Download Sensory Neurons

THE BRAIN: the Neuron/brain cell
EVERYTHING PSYCHOLOGICAL IS ALSO BIOLOGICAL.
To understand things like sleep and dreams, depression and schizophrenia,
hunger and sex, stress and disease, we must understand human BIOLOGY.
I. The foundation: Neuron/nerve cells.
A.
100 billion +, throughout the body
B. they ZAP - they communicate, and send
ELECTRICAL messages.
C. they ZAP - send CHEMICAL messages
D. Every mood/urge/thought you have is zapped, and it is chemical
Neural and Hormonal Systems
Will Explain Why We FEEL……
Nervous
Strong
Pain
Sick
It all Starts with the Neuron
Neuron Structure
Neurons do NOT touch each other- the
space in between is called synaptic cleft.
Neural Bases of Psychology:
The Structure of a Neuron






Dendrite  Fine hair-like extensions on the end of a
neuron.
 Function: receive incoming stimuli.
Cell Body or Soma  The control center of the neuron.
 Function: Directs impulses from the dendrites to the
axon.
Nucleus  Control center of the Soma.
 Function: Tells the soma what to do.
Axon Pathway for the nerve impulse (electrical message)
from the soma to the opposite end of the neuron.
Myelin Sheath  An insulating layer around an axon. Made
up of Schwann cells.
Nodes of Ranvier  Gaps between schwann cells.
 Function: to keep charge going through the relatively
long axon – without these spaces, the charge might lose
its intensity before reaching the end of the cell
How Do Neurons Operate?

Neuron at Rest  Resting Potential
 Occurs when the neuron is at rest.
 A condition where the outside of the membrane is positively(+)
charged compared to the inside which is negatively(-) charged.
 Neuron is said to be polarized.
Neural Bases of Psychology:
Neural Communication
• Within a neuron, communication occurs
through an action potential (neural
impulse that carries information along the
axon of a neuron).
Steps of Action Potential
• Dendrites receive neurotransmitter from another
neuron across the synapse.
• Reached its threshold- then fires based on the
all-or-none response.
• Opens up a portal in axon, and lets in positive ions
(Sodium) which mix with negative ions (Potassium)
that is already inside the axon (thus Neurons at
rest have a slightly negative charge).
• The mixing of + and – ions causes an electrical
charge that opens up the next portal (letting in
more K) while closing the original portal.
• Process continues down axon to the axon
terminal.
• Terminal buttons turns electrical charge into
chemical (neurotransmitter) and shoots message
to next neuron across the synapse.
Action Potential
The All-or None Response
• The idea that
either the
neuron fires or
it does not- no
part way firing.
• Like a gun
How Neurons Communicate
Which sentence most closely describes
neural transmissions?
• A. an electric charge is created in the neuron, the
charge travels down the cell, and chemicals are
released that cross the synapse to the next cell
• B. a chemical change occurs within the cell, the
change causes an electric charge to be produced and
the charge jumps the gap between the nerve cells.
• C. the electric charge produced chemically inside a
group of neurons causes chemical changes in
surrounding cells
Neurotransmitters
• Chemical messengers released
by terminal buttons through the
synapse.
• We should know at least 6 types
and what they do.
Acetylcholine
• Its function is motor
movement and maybe memory.
Too much and you will….
Not enough and you will….
Lack of ACH has been linked to
Alzheimer’s disease.
Dopamine
• Its function is motor movement
and alertness.
Lack of dopamine is
associated with
Parkinson’s disease.
Overabundance is
associated with
schizophrenia.
Serotonin
• Function deals with mood
control.
Lack of serotonin
has been linked
to depression.
Endorphins
• Function deals with pain
control.
We become addicted
to endorphin causing
feelings.
What are agonists and
antagonists?
• They are drugs
• Agonists mimic neurotransmitters.
• Example: Nicotine is an ACh agonist
• Antagonists block neurotransmitters:
• Example: curare – a poison - is an
antagonist for ACh (paralyzes you)
Agonists and Antagonists
Examples: A person
smokes a cigarette.
Nicotine in the blood
causes an
EXCITATORY action
potential for
acetylcholine to fire.
The synaptic vesicles
release the
neurotransmitter
acetylcholine into
the synapse, and the
person feels more
alert
(their lungs are
another matter
altogether).
Examples: A person
is given morphine,
an opiate, at the
hospital for pain
from an operation.
The morphine is
administered into
the vein, which
means it goes
directly into the
blood. The morphine
tips the +- balance,
and this causes an
inhibitory action
potential to fire
which causes the
release of the
neurotransmitters
called endorphins.
When the
endorphins float
across the synapse,
the person doesn’t
feel the pain from
the surgery.
Examples: A person
takes an allergy pill
for seasonal
allergies. The
allergy pill goes into
the bloodstream,
and tips the +balance. This causes
an inhibitory action
potential to fire for
the neurotransmitter
GABA. When GABA
floats across the
synapse, the
person’s allergy
symptoms are
controlled.
However, they are
also sleepy and want
to go to sleep in a
hammock on a calm
beach somewhere,
because GABA is
inhibitory and
slows/calms
everything down.
• You eat some bad Chinese food and
feel you are losing control of your
muscles. The bacteria you ingested
from the food most likely interferes with
the use of:
• A. serotonin
• B. insulin
• C. acetylcholine
• D. thorazine
• E. adrenaline
What is reuptake?
• The mopping up of excess
neurotransmitter.
How does Prozac work?
• It is a serotonin reuptake inhibitor.
How does Cocaine work?
The white cocaine blocks the reuptake of dopamine.
Types of Neurons

There are 3 types of neurons.
1.
Sensory Neurons 
2.
3.
Neurons located near receptor
organs (skin, eyes, ears).

Function:
receive incoming stimuli from the
environment.
Motor Neurons  Neurons located near effectors
(muscles and glands)

Function:
Carry impulses to effectors to initiate a
response.
Interneurons  Neurons that relay messages between
other neurons such as sensory and motor neurons. (found
most often in Brain and Spinal chord).
Types of Neurons
Sensory Neurons
(Afferent Neurons)
• Take information from the
senses to the brain.
Motor Neurons
(Efferent Neurons)
• Take information from brain to
the rest of the body.
Central Nervous System
•Made up of Brain and Spinal Chord
•Made up of billions of neurons, sending electrical and chemical
messages.
CNS
brain
Spinal
chord
Entire Nervous System
………is a communication
system, much like Curtis High
School.
-
Administration/Support People
Classes/Teachers/Students
The Nervous
System
•This is just like the Nervous System – it’s one big
organization, divided into 1) the Central Nervous
System, and 2) the Peripheral Nervous System
Central Nervous System
Administration/Support People
Peripheral
Nervous System
Classes/Teachers/Students
The Nervous
System
Central Nervous System
Administration/Support
People
Peripheral
Nervous System
Classes/Teachers/
Students
These two systems are further divided into more
sections:
BRAIN
administration
Spinal
Chord
Support
personnel
Somatic
Division/
Autonomic
Division/
Voluntary
Involuntary
Electives
Required
classes
Peripheral Nervous System
CENTRAL
NERVOUS
SYSTEM
PERIPHERAL
NERVOUS
SYSTEM
•
The sensory and motor neurons that connect the central
nervous system to the rest of the body.
Divisions of the Peripheral
Nervous System
Somatic
and
Somatic/Skeletal/
Voluntary
SENSORY NERVES/
MOTORNERVES/
AFFERENT
EFFERENT
Parasympathetic
Autonomic
Autonomic/
Involuntary
Sympathetic
Divisions of the Peripheral Nervous
System - illustrated
Somatic
and
Somatic/Skeletal/
Voluntary
SENSORYNERVES/
MOTORNERVES/
AFFERENT
EFFERENT
Parasympathetic
Autonomic
Autonomic/
Involuntary
Sympathetic
• Mobilizes the body during extreme conditions
• Considered “fight or flight” system
• Involves E activities: emergency, excitement,
exercise, and embarassment
• If you are threatened:
–Heart rate and breathing increase
–Pupils dilate
–Skin cold and sweaty
–Bronchioles dilate
–Liver releases glucose
• The PSNS performs maintenance
activities and conserves body energy
• If the sympathetic stimulates, the
parasympathetic slows the system back
down (think of PARAchute)
• Provides homeostasis homeo = same
Homeostasis means same state you
were in before you saw the dog and the
snake!
Think how the right
side is different from
the left side.
A Simple Reflex
The Endocrine System
A system of glands that secrete
hormones.
Similar to nervous system,
except hormones work a lot
slower than neurotransmitters.
Hormones
Neurotransmitters
Endocrine system
• The Pituitary
gland – regulates
growth, also
releases a
hormone called
ACTH under
PROLONGED
stress, linked to
repressed immune
systems.
Endocrine system
Adrenal glands (adrenal cortex and the adrenal medulla)
– the adrenal medulla, the inner part of the adrenal
gland, releases stress hormones,
epinephrine/adrenaline – in response to short-term
stress.
Endocrine system
• Thyroid glands release hormones that control metabolic
rate/related to food intake (these mice could also have problems in the
hypothalamus)
Endocrine system
• Pancreas – releases insulin –
regulates blood sugar/glucose
levels.
•Can become diabetic/problems
with insulin.
Endocrine system
• Gonads – ovaries in women, testes in men.
Hormones produced
include estrogen/progesterone (more in female), testosterone/androgens
(more in male).
Endocrine system - 3
Pineal gland – regulates sleep/wake cycles
The amygdala determines what is emotionally important, and a poisonous
snake hissing in your path is going to be given top priority.
To make sure we pay attention, the amygdala also helps us lay down an
emotional memory of the snake. The neighboring hippocampus, responsible for
processing memories for long-term storage, is activated and told by the
amygdala to never forget the snake! Learned fear responses enhance our
survival chances when the threat is real. However, this process has also been
implicated in a number of anxiety disorders.
The fight-or-flight response
Stimuli comes from two areas to start things off – either the peripheral
nerves (sensory neurons) or the brain – to activate the stress response
system of the body.
ONE: Environmental
stimuli that cause
pain, an allergic
reaction, or an
internal stimulus
caused by a fall in
blood pressure. The
midbrain and the
thalamus relay
sensory info to the
hypothalamus, and to
the cerebral cortex,
for processing.
From sensory
nerves to
hypothalamus
TWO: Fear or
anxiety, real or
imagined, may
occur that causes
the brain to go into
action. In this case,
messages to the
hypothalamus are
relayed from the
upper brain
structures – the
cerebral cortex, the
amygdala, etc.
From brain to
hypothalamus
STRESS – HOW SYSTEM WORKS
When our nervous system decides there is a threat, the system
goes into action. The “fight or flight” response has been
activated.
The hypothalamus signals the pituitary to
contact the endocrine system, and tell the
ADRENAL GLANDS to do their thing.
PITUITARY
hypothalamus
Pituitary
gland
the ADRENAL GLANDS,
located on top of the
stomach, flood stress
hormones into the blood.
Stress Hormones:
Epinephrine/Adrenaline
- (know both names)
Acts on cardiovascular
system
Norepinephrine –
strengthens muscles and
senses
And………
the ADRENAL GLANDS,
flood stress hormones
into the blood.
CORTISOL
Esp. under long-term
stress. CORTISOL helps
our brain process
glucose more efficiently.
Also SUPPRESSES action
of immune system.
Glucose – brain’s fuel.
General Adaptation Syndrome
A theory about how the body and brain PHYSICALLY
process stress – 3 steps:
1) ALARM
2) RESISTANCE
3) EXHAUSTION
So………….. First, we do
fight-or-flight.
Then, we release cortisol.
Then, over time everything
breaks down – mental and physical.
Don’t forget to write your answers on a
separate piece of paper to grade when
you’re done!
1. A neuron without terminal buttons would
be unable to
a) receive information from neighboring
neurons
b) generate an action potential
c) direct the synthesis of
neurotransmitters
d) secrete neurotransmitters
2. Paul Broca found that the loss of the
ability to speak intelligibly is associated
with damage to a region of the brain in the
a) left frontal lobe
b) thalamus
c) left temporal lobe
d) right parietal lobe
3. Scientists are able to see changes in the
brain as it processes information by
means of
a) lesioning
b) autopsy
c) CT
d) PET
4. The simplest behaviors we carry on
a) are learned when we are infants
b) do not involve the central nervous
system
c) are called instincts
d) include sneezing and blinking
5. Of the following, the effect of the
adrenalin on the body is most similar to
the effect of the
a) cerebellum
b) parathyroids
c) somatic nervous system
d) sympathetic nervous system
6. Mr. Jenkins’ suffered a “stroke” as a
result of a brain injury. Although he can
still move the fingers on his right hand, he
has lost sensation in these parts. Of the
following, the site of damage to his brain is
most likely in the
a) right frontal lobe
b) right temporal lobe
c) left frontal lobe
d) left parietal lobe
7. Of the following, which are located
exclusively in the central nervous system?
a) afferent neurons
b) interneurons
c) efferent neurons
d) glial cells
8. Which of the following glands interact(s)
most directly with all of the others to help
regulate body processes?
a) pituitary
b) adrenals
c) parathyroids
d) ovaries
9. Gunshot wounds, tumors, and strokes all
result in
a) infections
b) significant loss of function
c) lesions
d) pain
10. Which of the following must be males?
a) dizygotic twins
b) monozygotic twins
c) down syndrome children
d) Klinefelter’s syndrome children
11. When you are walking, the brain sends
messages to the skeletal muscles in the
legs by way of
a) efferent fibers
b) sensory fibers
c) afferent fibers
d) central fibers
12. The hindbrain structure involved with
sleep and arousal is the
a) hypothalamus
b) cerebrum
c) thalamus
d) pons
13. The basic parts of a neuron are
a) vesicles, terminal buttons, synapses
b) cell body, axon, dendrites
c) myelin, nodes, axon terminals
d) hindbrain, midbrain, forebrain
14. Branches are to trees as _______ are
to neurons
a) axons
b) cell bodies
c) dendrites
d) nuclei
15. Determining the location of specific
genes on specific chromosomes is
referred to as
a) genetic mapping
b) phenomapping
c) chromosomal atlasing
d) genome projection
Chapter 3 Answer Key
1. D
2. A
3. D
4. D
5. D
6. D
7. B
8. A
9. C
10. D
11.
12.
13.
14.
15.
A
D
B
C
A