Task 2- cells, action potential

Question 1

Sensory neurons

Answer 1

detects changes in external or internal environment and sends info about it to CNS

Question 2

Motor neurons

Answer 2

to muscles, organs and glands

Question 3

interneurons

Answer 3

neuron with short axon or no axon at all in CNS

-receives input from and sends output to other neuron

Question 4

Dendrites

Answer 4

• input zone; receives electrical/chemical messages
• messages are ➮ inhibitory or ➮ excitatory messages
• if impulses transmitted are large enough = action potential

Question 5

inhibitory messages

Answer 5

cell body will NOT transmit message to axon

Question 6

excitatory message

Answer 6

cell body will send the message down to axon and pass to other neurons

Question 7

Cell body (soma)

Answer 7

• Integration zone; combines the info of neuron and determines whether to send signal of its own
• semipermeable membrane

Question 8

support structure of cell are

Answer 8

endoplasmic reticulum, golgi ap. and mitochondria

Question 9

nerve cells = neurons

Answer 9

basic unit of nervous system, composed of dendrites, soma and axon
o Each neuron receives inputs (dendrites)
o Integrates those inputs (soma)
o Distributes processed information (axon)

Question 10

Organelles inside Neuron:

Mitochondria

Answer 10

energy production

Question 11

Organelles inside Neuron:

Cell nucleus

Answer 11

contains genetic instructions

Question 12

Organell inside Neuron:

Ribosomes

Answer 12

translate genetic instructions into proteins

Question 13

Soma

Answer 13

receive additional synaptic contacts; inputs are combined and transformed in the cell body
->integration zone

Question 14

Axon

Answer 14

leads away from cell body, transmits cell’s output information in the form of electrical impulses
->conduction zone

Question 15

Axon terminals

Answer 15

Synaptic buttons; transmit neuron activity to other cell at synapses
-> output zone

Question 16

Multipolar Neurons

Answer 16

many dendrites, single axon

• > most common
• found in CNS -> Motorfunction

Question 17

Bipolar Neurons

Answer 17

single dendrite, single axon
-> common in sensory system
visual, hearing

Question 18

Unipolar neurons

Answer 18

• single extension, axon that branches in two directions; one end is input zone (like dendrites), the other is the output zone
• > transmit information from body into the spinal cord
• ONE process

Question 19

leak channels

Answer 19

– channels that are open all the time in order to let Na+ and K+ get through them

Question 20

Voltage gated sodium channels

Answer 20

open when the membrane potential crosses a threshold value, Na+ gets through them inside the neuron

Question 21

Voltage gated potassium channels

Answer 21

opens at +50mV (Depolarization peak); K+ get through them outside the neuron, are a little slower to close again
->Hyperpolarization

Question 22

Excitatory postsynaptic potentials (EPSPs)

Answer 22

increase likelihood of neuron to fire
-Brings a positive charge-> Causes partial
depolarization.

Question 23

Inhibitory postsynaptic potentials (IPSPs)

Answer 23

decrease likelihood of neuron to fire

-Brings a negative charge-> Causes partial hyperpolarization.

Question 24

Ions that contribute to membrane potential

4

Answer 24

o Sodium ions (Na+)
o Potassium ions (K+)
o Chloride ions (Cl-)
o Negatively charged protein ions (A-)

Question 25

All-or-none law

Answer 25

An action potential either occurs or does not occur
->once triggered, it is transmitted down the axon to
its end and always remain the same size.

Question 26

rate law

Answer 26

A single action potential is not the basic element of information!!
Variable information is represented by an
axon’s RATE OF FIRING

Question 27

Temporal summation

Answer 27

Occurs when one presynaptic neuron releases neurotransmitters many times over a period of time.

Question 28

Spatial Summation

Answer 28

Occurs when multiple presynaptic neurons together release enough neurotransmitters to exceed the threshold of the postsynaptic neuron.

Question 29

Saltatory conduction

Answer 29

Action potentials only occur in nodes of Ranvier and they appear to jump from one node to another along the axon. The current spreads electrically through internodes.

Question 30

Axon polarization

Answer 30

the overall balance between the positive and negative charges is such that the inside of the axon is electrically negative with respect to the outside
->Axon is polarized in its resting state – RESTING POTENTIAL

Question 31

Myelin sheath

Answer 31

Acts as an insulator. It surrounds the neurons, protects the axon and aids in the speed of transmission.

Question 32

Synapse

Answer 32

Communication sites where neurons pass nerve

impulses among themselves.

Question 33

Nucleus

Answer 33

Contains the chromatin and the genetic make- up of the organism.

Question 34

Channel proteins

Answer 34

allow certain molecules to pass through

Question 35

Signal proteins

Answer 35

Transfer signal to inside of neuron when molecules bent to them on outside of membrane

Question 36

Diffusion

Answer 36

tndency of molecules to move from a higher concentration area to a lower one until equilibrium is reached.

Question 37

Osmosis

Answer 37

Passive movement of water molecules from one place to another until a uniform concentration is achieved.

Question 38

Active transport

Answer 38

transport of substance from lower to higher concentration of substance
-> using energy from cell

Question 39

Selective permeability

Answer 39

Membrane has some control over what can cross
->only certain molecules either enter or
leave the cell.
-Each ion channel works for one type of ion.

Question 40

Intracellular fluid

Answer 40

fluid contained within the cell

->A- (organic anions), K+ (high concentration), Cl- and Na+ (low c.)

Question 41

Extracellular fluid

Answer 41

Located outside the cell

->Cl- and Na+ (high concentration), K+ (low concentration).

Question 42

Resting membrane potential

Answer 42

is about -70 mV – Inside of the neuron is 70 mV less than the outside.

Question 43

Cations

Answer 43

more positive outside

Question 44

Anions

Answer 44

more negative inside

Question 45

Concentration gradient

Answer 45

Concentration inside versus the concentration outside.
- It causes DIFFUSION because if there is a lot in one side and little in the other side, the brain wants to establish equilibrium.

Question 46

Electrical gradient

Answer 46

If there is a lot of positive inside and less outside, it will move.

Question 47

Sodium-potassium pump

Answer 47

Actively pumps Na+ out of the cell and pumps K+ into it.

Question 48

Depolarisation

Answer 48

-if signal strong enough and voltage reaches threshold it triggers action potential
-More gated channels open and more Na+ enter the cell -> Cell depolarizes in order to reverse charges across
membrane = Inside of the cell becomes positively charged and outside negatively charged.

Question 49

Spike potential

Answer 49

Peak of the action potential CAUSES the gated sodium channels to close and potassium channels to
open.

Question 50

Repolarization

Answer 50

• Potassium ions =outside the membrane

- sodium ions stay inside – Repolarizing the cell = polarization opposite of the initial polarization

Question 51

Hyperpolarization

Answer 51

neuron = hyperpolarized
-> more potassium ions are on the outside than sodium ions
are on the inside
– When K+ gates close, neuron has more K+ ions outside than Na+ inside
->Cell’s potential drops lower than resting potential.

Question 52

Refractory period

Answer 52

-returns potassium= inside
-sodium=outside
– Sodium-potassium pump works again
moves Na+ ions->outside and K+ ->inside
=>Neuron returns to normal polarized state.