Unit 3 A Biological Bases of

BehaviorNeural Processing and the Endocrine System

Unit 3A:Biological Bases of Behavior:Neural Processing and the Endocrine System

Unit Overview• Neural Communication• The Nervous System• The Endocrine System

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Biological Psychology

branch of psychology concerned with the links between biology and behavior

some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Neural Communication

Types of Neurons

• Sensory neurons• Carry information from sensory systems to the brain• Also referred to as afferent

• Motor neurons• Carry information from the brain to muscles and glands• Also referred to as efferent

• Interneurons• Carry information between other neurons

Structure of Neurons

• Dendrites• Carry information to the cell body from other neurons

• Cell Body (Soma)• Contains nucleus

• Axon• Carries information to the next cell

• Myelin Sheath• Insulates the axon and speeds up the neural impulse

• Terminal Branches • Found at the end of neurons, connects to the dendrites of next

neuron, contains chemical messengers.

Neurons

Neurons

•Speed of a neuron impulse• Range from 2 to 200 MPH• Measured in milliseconds

• (thousandths of a second)

Neurons

•Firing of a neuron• Action potential• Ions

• Positively versus negatively charged

•Resting potential•Selectively permeable

Neural Communication Resting Potential

Nothing is happening. The gates are closed and the positive ions are on the outside with the negative ions on the inside of the cell.

• “Negative Ions inside the Neuron is Natural” Action Potential – (Neural Impulse)

a neural impulse; a brief electrical charge that travels down an axon

generated by the movement of positively charged atoms in and out of channels in the axon’s membrane

This process is due to stimulation from either heat, chemicals, pressure or light

Neurons

•Firing of a neuron• Depolarize• Refractory period• Excitatory versus inhibitory• Threshold• All or none response

The Neural Impulse

• Polarization• When the inside of the Neuron is negatively charged relative to the outside

(resting potential)

• Depolarization• When the electrical charge of a cell moves toward zero

Neural Communication

• Refractory Period (Reload, Recharge)• The time it takes for the positive ions to be pumped out.

Threshold the level of stimulation required to trigger a neural impulse

Action Potential

How Neurons Communicate

•Synapse•Synaptic gap (synaptic cleft)•Neurotransmitters•Reuptake

Synapse

Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or

cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.

Neurotransmitters

Neurotransmitters (chemicals) released from the sending neuron travel

across the synapse and bind to receptor sites on

the receiving neuron, thereby influencing it to

generate an action potential.

Reuptake

Neurotransmitters in the synapse are

reabsorbed into the sending neurons

through the process of reuptake. This

process applies the brakes on

neurotransmitter action.

How Neurons Communicate

How Neurotransmitters Influence Us

•Acetylcholine (AcH)•Dopamine•Serotonin•Norepinephrine•GABA•Glutamate•Endorphins

How Neurotransmitters Influence UsHow Drugs and Other Chemicals Alter Neurotransmitters

•Agonists versus antagonists• Agonists (Act)• Antagonists (Block)

Agonists and Antagonists

Psychopharmacology

• Curare (koo-ra-ray)• Can stun or kill prey quickly• Blocks ACh receptors causing paralysis

• Antipsychotic medications• Block dopamine receptors• Reduces schizophrenic hallucinations

• Caffeine• Increases the release of excitatory neurotransmitters by blocking the

inhibitory neurotransmitter adenosine (a-den-oh-seen)

Psychopharmacology

• How do drugs and alcohol affect our brains?• Mouse party

The Nervous System

• Nervous System: The bodies speedy, electrochemical communication network.

• Central Nervous System (CNS): the brain and spinal cord• Peripheral Nervous System (PNS): the sensory and motor neurons

that connect the body to the CNS

Peripheral Nervous System

• Somatic Nervous System: Controls Voluntary Actions. (I volunteer “Somah” community is a better place. )

• Autonomic Nervous System: Controls our glands and muscles of internal organs.. “My love, you Autonomically make my heart beat”

• Sympathetic Nervous System: arouses and expands energy. When I feel sympathy for someone, my heart beats for them.

• Parasympathetic Nervous System: Conserves energy and calms the body. ”I’m so calm I feel paralyzed.”

A Simple Reflex

The Nervous SystemReflex

a simple, automatic, inborn response to a sensory stimulus

Skinreceptors

Muscle

Sensory neuron(incoming information)

Motor neuron(outgoing information)

Brain

Interneuron

Spinal cord

Endocrine System

• Endocrine System: the body’s “Slow” communication system. • Hormones: Chemical messengers that travel through the body and

brain and affect our behavior. • Adrenal Glands: secrete hormones that arouse the body in times of

stress. • Pituitary Glands: Regulates growth and controls the other endocrine

glands.