Fundamentals of the Nervous System

1. Fundamentals of the Nervous System Chapter 12 Part I

2. Sorry it took me some time to respond I lost the first ppt I did on Saturday. This is to replace it. • The quiz on Saturday will be on Fig 12.3 • Now that we are pass the skeletal and muscular system you will be responsible for the nervous system chapters. • Please read the chapter before class Or at least the diagrams, tables, end of the chapter summary and questions!

3. Nervous System • Master control and communications system - cells communicate rapidly through electrical signals • Has 3 overlapping functions: 1) Sensory receptors monitor changes both inside and outside the body - each change is called a stimulus, and the gathered information is called sensory input 2) Processes and interprets sensory input - makes decisions – a process called integration 3) Dictates a response by activating effector organs - response by muscles or glands – motor output

4. Basic Divisions of the Nervous System • Divisions of the nervous system: CNS and PNS • CNS – central nervous system - consists of the brain and spinal cord - interprets incoming sensory signals and dictates motor responses based on past experiences, reflexes, and current conditions

5. Peripheral Nervous System • Outside the CNS, consists mainly of nerves extending from the brain and spinal cord - cranial nerves cary signals to and from the brain - spinal nerves carry signals to and from the spinal cord • Peripheral nerves serve as communication lines that link all body regions to the CNS • Ganglia of the PNS – areas where the cell bodies of neurons are clustered

6. Basic Divisions of the NS Fig 12.2

7. Sensory Input and Motor Output • NS receives sensory inputs and dictates motor outputs • Sensory or afferent (‘carrying toward’) signals are picked up by sensory receptors - located throughout the body - carried by nerve fibers of the PNS into the CNS • Motor or efferent (‘carrying away’) signals are carried away from the CNS by PNS nerve fibers - innervate muscles and glands to effect a muscle contraction or a glandular secretion

8. Sensory Input and Motor Output • Sensory inputs and motor outputs are divided by the body regions they serve • Somatic body region - structures external to the ventral body cavity (outer tube) - skin, skeletal musculature, bones • Visceral body region - contains the viscera within the ventral body cavity (inner tube) - digestive tube, lungs, heart, bladder, etc.

9. Sensory Input and Motor Output Somatic and visceral regions - four main subdivisions 1) Somatic sensory – innervation of the outer tube skin, body wall, and limbs 2) Visceral sensory – innervation of the viscera 3) Somatic or voluntary motor – motor innervation of the outer tube specifically skeletal muscle 4) Visceral or involuntary motor – innervation of the inner tube - smooth and cardiac muscle and glands - outer outer tube structures, arrector pili muscle and smooth muscle in vessels, and sweat glands

10. Types of sensory and motor Information carried by the NS general = ‘widespread’ special = ‘localized Fig 12.3

11. Somatic Sensory • General somatic senses – receptors widely spread throughout the skin and in the body wall - touch, pain, vibration, pressure, temperature • Proprioception (‘sensing one’s own body’) – detect stretch in tendons and muscles - body sense of position and movement in space • Special somatic senses - hearing, balance or equilibrium (receptors in the inner ear), vision (receptors in the eye), smell

12. Visceral Sensory • General visceral senses of stretch, pain, temperature, nausea, and hunger - widely felt in digestive and urinary tracts, and reproductive organs • Special visceral (chemical) senses - taste and smell localized to the tongue and nasal cavity

13. Somatic Motor • General somatic motor part of the PNS signals contraction of skeletal muscles - often called ‘voluntary nervous system’ - under our voluntary control

14. Visceral Motor • General visceral motor part of the PNS - regulates the contraction of smooth and cardiac muscle - makes up the autonomic nervous system (ANS) - controls function of visceral organs - ofter call ‘involuntary nervous system’