Chapter 2- Nerve Cells and Nerve Impulses

Question 1

What did Cajal discover?

Answer 1

the gap between the neurons, previously it was thought that they were all connected

Question 2

What is the Plasma Membrane?

Answer 2

surface of the cell

Question 3

What is the nucleus?

Answer 3

where the chromosomes are

Question 4

What are the Mitochondria?

Answer 4

structure that performs metabolic activities ( provides energy)

Question 5

What are Ribosomes?

Answer 5

Sites at which the cell synthesizes new protein molecules

Question 6

What is the Endoplasmic Reticulum?

Answer 6

Network of thin tubes that transports newly synthesized proteins

Question 7

What is a soma?

Answer 7

Cell body- contains the nucleus, ribosomes, and mitochondria

Question 8

What are Dendrites?

Answer 8

branching fibers of the neurons, greater the surface area of the dendrite, the more information it can receive “ dendritic spines”

Question 9

What is an axon?

Answer 9

Thin fiber, neurons information sender

Question 10

What is the Myelin Sheath?

Answer 10

insulating material coating the axon

Question 11

What are the Nodes of Ranvier?

Answer 11

interruptions in the myelin sheath

Question 12

What is the presynaptic terminal

Answer 12

where the axons releases chemicals that cross through the junctions between one neuron and the next

Question 13

What are motor neurons?

Answer 13

soma in the spinal cord sends and receives excitation through its dendrites and conducts impulses along its axon to a muscle

Question 14

What is a sensory neuron?

Answer 14

specialized at one end to be highly sensitive to a particular type of stimulation

Question 15

What is an afferent axon?

Answer 15

brings information into a structure

Question 16

What is an efferent axon?

Answer 16

carries information away from a structure

Question 17

What is an Interneuron/ Intrinsic neuron?

Answer 17

when a cell’s dendrites and axon are entirely contained within a single structure

Question 18

What are Glia?

Answer 18

The other major components of the nervous system

Question 19

What are Astrocytes?

Answer 19

( glia) star shaped cells that wrap around the presynaptic terminal of a group of functionally related axons. Helping synchronize the activity of the axons, enabling messages to be sent in waves

Question 20

What are Microglia?

Answer 20

very small cells that remove waste material

Question 21

What are Oligodendrocytes?

Answer 21

in the brain, specialized type of glia that build the myelin sheath with Schwann cells that are in the periphery of the body

Question 22

What are Radial Glia?

Answer 22

guide the migrations of neurons and their axons and dendrites during embryonic development

Question 23

What is Active-Transport?

Answer 23

Protein- mediated process that expends energy to pump chemicals from the blood into the brain

Question 24

To be able to use Glucose, what vitamin does the body need>

Answer 24

B1- thiamine

Question 25

What is Korsakoff’s Syndrome?

Answer 25

Caused by prolonged thiamine deficiency, marked by sever memory impairments

Question 26

What is an electrical gradient?

Answer 26

polarization- the difference in electrical charge between the inside and the outside of the cell. The inside is negatively charged

Question 27

What is the resting potential?

Answer 27

difference in voltage in a resting neuron

Question 28

What is the Sodium-Potassium Pump?

Answer 28

A protein complex that repeatedly transports three sodium ions out of the cells, while drawing two potassium ions in.

More sodium outside, more potassium inside

Both the electrical and concentrations gradients encourage sodium to move into the cells, but when the membrane is at rest, the sodium channels are closed

Question 29

What are actions potentials?

Answer 29

Messages sent by axons, when an axon is at rest… there is a negative potential inside the axon

Question 30

What is Hyperpolarization?

Answer 30

makes it more negative and less likely to produce an action potential

Question 31

What is Depolarization?

Answer 31

makes it more likely to produce an action potential ( reduces charge closer to zero)

Question 32

What is the Threshold of Excitation?

Answer 32

beyond it produces a massive depolarization of the membrane, causes the sodium channels to open and allows sodium ions to flow into the cell

Question 33

What are voltage-gated channels?

Answer 33

Regulate sodium and potassium - permeability depends on the voltage difference across the membrane

Question 34

What is the resting potential?

Answer 34

sodium channels are closed and potassium channels are almost closed

Question 35

What do local anesthetic drugs do?

Answer 35

Novacain and Xylocaine. Attach to the sodium channels of the membrane, preventing sodium ions from entering, which stops actions potentials. The axons can’t transmit the message of “ pain” to your brain

Question 36

What is the all or none law?

Answer 36

amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiates it, provided the stimulus reaches the threshold

Question 37

What is the absolute refractory period?

Answer 37

Membrane cannot produce an action potential, regardless of stimulation

Question 38

What is the relative refractory period?

Answer 38

a stronger than usual stimulus is needed to initiate an action potential

has two mechanisms Sodium channels are closed and potassium is flowing out of the cell at a faster than usual rate

Question 39

In a motor neuron, where foes an action potential begin?

Answer 39

The axon hillock, a swelling where the axon exits the soma

Question 40

What is propagation of the action potential?

Answer 40

transmission of an action potential down an axon, just as strong at the end as it was at the beginning

Question 41

Because the areas that the message “ just passed” are still in their refractory period…

Answer 41

an action potential cannot reinvade the area it just passed

Question 42

What is Saltatory Conduction?

Answer 42

flow of action potential from one node of Ranvier to another

Question 43

What is Multiple Sclerosis?

Answer 43

immune system attacks myelin sheaths. If an axon loses its myelin, it still lacks sodium channels in the areas previously covered with myelin. Most Action potentials die out between one node and the next

Question 44

What are local neurons?

Answer 44

neurons without an axon, do not follow the all or none law, the signal decreases as it travels because it is not being “ reborn” so it gradually decays

Question 45

What are graded potentials?

Answer 45

membrane potentials that vary in magnitude without following the all or none law

when local neurons are stimulated, it depolarizes or hyperpolarizes in proportion to intensity of stimulus