Neurons : a nerve cell and the basic building block of the nervous system

• a nerve = is a bundle of axons and link the central nervous system with the bodys receptors, muscles and glands.

3 types of neurons

• sensory : recieve information from outside world and send to brain via the spinal cord (afferent neuron) (affecting you = afferent)

• Motor: carry signal from the spinal cord to the muscles and glads to produce movement (efferent neuron) (moving = effort)

• Interneurons: connect sensory and motos neurons togheter, found in brain and spinal cord

Togheter → the make up the reflex arc ( how the peripheral and central NS communicate)

Glial cells

• Type of cell in the nervous system that provides structure, insulation, communication and waste transport.

• Outnumber neurons 50:1

• Help neurons wire togheter in the developing brain, nurture them in the adult brain, insulate axons and myelin, mop up dead cels, recycle used NTs, and protect the brain from infection

Neuron parts

• Dentrite - recieved messages from neuboring cells

• cell body/soma - neurons life support center, indicates wheter to continue message or not

• axon - passes messages away from cell body to neigboring neurons, muscles, glands

• Myelin sheath - covers some axons to protect and speed up neural signal; when deteriorates, can lead to problems, such as multiple scleroris

Neuron parts = Axon Terminal- end of axon that lead to neighboring cells to send message

Terminal Buttons - end of axon terminal, where neurotransmitters are stored and released to send message

Synapse - junction between sending and receiving neurons; synaptic gap where NTs are released

Receptor - cell on end of dendrites that NTs connect to in order to send message to next neuron and start process over

Sending the message
- action potential is triggered by an electric shock that is above the threshold

• all or nothing (no varying levels of action potential)

• refractory period: time it takes to recover from one action potential and move on to anothers

Steps of Action Potential

1: Resting potential

2: Threshold passed

3: Voltage rises - Depolarization

4: Voltage falls - Repolarization

5: Refractory period

All-or-nothing principle – the toilet either flushes completely or not at all; it doesn’t flush a little or a lot

Direction of impulse – the toilet only flushes one way, the impulse can’t come the other direction (you hope!)

Refractory period – after you flush the toilet, it won’t flush again for a certain period of time, even if you push the handle repeatedly

Threshold – you can push the handle a little bit, but it won’t flush until you push the handle past a certain point

Resting potential –the toilet is waiting to fire, and the water in the tank represents the overall negative charge inside the neuron waiting for depolarization

Action potential – opening the flap in the tank and the water rushing through the pipes

Depolarization – represented by the toilet flushing