discussions on the connection of biology and behavior

1. Biological Bases
of Behavior

2. The Biology Behind the
Psychology
• “Everything Psychological is ultimately
Biological.”
– What does this say to you?

3. Neurons: building blocks
of the Nervous System

4. Neural Communication
• Action potential: a neural impulse
• Threshold: minimum intensity needed to fire impulse
• Neuron firings are all-or-none responses
• Synapse: gap between neurons (also called a synaptic gap
or cleft)
• Neurotransmitters: chemical messengers that bind to
receptor sites on receiving neuron
• Reuptake: sending neuron reabsorbs excess
neurotransmitters

5. Types of Neurons
• Sensory Neurons (afferent) ~ 2 million
– Sends messages from sense organs  brain
• Motor Neurons (efferent) ~ 2-3 million
– Sends messages from brain  muscles, organs, glands
• Interneurons ~ Billions & Billions
– Relay messages between sensory & motor neurons
• Glial cells – “The forgotten cell”
– Glue cells which help connections, insulate, and clean up

6. Influence of
Neurotransmitters
• Each neurotransmitter has a specific effect on behavior & emotions
• Acetylcholine: muscle action, learning, memory
• Dopamine: movement, learning, attention, emotion
• Serotonin: mood, hunger, sleep, arousal
• Norepinephrine: alertness, arousal
• GABA (gamma-aminobutyric acid): inhibitory neurotransmitter
• Glutamate: excitatory neurotransmitter, memory
• Find a condition or disease associated with the blockage or increase
in one of these neurotransmitters.

7. Drugs &
Neurotransmitters
• Endorphins: natural “opiates” released in response
to pain or vigorous exercise
• Why not flood the brain with artificial opiates??
– Brain will stop producing natural ones
– Withdrawal symptoms
• Drugs affect communication at the synapse
– Agonist Molecule: excites, mimics neurotransmitter
– Antagonist Molecule: inhibits, blocks neurotransmitter

8. Neuron FAQ’s
• 100 Billion neurons in the human body
–It would take you 3,171 years to count all the
neurons (1 per second)
• 4-100 Microns wide (1 micron=1/1000th of a
millimeter)
• Your neurons are for life! You will have less and
less as you get older

9. Central Nervous
System
Brain & Spinal
Cord
Peripheral
Nervous System
Somatic
(Skeletal)
Autonomic
(Internal Organs)
Sympathetic
(Arousing)
Parasympathetic
(Calming)
(Links CNS with
muscles, glands,
sense receptors)
The Nervous System
• Nerves: neural cables
containing many axon
Neuron to
neuron
communication

10. Endocrine System
• Slower than nervous system
• Uses hormones (another chemical messenger) to
communicate
• Flow from tissues through bloodstream to other
tissues
• Adrenal glands: above kidneys; secrete hormones
to arouse body during stress
• Pituitary glands: controlled by hypothalamus,
regulates growth and controls endocrine glands

11. The Brain
How does our brain produce behavior and
mental processes?

12. Studying the Brain
• Electroencephalogram (EEG)
– Measures brains electrical waves by attaching
electrodes to the scalp
• Positron Emission Tomography (PET Scan)
– Injection of radioactive glucose (brain sugar) to
detect where fuel goes under different situations
• Magnetic Resonance Imaging (MRI)
– Magnet aligns spinning atoms of brain to show
tissue and brain anatomy
• Functioning MRI (fMRI)
– Shows brain function & bloodflow

13. Functions of the brain
• It receives information from, and controls the activities
of trunk and limbs mainly through its connections with
the spinal cord.
• It receives the information from, and controls the
activities of head and neck structures though cranial
nerves
• It assimilates experiences, a requisite to higher mental
processes such as memory, learning and intelligence
• It is also responsible for one’s personality, thoughts and
aspirations.

15. Right vs. Left Brain

16. • We only use 10% of our brain
• Your brain does not grow new cells
• Some people are right-brained,
others left-brained
• Brain damage cannot be repaired