UNIT 3 THE BIOLOGICAL

BASES OF BEHAVIOR

Mod. 9 Biological

Psychology and

Neurotransmission

9.1 Why are psychologists concerned with

human biology?

• All the way back to Plato and his emphasis on the mind

(Aristotle thought it was the heart)

• Franz Gall: phrenology

• Study of bumps on the head showing personality

• Helped to focus on the function and location of brain

• Biological psychology: study links between biological

activity and psychological events

People are systems composed of subsystems

who have their own subsystems…

• Biopsychosocial: to understand our behavior, we study

how the biological, psychological, and social systems

work together

Neural Communication

• Same between humans and animals

• Allows us to study simple animals and learn a great deal

9.2 What are the parts of a neuron and

how are neural impulses generated? • Neurons are building blocks of the nervous system

There are different types of neurons but they have the

same form…

• Cell body

• Dendrites: extensions from cell body (tree branches)

**receive messages and pass impulse to cell body

• Axon: a fiber that passes impulses its ending

**connects to other neurons/muscles/glands

DENRITES LISTEN, AXONS SPEAK!

• Some axons are encased with myelin sheath

• Layer of fat to insulate and speed up messages

• Still being formed up to 25 years old!

• Multiple Sclerosis attacks the myelin

• Messages/impulses are triggered by chemical signals

from other neurons (or senses)

• Action Potential: an electrical charge that occurs when a neuron

fires

• Travels 2-180 mph

• Starts as a chemical reaction then converted to electricity

• Caused by the interchange of ions

• Fluid outside the axon is mostly positive (sodium)

• Fluid inside is mostly negative (potassium)

• When a neuron fires, sodium moves in as potassium floods out

• When a neuron is ready and capable of firing, called resting

potential

• Neurons cannot fire constantly, ions must flow out to

starting point: Refractory period

• Like a webpage refreshing

One neuron receives 1000s of signals

from others…

• Excitatory: neurons that will cause the next ones to fire

• Inhibitory: neurons that stop messages from being

transferred on

*If a message is excitatory the impulses are strong enough

to cross/push a threshold: amount of stimulus needed to

fire

All-or-none: either a neuron fires or it doesn’t

9.3 How do nerve cells communicate with

other nerve cells? • Small gap exists between neurons

• Synapse: space between axon ending and dendrite

• Space itself called synaptic gap/cleft

So, how do neurons communicate??

• Terminal knob released neurotransmitters

(NTs)…chemical messengers

• They will either excite or inhibit

• Reuptake: the sending neuron reabsorbs the excess

neurotransmitters

9.4 How do NTs influence behavior and

how do drugs and other chemicals affect

NTs? • Many questions about where NTs are/how they are

affected…more later!

• NTs interact with each other and with receptors

• Acetylcholine (ACh) is one of the best understood

• Role in learning and memory

• Found in motor neurons

• When released=muscles contract, when blocked=paralysis

• Endorphins: natural painkillers

How Drugs and Other Chemicals Alter

Neurotransmitters • Brain stops producing endorphins if painkillers are over

used—severe discomfort

• Drugs/chemicals excite and inhibit

• Agonist: mimic the drug (opiates)

• Antagonists: block NTs (Botulin)