General psychology

1. 2
Three types of Neurons
Types of Neurons
Sensory Motor Interneurons

2. 3
Sensory Neuron
Also called AFFERENT Neurons
Transmit impulses from the receptors in our sense
organs (the eyes, ears, skin, nose, tongue and
muscles, organs ) to the brain.
Vision, hearing, taste and smell nerves are
cranial and do NOT use the spinal cord
Touch ( pressure, temperature & pain)
nerves travel up the spinal cord and then to
the brain.
Deals with INCOMING messages from the
outside world
Also can transmit incoming messages from internal
organs for pain ( ulcer, appendicitis)
They have very long axons.

3. 4
Motor Neurons
Also called EFFERENT Neurons
Carry messages FROM the brain or spinal
cord to Muscles and Tendons throughout the
body
( including the heart, diaphragm, intestines,
bladder and glands)
Deals with OUTGOING messages from the
brain/spinal cord to act upon the outside
world
They have very long axons

4. 5
INTERNEURONS
Only found in the brain, spinal cord, and eye.
Intervene between sensory neurons and
motor neurons.
They carry messages between other
interneurons in the spinal cord and brain.
Many more interneurons than sensory or
motor neurons
Easy to recognize – they have short axons

5. 6
Spinal
Cord
BrainSensory
Neuron
Sensory Neurons
INPUT from sensory organ (skin) to the
brain and spinal cord.
Drawing shows a
red sensory
neuron in the skin
for touch.

6. 7
Spinal
Cord
BrainSensory
Neuron
Motor
Neuron
Motor Neurons
OUTPUT from the brain and spinal cord to the
muscles telling you to move hand from
source of pain.

7. 8
Spinal
Cord
BrainSensory
Neuron
Motor
Neuron
Interneurons
Interneurons
carry
information
between other
neurons only
found in the
brain and
spinal cord.

8. 9
THE NERVOUS SYSTEM
Central Nervous System CNS:
* brain & Spinal cord
Peripheral Nervous System PNS
* sensory and motor neurons OUTSIDE of
the brain and spinal cord
* connects CNS to muscles, glands, and
sense receptors

9. 10
The Peripheral Nervous System
Divided into two parts:
A) SOMATIC nervous system = controls
body’s muscles and is VOLUNTARY
Ex. scratch nose, move arm, squint….
B) AUTONOMIC nervous system = controls
action of internal organs and glands and is
INVOLUNTARY
Ex. heart rate, digestion, respiration,
bladder, sex organs…

10. 11
SOMATIC OR AUTONOMIC?
Climbing stairs
Colon contracts
Curl tongue
Pick up a toy
Clench fist
Get Goosebumps
Heart beats
Raise hand
Pupils dilate
Release of cortisol

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AUTONOMIC Nervous System
Divided into two additional systems:
a) SYMPATHETIC Nervous System = prepares
body for emergency (“Fight or Flight”)
Helps us deal with stress.
b) PARASYMPATHETIC Nervous System =
brings body back to rest/calm after a
stressful event (homeostasis)

12. 13
AUTONOMIC Nervous System
Sympathetic Parasympathetic
EYES pupils dilate pupils contract
SALIVATION decreases increases
SKIN perspires dries
RESPIRATION increases decreases
HEART accelerates slows
DIGESTION shuts down activates
LIVER increase glucose decrease glucose
ADRENAL GLAND secretes stress hormones decrease stress hormones

13. 14
Sympathetic and parasympathetic divisions
of the nervous system

14. 15
Divisions of the Nervous System

15. 16
Structures of a neuron

16. 17
The cell body or Soma
Round, centrally
located structure
Contains DNA
Controls protein
manufacturing
Directs metabolism
No role in neural
signaling
Contains the cell’s Nucleus

17. 18
Dendrites: INPUT
MANY short branching
extensions from the
cell body
Information
COLLECTORS
Conduct impulses TO
the cell body
RECEIVE
inputs/messages from
neighboring neurons
Inputs may number in
thousands

18. 19
Dendritic Growth
Mature neurons
generally can’t
divide
But new dendrites
can grow
Provides room for
more connections
to other neurons
New connections
are basis for
learning

19. 20
Axon: OUTPUT
Single LONG
extension from the
cell body
The cell’s OUTPUT
structure that SENDS
messages to other
neurons or
muscles/glands
2 distinct parts
tubelike structure
branches at end of tube
called “terminals” that
connect to dendrites of
nearby cells

20. 21
Myelin sheath
White fatty casing on
axon
Acts as an electrical
insulator
Not present on all cells
When present increases
the speed of neural
signals down the axon.
Myelination is not
completed until about
age 20 - 25.
Special diseases of the
myelin sheath are Multiple
Sclerosis (MS) and Guillain-
Barre syndrome.
Myelin Sheath

21. 22
Glial Cell
Means “glue”
Nonneural white fatty cells that cover the axon to
create myelin sheath. These are call “schwann”
cells in the peripheral nervous system.
Also interspersed among the neurons in the brain to
give it support, structure, and supply nutrients. Holds
the brain together like glue! These are called
“astrocytes”.
Brain has approx. 10 billion to I trillion neurons BUT
100 billion to 10 trillion glial cells.
Tumor in the brain is made of glial cells NOT neurons.
Glial cells can rapidly reproduce.
Neurons can regenerate but not very rapidly.

22. 23
Nodes of Ranvier
small gaps
in the myelin
sheath where
each glial cell
ends.

23. 24

24. 25
Neurons – magnified view

25. 26
How neurons communicate
Neurons communicate by means of an
electrochemical signal.
The signal that travels WITHIN a
Neuron is ELECTRICAL
The signal that travels between
neurons is CHEMICAL

26. 27
ELECTRICAL SIGNAL within a Neuron
Electricity can flow within a neuron due to properties
of the CELL MEMBRANE
SEMI-PERMEABLE ( selectively permeable) Some
things can go through but other things are trapped
either on the inside or outside.
PUMPS spend energy to force things to go into or
out of a neuron
CHANNELS are proteins with holes in them. They
sit in the cell membrane and serve as gates to let
certain things flow into or out of the cell.

27. 28
Electrical signals - cont
Ion PUMPS keep an UNEVEN distribution of electrical
charges inside and outside the neuron cell.
IONS – atoms that carry units of (+) or (–) electrical
charge.
SODIUM (Na+) is a + charged ion that has a
difficult time getting through the membrane.
Chloride (Cl-) is a – charged ion that also has a
hard time getting through the membrane.
POTASSIUM (K+) is a + charged ion that easily
travels inside and outside the neuron’s membrane.

28. 29
RESTING POTENTIAL
When a neuron is not being stimulated and is
not sending out signals.
The inside of the cell is electrically negative
relative to the outside which is positive.
The inside of the neuron is 70mV less than
the outside. ( -70mV)
There is more sodium outside and more
potassium inside the neuron.
The cell is said to be POLARIZED

29. 30
Ion concentrations
Cell Membrane in resting state
K+
Na+ Cl-K+
A-
Outside of
Cell
Inside of Cell
Na+ Cl-

30. 31
The Cell Membrane is Semi-
Permeable
Cell Membrane at rest
Na+ Cl-K+
Na+
Cl-
K+ A-
Outside of Cell
Inside of Cell
Potassium (K+)
can pass through
to equalize its
concentration
Sodium and
Chlorine cannot
pass through
Result - inside is
negative relative
to outside
- 70 mv

31. 32
ACTION POTENTIAL
A stimulation ( sight, sound, touch ..etc)
opens the ion channels so that sodium starts
to get pumped into the cell .
This changes the internal charge and when it
rises from -70mV to -55mV it reaches a
THRESHOLD and it triggers a nerve IMPULSE
or ACTION POTENTIAL. The cell is now firing!
The firing is an “ALL OR NONE” response – it
either fires or doesn’t fire – there are no
levels of intensity.
The cell is said to be DEPOLARIZED.

32. 33
Depolarization leading to an
Action Potential
membrane allows sodium (NA+) into cell as channels open
INSIDE of cell rapidly becomes more positive than outside

33. 34
Action Potential Within a Neuron

34. 35
Neuron Communication
All-or-None Principle
The principle that if a neuron
fires it will always fire at the
same intensity
All action potentials are of the
same strength.
A neuron does NOT fire at 30%,
45% or 90% but at 100% each
time it fires.

35. 36
REPOLARIZATION
After cell fires it will reach a peak at +40 to +30mV
THEN sodium channels shut down and potassium
channels open as + charged ions are pushed out of the
cell.
This brings the internal charge back down toward -70mV
HOWEVER – so much potassium flows out of the cell that
it’s internal charge drop BELOW the resting potential
of -70mV and goes down to -80mV.

36. 37
Repolarization follows
After depolarization potassium (K+) moves out
restoring the inside to a negative voltage
This is called repolarization

37. 38
REFRACTORY PERIOD
When the internal charge of a neuron drops
below -70mV the neuron CANNOT FIRE. This
refractory period lasts about .001 seconds.
Eventually the ion pumps bring the internal
charge back up to -70mV and the cell is once
again at rest and ready for an action
potential to occur.
Action Potentials always begin at the cell
body of the neuron and travel down the AXON

38. 39
Finally, Hyperpolarization
Repolarization leads to a voltage below the resting
potential, called hyperpolarization
Now neuron cannot produce a new action potential
This is the refractory period

39. 40

40. 41
Animation of action potential
down an axon
http://www.youtube.com/watch?v=yQ-wQsEK21E&
http://www.youtube.com/watch?v=U0NpTdge3aw&

41. 42
Self-propagation – Moving electrical
charge down the axon
When an electrical impulse travels down the
axon from the cell body it will form a domino
effect at each node of Ranvier. Na+ channels
will open and then close causing the
electrical message to move in only one
direction down the axon toward the axon
terminal branches.

42. 43
Chemical Signal – between neurons
When an impulse reaches the ending terminal
of an axon it stimulates the opening of
SYNAPTIC VESICLES ( sacs) that contain
chemical NEUROTRANSMITTERS.
These chemicals flow into the SYNACTIC
CLEFT which is the space between the end of
one neuron’s axon and the dendrite of a
nearby neuron.
Neurotransmitters are chemical messengers
that travel across the synaptic gap and bind
to receptor sites on the receiving dendrite.

43. 44
Synapse
axon terminals contain small storage sacs
called synaptic vesicles
vesicles contain
neurotransmitter
molecules
Sending
Neuron
Synapse
Axon
Terminal

44. 45
Neuron to Neuron
Axons branch out
and end near
dendrites of
neighboring cells
Axon terminals are
the tips of the
axon’s branches
A gap separates the
axon terminals from
dendrites
Gap is the Synapse
Cell
Body
Dendrite
Axon

45. 46
SYNAPSE
Specific neurotransmitters “bind” with
specific postsynaptic receptor sites on the
dendrite.
LOCK and KEY model – neurotransmitters
MUST match receptor site on dendrite.
Neurotransmitter can either stimulate
(depolarize) the next neuron causing it to fire
or they can inhibit ( hyperpolarize) the next
neuron and stop any transmission of
electrical charge.

46. 47
Locks and Keys
Neurotransmitter
molecules have
specific shapes
positive ions (NA+ )
depolarize the neuron
negative ions (CL-)
hyperpolarize the neuron
When NT binds to
receptor, ions enter:
Receptor molecules have
binding sites

47. 48
Postsynaptic Firing
Excitatory synapse – Neurotransmitter binds at
receptor and makes the neuron more positive by
opening sodium channels. This, in turn, will pass the
firing message along to next neuron.
Inhibitory synapse –Neurotransmitter binds at receptor
and makes the neuron more negative by closing
sodium channel and opening chloride channels. This,
in turn, will stop the firing message.
The SUM TOTAL of all inhibitory and excitatory
incoming messages at the receptor sites on the
dendrite will determine if the cell will fire or not.

48. 49
RE-UPTAKE
Released neurotransmitters are eventually
removed from the synapse by Re-Uptake.
Neurotransmitters are sucked back up into
the vesicles on the terminal button of the
axon.
Some neurotransmitters are also removed by
enzymes that destroy the neurotransmitter
while it is floating in the synapse.

49. 50

50. 51
View of Neuron communication
http://www.youtube.com/watch?v=r71RoIkftd4

51. 52
Animation of neuron firing
down the axon to synapse
http://www.youtube.com/watch?v=TKG0MtH5crc

52. 53
CLASS LAB
Passing neural messages
Seconds to pass simple message from shoulder to
brain –down arm to hand.
Seconds to pass message from ankle to brain and
then down arm to hand ( longer pathway)
Time to pass message from shoulder to brain -
PROCESS MESSAGE – then pass back down arm to
hand. (more complex)
Compare dollar drop
SELF (internal signal at release of bill)
OTHER ( external signal (EYES) at release of bill)

53. 54
Types of Neurotransmitters
Acetylcholine (ACh)
Found in neuromuscular junctions
Involved in muscle movements
learning and memory
attention and arousal
Problems:
Too little = Alzheimer’s and paralysis
Too much = muscle spasms /convulsions

54. 55
Disruption of
Acetylcholine Functioning
Curare & botulin are poisons that
blocks ACh receptors (botox
injections)
paralysis results
Nerve gases and Black Widow
spider venom create too much ACh
leads to severe muscle spasms and
possible death

55. 56
Dopamine (DA)
Involved in muscle movement
attention/arousal
learning & thought
mood/emotion
Too little = Parkinson’s disease
Too much = Schizophrenia

56. 57
Parkinson’s Disease
Results from loss of dopamine-producing neurons
in the substantia nigra of the brain’s basal ganglia
Symptoms include
difficulty starting and stopping voluntary
movements
tremors at rest
stooped posture
rigidity
poor balance

57. 58
Parkinson’s Disease
Treatments
L-dopa ( levodopa) agonist
transplants of fetal dopamine-producing
substantia nigra cells
thalamotomy – destroy area of the
thalamus that sends motor messages to
the limbs
electrical stimulation of the thalamus has
been used to stop tremors

58. 59
Deep stimulation
http://www.youtube.com/watch?v=EMnfROo7k9A

59. 60
Serotonin
Involved in sleep
mood/depression
hunger
arousal
Too little= depression
Too much = anxiety, inhibits dreaming
Prozac and SSRI’s (selective serotonin reuptake
inhibitors) are used to treat depression. They
work by keeping serotonin in the synapse longer,
giving it more time to exert an effect.

60. 61
How SSRI’s work to > serotonin in
the synapse

61. 62

62. 63
Endorphins
Natural opiates in brain
Controls pain and pleasure
Too little = pain, discomfort, depression
Too much = euphoric high
Runner’s high— feeling of pleasure after a
long run is due to heavy endorphin
release to offset pain in muscles.
No pain during catastrophic accident

63. 64
Norepinephrine (NE)
Involved in Mood
Arousal from stess
Learning & memory
Too little = depression
Too much = anxiety

64. 65
GABA - Gama Amino Butyric Acid
Inhibition of brain activity
Too little = eating disorders, sleep
disorders, epilepsy, anxiety and
Huntington’s disease
Symptoms:
jerky involuntary movements
mental deterioration

65. 66
Melatonin
Affects biological clock or circadian rhythm
and mood.
Created in the pineal gland near the brain
Lack of sunlight to the eye increases
melatonin
Too much = seasonal depression, sleepiness
Too little = alertness, insomnia

66. 67
Glutamate
Involved in memory
Too much = migraine
Too little = memory problems

67. 68
Some Drugs work on neuron
receptors in the synapse
Agonist : drug that is
so similar to the
neurotransmitter that it
mimics it and fits into
the receptor site acting
just like the real
neurotransmitter.
Ex. opiates–endorphin
l-dopa – dopamine
cocaine- dopamine
Problem: Can cause the
brain to stop making the
real neurotransmitters.

68. 69
Drugs
Antagonist - drug that is shaped like
the neurotransmitter BUT fits the
receptor site poorly and ends up
BLOCKING the real neurotransmitter
from passing. Inhibits.
Ex. beta blockers – block adrenaline
botulin – blocks acetylcholine

69. 70
Agonists

70. 71
Figure 2.7 How Drugs Affect Synaptic Transmission
Hockenbury: Psychology, Fourth Edition
Copyright © 2005 by Worth Publishers

71. 72
REFLEXES – Reflex Arc
Part of the autonomic system.
Most sensory messages travel up the spinal
cord to the brain and then back down spinal
cord to muscles.
REFLEXES bypass the brain and travel
directly to the spinal cord and back to the
muscle.
PURPOSE : Faster responses

72. 73

73. 74
animation
http://www.sumanasinc.com/webcontent/animatio

74. 75
Ganglion
A clump of neuron cell bodies.

75. 76
The Nerves
Nerves consist of neural “cables” containing many axons.
They are part of the peripheral nervous system, and
connect muscles, glands, and sense organs to the central
nervous system.
They are part of the peripheral nervous system, and connect muscles

76. 77
NEURAL NETWORKS
Cluster of neurons in the CNS that carry on a
specific function.
Ex. memory, learning, problem solving
strategy,…

77. 78
ENDOCRINE SYSTEM
Set of glands that secrete HORMONES in into
the bloodstream.
The body’s “slow” chemical communication
system. Communication is carried out by
hormones synthesized by a set of glands.
Very closely connected to the nervous
system.

78. 79
The Endocrine System

79. 80
Hormones
Hormones are chemicals synthesized by the endocrine
glands and secreted in the bloodstream. Some are identical
to neurotransmitters but work much SLOWER. Their
effects last LONGER than neurotransmitters.
Example: the hormone ADRENALINE (neurotransmitter
epinephrine) increases heart rate, blood pressure, blood
sugar and feelings of excitement during emergency
situations.