Chapter 15: Nervous System

1. Chapter 15: Nervous System

2. We mean THIS kind of “nervous!” The NERVOUS System (no, not that kind of nervous) I think my urinary system just functioned

3. #1 Review Review Review Ask yourself, do you know how to describe: • Homeostasis • Stimulus & Response • Structures • Functions • Maintaining internal balance • Responding to change/information • Parts • Jobs ?

4. HELPME! #2 Nervous System Overview Our friend Joe has suffered some real mishaps in his life… *&@%#!

5. #3 Nervous System Overview, contd. In all those events in Joe’s life, he counted on his nervous system to come through for him… Imagine if Joe touched the stove but had no clue that it was hot and left his arm on it for 20 seconds. Imagine if Joe stepped on the nail and had no idea he was walking around with it for the rest of the day. Imagine if Joe’s arm didn’t realize it had 4 canine teeth punctures in it and never decided to heal them up. Imagine if he couldn’t see, hear or even smell that he’d wandered onto the 14 Freeway

6. #4 Nervous System Overview, contd. But Joe’s body DOES do those things…and so much more, thanks to his brain! study laugh touch think play feel emotions talk move dream remember learn HUMAN That’s a lot…and it’s so much of what makes us, well…

7. #5 Nervous System Overview, contd. You can’t help but interact with your environment. You can feel how uncomfortable your stool is, hear the hum of the air or heat when it comes on, smell the aroma of the last group that was in your classroom (ugh), and see hundreds of new images every second. Wow! WOW

8. #6 Nervous System Overview, contd. I hope by now the terms “homeostasis” and “stimulus : response” aren’t new ideas to you. Well, if any system is the king of homeostasis and the queen of Stimulus : response, then this is it! Your brain and nerves (the nervous system) regulates most body functions & responds to the environment (through senses). This is it. The human brain. About the size of your fists put together, it stores everything you have known or ever will know. Weird, when you think about it.

9. the big boss Like a super-busy telephone switchboard, your brain uses nerves (think: wires of the body) to receive and send signals CONSTANTLY. Nervous System circulatory skeletal integumentary urinary respiratory muscular digestive any others #7 FUNCTIONS of the Nervous System 1. Maintains homeostasis using all other body systems 2. Uses nerves to process stimuli and carry out responses

10. #8 STRUCTURES of the Nervous System Let’s start small and work our way bigger…nerves (think of them like wires) are actually special support cells and other nerve cellscalled neurons. Neurons are VERY unique. Let’s see some ways: • In regards to cells, neurons can be huge…they can be wide enough • in diameter to be seen without a microscope, and some are almost • 3 feet long! Thick nerves seen here are bundles of individual neurons.

11. #9 Structures, contd. • Neurons aren’t programmed to die like your other body cells…the neurons you were born with are the same ones you’ll have when you’re 89 years old. Very few are made after the age of about two. (dendrites) (cell body) • Using ions (electrically charged • atoms), neurons are able to pass • signals down their very long • tails (axons) at more than the length • of a football field per second. Yeah— • they’re fast. And weird looking. (axon)

12. #10 Structures, contd. We’ll talk about two main kinds of neurons…those that are going TO the brain, and those that are leaving FROM the brain. a. sensory neurons – send signals to brain from senses The smell of freshly-baked muffins, the soft fur of a kitten against your cheek, how hot you are after running 4 laps on the track…all of these sensory signals are logical to you only because the brain processes the information sent to it by nerves.

13. #11 Structures, contd. • So your sensory neurons have sent signals telling your brain that you: • Need to get up off the cactus you just sat on • Need to raise your left hand to catch the softball • Need to plug your ears because the cannon is about to be fired …how do you actually go about DOING those things? It’s all thanks to your: (b.) motor neurons – send signals from brain to muscles or organs

14. #12 Structures, contd. Think of examples of how reflexes can save you from harm! So, a sensory neuron sends a signal to your brain, your brain processes it, and it then might send a signal down a motor neuron to a muscle to respond. But sometimes you need this to all happen super-fast! A (c.) reflex is a quick, automatic reaction caused by sensory & motor neurons skipping the brain. This reflex doesn’t involve any “thinking” of your brain. See…your sensory neurons send signals to your spinal cord, which is “smart” enough to respond immediately (without wasting time asking for permission to the brain) and uses your motor neuron to jerk your leg up.

15. #13 Structures, contd. If you ever hear of scientists/doctors referring to the CNS, they’re talking about the Central Nervous System. The CNS consists of the brain & spinal cord. It’s the “thinking” & “control” part of your nervous system. In the diagram on the right, you’ll see that your other nerves (both sensory and motor neurons) everywhere else are called the “peripheral” nervous system.

16. #14 Structures, contd. Ok, this is it. The…I mean…THE boss organ of your body. This is the ultimate ruler of your whole self. People have marveled over it for thousands of years and we learn more of how it works every day it seems. As far as the brain goes, we’ll just worry about its 3 main parts. For now, please just remember this: your brain is NOT a muscle. It’s nerve cells! weird looking

17. #15 Structures, contd. In the blank part of your notes page, let’s sketch a simple brain. It’s not difficult. First, do a basic outline which is sort of like a mitten. Now add in some of the folds (which show how tightly packed your brain is inside your skull). 1. Perfect…now label this section “1”. This huge section is the (1.) cerebrum– it controls movement, senses, memory, thinking. It’s the source of your emotions, too. Wow. Think about how God made this incredible lump of cells. Seriously, give it some thought. Simply amazing.

18. #16 Structures, contd. Let’s add in a new section: Draw in a blob at the bottom right. Make it stripey. Label it “2”. 2. 2.cerebellum – this part of the brain coordinates your muscles and balance. If you stand up, think of all the dozens of tiny muscular contractions your thigh, foot, calf, etc. muscles have to do every second to correct your slight teetering to one side or the other. Your cerebellum makes it happen.

19. #17 Structures, contd. Draw this: 3. This widened section of the spinal cord near where it joins your brain is called the (3.) brain stem – it THANKFULLY controls your involuntary life functions, ex: breathing, heartbeat Imagine if the medulla failed. Yikes!

20. #18 Structures, contd. As far as the spinal cord goes, it can do a little thinking on its own, which is why its considered a part of the CNS, but its main job is to carry messages to and from the brain. You already know how important it is that your vertebrae successfully protect your spinal cord. If not, it can be injured permanently, with little or no chance at recovery. actor Christopher Reeve before and after his tragic horse-riding accident

21. #19 DISORDERS of the Nervous System Well, there are so many to choose from that affect your brain and/or nerves. Here’s just a few. Same guy, a few minutes later. Fortunately, he didn’t suffer any long-term paralysis, but he DID have a concussion. (1.) A concussion happens when the skull slams into the brain, “shocking” it. This happens when the brain sits still due to inertia, but a collision moves the skull into the brain very quickly. (ouch for this guy)

22. President Reagan and Charlton Heston both suffered from Alzheimer’s. #20 Disorders, contd. Here’s a truly sad and tragic one. As some people age, their brain cells stop communicating with each other,causing memory loss. This is known as (2.) Alzheimer’s Disease (not “old timer’s disease”). This almost always is found in elderly people, and the cause is not Really well-understood. There is no cure, and the only treatment seems to be the patience and understanding of the sufferer’s loved ones. Imagine leaving the house and not remembering why you left in the first place, then forgetting which house was yours, and simply feeling totally, helplessly lost. Imagine opening your eyes from a nap and not having a clue who your own daughter or husband were as they sat next to you. Hopefully, someday there will be a cure for this.

23. #21 Disorders, contd. Imagine your hand shaking uncontrollably…eating with a fork or tying your shoes is so frustrating and uncomfortable…and embarrassing. Eventually you have a hard time making your mouth and tongue form the sounds of words you’re trying to speak. This is the effects of (3.) Parkinson’s Disease. This is a disease caused by brain damage that causes loss of muscular control & coordination. Michael J. Fox and Muhammad Ali.

24. #22 Disorders, contd. If a blood clot blocks some areas of the brain from getting oxygen, those cells die. Well, they’re not replaced, so whatever those cells used to control will likely suffer from limited or non-function. This is a (4.) stroke – clot in a brain blood vessel…can cause death of brain tissue. Strokes are very serious, and can definitely be life threatening. People who survive strokes may have one side of their face “droop” since they can’t control the muscles there anymore.

25. La dee da dee dum… #23 Review So, could you live without this system? NO! If Joe’s brain “stopped” or “disappeared” he would fall dead instantly.

26. #24 Review, contd. What does the Nervous System do for homeostasis? ALL it does IS homeostasis! That’s all it does, all day all night! AND the same goes for Stimulus : Response. Your brain is CONSTANTLY processing signals…so much so that it causes you to flush some of those things out or re-visit them in your dreams!

27. #25 Review, contd. You really only get one brain. There’s no brain “transplant” either. When you kill those brain cells, they don’t magically repair them- selves, usually. So TAKE CARE OF IT! Think of Ozzy! Slksd asl sdkla dnndng ngnang Snd ansdndn ansdsuwe sld Stay off the drugs, kids! Lsdkal Dsklsjdj djannd ehenan engna Ennq ueueusn dndns andooop Sndnda ndnnnnngggnn

28. #26 And That’s… THE END

29. Answer the following questions on a sheet of notebook paper. • What are the three main functions of a nervous system? • What structures comprise the Central Nervous System (CNS)? • What are sensor neurons? • What are motor neurons? • Sensory and motor neurons are collectively called the ______________________. • The structural and functional unit of the nervous system is the ___________________. • What is a reflex? • What are the 3 main parts of the brain and their functions? • What is the main function of the spinal cord? • What happens to the brain when you get a concussion? • How are strokes caused? • Nerve cells are also called?