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1. Warm-Up
1. Name the 2 main organs of the nervous
system.
2. Draw and label the parts of a neuron.

2. Warm-Up
• Label the parts of the neuron below.
A
B
E
F
C
G
D

3. Warm-Up
1. One neuron transmits a nerve impulse at 40
m/s. Another conducts at the rate of 1 m/s.
Which neuron has a myelinated axon?
2. List the following in order:
A. K+
channels open and K+
floods out of cell
B. Membrane is polarized (resting potential)
C. Neurotransmitters are released from vesicles into
synaptic cleft
D. Na+
channels open and Na+
floods into cell
E. Stimulus triggers membrane depolarization
3. What restores the resting potential of a
neuron?

4. The Nervous System

5. Nervous System
• Master controlling and communicating system

6. Basic Functions
1.1. Sensory inputSensory input – gather information
2.2. IntegrationIntegration – process and interpret sensory input
3.3. Motor outputMotor output – response by muscles and glands

7. Organization
A.A. Central Nervous System (CNS)Central Nervous System (CNS)
▫ Brain & spinal cord
▫ Integrative and control centers
A.A. Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)
▫ Nerves (spinal nerves, cranial nerves)
▫ Communication lines between CNS and rest of body
▫ Two Divisions:Two Divisions:
1.1. Sensory (afferent) DivisionSensory (afferent) Division: Sensory receptors 
CNS
2.2. Motor (efferent) DivisionMotor (efferent) Division: CNS  effectors
(muscles & glands)

8. Motor Division
• Somatic nervous systemSomatic nervous system (voluntary) – control
skeletal muscles
• Autonomic nervous systemAutonomic nervous system (ANS) (involuntary)
– regulate smooth muscles, cardiac, glands
▫ Subdivisions: sympatheticsympathetic & parasympatheticparasympathetic

10. Nervous TissueNervous Tissue
1.1. NeuronsNeurons (nerve cells) - transmit message
Anatomy:
▫ Cell bodyCell body – contains nucleus; metabolic center
▫ DendriteDendrite – fiber that conveys messages toward cell
body
▫ AxonAxon – conduct nerve impulses away from the cell body
▫ Axon terminalsAxon terminals – end of axon; contain neurotransmitters
& release them
▫ Synaptic cleft/synapseSynaptic cleft/synapse – gap between neurons

12. Nervous TissueNervous Tissue
2. Supporting cells (NeurogliaNeuroglia)
CNSCNS:: astrocytes, microglia, ependymal cells, oligodendrocytesastrocytes, microglia, ependymal cells, oligodendrocytes
 barrier between capillaries and neurons
 protect neurons
 immune/defense
 line brain and spinal cord cavities
 wrap nerve fibers
 produces myelin sheaths (covering)
PNSPNS: Schwann cells, satellite cells: Schwann cells, satellite cells
 surround large neurons
 protect & cushion

14. • MyelinMyelin:: whitish, fatty material that covers nerve fibers
to speed up nerve impulses
• Schwann cellsSchwann cells:: surround axons and form myelin sheath
• Myelin sheathMyelin sheath:: tight coil of wrapped membranes
• Nodes of RanvierNodes of Ranvier: gaps between Schwann cells

15. • GangliaGanglia: collections of cell bodies
• Bundles of nerve fibers = tractstracts (CNS) or nervesnerves (PNS)
• White matterWhite matter: dense collections of myelinated fibers
• Gray matterGray matter: unmyelinated fibers & cell bodies

16. It’s a Mad, Mad, Mad Neuron

17. Classification of Neurons

18. 1. Functional Classification: direction nerve
impulse is traveling
Sensory
neurons
Motor
neurons
Interneurons
carry impulses
from sensory
receptors to CNS
carry impulses
from CNS to
muscles & glands
connect sensory &
motor neurons
Vision, hearing,
equilibrium, taste,
smell, pain,
pressure, heat

20. 2. Structural Classification: # processes
extending from cell body
Multipolar Bipolar Unipolar
1 axon, several
dendrites
1 axon, 1 dendrite 1 process
Most common
(99%)
Rare
Short with 2
branches (sensory,
CNS)
Eg. Motor
neurons,
interneurons
Eg. retina, nose,
ear
Eg. PNS ganglia

22. Nerve Impulses

23. Neuron Function
1.1. IrritabilityIrritability: ability to respond to stimulus &
convert to nerve impulse
2.2. ConductivityConductivity: transmit impulse to other
neurons, muscles, or glands

24. Exciting a Neuron:
• Cell membrane at rest = polarizedpolarized
▫ Na+
outside cell, K+
inside cell
▫ Inside is (-) compared to outside
• Stimulus  excited neuron (Na+
rushes in) 
becomes depolarizeddepolarized
• Depolarization activates neuron to transmit an
action potentialaction potential (nerve impulse)
▫ All-or-none response
▫ Impulse conducts down entire axon
• K+ diffuses out  repolarizationrepolarization of membrane
• Na+/K+ ion concentrations restored by sodium-sodium-
potassium pumppotassium pump (uses ATP)

25. Resting membrane potential (-70mV)

26. Gated Ion Channels (Na+
and K+
)

27. Depolarization

30. • Saltatory conductionSaltatory conduction: electrical signal jumps from
node to node along myelinated axon (30x faster!)

31. Multiple Sclerosis (MS)
• Autoimmune disease
• Myelin sheaths destroyed  reduced to
hardened lesions (scleroses)
• Blindness, muscle weakness, speech
disturbance, urinary incontinence
• Treatment: interferons, glatiramer (hold off
attacks)

33. Nerve Conduction
• Action potential reaches
axon terminal  vesicles
release neurotransmittersneurotransmitters
(NT)(NT) into synaptic cleftsynaptic cleft
• NT diffuse across synapse
 bind to receptors of
next neuron
• Transmission of a nerve
impulse = electrochemicalelectrochemical
eventevent

34. Neuron Talk

35. Neurotransmitters
• 50+ identified
• ExcitatoryExcitatory: cause depolarization
• InhibitoryInhibitory: reduce ability to cause action potential
• Eg. acetylcholine, serotonin, endorphins

36. Mouse Party

37. Neurotransmitters
NeurotransmitterNeurotransmitter ActionAction Affected by:Affected by:
Acetylcholine muscle contraction botulism, curare
(paralytic), nicotine
Dopamine “feeling good” cocaine,
amphetamines
Serotonin sleep, appetite, nausea,
mood, migraines
Prozac, LSD,
ecstasy
Endorphins inhibit pain morphine, heroin,
methadone
GABA main inhibitory NT alcohol, Valium,
barbiturates

39. Reflexes
• Rapid, predictable, involuntary responses to stimuli
1.Somatic Reflexes: stimulate skeletal muscles
▫ Eg. jerking away hand from hot object
1.Autonomic Reflexes: regulate smooth muscles,
heart, glands
▫ Eg. salivation, digestion, blood pressure, sweating

40. Reflex Arc (neural pathway)
Five elements:
1. Receptor – reacts to stimulus
2. Sensory neuron
3. CNS integration center
4. Motor neuron
5. Effector organ – muscle or gland

43. Reflex Activities
Patellar (Knee-jerk)
Reflex
Pupillary Reflex

44. Patellar (Knee-jerk)
Reflex
Pupillary Reflex
• Stretch reflex
• Tapping patellar ligament
causes quadriceps to
contract  knee extends
• Help maintain muscle
tone, posture, & balance
• Optic nerve  brain stem
 muscles constrict pupil
• Useful for checking brain
stem function and drug
use

45. Flexor (withdrawal) reflex:
painful stimulus  withdrawal of
threatened body part
▫ Pin prick
Plantar reflex:
draw object down sole of foot 
curling of toes
▫ Babinski’s sign: check to see if
motor cortex or corticospinal tract
is damaged

46. Voluntary Reactions
• More neurons and synapses are involved 
longer response times
Reflex = Involuntary Reaction Voluntary Reaction