The Nervous System

1. The Nervous System

2. Divisions of the Nervous System

3. Central Nervous System • Includes the brain and spinal cord • Is where sensory information is received and motor (movement) control is initiated • Protected by • bone • Brain – skull • Spinal cord – vertebrae • 3 protective membranes called meninges • Space between meninges is cerebrospinal fluid (cushions and protects)

4. The Brain • Brain weighs about 3 pounds • Has hundreds of billions of neurons • You had the maximum number of neurons when you were born • 1000’s of neurons are lost every day and are never replaced • Don’t notice this until later in life when the loss is so large • This is why elderly people often become forgetful

5. The unconscious brain – parts of the brain that work without us thinking about them • Medulla oblongata • Closest to spinal cord • Controls heart rate, breathing, bp, reflex reactions (coughing, sneezing, vomiting, hiccupping, swallowing) • Thalamus • Receives sensory information (except for smell) from all parts of the body • Sends this info to the cerebrum for further processing • Cerebellum • Balance and complex muscular movement/coordination • Butterfly shaped • Receives sensory info from inner ear

6. hypothalamus • Regulation of homeostasis • Maintains internal environments • Detects hunger, sleep, thirst, body temp, water balance, bp • Controls the pituitary gland • Link between nervous system and endocrine (hormone) system • Responsible for fight or flight response • Pleasure centers located here • corpus callosum • Horizontal connecting piece between 2 halves of the brain • Transmits info between the right and left cerebral hemispheres

7. The conscious brain – The cerebrum • Largest most prominent, most highly developed part of the brain • Intellect, learning, memory and sensations are formed here • Divided into the right and left cerebral hemispheres • Right hemisphere controls the LEFT side of the body • Left hemisphere controls the RIGHT side of the body

8. Left Brain Right Brain Test

9. What each hemisphere does

10. Cerebral Lobes • Frontal lobe: movement, higher intellectual processing • Problem solving, concentration, planning, judging consequences • Parietal lobe: sensations • Touch, temperature, pressure, pain • Understanding speech and using words • Temporal lobe: hearing, smelling, interpreting experiences • Memory • Occipital lobe: vision

12. Spinal Cord • The “super highway” of the nervous system • Contains central canal filled with cerebrospinal fluid • Gray matter • Inner layer • Contains cell bodies of neurons • Looks like a butterfly with open wings • Cells bodies receive sensory information and send the motor information where it needs to go • White matter • Outer layer • Contains long fibers of internuerons bundled together in tracts • Tracts connect spinal cord to brain