The Nervous System & the control of movement

1. The Nervous System& the control of movement Chapter 6

2. Q: What is the main role of the Nervous System? A: To “assemble info about conditions external & internal to the body, to analyze this information and initiate an appropriate response”. “COMMUNICATION NETWORK”

4. What are the 2 Major Components of the Nervous System? 1. The Central Nervous System 2. The Peripheral Nervous System

5. CNS (Central Nervous System) • Two Parts: • The Brain B) The Spinal Cord (& vertebral column)

6. CNS ‘A’ - The Brain • Main control center for survival • Emotions • The brain is made up of 6 parts:

7. The 6 Brain Segments • Cerebrum: -largest section -controls sensory, motor & intelligence functions -2 hemispheres / 8 ‘lobes’

8. The 6 Brain Segments (continued) 2) Cerebellum - coordinates balance & muscle movement 3) Brain Stem - links cerebrum to the spinal cord ---> Autonomic functions like “muscle tone”

9. The 6 Brain Segments (continued) 4. Diencephalon -divided into the: Thalemus -pain & attention ii) Hypothalemus -appetite -emotions -body temperature

10. The 6 Brain Segments (continued) 5. Limbic System: -regulates basic drives like hunger, emotions, aggression 6. Reticular Activating System -crucial for maintaining consciousness

11. CNS ‘B’ - Spinal Cord(& Vertebral Column) • Main info pathway between brain & PNS • Spinal Cord - 45cm (brain stem to L2) • Spinal Nerves carry: -sensory info to CNS & -motor commands away from CNS

12. What are the 2 Major Components of the Nervous System? 1. The Central Nervous System 2. The Peripheral Nervous System

13. PNS (Peripheral Nervous System) • 12 Cranial Nerves / 31 Spinal Nerves (sensory fibers) • Responsible for voluntary actions & bodily functions • Eg heart beat, muscle control • Made of Autonomic NS & Somatic NS • Efferent nerves (motor) - carry info from CNS to organs (Efferent-->muscles) • Afferent nerves (sensory)- carry info to brain --> Afferent-->brain)

14. PNS ‘A’- Autonomic Nervous System • Involuntary i) Sympathetic System: -prepares body for emergencies (fight or flight response) ii) Parasympathetic System: -returns boy to normal after ‘emergency’

15. PNS ‘B’- Somatic Nervous System Components: -afferent & efferent nerve fibers -PNS controls and knows what our muscles/tendons are doing & feeling (ie pain, cold, balance, etc.)

16. REFLEX ARC -Automatic response to stimulation -if command center for the flex is: a)the brain ---> cerebral reflex arc b)the spinal cord --->spinal reflex arc

17. Autonomic Reflexes -some involve smooth muscle, cardiac muscle, glands -regulates digestion, blood pressure, sweating

18. Somatic Reflexes -involve stimulation of skeletal muscle ie -stretch reflex, withdrawl reflex

19. Basic Reflex Arc • The components of a basic reflex include; i) receptor ii) adjustor iii) effector

20. Reflex Arc The components of a reflex arc include; i) receptor ii) sensory or AFFERENT nerve (brain) iii) intermediate nerve fibers (adjustor) which interprets the signal & issues an appropriate response iii) motor or Efferent nerve (muscle) v) effector organ (muscle) -if command center for the flex is: a)the brain ---> cerebral reflex arc b)the spinal cord --->spinal reflex arc

21. Proprioceptors Provide info re: - muscle contraction - position of limbs - body posture - balance

22. Proprioceptors There are 2 receptors: • Golgi Tendon Organs (GTO) • Muscle Spindles

23. Golgi Tendon Organs • tension detectors • In the tendon of the muscle • Tension Reflex: GTO, Afferent Neuron, CNS, Efferent Neuron, Motor unit

24. Muscle Spindles -senses changes in muscle length -2 afferent neurons & 1 efferent neuron -very sensitive “Stretch Reflex” (see table 6.1 on pg. 101 in text)