The Nervous System. Taking care of all your movement and sensory needs since Or 2003, depending on birth year

Transcription

1 The Nervous System Taking care of all your movement and sensory needs since Or 2003, depending on birth year

2 Basic Information (on sheet, not notes ) Organ System Function Organs/Parts Nervous System To bring in sensory data To send out motor commands Processing information Brain Spinal Cord Nerves }- Central nervous system Brain Spinal Cord Nerve Cell

3 All together now

4 Nerve Cells (not notes) Nerve cells (also known as neurons ) are very unusually shaped: rather than being rounded they are long and thin. Some can be over a meter long! They have a specialized input areas called dendrites and a long output tail called an axon.

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6 Neurons (not notes) Neurons send signals down their axons, which they touch other cell dendrites, creating a network. Neuron is the name of the individual cell Nerve is the name for a collection of neurons

7 Bringing Information In (notes) Information is brought in by sensory neurons All sensory organs (eyes, ears, etc.) have sensory neurons in them In order to sense anything, you have to have a sensory neuron for that type of information Nociception is the sensing of pain. This is separate from sensations of pressure, temperature, etc.

8 Bringing Information In (not notes) Some parts of the body do not have sensory receptors The central nervous system (brain and spinal cord) do not have any sensory receptors.

9 Sending out moving commands (notes) Motor neurons are neurons that go from your brain/spine to your muscles, telling them when to move. Like sensory neurons, you can t send signals to places you don t have nerves.

10 Spinal Cord (notes) The spinal cord is the superhighway for your nerves, where they all come together and go to the brain. Gray matter (cell bodies) Cross section of spinal cord White matter (axons) Input area

11 Reflexes (not notes) Some reactions are too important to wait for the signal to go all the way to the brain In this case, the sensory signal only has to reach the spinal cord and motor commands are immediately given

12 Spinal Cord Injury (not notes) If the spinal cord is injured, it results in loss of feeling and control below the point of injury Interestingly, this may or may not stop reflexes Doctors can often use this as an initial diagnosis of the extent of a spinal injury

13 The Brain (notes) The brain is made of many specialized regions that handle specific jobs for the nervous system

14 Phrenology (not notes) Phrenology is the disproven belief that it was possible to tell a person s qualities by feeling their skull It is the origin of the phrase, you should get your head checked

15 The Real Map (not notes)

16 How Do We Know This? (not notes) Wilder Penfield was a Canadian neurosurgeon who (with the patients permission) stimulated areas of their brain while they were having open-head surgery What Penfield found was that when he pressed on certain areas it would affect his patients ability to perform certain tasks

17 How the brain organizes the body by touch

18 Penfield homunculus or how much area the brain devotes to certain parts of the body

19 What About Personality? (not notes) Scientists are still studying the relationship between brain areas and how we behave However, there is one classic case that gives great insight into this search

20 Phineas Gage (not notes) Phineas Gage was a railroad foreman in the mid-1800s He was considered an extremely reliable, trustworthy man by his friends and family One day he was tamping gunpowder into a hole for charging and something went wrong

21 Phineas Gage (continued, not notes) The gunpowder went off, blowing the tamping iron upward through Phineas head Amazingly, he survived the injury but was changed Diagram of path of tamping rod

22 Phineas Gage (continued, not notes) Gage s social ability and self control was severely impaired. To quote one observer: He is fitful, irreverent, indulging at times in the grossest of profanity, manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires.devising many plans of future operations, which are no sooner arranged than they area abandoned in turn for others appearing more feasible.

23 The Brain (not notes) The human brain is the most complex thing we know of It has ~100,000,000,000 neurons connected together in a massive, complicated web There are more ways neurons can be connected in your brain than there are atoms in the visible universe