Chapter 10 Lecture PowerPoint Nervous System I Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

10.1: Introduction Cell types in neural tissue: Neurons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cell types in neural tissue: Neurons Neuroglial cells (also known as neuroglia, glia, and glial) Dendrites Cell body Nuclei of neuroglia Axon © Ed Reschke

Nerves are made of many nerve cells Afferent-sensory nerves carry message to brain Efferent-motor neurons carry message from brain to muscle

Divisions of the Nervous System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brain Central Nervous System (CNS) Brain Spinal cord Peripheral Nervous System (PNS) Cranial nerves Spinal nerves Cranial nerves Spinal cord Spinal nerves (a)

Peripheral nervous system Somatic system 12 pairs cranial nerves 31 pairs spinal nerves Autonomic Sympathetic Fight or flight Parasympathetic

Divisions Nervous System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central Nervous System (brain and spinal cord) Peripheral Nervous System (cranial and spinal nerves) Brain Cranial nerves Sensory division Sensory receptors Spinal cord Spinal nerves Motor division Somatic Nervous System Skeletal muscle Autonomic Nervous System Smooth muscle Cardiac muscle Glands (a) (b)

10.2: General Functions of the Nervous System The three general functions of the nervous system: Receiving stimuli = sensory function Deciding about stimuli = integrative function Reacting to stimuli = motor function

Functions of Nervous System Sensory Function Sensory receptors gather information Information is carried to the CNS Motor Function Decisions are acted upon Impulses are carried to effectors Integrative Function Sensory information used to create: Sensations Memory Thoughts Decisions

10.3: Description of Cells of the Nervous System Neurons vary in size and shape They may differ in length and size of their axons and dendrites Neurons share certain features: Dendrites A cell body An axon

Neuron Structure Chromatophilic substance (Nissl bodies) Dendrites Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chromatophilic substance (Nissl bodies) Dendrites Cell body Nucleus Nucleolus Neurofibrils Axonal hillock Impulse Axon Synaptic knob of axon terminal Nodes of Ranvier Myelin (cut) Nucleus of Schwann cell Axon Schwann cell Portion of a collateral

Classification of Neurons: Functional Differences Sensory Neurons Afferent Carry impulse to CNS Most are unipolar Some are bipolar Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central nervous system Peripheral nervous system Cell body Dendrites Interneurons Link neurons Aka association neurons or internuncial neurons Multipolar Located in CNS Sensory receptor Cell body Axon (central process) Axon (peripheral process) Sensory (afferent) neuron Interneurons Motor (efferent) neuron Axon Effector (muscle or gland) Motor Neurons Multipolar Carry impulses away from CNS Carry impulses to effectors Axon Axon terminal

Types of Neuroglial Cells in the PNS 1) Schwann Cells Produce myelin found on peripheral myelinated neurons Speed up neurotransmission

10.5: The Synapse Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nerve impulses pass from neuron to neuron at synapses, moving from a pre-synaptic neuron to a post-synaptic neuron. Synaptic cleft Impulse Dendrites Axon of presynaptic neuron Axon of postsynaptic neuron Axon of presynaptic neuron Cell body of postsynaptic neuron Impulse Impulse

Action Potentials +40 Action potential +20 –20 Resting potential Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. +40 Action potential +20 –20 Resting potential reestablished Membrane potential (millivolts) –40 Resting potential –60 –80 Hyperpolarization 1 2 3 4 5 6 7 8 Milliseconds

Animation: The Nerve Impulse Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

Neurotransmitters

Reflex Arc Five components 1. Receptor (sensory cell) 2. Sensory neuron 3. Integration center (association neuron, synapses) 4. Motor neuron 5. Effector (muscle or gland cells) 31 Oct. 2012 Reflexes.ppt

REFLEXES Reflex: Rapid, predictable response to a stimulus. Unlearned, involuntary, "hard-wired" into our neuroanatomy at the cellular & tissue level. 31 Oct. 2012 Reflexes.ppt

Protection: 3 meninges: dura mater (outer) arachnoid mater (middle) Bone Meninges CSF (cerebrospinal fluid) Protection: 3 meninges: dura mater (outer) arachnoid mater (middle) pia mater (inner) 3 potential spaces epidural: outside dura subdural: between dura & arachnoid subarachnoid: deep to arachnoid

Spinal nerves continued Divided based on vertebral locations 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal Cauda equina (“horse’s tail”): collection of nerve roots at inferior end of vertebral canal

Examples of Reflexes: Stretch Reflex (Knee jerk) 1. Muscle spindles sense stretch of muscle, 2. Increase rate of sensory impulses to spinal cord 3. One synapse to motor neuron(s) monosynaptic 4. Motor neurons stimulate muscle to 5. Contract & restore tension. 31 Oct. 2012 Reflexes.ppt

Spinal Nerves ALL are mixed nerves (except the first pair) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ALL are mixed nerves (except the first pair) 31 pairs of spinal nerves: 8 cervical nerves (C1 to C8) 12 thoracic nerves (T1 to T12) 5 lumbar nerves (L1 to L5) 5 sacral nerves (S1 to S5) 1 coccygeal nerve (Co or Cc) Posterior view C1 C2 C3 C4 Cervical nerves C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 Thoracic nerves T7 T8 T9 T10 T11 T12 L1 Cauda equina L2 L3 Lumbar nerves L4 L5 S1 S2 S3 Sacral nerves S4 S5 Co Coccygeal nerve

Disorders of the nervous system Meningitis- inflammation of the linings of the brain and spinal cord Encephalitis- inflammation of the brain Epilepsy-seizure disorder. Excessive discharge from neurons. 1 in 200 suffer. Grand mal or petit mal seizures Cerebral palsy- disturbance in voluntary muscular action Parkinson’s –decreased neurotransmitter MS multiple sclerosis- autoimmune