1. Brain and Behavior

2. Neuron and Its Parts Neuron: Individual nerve cell
Dendrites: Receive messages from other neurons
Soma: Cell body; body of the neuron
Axon: Fiber that carries information away from the cell body
Myelin (Sheath): Protects Axon
Axon Terminals: Branches that link the dendrites and somas of other neurons

3. Figure 2.1
FIGURE 2.1 A neuron, or nerve cell. In the right foreground you can see a nerve cell fiber in cross section. The upper left photo gives a more realistic picture of the shape of neurons. Nerve impulses usually travel from the dendrites and soma to the branching ends of the axon. The nerve cell shown here is a motor neuron. The axons of motor neuron stretch from the brain and spinal cord to muscles or glands of the body.

4. Synapses
Messages from one neuron to another pass over a microscopic gap called a synapse
Synapse: Microscopic gap between two neurons over which messages pass

5. Figure 2.5
FIGURE 2.5 A highly magnified view of a synapse. Neurotransmitters are stored in tiny sacs called synaptic vesicles (VES-ihkels). When a nerve impulse reaches the end of an axon, the vesicles move to the surface and release neurotransmitters. These molecules cross the synaptic gap to affect the next neuron. The size of the gap is exaggerated here; it is actually only about one millionth of an inch. Some transmitter molecules excite the next neuron, and some inhibit its activity.

6. Neurotransmitters
Chemicals that alter activity in neurons; brain chemicals that carry messages.
Acetylcholine: Activates muscles
Dopamine: Muscle control
Serotonin: Mood and appetite control
• Receptor Site: Areas on the surface of neurons and other cells that are sensitive to neurotransmitters

7. Nerves and Neurons
Nerves: Large bundles of axons and dendrites (Not neurons)
Myelin: Fatty layer of tissue that coats axons
Multiple Sclerosis (MS) occurs when myelin layer is destroyed; numbness, weakness, and paralysis occur
Neurogenesis: Production of new brain cells

8. Neural Networks Central Nervous System (CNS): Brain and spinal cord
Peripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord
Somatic System: Links spinal cord with body and sense organs; controls voluntary behavior
Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure

9. Figure 2.6
FIGURE 2.6 (a) Central and peripheral nervous systems. (b) Spinal nerves, cranial nerves, and the autonomic nervous system.

10. Two Divisions of the Autonomic System
Sympathetic: Arouses body; emergency system
Parasympathetic: Quiets body; most active after an emotional event

11. Figure 2.8
FIGURE 2.8 Sympathetic and parasympathetic branches of the autonomic nervous system. Both branches control involuntary actions. The sympathetic system generally activates the body. The parasympathetic system generally quiets it. The sympathetic branch relays its messages through clusters of nerve cells outside the spinal cord.

12. FIGURE 2.7 Subparts of the nervous system.

13. Cerebral Cortex Definition: Outer layer of the cerebrum
Cerebrum: Two large hemispheres that cover upper part of the brain
Corticalization: Increase in size and wrinkling of the cortex
Cerebral Hemispheres: Right and left halves of the cortex
Corpus Callosum: Bundle of fibers connecting cerebral hemispheres

14. Figure 2.19
FIGURE 2.19 Basic nerve pathways of vision. Notice that the left portion of each eye connects only to the left half of the brain; likewise, the right portion of each eye connects to the right brain. When the corpus callosum is cut, a “split brain” results. Then visual information can be sent to just one hemisphere by flashing it in the right or left visual field as the person stares straight ahead.

15. Figure 2.22

16. Subcortex Hindbrain (Brainstem)
Medulla: Connects brain with the spinal cord and controls vital life functions such as heart rate and breathing
Pons (Bridge): Acts as a bridge between medulla and other structures
Influences sleep and arousal
Cerebellum: Located at base of brain
Regulates posture, muscle tone, and muscular coordination

17. Subcortex: Reticular Formation (RF)
Lies inside medulla and brainstem
Associated with alertness, attention and some reflexes (breathing, coughing, sneezing, vomiting)
Reticular Activating System (RAS): Part of RF that keeps the cortex active and alert
Its alarm clock

18. Figure 2.25
FIGURE 2.25 This simplified drawing shows the main structures of the human brain and describes some of their most important features. (You can use the color code in the foreground to identify which areas are part of the forebrain, midbrain, and hindbrain.)

19. Forebrain
Structures are part of the Limbic System: System within forebrain closely linked to emotional response
Thalamus: Relays sensory information to the cortex; switchboard
Hypothalamus: Regulates emotional behaviors and motives (e.g., sex, hunger, rage, hormone release)
Amygdala: Associated with fear responses
Hippocampus: Associated with storing memories; helps us navigate through space

20. Figure 2.26
FIGURE 2.26 Parts of the limbic system. Although only one side is shown here, the hippocampus and the amygdala extend out into the temporal lobes at each side of the brain. The limbic system is a sort of “primitive core” of the brain strongly associated with emotion.

21. Endocrine System
Glands that pour chemicals (hormones) directly into the bloodstream or lymph system
Pituitary Gland: Regulates growth via growth hormone
Too little means person will be smaller than average
Hypopituitary Dwarfs: As adults, perfectly proportioned but tiny
Too much leads to giantism
Excessive body growth

22. Endocrine System Concluded
Pineal Gland: Regulates body rhythms and sleep cycles.
Releases hormone melatonin, which responds to daily variations in light.
Thyroid: In neck; regulates metabolism.
Hyperthyroidism: Overactive thyroid; person tends to be thin, tense, excitable, nervous.
Hypothyroidism: Underactive thyroid; person tends to be inactive, sleepy, slow, obese.

23. The Adrenal Glands
Adrenals: Arouse body, regulate salt balance, adjust body to stress, regulate sexual functioning; located on top of kidneys
Releases epinephrine and norepinephrine (also known as adrenaline and noradrenaline)
Epinephrine arouses body; is associated with fear
Norepinephrine arouses body; is linked with anger