2structure

Question 1

cerebrum

Answer 1

• largest part of the human brain
• The cerebrum is divided
  into two hemispheres — the right hemisphere and the
  left hemisphere. Bridging the two hemispheres is a bundle
  of fibers called the corpus callosum. The two hemispheres
  communicate with one another across the corpus callosum.

Question 2

cerebral cortex

Answer 2

Covering the outermost layer of the cerebrum is a
sheet of tissue called the cerebral cortex. Because of its gray
color, the cerebral cortex is often referred to as gray matter.
The wrinkled appearance of the human brain also can be
attributed to characteristics of the cerebral cortex. More than
two-thirds of this layer is folded into grooves. The grooves
increase the brain’s surface area, allowing for inclusion of
many more neurons.

Question 3

basal ganglia

Answer 3

a key part of the forebrain; cerebral nuclei deep in the cerebral cortex. The basal ganglia are a cluster of interconnected areas
located beneath the cortex in the depths of the cerebral
hemispheres.

Question 4

midbrain

Answer 4

consists of two pairs of small hills called
colliculi. These collections of neurons play a critical role
in visual and auditory reflexes and in relaying this type of
information to the thalamus. The midbrain also has clusters
of neurons that regulate activity in widespread parts of the
central nervous system and are thought to be important for
reward mechanisms and mood.

Question 5

cerebellum

Answer 5

like the cerebrum, also has two hemispheres

Question 6

spinal cord

Answer 6

the extension of the brain through the

vertebral column

Question 7

CNS

Answer 7

formed by the forebrain, midbrain, hindbrain, and spinal cord. brain is protected by skull, spinal cord protected by vertebral column.

Question 8

PNS

Answer 8

consists of nerves and small concentrations of gray matter called ganglia, a
term specifically used to describe structures in the PNS.

Question 9

autonomic nervous system

Answer 9

made of neurons
connecting the CNS with internal organs. It is divided
into two parts: sympathetic and parasympathetic

Question 10

cell body

Answer 10

contains the nucleus and cytoplasm

Question 11

axon

Answer 11

axon extends
from the cell body and often gives rise to many smaller
branches before ending at nerve terminals. Many axons are
covered with a layered myelin sheath, which accelerates the
transmission of electrical signals along the axon. This sheath
is made by specialized cells called glia.

Question 12

dendrites

Answer 12

extend
from the neuron cell body and receive messages from other
neurons

Question 13

synapses

Answer 13

are the contact points where one neuron
communicates with another. The dendrites are covered with
synapses formed by the ends of axons from other neurons

Question 14

where is ACh present?

Answer 14

This chemical is released
by neurons connected to voluntary muscles,
causing them to contract, and by neurons that
control the heartbeat. ACh is also a transmitter
in many regions of the brain. ACh is synthesized in axon terminals.

Question 15

where are amino acids present?

Answer 15

widely distributed

throughout the body and the brain

Question 16

where are catecholamines present?

Answer 16

Dopamine and norepinephrine are widely present in the

brain and peripheral nervous system.

Question 17

where is serotonin present?

Answer 17

This neurotransmitter is present in the

brain and other tissues, particularly blood platelets and the lining of the idgestive tract.

Question 18

where are peptides present?

Answer 18

peptides are synthesized in the cell body and greatly

outnumber the classical transmitters discussed earlier (ACh, catecholamines, serotonin, AAs)

Question 19

where are trophic factors present?

Answer 19

These small proteins are made in
brain cells, released locally in the brain, and bind to receptors
expressed by specific neurons.

Question 20

prostaglandins

Answer 20

Prostaglandins are a class of compounds made from lipids
by an enzyme called cyclooxygenase. They are very small. Type of lipid messenger.

Question 21

amyloid plaques

Answer 21

in people who died from Alzheimer’s, a small fibrillar peptide, termed beta amyloid, in the
spaces around synapses. These accumulations of tissue are
referred to as neuritic plaques.

Question 22

tau tangles

Answer 22

in people who died from Alzheimer’s. neurofibrillary tangles, have been identified
as a modified form of the protein tau, which is found in the
cell bodies of neurons. the protein tau is rod-shaped.

Question 23

primary brain tumors

Answer 23

arise within the brain

Question 24

metastatic / secondary brain tumors

Answer 24

spread from
other parts of the body through the bloodstream and enter
the brain

Question 25

cerebral edema

Answer 25

swelling as a result of excess accumulation of

water in the brain

Question 26

lesions

Answer 26

imaging can reveal lesions
produced by the initial injury. These lesions can consist of
bleeding on the surface or within the brain as well as the
formation of contusions, or bruises. Once blood leaks from
vessels and comes into direct contact with brain tissue, it
causes localized pressure, reducing cerebral blood flow. The
blood itself also can be toxic to brain cells.

Question 27

neuropathic pain

Answer 27

comes from injury to the nervous

system

Question 28

diabetic neuropathy

Answer 28

damage to nerves in the body resulting from high blood sugar

levels

Question 29

neuralgia

Answer 29

nerve pain or numbness, from viruses such

as shingles

Question 30

nociceptor

Answer 30

the peripheral nerve
fiber that initially responds to the injury stimulus. The sensory fibers that respond to stimuli that damage
tissue and can cause pain

Question 31

3 major cell types of the brain:

Answer 31

neurons; astrocytes, the cells
that nourish and protect neurons; and oligodendrocytes,
the cells that surround axons and allow them to conduct
their signals efficiently.

Question 32

MRI image

Answer 32

Tissue that contains a lot of water and fat produces a
bright image; tissue that contains little or no water, such as
bone, appears black.

Question 33

cornea

Answer 33

does about three-quarters of the focusing. vision begins with light passing thru the cornea.

Question 34

lens

Answer 34

• adjusts the focus. light passes thru the lens after it passes thru the cornea
• The shape
  of the lens is altered by the muscles just behind the iris so that
  near or far objects can be brought into focus on the retina.

Question 35

retina

Answer 35

a sheet of photoreceptors; part of CNS but located at the back of the eye. the cornea and lens combine to produce a clear image of the visual world on the retina. the image is reversed: objects to the right of the center project images to the left part of the retina

Question 36

photoreceptors

Answer 36

gather visual information by absorbing
light and sending electrical signals to other retinal neurons
for initial processing and integration. The signals are then
sent via the optic nerve to other parts of brain, which
ultimately processes the image and allows us to see.

Question 37

iris

Answer 37

The size of the pupil, which regulates how

much light enters the eye, is controlled by the iris.

Question 38

lateral geniculate nucleus

Answer 38

an intermediate way station between the

retina and visual cortex

Question 39

photoreceptor types

Answer 39

• rods: extremely sensitive to light and allow us to see in dim light,
  but they do not convey color; 95 percent
• Most of our vision, however, comes
  from cones that work under most light conditions and are
  responsible for acute detail and color vision.

Question 40

photoreceptor subtypes

Answer 40

The human eye contains three types of cones (red,
green and blue), each sensitive to a different range of colors.
Because their sensitivities overlap, cones work in combination
to convey information about all visible colors.

Question 41

parts of the retina

Answer 41

• central part: FOVEA, where light is focused; only contains red and green cones
• around fovea: MACULA, critical for reading and driving

Question 42

receptive field

Answer 42

the
region of visual space providing input to a
visual neuron is called its receptive field.

Question 43

3 retina layers

Answer 43

The rod and cone photoreceptors in the first layer send signals
to the middle layer (interneurons), which then relays signals
to the third layer, consisting of multiple different types of
ganglion cells, specialized neurons near the inner surface of the
retina. Each neuron in the middle and third layer typically receives input from many cells in the previous layer.

Question 44

optic nerve

Answer 44

The axons of the ganglion cells form the optic nerve.

Question 45

primary visual cortex

Answer 45

a thin sheet of tissue (less
than one-tenth of an inch thick), a bit
larger than a half-dollar, which is located
in the occipital lobe in the back of the
brain. The primary visual cortex is densely packed with
cells in many layers, just as the retina is.

Question 46

primary visual cortex layers

Answer 46

In its middle layer,
which receives messages from the lateral geniculate nucleus,
scientists have found responses similar to those seen in
the retina and in lateral geniculate cells. Cells above and
below this layer respond differently. They prefer stimuli in
the shape of bars or edges and those at a particular angle
(orientation). Further studies have shown that different
cells prefer edges at different angles or edges moving in a
particular direction.

Question 47

oval window

Answer 47

stapes (stirrup) pushes on the oval window, separates the air-filled middle ear from the fluid-filled inner ear to produce pressure waves in the inner ear’s
snail-shaped cochlea.

Question 48

cochlea

Answer 48

snail shaped; The separation of frequencies occurs in the
cochlea, which is tuned along its length to different frequencies,
so that a high note causes one region of the cochlea’s basilar
membrane to vibrate, while a lower note has the same effect on
a different region of the basilar membrane.

Question 49

hair cells

Answer 49

Riding on the vibrating basilar membrane are hair cells
topped with microscopic bundles of hairlike stereocilia, which
are deflected by the overlying tectorial membrane. Hair cells
convert the mechanical vibration to electrical signals, which in
turn excite the auditory nerve. Because each
hair cell rides on a different part of the basilar membrane, each
responds to a different frequency.

Question 50

auditory nerve

Answer 50

30,000 fibers. The auditory
nerve then carries the signals (electrical, converted by hair cells) to the brainstem. each nerve fiber
carries information about a different frequency to the brain.

Question 51

taste buds

Answer 51

special structures embedded within small protuberances on the
tongue called papillae. Other taste buds are found in the back of
the mouth and on the palate. Each taste bud consists of 50 to 100
specialized sensory cells, which are stimulated by tastants such
as sugars, salts, or acids.

Question 52

odorant

Answer 52

Airborne odor molecules, called
odorants, are detected by specialized
sensory neurons located in a small patch
of mucus membrane lining the roof of the
nose. Odorants stimulate receptor proteins found on hairlike cilia at the tips of the sensory cells, a process that initiates a neural response.

Question 53

odor pcoess

Answer 53

each odorant’s pattern of activity is then
sent to the olfactory bulb, where other
neurons are activated to form a spatial map
of the odor. Neural activity created by this
stimulation passes to the primary olfactory
cortex at the back of the underside, or
orbital, part of the frontal lobe. Olfactory
information then passes to adjacent parts of the orbital cortex,
where the combination of odor and taste information helps
create the perception of flavor

Question 54

skeletal muscles

Answer 54

Most muscles attach to points on the skeleton
and cross one or more joints. Each skeletal muscle is made up of thousands of
individual muscle fibers, and each muscle fiber is controlled
by one alpha motor neuron in either the brain or the
spinal cord.

Question 55

motor unit

Answer 55

each single alpha motor neuron
controls many muscle fibers (ranging from a few to 100
or more); an alpha motor neuron and all the muscle
fibers it contains form a functional unit referred to as a
motor unit. Motor units are the critical link between the
brain and muscles.

Question 56

reflexes

Answer 56

Perhaps the simplest and most fundamental movements
are reflexes. These are relatively fixed, automatic muscle
responses to particular stimul.

Question 57

inhibitory interneurons

Answer 57

The
same sensory stimulus that causes the stretch reflex causes inactivation, or inhibition,
of the motor neurons of the antagonist muscles through
connecting neurons, called inhibitory interneurons, within the spinal cord.

Question 58

gamma motor neurons

Answer 58

the sensitivity
of the muscle spindle organs is monitored by the brain
through a separate set of gamma motor neurons that
control the specialized muscle fibers and allow the brain to
fine-tune the system for different movement tasks.

Question 59

Golgi tendon organs

Answer 59

Other
specialized sense organs in muscle tendons — the Golgi
tendon organs — detect the force applied by a contracting muscle, allowing the brain to sense and control the muscular
force exerted during movement.

Question 60

flexion

Answer 60

source of potential injury

Question 61

flexion withdrawal

Answer 61

that occurs when the bare foot encounters a sharp
object. The leg is immediately lifted from the source of
potential injury (flexion), but the opposite leg responds
with increased extension so that we can maintain our
balance. The latter event is called the crossed extension reflex.

Question 62

motor cortex

Answer 62

One important brain area that is responsible for
voluntary movement is the motor cortex, which exerts
powerful control over the spinal cord, in part through
direct control of its alpha motor neurons. Some neurons
in the motor cortex appear to specify the coordinated
action of many muscles to produce the organized
movement of a limb to a particular point in space.
Others appear to control only two or three functionally
related muscles, such as those of the hand or arm, that
are important for finely tuned, skilled movement.

Question 63

During the early stages of embryonic

development, three layers emerge

Answer 63

the endoderm, the
ectoderm, and the mesoderm. These layers undergo many
interactions to grow into organ, bone, muscle, skin, or
nerve tissue.

Question 64

growth cone signaling molecules

Answer 64

These signaling
molecules include proteins with names such as netrin,
semaphorin, and ephrin. In most cases, these are families of
related molecules; for example, researchers have identified at
least fifteen semaphorins and at least nine ephrins.

Question 65

cochlear implants

Answer 65

cochlear
implants introduced in infancy are most effective in restoring
hearing to the congenitally deaf.