Nervous SystemNervous System

FunctionFunction

Allows your body to react to your Allows your body to react to your environment and stimuli.environment and stimuli.

OrgansOrgans

BrainBrain

Spinal cordSpinal cord

Nerve cells (neurons)Nerve cells (neurons)

BrainBrain

Coordinates all of your body’s activitiesCoordinates all of your body’s activities

3 parts: cerebrum, cerebellum, brain stem3 parts: cerebrum, cerebellum, brain stem

Cerebrum

Cerebellum

Brain Stem

https://www.youtube.com/watch?v=rSQNi5sAwuc

Spinal cordSpinal cord

43 cm long and the diameter of your thumb43 cm long and the diameter of your thumb

Made of bundles of neurons to carry signals Made of bundles of neurons to carry signals to and from the brain from the rest of the to and from the brain from the rest of the body.body.

NeuronsNeuronsParts: Parts: – Cell body Cell body – Dendrites (receive input)Dendrites (receive input)– Axons (deliver message)Axons (deliver message)

Direction of message

How it worksHow it works

Nerve Nerve MessagesMessages

Messages sent through a Messages sent through a synapsesynapse (gap) (gap)

https://www.youtube.com/watch?v=p5zFgT4aofA

https://www.youtube.com/watch?v=WhowH0kb7n0

Messages move along neurons like batons Messages move along neurons like batons in a relay race to spine, brain, and backin a relay race to spine, brain, and back

120 meters/second120 meters/second

These signals can continue to These signals can continue to work even if the brain is not work even if the brain is not

sending the signalsending the signalhttps://www.youtube.com/watch?https://www.youtube.com/watch?v=2YZJt_Bw3eo (twitching frog legs)v=2YZJt_Bw3eo (twitching frog legs)

https://www.youtube.com/watch?https://www.youtube.com/watch?v=rSQNi5sAwuc (TED talk- control v=rSQNi5sAwuc (TED talk- control someone else’s arm with your brain)someone else’s arm with your brain)

ReflexReflex

Involuntary, automatic response to a Involuntary, automatic response to a stimulus (hot, cold, sharp)stimulus (hot, cold, sharp)

They can’t be controlled because they They can’t be controlled because they occur before you know what happened.occur before you know what happened.

Reflex responses are controlled by spinal Reflex responses are controlled by spinal cord, not brain = faster responsecord, not brain = faster response

Examples of reflexesExamples of reflexes

Blinking, sneezing, knee tap, flinching, etc.Blinking, sneezing, knee tap, flinching, etc.

diving, grasping, and moro (in babies)diving, grasping, and moro (in babies)

Diving

Drug EffectsDrug EffectsDepressants (alcohol and Depressants (alcohol and marijuana) – slow your nervous marijuana) – slow your nervous system response timesystem response time

Stimulants (caffeine and Stimulants (caffeine and methamphetamines) – speed up methamphetamines) – speed up activityactivity

https://www.youtube.com/watch?v=4spIzhl2cGE

reviewreview

https://www.youtube.com/watch?https://www.youtube.com/watch?v=jJfESattZOYv=jJfESattZOY