninges of theSpinal Cord • Dura Mater • Arachnoid -SubarachnoidSpace • Pia Mater

  39. The BRAIN

  40. 7.07 Identify the four principle parts of the brain. cerebrum, cerebellum, brain stem, diencephalon • One of the largest organs in the body • Controls all mental functions • Component of the CNS • Composed of over 100 billion neurons • Comprises 2-3% of body weight • Utilizes over 20% of body’s energy

  41. CEREBRUM - occupies most of the cranium and is divided into right and left halves called hemispheres • CEREBELLUM - the posterior-inferior portion of the brain • BRAIN STEM - consists of the medulla oblongata, thepons, and the midbrain • it is continuous with the spinal cord • DIENCEPHALON - located above the brainstem, composed primarily of the: • Thalamus - Hypothalamus

  42. The Brain

  43. 7.08 Describe the functions of the three structures of the brain stem. • The most inferior portion of the brain • Connects the brain to the spinal cord • Composed of Three Areas • The Medulla Oblongata • The Pons • The Midbrain

  44. 7.08 The Medulla Oblongata • Most inferior portion of the brain stem • Connects the brain stem to the spinal cord • Respiratory Center *** • Adjusts rhythm and depth of breathing • Cardiovascular Center *** • Regulates heart rate and contraction force • Influences vasoconstriction and vasodilation • Also controls coughing, vomiting, swallowing, and hiccupping

  45. The Medulla Oblongata

  46. The Medulla Oblongata

  47. 7.08 The Pons • Lies superior to the medulla oblongata • Together with the respiratory center in the medulla helps control respiration

  48. The Pons

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