The Nervous System

I. The Nervous System A. Two main divisions: Two main divisionsTwo main divisions 1.The Central Nervous System (CNS) 2.The Peripheral Nervous System (PNS)

B. The CNS 1. Two main parts: The Brain: the main switch where impulses originate and flow.The Brain: the main switch where impulses originate and flow. The Spinal Cord: the link between the brain and the rest of the body.The Spinal Cord: the link between the brain and the rest of the body.

C. The Brain 1. MAJOR DIVISIONS1. MAJOR DIVISIONSMAJOR DIVISIONSMAJOR DIVISIONS –Cerebrum: part of the brain responsible for all voluntary activities of the body. LobesLobes FrontalFrontal TemporalTemporal ParietalParietal OccipitalOccipital

–Cerebellum: part of the brain that coordinates and balances the actions of muscle. –Brainstem: structure that connects the brain with the spinal cord. Coordinates and integrates all the information coming into the brain.

Lobes of the Brain temporal frontalparietal occipital Central Nervous System brain spinal cord cerebellum brainstem medulla oblongata Page 35 in UP

C. The PNS 1. Two major divisions Sensory: transmits impulses from the sense organs to the CNS.Sensory: transmits impulses from the sense organs to the CNS. Motor: transmits impulses from the CNS to the muscle or glands.Motor: transmits impulses from the CNS to the muscle or glands.

D. Motor Divisions in the PNS 1.Autonomic: regulates involuntary activities. a.Sympathetic nervous system: stimulates fight-or-flight reactions b.Parasympathetic: stimulates calmer functions such as digestion 2.Somatic: regulates activities under conscious control such as muscle movement and reflexes.

E. Neurons 1.Cells that carry messages throughout the nervous system. 2.Types Types Sensory Neurons: carry impulses from the sense organs to the brain and spinal cord. Sensory Neurons: carry impulses from the sense organs to the brain and spinal cord. Sensory Neurons: Sensory Neurons: Motor Neurons: carry impulses from the brain and spinal cord to muscles or glands. Motor Neurons: carry impulses from the brain and spinal cord to muscles or glands. Motor Neurons: Motor Neurons: Interneurons: (association) connect sensory and motor neurons and carries impulses between them. Interneurons: (association) connect sensory and motor neurons and carries impulses between them.

motor neuronsensory neuron

3. Parts of a motor neuron 3. Parts of a motor neuronParts of a motor neuronParts of a motor neuron cell body cell body Nucleus Nucleus Dendrites Dendrites Axon Axon Myelin sheath (schwann cells) Myelin sheath (schwann cells) Motor end plate Motor end plate Motor end brush Motor end brush

nucleus axon myelin Effector (muscle) motor end plate end brush cell body { dendrite cytoplasm Page 32

F. Impulses moves along a neuron Resting Potential: the difference in charge across a nerve cell membrane resulting from the negative charge on the inside and the positive charge on the outside = polarizedResting Potential: the difference in charge across a nerve cell membrane resulting from the negative charge on the inside and the positive charge on the outside = polarizedResting PotentialResting Potential Threshold: A minimum level of a stimulus required to activate a neuron.Threshold: A minimum level of a stimulus required to activate a neuron.

Action Potential: changes in membrane potential that characterize a nerve impulse. the depolarization and repolarization of the membrane. Action Potential: changes in membrane potential that characterize a nerve impulse. the depolarization and repolarization of the membrane. Action Potential Action Potential Myelin: substance composed of lipids and protein that forms an insulated sheath around an axon. It increases the rate of the impulse.

depolarization repolarization depolar.

a b c d e fgh a.synapse b.neurotransmitter c.axon terminal d.myelin e.axon f.cell body g.dendrite h.receptor answers Identify the parts of the neuron What direction does the impulse travel? Page 34

G. Stimulation of a neuron Receptors: special sensory neurons in sense organs that receive stimuli from the external environment.Receptors: special sensory neurons in sense organs that receive stimuli from the external environment. Effectors: muscle or glands that bring about a coordinated response.Effectors: muscle or glands that bring about a coordinated response.

Synapses: points of near contact which impulses are chemically passed from one neuron to another.Synapses: points of near contact which impulses are chemically passed from one neuron to another. Neurotransmitters: chemicals located within vesicles that are used by the neuron to signal another.Neurotransmitters: chemicals located within vesicles that are used by the neuron to signal another. –Example = acetyl choline,

H. Simple Reflex Arc H. Simple Reflex Arc Sensory neuron: neuron that carries impulses from the sense organs to the brain and/or spinal cord.Sensory neuron: neuron that carries impulses from the sense organs to the brain and/or spinal cord. Interneuron: (association) cell that connects sensory and motor neurons and carries impulses between them.Interneuron: (association) cell that connects sensory and motor neurons and carries impulses between them. Motor neurons: neuron that carries impulses from the brain and/or spinal cord to muscles and glands.Motor neurons: neuron that carries impulses from the brain and/or spinal cord to muscles and glands.

sensory neuron cell body (sensory neuron) receptors synapse motor neuron effector (muscle) association neuron Label the diagram Page 33

I. Diagnostic Techniques A. MRI – magnetic resonance imagingA. MRI – magnetic resonance imaging –Page 25 in Unit 13 packet DiagramDiagramDiagram Machine typesMachine typesMachine typesMachine types Images – knee, brainImages – knee, brainImages – knee, brainImages – knee, brain Image series of headImage series of headImage series of headImage series of head –Images tissues and not bones or teeth

B. CT – computed tomographyB. CT – computed tomography –Page 27 in Unit 13 packet MachineMachineMachine Images – kidneyImages – kidneyImages – kidneyImages – kidney –Series of x-ray images, can produce 3-d images C. SonogramC. SonogramSonogram –Page 26 in Unit 13 packet –Uses ultra sound to image internal organs