Neurons

Question 1

Signaling

Answer 1

Coordinates body functions

Question 2

Difference between endocrine system and nervous system?

Answer 2

Endocrine system: has hormones as signalers, is slow-acting, prolonged effects

Nervous system: neurotransmitters as signalers, fast-acting, ephemeral effects (stimulus -> action -> over)

Question 3

Neurons

Answer 3

Highly specialized for information processing; has dendrites, cell body w/nucleus, axon hillock, axons covered w/ myelin sheath, nodes of Ranvier, axon terminals, and synapses

Question 4

Dendrites

Answer 4

Top of the neuron that receives signals

Question 5

Cell body

Answer 5

Also called soma contains nucleus

Question 6

Axon hillock

Answer 6

Determines whether or not to fire the signal through the neuron

Question 7

Axon

Answer 7

Includes myelin sheath and nodes of Ranvier where the signal travels through

Question 8

Myelin sheath

Answer 8

Covers the axon and acts as a fatty insulator; makes the signal travel faster)

Question 9

Nodes of Ranvier

Answer 9

Gaps between myelin sheath that the signal lands on after jumping over myelin sheath

Question 10

Axon terminals

Answer 10

End of an axon and has synapses

Question 11

Synapses

Answer 11

Connect w/ another neuron and transfers signal

Question 12

How many neurons typically make up a circuit?

Answer 12

2-3

Question 13

How many sodium ions are pumped for how many potassium ions?

Answer 13

3 sodiums for 2 potassiums

Question 14

What does it mean when there is more Na+ ions outside and K+ ions inside?

Answer 14

More positive outside and more negative inside

Question 15

Hyperpolarization

Answer 15

Removing positive charges and resting potential becomes more negative; cell does not fire

Question 16

Depolarization

Answer 16

Resting potential becomes more positive due to more positive ions being entering the cell; cell does not fire

Question 17

Graded potentials

Answer 17

Stimulated neuron but not enough to fire; “false alarm”

Question 18

Action potential

Answer 18

Massive energy change when tons of ions flood in and out of cell; enough energy to pass the threshold allowing for neuron to fire; a lot of positive energy

Question 19

List the steps of an action potential.

Answer 19

1. Resting state-all voltage gated channels are closed
2. Depolarization-stimulus opens some Na channels causing the resting potential to become less negative (Na ions are outside)
3. Rising phase-membrane voltage exceeds threshold, causes all voltage gated ion Na channels to open
4. Falling phase-K channels open, Na channels close; becomes more negative as Na+ goes in
5. Hyperpolarization-K channels remain open longer than Na channels causing potential to return to resting potential (-70 V)

Question 20

All or nothing

Answer 20

Either a neuron fires or it does not

Question 21

Unidirectional

Answer 21

A signal moves through the neuron unidirectionally (in one direction cannot go back); signal jumps over myelin sheath and lands on Nodes of Ranvier

Question 22

Difference between neuron w/ myelin sheath and w/o.

Answer 22

W/ myelin sheath: fast

W/o myelin sheath: slow, increases radius of neuron to offset speed deficiency, in squids and other molluscs

Question 23

Saltatory conduction

Answer 23

Speeds up signal propogation

Question 24

What happens once neurotransmitters reach the synapse?

Answer 24

1. Action potential triggers release of synaptic vesicles
2. Neurotransmitters cross the synaptic cleft and bind to ligand gated channels
3. Ion channels open and changing of membrane potential occurs on the other neuron

Question 25

What would happen if the membranes directly touched?

Answer 25

The action potential will continue to trigger leading to a continuous signal. It will function as one cell. No touching would’ve allowed the signal to stop.

Question 26

Summation

Answer 26

Inputs are integrated in the axon hillock

Question 27

Excitatory potential (EPSP)

Answer 27

More likely to fire

Question 28

Inhibitory potential (IPSP)

Answer 28

Less likely to fire

Question 29

Sub threshold, no summation

Answer 29

Not enough to fire; involves excitatory potentials

Question 30

Temporal summation

Answer 30

Excite close in time=fire; involves excitatory potentials

Question 31

Spatial summation

Answer 31

Signals firing at the same time at diff. Parts of the target cell leads to firing; involves two different excitatory potentials

Question 32

Spatial summation of EPSP and IPSP

Answer 32

a lot of neuron signals but no firing; involves excitatory and inhibitory signals

Question 33

How are neurontransmitters returned?

Answer 33

Neurotransmitters are cleared from the synaptic cleft to reset the process. This is done by enzymes breaking down inactivated neurotransmitters in the synaptic cleft and the reuptake of neurotransmitters by the presynaptic neuron.

Question 34

Some medications block the reuptake of neurotransmitters by the presynaptic neuron in the synaptic cleft. What happens to the postsynaptic neuron as a result? Neurotransmitters remain bound to ligand gated ion channels longer, triggering more graded potentials (don’t fire) The neuron becomes hyper stimulated, increasing the magnitude of action potentials Neurotransmitters remain bound to voltage gated ions channels longer, triggering more action potentials The response rate of the postsynaptic neuron stays the same because it does not respond to neurotransmitters

Answer 34

Neurotransmitters remain bound to ligand gated ion channels longer, triggering more graded potentials

Question 35

Greater magnitude leads to taller action potentials. T or F?

Answer 35

False, greater magnitude means more action potentials