12.1 – Structure of the Nervous System

1. 12.1 – Structure of the Nervous System

2. Nervous System: • a high-speed communication system which delivers information to and from the brain and spinal cord and all over the body.

3. In any nervous system, there are 4 main components: • sensors: gather information from the external environment (sense organs) • conductors: carry information from sensors to modulators or from modulators to effectors (nerves) • modulators: interpret sensory information and send information to effectors (brain, spinal cord) • effectors: part of the body that responds because of information from a modulator (muscles, glands)

4. In any nervous system, there are 4 main components: • sensors: • conductors: • modulators: • effectors:

5. The Human Nervous System Two main components of the human nervous system: • central nervous system (CNS): the brain and spinal cord • peripheral nervous system (PNS): the nerves that enter and leave the brain and spinal cord

6. CNS • receives sensory information and initiates control • protected by several things: • skull – hard casing that protects the brain • vertebrae – protects spinal cord • meninges – three protective membranes surrounding the brain and spinal cord. They are filled with cerebrospinal fluid to help cushion. • Ventricles (cavities) in the brain which are filled with cerebrospinal fluid • grey matter: brownish-grey nerve tissue consisting of mainly cell bodies within the brain and spinal cord • white matter: the white nerve tissue of the brain and spinal cord, consisting of mostly myelinated neurons.

7. CNS Protection • Meninges

8. PNS 2 parts • autonomic nervous system: the part of the nervous system that relays information to the internal organs that are not under the conscious control of the individual. This system is made up of the sympathetic and the parasympathetic nervous systems. • sympathetic: speeds up muscle activity and activates in times of stress; “fight or flight response” ex. Increases heart rate, breathing rate, nervousness • parasympathetic: the network of nerves that counteract the sympathetic nervous system to slow down heart rate and relax muscles • somatic nervous system: the part of the nervous system that relays information to and from skin and skeletal muscles that are under conscious control of the individual

10. The Brain • Parts of the Brain (see Fig. 12.11, p. 399)

11. Cerebrum • largest part of the brain; cerebral cortex folded to increase surface area • responsible for complex behavior and intelligence; also interprets sensory inputs and initiates motor response • cerebral cortex divided into 4 lobes: • frontal lobe – contains primary motor area, premotor area, Bronca’s area (motor speech), and pre-frontal area (association) • temporal lobe – located at sides of head contains auditory association area, primary auditory area, and sensory speech (Wernche’s area) • parietal lobe – located near top of brain contains primary somatosensory area, somatosensory association area and primary taste area • occipital lobe – located at back of cerebrum contains primary visual area and visual association area • cerebral cortex divided into two hemispheres, right and left. The cortex consists of grey matter and the two hemispheres are connected by a structure called the corpus callosum, a layer of white matter which transmits between the two hemispheres really quickly.

12. Cerebellum • the part of brain that is responsible for muscle coordination • contains 50% of the brain’s neurons but only takes up 10% of the space

13. Midbrain • a short segment of the brainstem (midbrain, pons and medulla oblongata) between the cerebellum and pons; particularly involved in sight and hearing

14. Pons • contains bundles of axons traveling between the cerebellum and the rest of the CNS • functions with the medulla oblongata to regulate breathing rate and has reflex centers involved in head movement

15. Medulla Oblongata • attaches to the spinal cord at the base of the brain • involved in several important processes: - controlling heart rate - vomiting - adjusting blood pressure - hiccupping - controlling breathing - swallowing

16. Thalamus • sensory relay center of the brain that governs the flow of information from all other parts of the nervous system

17. Hypothalamus The part of the brain that acts as the main control centre for the autonomic nervous system, reestablishes homeostasis, and controls the endocrine hormone system

18. Review Can you name & locate the 4 lobes?

19. Review Which lobe might be damaged if you have hearing difficulties?

20. Review Which lobe might be damaged if you have sight problems?

21. Review • What is #37? • What is #36 • What is #32 • What are these 3 collectively called?

22. Review • Which part is the control center for the autonomic nervous system? • Which part of the brain is active when you gag on a chicken bone?

23. Review • Which part of the brain is well developed in athletes? • What is #10 composed of?

24. Review • Which part of the brain stem is NOT labeled

25. Review • You make up a question I can ask on the quiz.