1. AB THE NERVOUS SYSTEM . B. HELP THE BODY MAINTAIN HOMEOSTASIS.
1.THE GENERAL FUNCTIONS OF THE
NERVOUS SYSTEM INCLUDE
A. REGULATE AND CONTROL BODY
FUNCTIONS .
B. HELP THE BODY MAINTAIN
HOMEOSTASIS.
C. SENSES, INTERPRETS AND
RESPONDS TO STIMULI.
D. PROCESSES, STORES AND
REMEMBERS INPUT.

2. 2. STRUCTURAL DIVISIONS OF THE
NERVOUS SYSTEM:
A. CENTRAL NERVOUS SYSTEM (CNS)=
BRAIN AND SPINAL CORD.
B. PERIPHERAL NERVOUS SYSTEM
(PNS) = RECEPTORS – SPECIALIZED
NERVE ENDINGS THAT RESPOND
TO STIMULI, NERVES – BUNDLES
OF NEURON AXONS AND
GANGLIA – COLLECTIONS OF
NERVE CELL BODIES.

3. Sensory input
Sensor
Integration
Motor output
Effector
Peripheral nervous
system (PNS)
Central nervous
system (CNS)

4. CNS + PNS
CNS

5. A. SENSORY DIVISION – CARRIES
3. DIVISIONS OF THE PNS
A. SENSORY DIVISION – CARRIES
IMPULSES TO THE CNS
FROM SENSORY RECEPTORS.
(AFFERENT=INCOMING NERVES)
B. MOTOR DIVISION – CARRIES
NERVE IMPULSES FROM THE
CNS TO EFFECTOR ORGANS.
(EFFERENT= OUT GOING NERVES)
1. SOMATIC MOTOR – INNER-
VATES SKELETAL MUSCLE.
2. AUTONOMIC MOTOR – INNER-
VATES SMOOTH & CARDIAC.

7. 4. NERVE CELLS – NEURON – HAS CELL
BODY WITH NUCLEUS, DENDRITES =
ROOT-LIKE PROJECTIONS, AND THE
AXON WHICH CAN DIVIDE AT THE
END INTO THE AXON TREE.
- THE AXON MAY BE MYELINATED =
COATED WITH FATTY MATERIAL THAT
ACTS AS AN INSULATOR. IT IS
CREATED BY ROLLING FLATTENED
SCHWANN CELLS AROUND THE
AXON. SPACES BETWEEN = NODES

8. LE 48-5 Dendrites Cell body Nucleus Synapse Signal direction
Axon hillock
Axon
Presynaptic cell
Synaptic
terminals
Myelin sheath
Postsynaptic cell

9. LE 48-8 Nodes of Ranvier Layers of myelin Axon Schwann cell Schwann
Nucleus of
Schwann cell
Myelin sheath
0.1 µm

11. -Neurons also have “helper” cells called glia.
Glia are essential for structural integrity of
the nervous system and for functioning of
neurons
Types of glia: astrocytes, radial glia,
oligodendrocytes, and Schwann cells

12. 5. TYPES OF NEURONS: SENSORY, INTERNEURON AND MOTOR.
Gray
matter
Cell body of
sensory neuron in
dorsal root
ganglion
Quadriceps
muscle
White
matter
Hamstring
muscle
Spinal cord
(cross section)
Sensory neuron
Motor neuron
Interneuron

13. Varieties of neurons LE 48-6 Dendrites Axon Cell body Sensory neuron
Interneurons
Motor neuron

14. 6. MEMBRANE POTENTIAL = CHARGE DIFFERENCE BETWEEN THE
INSIDE AND OUTSIDE OF THE
MEMBRANE OF A NERVE CELL.
Microelectrode
–70 mV
Voltage
recorder
Reference
electrode

15. -MORE Na+ IN THE EXTRACELLULAR
FLUID AND MORE K+ INSIDE. THE
MEMBRANE IS MORE PERMEABLE
TO K+ SO IT LEAKS OUT GIVING
THE OUTSIDE A POSITIVE CHARGE.

16. -THE INSIDE OF THE NEURON HAS
AN OVERALL NEGATIVE CHARGE
BECAUSE IT HAS MANY, LARGE
NEGATIVE PROTEINS INSIDE.

17. 7. TYPICALLY THE CHARGE DIFFERENCE
BETWEEN INSIDE AND OUTSIDE
IS –70 mv AT RESTING POTENTIAL.

18. [Na+] 150 mM [K+] 150 mM [Cl–] 120 mM [A–] 100 mM
LE 48-10
CYTOSOL
EXTRACELLULAR
FLUID
[Na+]
15 mM
[Na+]
150 mM
[K+]
150 mM
[K+]
5 mM
[Cl–]
120 mM
[Cl–]
10 mM
[A–]
100 mM
Plasma
membrane

19. 8. ACTION POTENTIAL (NERVE IMPULSE)=
A CHANGE IN THE POLARITY ACROSS
THE MEMBRANE BROUGHT ABOUT
BY A STIMULUS.

20. Gated ion channels open or close in response
to one of three stimuli:
-Stretch-gated ion channels open when the
membrane is mechanically deformed.
-Ligand-gated ion channels open or close
when a specific chemical binds to the channel.
-Voltage-gated ion channels respond to a
change in membrane potential.

21. -IN RESPONSE, Na+ GATES OPEN,
Na+ RUSHES INTO THE CELL. THEN
INSIDE IS POSITIVE AND THE
OUTSIDE IS NEGATIVE = REVERSAL
OF CHARGE CALLED
DEPOLARIZATION.
NEXT: K+ GATES OPEN, K+ OUT OF
THE CELL = REPOLARIZATION.

22. -WAVE OF POLARIZATION AND
DEPOLARIZATION TRAVELS THE
AXON AND IS CALLED AN
ACTION POTENTIAL.
9. DURING DEPOLARIZATION, THE
CHARGE SHIFTS FROM –70MV TO
+30MV.
10. REFRACTORY PERIOD – PERIOD OF
REST BEFORE A NEURON CAN BE
STIMULATED TO FIRE AGAIN.

23. LE 48-13_5 Na+ Na+ Na+ Na+ K+ Rising phase of the action potential K+
Falling phase of the action potential
+50
Action
potential
Na+
Na+
Membrane potential
(mV)
–50
Threshold K+
Resting potential
–100
Depolarization
Time
Na+
Na+
Extracellular fluid
Potassium
channel
Activation
gates
Na+ K+
Plasma membrane
Undershoot
Cytosol
Sodium
channel K+
Inactivation
gate
Resting state

28. LE 48-14c Axon Action potential
An action potential is generated as Na+ flows inward across the membrane at one location.
Action
potential K+
Na+ K+
The depolarization of the action potential spreads to the neighboring region of the membrane, re-initiating the action potential there. To the left of this region, the membrane is repolarizing as K+ flows outward.
Action
potential K+
Na+ K+
The depolarization-repolarization process is repeated in the next region of the membrane. In this way, local currents of ions across the plasma membrane cause the action potential to be propagated along the length of the axon.

29. 11. IN MYELINATED NEURONS, THE
ACTION POTENTIALS ONLY OCCUR
AT THE NODES. THE NEURAL
IMPULSE JUMPS FROM ONE NODE
TO THE NEXT. THIS INCREASES THE
SPEED AND IS CALLED
SALTATORY PROPAGATION.

30. 12. SYNAPSE – WHERE 2 NEURONS MEET OR WHERE A NEURON CONTACTS
MUSCLE OR GLAND TISSUE. THE AP
IS RELAYED FROM ONE TO THE
NEXT.
Synaptic
terminals
of pre-
synaptic
neurons
Postsynaptic
neuron
5 µm

31. 13. REVIEW PARTS OF A SYNAPSE –
PRESYNAPTIC TERMINAL, VESICLES
CLEFT, RECEPTOR PROTEINS,
AND POSTSYNAPTIC TERMINAL.

34. 14. THE SPINAL CORD
A. COMMUNICATION LINK BETWEEN
THE BRAIN AND THE BODY.
B. INTEGRATES SOME INFO.
CONTROLLING SPINAL REFLEXES.
C. EXTENDS FROM BASE OF BRAIN
(FORAMEN MAGNUM) TO SECOND
LUMBAR VERTEBRAE.

35. 15. THERE ARE 31 SPINAL NERVES THAT
BRANCH OFF THE SPINAL CORD.
16. GRAY MATTER- INTERIOR OF SPINAL
CORD - COMPRISED OF NERVE CELL
BODIES. ORGANIZED INTO HORNS:
DORSAL HORNS= SENSORY NEURONS
SYNAPSE WITH ASSOCIATION
NEURONS.
VENTRAL HORNS= CELL BODIES OF
MOTOR NEURONS.
17. WHITE MATTER - SURROUNDS GRAY
MATTER AND CONTAINS TRACKS.

38. 18. ASCENDING TRACKS- CARRY SENSORY
INFO. TO THE BRAIN.
19. DESCENDING TRACKS - CARRY MOTOR
COMMANDS FROM THE BRAIN TO
THE BODY.
20. REFLEXES ARE AUTONOMIC RESPON-
SES TRIGGERED BY SPECIFIC STIMULI.
A. SENSORY RECEPTOR STIMULATED.
B. SENSORY NEURON CARRIES
IMPULSE TO THE CNS.
C. ASSOCIATION NEURON CONNECTS
SENSORY NEU. TO MOTOR NEURON

39. D. MOTOR NEURON EXTENDS FROM
SPINAL CORD TO EFFECTOR.
E. EFFECTOR ORGAN (MUSCLE OR
GLAND) RESPONDS.

40. 21. AUTONOMIC NERVOUS SYSTEM
A. RESPONSIBLE FOR INVOLUNTARY
ORGAN CONTROL.
B. MOTOR NEURONS TO GLANDS
CARDIAC AND SMOOTH MUSCLE.
22. SYMPATHETIC DIVISION - FIGHT OR
FLIGHT SYSTEM. INC. HEARTRATE,
RELEASE EPINEPHRINE, SWEAT ETC.

41. 23. PARASYMPATHETIC DIVISION -
OPPOSITE OF SYMPATHETIC. BRINGS
BODY BACK TO NORMAL RANGE
AFTER FIGHT OR FLIGHT RESPONSE
IS OVER.

42. LE 48-22 Parasympathetic division Sympathetic division
Action on target organs:
Action on target organs:
Constricts pupil
of eye
Dilates pupil
of eye
Location of
preganglionic neurons:
brainstem and sacral
segments of spinal cord
Location of
preganglionic neurons:
thoracic and lumbar
segments of spinal cord
Stimulates salivary
gland secretion
Inhibits salivary
gland secretion
Sympathetic
ganglia
Constricts
bronchi in lungs
Relaxes bronchi
in lungs
Cervical
Neurotransmitter
released by
preganglionic neurons:
acetylcholine
Neurotransmitter
released by
preganglionic neurons:
acetylcholine
Slows heart
Accelerates heart
Inhibits activity of
stomach and intestines
Location of
postganglionic neurons:
in ganglia close to or
within target organs
Stimulates activity
of stomach and
intestines
Thoracic
Location of
postganglionic neurons:
some in ganglia close to
target organs; others in
a chain of ganglia near
spinal cord
Inhibits activity
of pancreas
Stimulates activity
of pancreas
Stimulates glucose
release from liver;
inhibits gallbladder
Stimulates
gallbladder
Lumbar
Neurotransmitter
released by
postganglionic neurons:
acetylcholine
Stimulates
adrenal medulla
Neurotransmitter
released by
postganglionic neurons:
norepinephrine
Promotes emptying
of bladder
Inhibits emptying
of bladder
Promotes erection
of genitalia
Sacral
Promotes ejaculation and
vaginal contractions
Synapse

43. LE 48-22 Parasympathetic division Sympathetic division
Action on target organs:
Action on target organs:
Constricts pupil
of eye
Dilates pupil
of eye
Location of
preganglionic neurons:
brainstem and sacral
segments of spinal cord
Location of
preganglionic neurons:
thoracic and lumbar
segments of spinal cord
Stimulates salivary
gland secretion
Inhibits salivary
gland secretion
Sympathetic
ganglia
Constricts
bronchi in lungs
Relaxes bronchi
in lungs
Cervical
Neurotransmitter
released by
preganglionic neurons:
acetylcholine
Neurotransmitter
released by
preganglionic neurons:
acetylcholine
Slows heart
Accelerates heart
Inhibits activity of
stomach and intestines
Location of
postganglionic neurons:
in ganglia close to or
within target organs
Stimulates activity
of stomach and
intestines
Thoracic
Location of
postganglionic neurons:
some in ganglia close to
target organs; others in
a chain of ganglia near
spinal cord
Inhibits activity
of pancreas
Stimulates activity
of pancreas
Stimulates glucose
release from liver;
inhibits gallbladder
Stimulates
gallbladder
Lumbar
Neurotransmitter
released by
postganglionic neurons:
acetylcholine
Stimulates
adrenal medulla
Neurotransmitter
released by
postganglionic neurons:
norepinephrine
Promotes emptying
of bladder
Inhibits emptying
of bladder
Promotes erection
of genitalia
Sacral
Promotes ejaculation and
vaginal contractions
Synapse