Organization of the Nervous System

Nervous System:

A. Central Nervous System

1. Brain

2. Spinal Cord

B. Peripheral Nervous System

1. Somatic Nervous System

   1. Sensory Input

   2. Motor Output (Voluntary)

2. Autonomic Nervous System

   1. Sympathetic - fight or flight; stress (immediate)

   2. Parasympathetic - resting/healing response (after)

Three Types of Neurons in the NS:

1. Sensory

2. Motor

3. Interneuron

Neurons and Reaction Time

Sequence:

1. Dendrites

2. Threshold

3. Action Potential

4. Cell Body

5. Axon

6. Myelin Sheath

7. Axon terminal

8. Neurotransmitter

9. Synapse

10. Receptor Sites on Dendrites

Endocrine System

The body’s other communication system

• Slower, but usually long-lasting effects

• Secrete hormones into bloodstream

e.g., Pituitary gland

• The “Master Gland”

• Controlled by the hypothalamus

• Influences growth and release of other hormones

Adrenal glands

• Involved in stress response (sympathetic activation)

• Release epinephrine/adrenaline (increase heart rate, blood pressure, blood sugar)

Brain Structures

A. Lower Level

1. Brain Stem

   1. Medulla (auto)

   2. Reticular Formation

2. Thalamus

3. Cerebellum

   1. controls muscle movements

B. Limbic System

1. Amygdala

   1. aggression, anger, afraid

2. Hypothalamus

3. Hippocampus

C. Cerebral (Cerebrum) Cortex

1. Temporal

2. Occipital

3. Parietal

4. Frontal

• Motor Cortex

• Somatosensory Cortex

• Association Areas

Studying Consciousness

Definitions:

Consciousness - awareness of ourselves and our environment

Consciousness - selective attention to ongoing perceptions, thoughts, and feelings

Selective Attention - the focusing of conscious awareness on a particular stimulus

Consciousness = “tip of the iceberg”

Change Blindness

Change Blindness - Failing to notice changes in the environment

Practical implications

• People vastly overestimate their ability to detect change in their environment

This research is one aspect of inattentional blindness

Circadian Rhythm

Circadian Rhythm - “regular bodily rhythms… that occur on a 24-hour cycle” (pg. 57)

Jet Lag - an individual’s internal rhythms are temporarily out of sync with the environment around. them

Symptoms of Jet Lag - changes in sleep, appetite, mood, motivation, energy levels, susceptibility to illness, etc.

Jet lag is worse when you go to the East over going to the West

The more time zones you cross, the greater the difficulty in adjusting

Recommendations to combat jet lag:

• A few days before, start adjusting your schedule to fit the destination

• Change your watch when on the plane

• When arrived, match the schedule of your destination

• The next day, stay out in the sun

Stages of Sleep

Monitored by electroencephalogram (EEG) - “a test that detects electrical activity in your brain using small, flat metal discs (electrodes) attached to your scalp” (mayoclinic.org)

1. NREM-1 (Non-Rapid Eye Movement)

• Light sleep

• Hypnagogic sensations - being startled awake while drifting to sleep

2. NREM-2

3. NREM-3

• Difficult to awaken - sleep walking/talking, etc. can happen

4. REM (Paradoxical Sleeping)

• More rapid brain waves -- brain waves slow down through 1-3, but perk up in REM

• Increased heart rate, rapid & irregular breathing, darting eyes (~30 secs), minimal muscle activity

  • Body is completely still, except eyes

• Dreams happen

• More alert if woken up in REM

Stages repeat every ~90 mins

• Briefer NREM-3; Longer NREM-2 & REM as the night goes on

Sleep Disorders - Narcolepsy

Narcolepsy - characterized by “uncontrollable sleep attacks, sometimes lapsing directly into REM sleep” (pg.63)

• National Institute of Health (NIH) definition: “A chronic neurological disorder caused by the brain’s inability to regulate sleep-wake cycles normally”

Sleep tends to be short (few seconds to several minutes, rare cases an hour or more)

Three Other Symptoms:

1. Cataplexy (sudden loss of muscle tone)

2. Vivid hallucinations

3. Brief, total, paralysis at beginning and end

• Sometimes fall asleep without realizing it

• Often triggered by intense emotion

• Unknown cause

• No cure or complete remission of symptoms

• Medications might help - (uppers and sometimes anti-depressants help symptoms)

Sleep Disorders - Sleep Apnea

Sleep Apnea - “characterized by temporary cessations of breathing during sleep and repeated momentary awakenings”

• Literally “cessation of respiration” (breathing stops)

• Breathing pauses can last from a few seconds to a couple of minutes

  • Maybe 30+ times and hour

Often not diagnosed

Two forms:

1. Obstructive sleep apnea (OSA) -- often with clinically overweight/obese people & kids with enlarged tonsils (snoring)

2. Central sleep apnea -- CNS struggles with talking to diaphragm and lungs to keep working (stopping breathing)

Treatment for OSA:

• change sleeping position

• Avoid CNS depressants (alcohol, sleeping pills)

• Lose weight

• Continuous Positive Airway Pressure (CPAP)

• Surgery -- (resetting of jaw can help)

Treatment for CNS:

• Respiratory stimulants