Chapter 4—The Brain information
The Nervous System
Connects the rest Receives information from
of the body to the the outside world and sends
central nervous it to muscles, organs, etc.…
system via bundles
of axons (nerves).
NeNervous SySystem (CNS)
SySystem (PNS) muscles, skin, glands, etc.…
Deals mostly with voluntary movement.es above
- Sensory nerves.gthe neck.
AAutonomi o Responsible for intake oft rate,
SSomatic c sensations and sendingood flow,
Nervous c them to CNS.ilation of pupils.
Nervous NeNervous - Motor nerves.
SSystem SSystem o “Motor” = moving.
o Send information FROM
CNS to the muscles.
o Tell the body what to do.
Slows down the body afterwards.
Increased appetite because cortisol makes BBrain
you crave carbs to gain energy for the next
fight or flight moment.
Structure of Neurons
1 Communication between Neurons
Neurons= building blocks on nerves.
1. Incoming message (neurotransmitters) is received by DENDRITE.
2. Goes from the DENTRITE to the CELL BODY.
3. It then goes from the CELL BODY to the AXON (long, thin fiber covered by MYELIN SHEATH)
a. Myelin Sheath is constructed of GLIA CELLS.
i. Glia Cells provide nourishment and remove toxins/waste from the myelin sheath.
ii. Node – message jumps from node to node.
FUNCTION OF MYELIN SHEATH is 2-fold:
- Protection from adjacent signals.
4. To the AXON TERMINAL—deposits the information on receiving neuron.
The more axons and dendrites you have, the more complex learning connections have occurred.
4. CONT’D: the axon doesn’t touch the receiving neuron. Instead, there is a SYNAPSE.
- Synaptic bulb.
- Synaptic vesicles, house neurotransmitters.
- They open and close
- Synaptic cleft (the space between the bulb and the receiving neuron.)
6. How do they open and close?
- Electrical impulse that occurs that is created by a change in voltage that allow
synaptic vesicle to open.
7. Messages accepted if neurotransmitter fits receptor site.
The communication between neurons is all or none = neurons fire or they don’t (on or off).
Excitatory message = on switch.
Inhibitory message = off switch.
3 Chemical Messages in the Nervous System
Travels through blood.
Too little leads to
Seratoninleep ImpMMelatonin sleep
Too little: Parkinson’s
Also responsible for pleasure.
DDopamin “Love hormone.”
Muscles and memory. ee Released when a
Too little: Alzheimer’s. mother is breast-
Highest peak: orgasm
4 Acetylcholin OdSeSexacil
Endeneneins EEstrogen Also leads to depression.
Active during emergency Released during an
response. emergency response
the same a