Biological Processes 2009

Chapter 4

Brain and Behavior

Organization of the Nervous System

The Central Nervous System (CNS)

– Composed of the brain and spinal cord• Spinal Cord

–Sensory neurons–Motor neurons–Interneurons–Reflexes

Spinal Reflex

Reflexes enable us to remove ourselves immediately from danger by avoiding the time it would take for a message to go to and from the brain. In this example, the interneuron in the spinal column intercepts the "extreme heat” message from the sensory neuron and directs the motor neurons to contract the hand muscles, thereby pulling the hand away from the burner.

Divisions of The Nervous System Central Nervous System (CNS)is protected by bone, comprises the brain and spinal cord.

Peripheral Nervous System (PNS), not protected by bone, comprises the nerves of the autonomic and somatic systems.

The autonomic system transmits messages btwn the brain and internal organs.

The somatic system transmits messages btwn the brain, sensory and motor nerves, which are linked to the skeletal muscles.

The Autonomic Nervous SystemNote how the two parts of the autonomic system, the sympathetic and parasympathetic systems, complement one another as they regulate the functions of the organs.

Neuron Anatomy: Messenger system that sends and receives information throughout the body. Each neuron has the same structure: dendrites, soma, axon, and terminal buttons.

http://outreach.mcb.harvard.edu/animations/synaptic.swf

http://outreach.mcb.harvard.edu/animations/synaptic.swf

Neurons and The SynapseNeurons relay electrochemical messages by releasing neurotransmitters that cross the synapse to the dendrites of the receiving neurons.

Neural Transmission. A neural impulse flows from the axon of a neuron to the axon's terminal buttons, instigating the release of neurotransmitter substances which bind to specific receptor sites that provide a fit to them. The relationship is like that of a key opening only a special kind of lock.

Nervous System Cells Functions

• The Action Potential Neuron communication

• Electrical signal that travels along an axon of a neuron

• Threshold of excitation

• Neural Transmission• Neurotransmitter

• Excitatory and inhibitory messages

• Reuptake

Simulation

NeurotransmittersAcetylcholine

Excites Receptors• Excites the peripheral nervous system to contract skeletal

muscles = movement

Memory, Attention, Arousal• Action may be blocked in Alzheimer’s Disease

Too Little: Example-Botulism

• Bacteria in food, prevents release of Ach-signal carrier to muscles =paralysis and death.

Too Much: Example-Black Widow Spider Poison

• Ach storm=spasms and tremors.

NeurotransmittersDopamine• Movement• Attention• Learning• Pleasure Pathways and responses.

– Cocaine – Prevents reabsorption--dopamine, – Dopamine stays in the synapse longer = heightened arousal.

Parkinson’s Disease– Deficit in Dopamine (Movement)

Schizophrenia– Excess of Dopamine (Attention, Learning, Responses)

– Antipsychotic meds • Prevent dopamine from binding to receptor sites;

– reducing stimulation and decreasing hallucinations.

Neurotransmitters

Serotonin Generally inhibitory

– Arousal

– Regulates Sleep/Waking states

– Regulation of mood (major influence in depression)

– Appetite

– Sensitivity to pain

– Inhibit dreaming

– Linked to depression

– Produce Anxiety (Influences anxiety disorders)

Action Potential with Neurotransmitters at the Synapse Simulation

Presynaptic Synapse Postsynaptic

Terminal Button Dendrite

Neurotransmitter Drug

Download this corrected figure from the Instructor Book Companion Web Site and

insert here.

Figure 3.11

The Structures/Functions of the Brain


The Hindbrain– Main function: “Life support”

• Examples: Breathing, heart rate

– Medulla Oblongata– Pons– Cerebellum

The Midbrain– Main function: “Relay stations”

• Coordinates sensory information

– Reticular Activating System (RAS)

Reticular Activating System

The reticular activating system is important in regulating sleep and waking, and arousal in general.


The Forebrain– The Limbic System

– Hippocampus

– Amygdala

– The Thalamus– basal ganglia

– The Hypothalamus- Regulation of body temp, eating, drinking and sexual behavior

Lobes of the Cerebral CortexThe cortex is divided into the frontal, parietal, temporal, and occipital lobes.The lobes have specific functions but also interact to perform complex processes.


The Four Lobes of the Brain

1. The Frontal lobeDecision making, planning, personality

http://www2.wwnorton.com/college/psych/psychsci2/content/video_exercises/assets/ch04_02.asp Adobe Flash

Primary motor cortex

2. The Parietal lobeprimary somatosensory cortex

3. The Temporal lobe • Broca’s Area• Wernicke’s Area

4. The Occipital lobe• optic chiasma

Motor Cortex and Somatic

– The Cerebral Cortex and Hemispheres• Cerebrum• Cerebral cortex• Cerebral hemispheres• Corpus callosum

– The Hemispheres of the Brain

– Split-Brain Studies


Split Brain Mechanics

Split Brain Studies

http://www.youtube.com/watch?v=lfGwsAdS9Dc

Prefrontal Cortex

Biological Processes 2009

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