5 Functional Divisions Somatic nervous system Controlled voluntarily Effectors are skeletal musclesNo further subdivisionsAutonomic (or visceral) nervous system (ANS)Controlled involuntarilyEffectors are smooth muscle, cardiac muscle, and glandsSubdivided intoSympathetic nervous systemParasympathetic nervous system
6 Checkpoint 8-1: What are the two divisions of the nervous system based on structure? Central nervous systemAutonomic nervous systemCheckpoint 8-2: The nervous system can be divided functionally into two divisions based on type of control and effectors. What division is voluntary and controls skeletal muscle, and what division is involuntary and controls involuntary muscles and glands?The somatic system is voluntary and controls skeletal muscleThe autonomic system is involuntary and controls involuntary muscles and glands
7 Neurons and Their Functions Functional cells of nervous systemHighly specializedUnique structure
8 Structure of a Neuron Cell body Nucleus Other organelles Cell fibers DendritesAxonsSome are protected by myelin sheath
9 Diagram of a motor neuron. ZOOMING IN • Is the neuron shownhere a sensory or a motor neuron?Motor neuron
12 Checkpoint 8-3: The neuron, the functional unit of the nervous system, has long fibers extending from the cell body. What is the name of the fiber that carries impulses toward the cell body and what is the name of the fiber that carries impulses away from the cell body?The dendrite carries impulses toward the cell body and the axon carries impulses away from the cell body. Try to remember it this way – DCBAD – dendrite > CB – cell body > A - axon
13 Checkpoint 8-4: Myelin is a substance that covers and protects some axons. What color describes myelinated fibers, and what color describes unmyelinated tissue of the nervous system?Myelinated fibers are whiteUnmyelinated tissue is gray matter
14 Types of Neurons Sensory neurons (afferent neurons) Conduct impulses to spinal cord, brainMotor neurons (efferent neurons)Conduct impulses to muscles, glandsInterneurons (central or association neurons)Conduct information within CNS
15 Nerves and Tracts Nerve: fiber bundle within PNS Tract: fiber bundle within CNSOrganized into fasciclesConnective tissue layersEndoneuriumPerineuriumEpineurium
16 Cross section of a nerve as seen under the microscope (x132).
17 Checkpoint 8-5: Nerves are bundles of neuron fibers in the PNS Checkpoint 8-5: Nerves are bundles of neuron fibers in the PNS. These nerves may be carrying impulses either toward or away from the CNS. What name is given to nerves that convey impulses toward the CNS, and what name is given to nerves that transport away from the CNS?Nerves that convey impulses toward the CNS are sensory or afferent.Nerves that carry impulses away from the CNS are motor or efferent.
18 Neuroglia Neuroglia (glial cells) Protect nervous tissue Support nervous tissueAid in cell repairRemove pathogens and impuritiesRegulation composition of fluids around and between cells
25 Checkpoint 8-7: An action potential occurs in two stages Checkpoint 8-7: An action potential occurs in two stages. In the first stage, the charge on the membrane reverses, and in the second stage, it returns to the resting state. What are the names of these two stages?The first stage is depolarization and the second stage is repolarizationCheckpoint 8-8: What ions are involved in generating an action potential?Sodium (Na+) and potassium (K-)
26 The Synapse Junction point for transmitting nerve impulse Axon (presynaptic cell)Dendrite (postsynaptic cell)Synaptic cleftNeurotransmitterEpinephrine (adrenaline)Norepinephrine (noradrenaline)AcetylcholineReceptors
28 Checkpoint 8-9: Chemicals are needed to carry information across the synaptic cleft at a synapse. As a group, what are all these chemicals called?Neurotransmitters
29 The Spinal Cord Links PNS and brain Helps coordinate impulses within CNSContained in and protected by vertebrae
30 Spinal cord and spinalnerves.ZOOMING IN • Is thespinal cord the samelength as the spinalcolumn? How does thenumber of cervicalvertebrae compare withthe number of cervicalspinal nerves?No, it isn’t. There are 7 cervical vertebrae but 8 cervical spinal nerves
31 Structure of the Spinal Cord Unmyelinated tissue (gray matter)Dorsal hornVentral hornGray commissureCentral canalMyelinated axons (white matter)Posterior median sulcusAnterior median fissureAscending and descending tracts
33 Checkpoint 8-10: The spinal cord contains both gray and white matter Checkpoint 8-10: The spinal cord contains both gray and white matter. How is this tissue arranged in the spinal cord?The gray matter is in the central portion and the white matter on the outsideCheckpoint 8-11: What is the purpose of the tracts in the white matter of the spinal cord?Sensory (afferent) impulses to the brain are transmitted in the ascending tracts and motor (efferent) impulses are transmitted in the descending tracts to the peripheral nervous system.
34 The Reflex Arc Receptor detects stimulus Sensory neuron transmits impulses to CNSCNS coordinates impulses and organizes responseMotor neuron carries impulses away from CNSEffector carries out response
35 Typical reflex arc.ZOOMING IN • Is this asomatic or an autonomic reflexarc? What type of neuron islocated between the sensoryand motor neuron in the CNS?This is a somatic reflex arc. Interneurons are located between the sensory and motor neuron.
36 Checkpoint 8-12: What name is given to a pathway through the nervous system from a stimulus to an effector?Reflex arc
37 Reflex ActivitiesSimple reflexRapidUncomplicatedAutomaticSpinal reflexCoordinated in spinal cordStretch reflex is example
38 The patellar (knee-jerk) reflex ZOOMING IN • How many total neurons are involved in this spinal reflex? Whatneurotransmitter is released at the synapse shown by number 5?2 neurons are involved. Acetylcholine is the neurotransmitter
39 The Spinal Nerves 31 pairs Each nerve attached to spinal cord by two rootsDorsal rootDorsal root ganglionVentral rootMixed nerves
40 Branches of the Spinal Nerves Plexus (network)Cervical plexusPhrenic nerveBrachial plexusRadial nerveLumbosacral plexusSciatic nerveDermatomes
41 Dermatomes.ZOOMING IN • Which spinal nervescarry impulses from the skin of thetoes? From the anterior hand andfingers?Toes - Ist sacral, anterior hand and feet – 8th cervical
42 Checkpoint 8-13: How many pairs of spinal nerves are there?
43 The Autonomic Nervous System (ANS) Regulates the action of glands, smooth muscles of hollow organs and vessels, and heart musclePreganglionic neuron connects spinal cord to ganglionPostganglionic neuron connects ganglion to effector
44 Checkpoint 8-14: How many neurons are there in each motor pathway of the ANS? All autonomic pathways contain 2 motor neurons connecting the spinal cord with the effector organ.
45 Divisions of the Autonomic Nervous System Sympathetic nervous systemThoracolumbar areaCollateral gangliaAdrenergicParasympatheticCraniosacralTerminal gangliaCholinergic
46 Autonomic nervous system. ZOOMING IN • Which divisionof the autonomic nervous systemhas ganglia closer to the effectororgan?Parasympathetic
47 Functions of the Autonomic Nervous System Sympathetic nervous systemFight-or-flight responseParasympathetic nervous systemReturns body to normalSystems generally have opposite effects on organ
48 Checkpoint 8-15: Which division of the ANS stimulates a stress response, and which division reverses the stress response?The sympathetic division stimulates a stress response and the autonomic division reverses it.