Chapter 2

Question 1

_____. specialized cells that convery sensory info into brainl carry out operations involved in thought, feeling, and action, and transmit commands out into body to control muscles and organs

Answer 1

Neurons

Question 2

how many neurons in humans brain? what percentage of brain do they make up? what are the other cells?

Answer 2

86 billion

half your brain

the other half are glial cells

Question 3

the most prominent part of the neuron

Answer 3

the cell body/ soma

Question 4

the largest organelle In the cell body

Answer 4

the nucleus which contains cell chromosomes

Question 5

purpose of a motor neuron

Answer 5

carries commands to the muscles and organs

Question 6

parts of the neuron

Answer 6

dendrites: extensions that branch out from the cell body to receive info from other neurons
axon: extends like a tail from the cell body and carries info to other locations

myelin sheath: wraps around the axon

axon terminals: contain neurotransmitters wich the neuron releases to communicate with a muscles, an organ, or the next neron in the chain

Question 7

the cell body (largest part) of enuron in mammals is _______ big (mm)

Answer 7

0.0005 - 0.1 mm

Question 8

giant squid axons size

Answer 8

1mm in diameter

Question 9

typical axons in mammals size

Answer 9

0.002 to 002 mm in diameter

Question 10

axons can be as short as ___ or as long as ___ in the tallest giraffes

Answer 10

0.1mm or 5m

Question 11

____ neurons carry info from the body and from the outside world into the brain and spinal cord

Answer 11

sensory neurons

Question 12

what’s difference in configuration between sensory neurons and motor neurons

Answer 12

motor neurons axons and dendrites extend in several directions from the cell body (multipolar neuron)

a sensory neuron can be either unipolar or bipolar

unipolar is when a single short stalk from the cell body divides into two branches

bipolar is when you have an axon on one side and a dendritic process on the other

Question 13

____ neurons connect one neuron to another in the same part of the brain or spinal cord. Are multipolar

Answer 13

interneurons

Question 14

what are the most numerous type of neuron

Answer 14

interneurons

Question 15

What neurons are multipolar

Answer 15

interneurons and motor neurons

Question 16

what kind of neurons are sensory neurons? explain

Answer 16

unipolar and bipolar

unipolar means that there is a single short stalk that divides into two branches

bipolar: axon and dendrites process are on opposite sides of the cell body

Question 17

form and location of each type of neuron

Answer 17

motor neurons - multipolar, located throughout nervous system

sensory neurons. - unipolar ( outside brain) - bipolar (outside brain and spinal cord)

interneurons - multipolar; brain and spinal cord

Question 18

the most critical factor in the neurons ability to communicate

Answer 18

the membrane that encloses the cell

Question 19

describe the neuron cell membrane

Answer 19

8 micrometers thin

is made of lipid and protein

the lipid molecules have a head (water soluable, attract sealike fluid) and tail end (water insoluble (repelled by sea water fluid)

so heads orient towards the fluid and tails away. the moledules turn their tails toward each other and form a double layer membrane

Question 20

examples of molecules that can go through the cell membrane freely

Answer 20

water, oxygen, and carbon dioxide

Question 21

polarization

Answer 21

a difference in electrical charge between the inside and outside of the cell. also called a voltage

Question 22

resting potential

Answer 22

the difference in charge between the inside and outside of the membrane of a neuron at rest ~ -70 but can be anywhere from -40 to -80

Question 23

what is the resting potential from

Answer 23

the unequal distribution of electrical charges on the two sides of the mmebrane. Caused by atms that have gained or lost electons and thus given a charge (Na+, K+, Cl-, A-)

Question 24

what makes the resting potential negative

Answer 24

the fluid outside neron contains mostly Na+ and Cl- ions and inside the neuron is mostly K+ and A. The inside has more negative than positive and on outside has mostly positive

Question 25

force of diffusion

Answer 25

what makes the ions move through the membrane to the side where they are less concentrated

Question 26

electrostatic pressure

Answer 26

the pressure that results from the different diffusion charges , and leads to ions being repeeled from the side that is similarly chargfed and attracted to side that is oppositly charged

Question 27

the force of diffusion versus electrostatic pressure

Answer 27

the force of diffusion is the force of concentration whereas electrostatic pressure refers to electrostatic charge difference and what charge the ions are attracted to

Question 28

in its resting state, the sodium and potassium channels are ______

Answer 28

closed

Question 29

skipped age 61-62

Answer 29

as i need to draw it out

Question 30

An action potential

Answer 30

an abrupt depolarization of the membrane that allows neurons to communication over long distances

Question 31

when the voltage-gated sodium ion channels open who much faster do the nearby sodium ions rusion into the axon

Answer 31

500 times greater than normal