AP Psychology
Ch. 2 The Biological Perspective
1 Nervous System
 The nervous system is a network of cells that carries
information to and from all parts of the body.
 Neuroscience deals with the neurons, nerves and
nervous tissue that makeup the nervous system.
2 Nervous System (Cont’d)
 A neuron is a specialized cell that sends messages
through the nervous system.
 Dendrites are parts of the neuron that receive
messages from other cells.
 The cell body is called the soma
 The axon is like a tail, which sends messages to other
cells.
3 Neurons
 Neurons make up approximately 10% of the brain.
 The remaining portion of the brain is made up of glial
cells which serve as a foundation for the neurons to
build on.
 Glial cells:
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

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Deliver neurons to neurons
Clean up dead neurons
Help process information
Generate new neurons
4 Neurons (Cont’d)
 Neurons are separated by two types of glial cells.
 Oligodendrocytes – myelin in the central nervous system
(brain & spinal cord)
 Schwann cells – myelin in the neurons of the body
 Bundles of myelin-coated cables form nerves.
5 - Neural Impulse
 When a cell is inactive it is called resting potential and
it is filled with negative ions.
 When the axon send an electrical charge from
positive ions it is called action potential.
 Axons contain short fibers called axon terminals with
little saclike structures known as synaptic vesicles.
 Inside the synaptic vesicles lies neurotransmitters
which transmit messages through a fluid-filled space
called a synapse or synaptic gap.
6 - Neural Impulses (Cont’d)
 Drugs and toxins can have an effect on neural
impulses.
 It depends on whether it was an excitatory or
inhibitory signal.
 Agonists are chemical substances that enhance the
effect of neurotransmitters.
 Antagonists are chemical substances that block or
reduce a cell’s response.
7 Neural Impulses (cont’d)
 Acetylcholine gets released to control muscles.
 Curare is a drug that causes paralysis because it
serves as an antagonist to block the release of
acetylcholine.
 Venom from a black widow is an agonist because it
enhances the release of acetylcholine leading to
convulsions.
8 Reuptake and Enzymes
 Reuptake is the process by which the
neurotransmitters get sucked back into the synaptic
vesicles.
 Acetylcholine is a neurotransmitter to trigger muscle
activity. An enzyme is a protein that is designed to
break apart the acetylcholine so it clears the synaptic
gap and doesn’t go through reuptake.
9 Reuptake and Enzymes
(cont’d)
 Serotonin is a neurotransmitter that regulates
people’s moods. Some people don’t produce enough
serotonin to activate the receptors on the next
neuron, leaving the person in a state of depression.
 People experiencing depression are often proscribed
SSRI’s (selective serotonin reuptake inhibitors) which
block reuptake so more serotonin can connect to the
receptor site.
10 – Central Nervous System
 The brain and the spinal cord make up the central
nervous system.
 The brain is the core of the central nervous system.
 The spinal cord is the highway where neurons send
messages back and forth from the brain to the body.
11 – Reflex ARC
 The reflex ARC is the messages sent from the body to
the brain and the reflex the brain sends back to the
body.
 Reflexes are immediate without thinking about a
response.
 3 Neurons:
 Afferent (sensory) neurons – messages to the spinal
cord
 Efferent (motor) neurons – messages from the spinal
cord to the muscles
 Interneurons – connect other neurons and make up the
spinal cord and the brain.
12 The Peripheral Nervous System
 Peripheral Nervous System (PNS) is the system of
nerves and neurons outside of the Central Nervous
System.
 The PNS can be divided into two systems:
 Somatic nervous system: comprised of the sensory
pathway which consists of all of the nerves (afferent
neurons) carrying messages to the CNS and the nerves
carrying (efferent neurons) messages from the CNS to
voluntary muscles.
 Autonomic nervous system: is the automatic nervous
system in the body which controls organs, glands,
involuntary muscles.
13 Autonomic Nervous System
 The autonomics nervous system is made up of two
systems, the sympathetic division and the
parasympathetic division.
 The sympathetic division is located by the spinal cord
and controls our fight or flight system. This division
would increase our heart rate, dilate our pupils and
secrete adrenaline from the adrenal glands.
 The parasympathetic division controls the neurons at
the top and bottom of the spinal cord and can be called
the eat, drink and rest system. The parasympathetic
division restores our body to normal.
14 Studying the Brain
 Testing on animals is done by stimulating or killing a
portion of the brain. A wire with an electrical current
is inserted into the brain of the animal to accomplish
this. Then scientists study the effects.
 For humans, scientists obviously cannot intentionally
cause brain damage. Instead they use a variety of
tests to study the brain.
15 Testing the Brain
 Electroencephalograph (EEG) - this machine is
designed to study the electrical activity of the
neurons in the brain.
 This is accomplished by attaching metal discs to the
patient’s head which send results to a computer.
Think of it as an ultrasound for the brain.
 Scientists use EEG results to learn about sleep,
seizures, tumors and the area of the brain being
active.
16 Testing the Brain (Cont’d)
 CT scans (computed tomography) are like an x-ray of
the brain.
 EEG’s only measure brain activity. CT scans can give
scientists and doctors a look inside the brain.
 CT scans are used to determine stroke damage,
tumors, injuries and other brain abnormalities.
17 Testing the Brain (Cont’d)
 MRI Scans (magnetic resonance imaging) is a machine
that creates a magnetic field around the person
placed inside it.
 The resulting image provides a 3D image of the brain,
which shows smaller details than a CT scan.
18 Testing the Brain (Cont’d)
 PET scans (positron emission tomography) provides a
deeper look at the brain in action.
 Radioactive glucose is injected into the patient which
projects an image of brain activity on a monitor.
 Patients are awake, so scientists can have them do
different tasks to see which area of the brain is being
used.
19 Testing the Brain (Cont’d)
 fMRI (functional MRIs) are a method that tracks
oxygen levels in the blood to determine which areas
of the brain are active.
 fMRI’s tend to be clearer than PET scans.
20 Structure of the Hindbrain
Medulla – located at the top of the spinal cord and
bottom of the brain.
Controls breathing, heartbeat, and swallowing.
This part of the brain sends and receives messages from
all of the sensory nerves.
21 Hindbrain (Cont’d)
 The pons are next to the medulla and serve as a
bridge between the different sections of the brain.
 The pons coordinate movement to each side of the
body.
 The pons also influence sleep, dreaming and arousal.
22 Hindbrain (Cont’d)
 The Reticular Formation (RF) is a set of neurons
running through the medulla and the pons.
 It’s function is to allow us to focus on certain things
and alert us to changes in our surroundings.
 RF also keeps people alert and aroused.
 Studies on the RF of rats show that they wake up if
their RF is stimulated. However if the rat’s RF is
destroyed, they slip into a coma and never awaken.
23 Hindbrain (Cont’d)
 The cerebellum is at the base of the skull and
sometimes referred to as the little brain.
 The cerebellum controls involuntary, fine motor
movement.
 It also coordinates movement.
 A damaged cerebellum could result in being very
uncoordinated, prone to dizziness and weakness and
possibly slurred speech.
24 Structures Under the Cortex
 The cortex is the wrinkled outer layer of the brain
packed with neurons and blood vessels.
 The limbic system is located in the upper brain and is
involved in our emotions, motivation and learning.
 The limbic system includes the hypothalamus,
hippocampus, and amygdala.
25 Under the Cortex (Cont’d)
 The thalamus processes the sensory information and
relays it to the appropriate part of the brain.
 The hypothalamus regulates body temperature,
thirst, hunger, sleeping and waking, sexual activity
and emotions.
 The hippocampus deals with forming memories.
Acetylcholine is a neurotransmitter that triggers
muscle movement but also works with the
hippocampus to develop memories.
26 Under the Cortex (Cont’d)
 The amygdala is responsible for fear responses and
memory of fear.
 People and animals with damage to the amygdala are
linked to a decreased fear response.
 1939, monkeys with large amounts of their temporal
lobes removed, were unafraid of snakes and humans.
 Rats with a damaged amygdala show no fear towards
cats.
27 Lobes of the Cortex
 The cortex is divided into two cerebral hemispheres.
 The two hemispheres are connected by a band of neural fibers
called the corpus callosum, which allows each side to
communicate with the other.
 The occipital lobe is located in the rear base and processes
information from the eyes.
 The parietal lobe is located at the top and back and processes
information from the skin, temperature and balance.
 The Parietal lobe also contains the somatosensory cortex which
receives info on touch and balance.
28 Lobes of the Cortex (Cont’d)
 The temporal lobes are located by the ear and temple
and it processes auditory input.
 The frontal lobe is responsible for planning,
personality, memory, decision making, language and
controlling emotion.
 The frontal lobe also contains the motor cortex which
controls voluntary muscles.
29 Endocrine Glands
 Glands are organs that secrete chemicals from ducts,
like saliva, tears, and sweat.
 Endocrine glands secrete hormones directly into the
bloodstream.
 Some hormones released by the endocrine glands
produce excitatory or inhibitory effects and thereby
trigger an emotional reaction.
30 Endocrine Glands (cont’d)
 The pituitary gland is an organ in the brain near the
hypothalamus that is referred to as the master gland
because it controls all of the endocrine glands.
 The pituitary controls salt levels, triggers the
production of breast milk and releases growth
hormone.
31 Endocrine Glands (cont’d)
 The pineal gland secretes melatonin for the sleep-wake cycle.
 The thyroid secretes a hormone called thyroxin to regulate
metabolism.
 The pancreas controls blood sugar and secretes insulin.
 The gonads include ovaries and testes which secrete hormones
for sexual behavior and reproduction.
 The adrenal glands secrete corticoids which are steroids for the
fight or flight reaction, along with cortisol to manage stress.