1. Biological Psychology
Key Point for this Unit: Everything psychological is simultaneously biological!!

2. NEURON
Dendrites
Dendrites – receive messages from other cells and conduct impulses toward the cell body

3. Cell Body – the cell’s life-support center
NEURON
Dendrites
Cell Body
Cell Body – the cell’s life-support center

4. NEURON
Dendrites
Cell Body
Axon
Axon – the extension of a neuron through which messages are sent to other neurons or to muscles or glands

5. NEURON
Dendrites
Cell Body
Axon
Myelin Sheath
Myelin Sheath – a layer of fatty cells covering the axon, helps speed neural impulses

6. Terminal branches of axon – form junctions with other cells
NEURON
Dendrites
Terminal branches of axon
Cell Body
Axon
Myelin Sheath
Terminal branches of axon – form junctions with other cells

7. Biological Psychology
It is all about the body!!!!
Concerned with the links between biology and behavior (also called Neuroscience)

8. The Nervous System
It starts with a NEURON: an individual nerve cell; the basic building block of the nervous system

9. How does a Neuron fire? Resting Potential: slightly negative charge.
Reach the threshold when enough neurotransmitters reach dendrites.
Threshold: level of stimulation required to trigger a neural impulse; excitatory signals minus inhibitory signals must equal a minimum intensity
Go into Action Potential; a neural impulse (brief electrical charge) that travels down an axon.
All-or-none response.

10. Neurons – How do they work?
Neurons send messages to other neurons – this is what keeps every part of our body in communication with every other part.
Neurons “fire” – send an impulse (message) down their length – or they don’t “fire”

11. Watch “The Action Potential” movie at home: http://brainu
Action Potentials
This “firing” of impulse messages is called the action potential.
An action potential is a brief electrical charge that travels down the axon of the neuron.
Find clip in Multimedia Manager, Media, Animations, PC, 02_01
Play Animation

12. What causes an impulse to fire or not fire?
When a neuron is at rest and capable of generating an action potential, it is called the resting potential
There are fluids inside and outside of the neuron, filled with electrically charged particles (ions)
When the neuron is at rest, there is a negative charge on the inside of the neuron compared to the outside.
At rest, the inside of the cell is at -70 millivolts

13. Neuron Communication Resting Potential
Graphic, Hockenbury slides

14. Action Potentials, cont.
Stimulation from inputs to dendrites causes the cell membrane to open briefly
Positively charged sodium ions flow in through the cell membrane
If resting potential rises above threshold, an action potential starts to travel from the cell body down the axon
Threshold - Each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential.

15. Figure 2.3 Action potential Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers

16. Action Potential, cont.
The shift in electrical charge travels along the neuron
The intensity of an action potential remains the same throughout the length of the axon
Refractory period - The “recharging phase” when a neuron, after firing, cannot generate another action potential

17. To help a mad scientist make a “mad, mad, mad neuron” in a cartoon game, see
For more information on action potentials, see
For an interactive game/demo to help you learn about action potentials, see

19. Neuron Communication All-or-None Principle
The principle that if a neuron fires it will always fire at the same intensity
A strong stimulus can trigger more neurons to fire, and to fire more often, but all action potentials are of the same strength and speed.
A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.
Just like a gun, there is no “part-way” firing

20. How is a neuron firing similar to a toilet flushing?
Consider the following concepts:
Depolarization
All-or-none principle
Direction of impulse
Refractory period
Threshold
Resting potential
Action potential
How about a school bus? See “The School Bus Story” ppt. here:

21. A tale of ionic influence on action potentials
The School Bus Story
A tale of ionic influence on action potentials

22. Setting the stage
Imagine a school bus, filled with unhappy kids on their way to school…

23. Meanwhile… Outiside, it’s a BEAUTIFUL day! Sun is shining
Birds are chirping
Everything is happy

24. The point is…
The unhappy (negative) kids, sealed inside their impermeable school bus, cannot get to the happiness (positivity) outside!

25. All of a sudden…
The bus driver opens the door! Yay! The bus is now permeable… but only in a selected place.
Area of selective permeability

26. And then?
Sunlight, happiness, butterflies, and positivity fill the negative kids on the bus with deep inner joy.

27. Yay, happy kids!
If enough kids go from sad to happy when the beautiful air whooshes in, they have reached the “threshold.” If/when this threshold is reached, they start getting rambunctious ("action potential"). 
After having wasted their energy being rambunctious, there's a short time ("refractory period") before they can start it up again.

28. How does this relate? The kids = negative ions. The bus = an axon.
The sunlight = positive sodium ions.
The bus pre-open door = a polarized neuron in its resting potential.
The driver = cell nucleus.
The opened door = selectively permeable gates.
The happy kids = an action potential… but only if enough of them become happy!

29. What happens when an action potential reaches the end of the axon and enters the terminal buttons?

30. TYPES OF NEUROTRANSMITTERS
Chemical messengers that that traverse the synaptic gap between neurons
REVIEW… remember agonists and antagonists???
Agonist – mimic neurotransmitters
**Example: Morphine mimics endorphins
Antagonist – block neurotransmitters
**Example: Poison blocks muscle movement
Did you know? Botox is an antagonist that paralyzes facial muscles!

31. Acetylcholine (ACH)
Involved with voluntary muscle movement, learning and memory
Lack of ACH has been linked to Alzheimer’s disease.

32. Dopamine Deals with motor movement and alertness.
Lack of dopamine has been linked to Parkinson’s disease.
Too much has been linked to schizophrenia.

33. Serotonin Involved in mood control.
Lack of serotonin has been linked to clinical depression.

34. Endorphins Involved in pain control.
Did you know? The word “endorphin” literally means “morphine within”!
Endorphins
Involved in pain control.
Many of our most addictive drugs deal with endorphins.
“Runner’s High” occurs when your brain signals the release of endorphins to reduce pain!

36. The Nervous System
The Nervous System - body’s speedy, electrochemical communication network consisting of nerve cells

37. Central Nervous System (CNS)
The Brain and spinal cord
Neural networks – interconnected neural cells; more connections made as experience gained

38. Peripheral Nervous System (PNS)
All nerves that are not encased in bone.
Sensory and motor neurons that connect the CNS to the rest of the body
Is divided into two categories….somatic and autonomic.

39. Somatic Nervous System
Controls voluntary muscle movement.
Uses motor neurons.

40. Autonomic Nervous System
Controls the automatic functions of the body.
Divided into two categories…the sympathetic and the parasympathetic

41. Sympathetic Nervous System
Arouses the body
Fight or Flight Response.
Automatically accelerates heart rate and breathing, dilates pupils

42. Parasympathetic Nervous System
Calms the body
Automatically slows the body down after a stressful event.
Heart rate and breathing slow down, pupils constrict

43. Sympathetic and Parasympathetic

44. Types of Neurons Sensory Neurons – sends receptors to CNS
Interneurons – internal communication neurons
Motor Neurons – CNS to muscle and glands

45. Reflexes
Normally, sensory neurons take info up through spine to the brain.
With reflexes though, some reactions occur when sensory neurons reach just the spinal cord.
Automatic response to sensory stimulus; interneurons react to sensory neurons w/o going to brain