Neurons

SRJC, BIO 2.2, Swinstrom

Explain the parts of a neuron

Sensory input

Transmits information about external stimuli and internal conditions

Interneurons

integrate sensory input they form the local circuits that connect neurons in the brain or ganglia

Motor neurons

transmit signal to muscle cells causing them to contract

How is resting potential maintained?

by having a polarized cell. the Cell body is negatively charged and the outside is positively charged. the sodiumpotasium pump removes 3 Na and brings in 3 K maintain the insdie negative. Potassium is the main source of resting potential since ther is a constant outflow of it

What are the five stages of action potential

1. resting

2. Reaching thershold

3. rising phase of action potential

4. fall phase of action potential

5. undershoot

Resting

sodium and potassium gated ion channels are close

Reaching Thershold

depolirizing membrane sodium ion gated channel opens up potassium channels stay closed. Sodium rushes in once enough rushes in thershold is reached and triggers an action potential.

Rising Phase of Action Potential

more sodium gated ion channels open causing more sodium to rush in causing the cell body to become positive

Falling Phase of Action Potential

sodium gated ion channels inactivated, preventing sodium from flowing through. Most potassium channels open letting potassion outflow making the inside of the cell negative again

Undershoot

Sodium channels close, potassium channels are still opening. As potassium channels close sodium channels unblock. sodium potassium pump returns neuron to resting potential

How does action potential rush down the axon?

It creates a wave of depolarization don the axon with Na rushing in and potassium rushing out.

What speeds up action potential?

Larger diameter allows the signal to move faster. There is a myeline sheath that increases its diameter which causes the signal to jump between nodes.

How do neurons communicated with each other?

The action potential at the end of the synaptic terminal causes chemical changes. These changes open up calcium-gated ion channels that secrete calcium into the synapse. The calcium goes into the axon, causing the vesicle to fuse with the membrane and diffuse neurotransmitters across the synapse and attach to a receptor on the other side (another cell body). This may induce an action potential in the receiving cell