1. Communication in the Human Body

2. Two Systems Nervous Endocrine Fast and short term communication
Electrical (neurons)
Chemical (neurotransmitters)
Endocrine
Slow and long term communication
Chemical (hormones)

3. Your Senses Location Distance (mm) Observations Arm Finger Tip
Back of Neck

4. What’s Happening Neuron’s (Cells that make up nerves) 3 parts:
Dendrite (where input happens (receptors))
Cell Body (where organelles are located)
Axon – message is sent down (axon terminal – output)
Neurons are bundled together to make a nerve!

5. Types of Neurons
Sensory Neuron – organ to central nervous system (CNS)
Interneuron – make up CNS
Motor Neuron – from CNS to organ

6. Neurons are Specific
Individual Neurons respond to only 1 type of stimulus.
Example Touch (3 types of neurons)
Pressure
Pain
Temperature

7. How Neurons Work
Neurons are polarized (negative inside and positive outside)
When “fire” they temporarily depolarize
This is propagated down the axon to the axon terminal
All or none (action potential)– either enough stimulus (threshold) for nerve to completely “fire” or does not “fire” at all

8. Neurotransmitters Communication between neurons at the synapse
Small space between axon terminal of one neuron and the dendrites of another.
Are specific – needs to be receptor for neurotransmitter on receiving dendrite
Released triggered by electrical signal.
Re-uptake: Neurotransmitters are reabsorbed and reused

9. 2 categories of neurotransmitters
Excite or cause action potential
Inhibit or prevent action potential
Many drugs mimic or act like neurotransmitters

10. Endocrine System Chemical messengers
Specific – has to be a receptor for the hormone in order for the cell to respond to it.
Control – normally a negative feedback loop
Some drugs can also mimic hormones