Unit 2- Day 2

February 12/13

Quiz #2

• 1. What are the two components of the central nervous system?

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• 2. Name two parts of a neuron.

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• BONUS
• 3. How many days, and how long per day, do you need to meditate during this unit?

The Nervous System

• Regulates our internal functions
• Two main parts:
• CENTRAL NERVOUS SYSTEM
• BRAIN AND SPINAL CORD
• PERIPHERAL NERVOUS SYSTEM
• NERVE CELLS SEND MESSAGES BETWEEN CENTRAL NERVOUS SYSTEM AND PARTS OF BODY

The Nervous System

• Nerves
• neural “cables” containing many axons
• part of the peripheral nervous system
• connect the central nervous system with muscles, glands, and sense organs

Somatic vs. Automatic Nervous Systems

• Somatic
• SENSORY MESSAGES TO CENTRAL NERVOUS SYSTEM
• ACTIVATED BY PAIN, TOUCH, TEMP CHANGES, CHANGES IN BODY POSITION

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• Automatic
• REGULATES VITAL FUNCTIONS- HEARTBEAT, BREATHING, DIGESTION
• Two divisions: Sympathetic and Parasympathetic
• S = STRESS; “fight or flight”, action
• P = PEACE; restores balance, normalizes

NEURONS (Nerve cells)

• Communication (each other and other structures)
• More than 100 billion neurons- most found in brain

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• Sensory– carry information received by the senses TO the central nervous system
• Motor– carry information FROM the central nervous system to the muscles and glands and influence function
• Many more

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• Example: Burned finger

Structure

Neural Communication

• Dendrite
• 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
• a layer of fatty cells segmentally encasing the fibers of many neurons
• enables vastly greater transmission speed of neutral impulses

Dendrites- receive info; Axon- carries away�Myelin sheath- speed

Neural Communication

• Synapse [SIN-aps]
• junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
• 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, neuro-transmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse

Neurotransmitters

• Chemicals that are stored in sacs in the axon terminals
• Several types
• Think of a spray bottle

The Nervous System

• Reflex
• a simple, automatic, inborn response to a sensory stimulus

Neural Communication

Locks and Keys

• Neurotransmitter molecules have specific shapes

• When NT binds to receptor, ions enter

• Receptor molecules have binding sites

Neurotransmitters

• Diseases and psychological disorders- caused by presence of too many or too few kinds of neurotransmitters

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• Dopamine and Seratonin

Some Drugs Work on Receptors

• Some drugs are shaped like neurotransmitters
• Blockers: fit the receptor but poorly �and block the NT
• e.g., beta blockers

• Mimickers: fit receptor well and act like the NT
• e.g., nicotine

Neural Communication

Dopamine

• Involved in movement, attention and learning
• Dopamine imbalance also involved in schizophrenia
• Loss of dopamine-producing neurons is cause of Parkinson’s disease

Parkinson’s Disease

• Results from loss of dopamine-producing neurons
• Symptoms include
• difficulty starting and stopping voluntary movements
• tremors at rest
• stooped posture
• rigidity
• poor balance

Parkinson’s Disease

• Treatments
• L-dopa
• transplants of fetal dopamine-producing substantia nigra cells
• adrenal gland transplants
• electrical stimulation of the thalamus has �been used to stop tremors

Serotonin

• Involved in sleep
• Involved in depression
• Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect

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REUPTAKE INHIBITORS