Unit 2: Neuroscience REVIEW Everything psychological is simultaneously biological. Your every idea, every mood, every urge is a biological happening. You think, feel, and act with your body. The ancient philosopher, Plato correctly located the mind in the spherical head. But his student, Aristotle, believed the mind was in the heart. The heart remains our symbol for love, but science proves that it’s your brain, not your heart, that falls in love.

Neural Communication Neuron Soma a nerve cell the basic building block of the nervous system Soma cell body – organelles and cytoplasm serves as neuron’s control center We are each a system composed of subsystems that are in turn composed of even smaller subsystems. Tiny cells organize to form such body organs as our stomach, heart, and brain. These organs in turn form larger systems for digestion, circulation, and information processing. Those systems are part of an even larger system- you! Who in turn are part of your family, community, and culture. Therefore to understand our behavior deeply, we need to study how these biological, physical, and social systems work and interact. We will start small and build from the bottom up- from neurons up to the brain in this unit, and to the environmental and cultural influences that interact with our biology in later units.

Neural Communication Dendrite Axon Myelin [MY-uh-lin] Sheath the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body Axon the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands Myelin [MY-uh-lin] Sheath layers of fatty cells that encase the fibers of many neurons in segments Insulates axons and speeds their impulses Myelin Sheath- MS, disease in which the myelin sheath degenerates. Result is a slowing of communication to muscles and eventual loss of muscle control.

Neurons

Neurons

Neurons Soma or Cell Body (like all cells)

Neurons Soma or Cell Body (like all cells)

Neurons Soma or Cell Body (like all cells)

Neurons Soma or Cell Body (like all cells)

Neurons Soma or Cell Body (like all cells)

How Neurons Communicate Neurons communicate by means of an electrical signal called the action potential – a brief electrical charge that travels down an axon Action potentials are based on movements of ions between the outside and inside of the cell When an action potential occurs, a chemical message is sent to neighboring neurons

Neural Communication Synapse ("SIN-aps") Neurotransmitters Junction between the axon terminal of the sending neuron and the dendrite or cell body of the receiving neuron The tiny gap at this junction is called the synaptic gap or cleft Neurotransmitters Chemical messengers that traverse the synaptic gaps between neurons When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate an action potential All information processing in the brain involves neurons ‘talking to’ each other at synapses. Electrical impulses (action potentials) travel from one neuron to another across a tiny junction called the synapse When an action potential reaches an axon terminal, it stimulates the release of neurotransmitter molecules from sacs called vesicles. These molecules cross the synaptic gap and bind to the receptor sites on the receiving neuron. The sending neuron normally reabsorbs excess neurotransmitter molecules, a process called reuptake

Neurotransmitters Also review the neurotransmitters- jobs worksheet!

The Nervous System

CNS – Brain and Spinal Cord part of the CNS that plays important roles in sensation, movement, and information processing. Spinal Cord plays a role in body reflexes and in communication between the brain and the peripheral nervous system. A reflex travels from a sensory neuron to the spinal cord and returns through a motor neuron without first going to the brain. Knee-jerk response – most common example Pain response – your hand jerks away before your brain knows you’ve been hurt.

A Simple Reflex

Autonomic Nervous System (ANS) Sympathetic NS “Arouses” (fight-or-flight) Parasympathetic NS “Calms” (rest and digest) Looking more specifically at our autonomic nervous system (ANS), we see that there are two components of this system: the sympathetic nervous system and the parasympathetic nervous system.

Sympathetic NS “Arouses” The Nervous System Sympathetic NS “Arouses” (fight-or-flight)

The Nervous System Parasympathetic NS “Calms” (rest and digest) Restores Homeostasis