Biology Nervous System

Question 1

The nervous system is composed of both ___ (specialized nervous tissue) and neuroglia (cells that support and protect the neurons)

Answer 1

neurons

Question 2

___ are the functional units of the nervous system

Answer 2

neurons

Question 3

Neurons primary function is to convert stimuli into electrochemical signals and conduct these ___ throughout the body

Answer 3

signals

Question 4

Each neuron is generally an elongated cell consisting of ___, a cell body and an axon

Answer 4

dendrites

Question 5

___ are cytoplasmic extensions that receive information and transmit it toward the cell body

Answer 5

dendrites

Question 6

The cell body (soma) contains the nucleus and controls the ___ activity of the neuron

Answer 6

metabolic

Question 7

The axon is a long cellular process that transmits ___, also known as action potentials, away from the cell body

Answer 7

impulses

Question 8

The axon is a long cellular process that ___ impulses, also known as action potentials, away from the cell body

Answer 8

transmits

Question 9

Between the cell body and axon is the ___ hillock, where the incoming signals (from the dendrites) are summed and, if great enough, trigger an action potential down the axon.

Answer 9

axon

Question 10

The axons terminate in swellings known as ___ terminals (also called boutons or knobs)

Answer 10

synaptic

Question 11

When an action potential arrives at the synaptic terminal, ___ are released from these terminals into the synapse (or synaptic cleft), which is the gap between the axon terminals of one cell and the dendrites of the next cell

Answer 11

neurotransmitters

Question 12

Most mammalian axons area sheathed by an insulating substance known as ___, which prevents leakage of signal from the axons and allows for faster conduction of impulses

Answer 12

myelin

Question 13

The gaps between segments of myelin, the ___ of Ranvier, are where the action potential actually propagates

Answer 13

nodes

Question 14

Action potential propagation via the nodes of Ranvier occurs through a process known as ___ (“hopping”) conduction

Answer 14

saltatory

Question 15

___ is produced by glial cells known as oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system

Answer 15

myelin

Question 16

Neurons receive information at the dendrites, process information at the ___ hillock, and transmit information through the axon

Answer 16

axon

Question 17

The processing of the information is relatively straightforward: if sufficient ___ occurs at the axon hillock, then an action potential is triggered down the axon

Answer 17

depolarization

Question 18

There are no partial ___ potentials and therefore no variation in the strength of an action potential

Answer 18

action

Question 19

The potential difference at rest between the extracellular space and the intracellular space is called the resting ___

Answer 19

potential

Question 20

A typical resting membrane potential is -70 millivolts (mV), which means the inside of the ___ is more negative than the outside

Answer 20

neuron

Question 21

The uneven ion exchange of the sodium potassium pump (3 NA out 2 K in) results in one more positive charge leaving the ___ than entering it, creating a negative internal environment

Answer 21

cell

Question 22

Cell membrane is more permeable to K than Na allowing some of the K that was pumped into the cell to move back out through ___ diffusion, making the internal environment even more negative

Answer 22

facilitated

Question 23

If the membrane potential reaches the ___ potential of -55 mV, then voltage-gated Na channels open triggering the action potential

Answer 23

threshold

Question 24

In actuality, the membrane potential after ___ is 35 mV

Answer 24

depolarization

Question 25

During ___ the membrane potential can range between -70 and -75 mV

Answer 25

hyperpolarization

Question 26

Depolarization occurs when a cell reaches threshold ___ and voltage-gated Na channels open allowing the influx of Na into the neuron

Answer 26

potential

Question 27

The result of this influx is that the cell membrane potential reaches 35 mV and the cell is said to be ___

Answer 27

depolarized

Question 28

During ___, at the peak potential of 35 mV, voltage gated K channels open

Answer 28

depolarization

Question 29

During depolarization, since there is a high intracellular concentration K, the opening of K channels allows for the efflux (leaving) of K down its ___ gradient

Answer 29

concentration

Question 30

During depolarization, the efflux of positive charges is termed ___ and results in the membrane potential decreasing to a negative value thus repolarizing the membrane

Answer 30

repolarization

Question 31

When the cell membrane decreases to below resting potential this is known as the ___ period

Answer 31

refractory

Question 32

The refractory period: a period of time after the action potential in which new action potentials are very ___ to initiate

Answer 32

difficult

Question 33

___operate only in one direction and because refractory periods make the backward travel of action potentials

Answer 33

synapses

Question 34

The greater the diameter of the axon and the greater its ___, the faster the impulses travel

Answer 34

myelination

Question 35

Myelin increases the conduction velocity by insulating segments of the axon such that the membrane is permeable to ions only in the ___ of Ranvier

Answer 35

nodes

Question 36

The synapse is the gap between the axon terminal of one neuron (the ___ neuron) and the dendrites of the next neuron (the postsynaptic neuron)

Answer 36

presynaptic

Question 37

Neurons may also communicate with postsynaptic cells other than neurons, such as cells in muscles or glands, these are called ___ cells

Answer 37

effector

Question 38

The axon terminal contains thousands of membrane-bound vesicles full of chemical messengers known as ___

Answer 38

neurotransmitters

Question 39

When the action potential arrives at the axon terminal and depolarizes it, the synaptic vesicles fuse with the presynaptic membrane and release ___ into the synapse

Answer 39

neurotransmitter

Question 40

The released neurotransmitter will lead to depolarization of the postsynaptic cell and consequent firing of an ___ potential

Answer 40

action

Question 41

Neurotransmitter is removed from the synapse in a variety of ways: it may be taken back up into the nerve terminal (via a protein known as an uptake carrier) where it may be reused or degraded; it may be ___ by enzymes located in the synapse (e.g., acetylcholinesterase inactivates the neurotransmitter acetylcholine); or it may simply diffuse out of the synapse

Answer 41

degraded

Question 42

Neurons that carry sensory information about the external or internal environment to the ___ or spinal cord are called afferent neurons

Answer 42

brain

Question 43

Neurons that carry motor commands from the ___ or spinal cord to various parts of the body (e.g., muscles or glands) are called efferent neurons

Answer 43

brain

Question 44

Some neurons (interneurons) participate only in local circuits, linking ___ and motor neurons in the brain and spinal cord; their cell bodies and their nerve terminals are in the same location

Answer 44

sensory

Question 45

Nerves are essentially ___ of axons covered with connective tissue

Answer 45

bundles

Question 46

A network of nerve fibers is called a ___

Answer 46

plexus

Question 47

Neuronal cell bodies often cluster together: such clusters are called ___ in the periphery; in the central nervous system, they are called nuclei

Answer 47

ganglia

Question 48

CNS Astrocytes: maintain the integrity of the blood-brain barrier, regulate nutrient and dissolved gas concentrations, an absorb and recycle neurotransmitters Oligodendrocytes: myelinate CNS axons as well as provide structural framework for the CNS Microglia: remove cellular debris and pathogens Ependymal cells: line the brain ventricles and aid in the production, circulation, and monitoring of cerebral spinal fluid PNS Satellite cells: surround the neuron cell bodies of the ganglia Schwann cells: enclose the axons in the PNS and aid in the ___ of some peripheral axons

Answer 48

myelination

Question 49

The forebrain consists of the telencephalon and the ___

Answer 49

diencephalon

Question 50

A major component of the telencephalon is the cerebral cortex, which is the highly convoluted gray matter that can be seen on the ___ of the brain

Answer 50

surface

Question 51

The cortex processes and integrates sensory input and motor ___ and is important for memory and creative thought

Answer 51

responses

Question 52

The telencephalon also includes the olfactory bulb, the center for reception and ___ of olfactory (smell-related input)

Answer 52

integration

Question 53

The diencephalon contains the ___ and hypothalamus

Answer 53

thalamus

Question 54

The thalamus is a relay and integration center for the spinal cord and cerebral ___

Answer 54

cortex

Question 55

The midbrain (mesencephalon) is a relay center for visual and ___ impulses

Answer 55

auditory

Question 56

The hindbrain is the posterior part of the brain and consists of the ___, the pons and the medulla

Answer 56

cerebellum

Question 57

One function of the ___ is to act as a relay center to allow the cortex to communicate with the cerebellum

Answer 57

pons

Question 58

Together, the midbrain, pons, and ___ constitute the brainstem

Answer 58

medulla

Question 59

Sensory information enters the spinal cord through the ___ horn

Answer 59

dorsal

Question 60

All motor information exits the spinal cord through the ___ horn

Answer 60

ventral

Question 61

The sensory nerves that enter the CNS and motor nerves that leave the CNS are ___ of the peripheral nervous system

Answer 61

part

Question 62

Peripheral nervous system has the ___ and the autonomic

Answer 62

somatic

Question 63

The somatic nervous system (SNS) innervates skeletal muscles and is responsible for voluntary movement as well as reflex arcs(pathways that control ___ reflexes)

Answer 63

motor

Question 64

The autonomic nervous system (ANS) is sometimes also called the involuntary nervous system because it regulates the body's internal environment without the aid of ___ control

Answer 64

conscious

Question 65

The ANS innervates ___ and smooth muscle

Answer 65

cardiac

Question 66

The sympathetic division is responsible for the flight or fight responses that ready the body for action in an ___ situation

Answer 66

emergency

Question 67

Sympathetic nervous system uses norepinephrine as its primary ___

Answer 67

neurotransmitter

Question 68

The parasympathetic nervous system uses ___ as its primary neurotransmitter

Answer 68

acetylcholine

Question 69

The eyeball is covered by a thick, opaque layer known as the sclera, which is also known as the ___ of the eye

Answer 69

white

Question 70

Beneath the sclera is the ___ layer, which helps to supply the retina with blood

Answer 70

choroid

Question 71

The innermost layer of the eye is the ___, which contains the photoreceptors that sense light

Answer 71

retina

Question 72

The transparent ___ at the front of the eye bends and focuses light rays

Answer 72

cornea

Question 73

After the front of the eye bends and focuses light rays the rays then travel through an opening called the pupil, whose ___ is controlled by the pigmented, muscular iris

Answer 73

diameter

Question 74

After the ___, the light continues through the lens, which is suspended behind the pupil

Answer 74

pupil

Question 75

The lens, the shape and focal length of which is controlled by ___ muscles, focuses the image onto the retina

Answer 75

ciliary

Question 76

The eye also contains a jelly like material called the ___ humor that helps maintain its shape and optical properties

Answer 76

vitreous

Question 77

The ___ humor is a more watery substance that fills the space between the lens and the cornea

Answer 77

aqueous

Question 78

Cones respond to high intensity ___ are sensitive to color whereas rods detect low intensity illumination and are important in night vision

Answer 78

illumination

Question 79

While there are many more rods than cones in the human eye, the central section of the retina, called the ___, has a high concentration of cones

Answer 79

macula

Question 80

A sound wave first reaches the cartilaginous ___ (sometimes called auricle), the visible part of the ear

Answer 80

pinna

Question 81

After the auricle, sound is then channeled into the external auditory canal, which focuses the sound wave toward the ___ membrane (eardrum) located at the end of the external auditory canal

Answer 81

tympanic

Question 82

After the eardrum, the tympanic membrane vibrates with the frequency and magnitude of the incoming soundwave , thereby transferring the vibrational energy from the ___ to itself

Answer 82

air

Question 83

The tympanic membrane is the boundary between the ___ and middle ear

Answer 83

outer

Question 84

The middle ear contains three bones: the malleus (hammer), incus (anvil), and ___ (stirrup)

Answer 84

stapes

Question 85

The ___, incus and stapes are collectively called ossicles

Answer 85

malleus

Question 86

The ossicles vibrate with the same frequency as the ___ membrane and transfer the energy to another membrane, the oval window

Answer 86

tympanic

Question 87

The oval window is much smaller than the tympanic membrane; thus the transfer of energy between the two membranes ___ the vibrations

Answer 87

amplifies

Question 88

The inner ear which begins after the oval window contains the ___ and vestibule

Answer 88

cochlea

Question 89

The vibration of the oval window pushes against fluid (___), resulting in pressure waves that travel through the fluid-filled cochlea

Answer 89

perilymph

Question 90

The pressure waves of the perilymph are detected by hair cells, which transform mechanical stimuli into action potentials that travel down the ___ nerve

Answer 90

auditory

Question 91

The auditory nerve follows the auditory pathway until it reaches the auditory ___, which is responsible for the processing of auditory information

Answer 91

cortex

Question 92

The inner ear also contains the ___, which is a fluid filled structure responsible for balance and acceleration detection of the organism

Answer 92

vestibule