chapter 1

Question 1

Dendritic spines

Answer 1

short outgrowths that increase the surface area available for synapses

Question 2

myelin sheath

Answer 2

insulating material that covers vertebrate axons

Question 3

Nodes of Ranvier

Answer 3

interruptions in the myelin sheath of vertebrate axons

Question 4

presynaptic terminals

Answer 4

end points of an axon or the end bulb where the axon releases chemicals that cross to another cell

Question 5

afferent axon

Answer 5

axons that bring information into a structure

Question 6

efferent axon

Answer 6

carries information away from structure

Question 7

blood brain barrier

Answer 7

mechanism that excludes most chemicals from the vertebrate brain

Question 8

active transport

Answer 8

a protein-mediated process that expends energy to enable a molecule to cross a membrane

Question 9

electrical gradient (polarization)

Answer 9

a difference in electrical charge inside and outside of the cell

Question 10

selectively permeable

Answer 10

providing a barrier that permits some chemicals to pass more readily than others

Question 11

sodium-potassium pump

Answer 11

protein complex that repeatedly transports 3 sodium ions out of the cell while drawing in 2 potassium ions

Question 12

concentration gradient

Answer 12

the difference in distribution of ions across the membrane

Question 13

action potential

Answer 13

all or none message sent by an axon

Question 14

depolarization

Answer 14

to reduce polarization toward zero across a membrane (more positive charge)

Question 15

hyperpolarization

Answer 15

increased polarization (increase the negative charge)

Question 16

voltage- gated channels

Answer 16

membrane channel whose permeability to sodium (or some other ion) depends on voltage difference across membrane

Question 17

Santiago Ramon y Cajal was the first to demonstrate what?

Answer 17

that individual cells compromising the nervous system remained separate

Question 18

structures of an animal cell

Answer 18

membrane, nucleus, mitochondria, ribosomes, and endoplasmic reticulum

Question 19

Membrane (plasma membrane)

Answer 19

structure that separates the inside of cell from outside environment

Question 20

Nucleus

Answer 20

contains the chromosomes

Question 21

mitochondria

Answer 21

structures that perform metabolic activities and provides energy that cells require

Question 22

ribosomes

Answer 22

sites at which the cell synthesizes new protein molecules

Question 23

endoplasmic reticulum

Answer 23

networks of thin tubes that transports newly synthesized proteins to their location

Question 24

general parts of a neuron are?

Answer 24

dendrites, cell body, axon, and presynaptic terminals

Question 25

dendrites

Answer 25

branching fibers from a neuron that receive info from other neurons

Question 26

soma/cell body

Answer 26

contains the nucleus, mitochondria, and ribosomes

Question 27

axon

Answer 27

thin fiber of constant diameter and responsible for transmitting nerve impulses toward other neurons, organs, or muscles

Question 28

types of glia

Answer 28

astrocytes, microglia, oligodendrocytes and Schwann cells, and radial glia

Question 29

Astrocytes

Answer 29

star shaped glia that help synchronize the activity of the axon and wrap around the dendrites connecting to functionally related axons

Question 30

microglia

Answer 30

act as part of immune system; remove waste material, viruses, fungi from brain, and remove dead or damaged neurons

Question 31

Oligodendrocytes and Schwann cells

Answer 31

build the myelin sheath that surrounds and insulates certain vertebrate axons, and supply an axon with necessary nutrients for proper functioning

Question 32

radial glia

Answer 32

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

Question 33

what is the nerve impulse?

Answer 33

electrical message that is transmitted down the axon of a neuron

Question 34

what is the range for the speed of nerve impulses?

Answer 34

it ranges from less than 1 meter/second to 100 meters/second

Question 35

what is the membrane of a neuron (thickness, layers, and what it's made of)?

Answer 35

8 nm (nanometers) thick, composed of 2 layers, and made of phospholipid molecules

Question 36

what is the resting potential of a neuron and its millivolts?

Answer 36

condition of a neuron's membrane when it has not been stimulated or inhibited; approx. -70 mv

Question 37

what is threshold and its specific charge?

Answer 37

min. amount of membrane depolarization necessary to trigger an action potential; around -55 to -65 mv

Question 38

all- or- none law

Answer 38

the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it

Question 39

what happens during an action potential with sodium, potassium, and charge inside of membrane?

Answer 39

- at the start, sodium ions are mostly outside the neuron and potassium ions are inside - when membrane is depolarized, sodium and potassium channels open - at the peak of action potential, the sodium channels close (inside of cell is now positively charged)

Question 40

refractory period

Answer 40

period during which time the neuron resists the production of another action potential

Question 41

absolute refractory period

Answer 41

the first part of the period in which the membrane cannot produce an action potential

Question 42

relative refractory period

Answer 42

the second part, in which it takes a stronger than usual stimulus to trigger an action potential

Question 43

the refractory period depends on 2 facts:

Answer 43

- sodium channels are closed - potassium is flowing out of cell at faster than usual rate

Question 44

propagation of the action potential and how it works

Answer 44

the transmission of the action potential down the axon; depolarization triggers opening of voltage gated sodium channels

Question 45

what is saltatory conduction and how does it work

Answer 45

the jumping of action potentials from node to node

Question 46

where does our knowledge about local neurons come from and what misconceptions have resulted

Answer 46

- knowledge has come from the study of large neurons - led to misconception that small neurons were immature