2structure Flashcards

1
Q

cerebrum

A
  • 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.
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2
Q

cerebral cortex

A

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.

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3
Q

basal ganglia

A

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.

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4
Q

midbrain

A

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.

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5
Q

cerebellum

A

like the cerebrum, also has two hemispheres

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6
Q

spinal cord

A

the extension of the brain through the

vertebral column

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7
Q

CNS

A

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

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8
Q

PNS

A

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

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9
Q

autonomic nervous system

A

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

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10
Q

cell body

A

contains the nucleus and cytoplasm

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11
Q

axon

A

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.

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12
Q

dendrites

A

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

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13
Q

synapses

A

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

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14
Q

where is ACh present?

A

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.

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15
Q

where are amino acids present?

A

widely distributed

throughout the body and the brain

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16
Q

where are catecholamines present?

A

Dopamine and norepinephrine are widely present in the

brain and peripheral nervous system.

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17
Q

where is serotonin present?

A

This neurotransmitter is present in the

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

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18
Q

where are peptides present?

A

peptides are synthesized in the cell body and greatly

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

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19
Q

where are trophic factors present?

A

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

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20
Q

prostaglandins

A
Prostaglandins are a class of compounds made from lipids
by an enzyme called cyclooxygenase. They are very small. Type of lipid messenger.
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21
Q

amyloid plaques

A

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.

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22
Q

tau tangles

A

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.

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23
Q

primary brain tumors

A

arise within the brain

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24
Q

metastatic / secondary brain tumors

A

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

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25
cerebral edema
swelling as a result of excess accumulation of | water in the brain
26
lesions
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.
27
neuropathic pain
comes from injury to the nervous | system
28
diabetic neuropathy
damage to nerves in the body resulting from high blood sugar | levels
29
neuralgia
nerve pain or numbness, from viruses such | as shingles
30
nociceptor
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
31
3 major cell types of the brain:
neurons; astrocytes, the cells that nourish and protect neurons; and oligodendrocytes, the cells that surround axons and allow them to conduct their signals efficiently.
32
MRI image
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.
33
cornea
does about three-quarters of the focusing. vision begins with light passing thru the cornea.
34
lens
- 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.
35
retina
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
36
photoreceptors
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.
37
iris
The size of the pupil, which regulates how | much light enters the eye, is controlled by the iris.
38
lateral geniculate nucleus
an intermediate way station between the | retina and visual cortex
39
photoreceptor types
- 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.
40
photoreceptor subtypes
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.
41
parts of the retina
- central part: FOVEA, where light is focused; only contains red and green cones - around fovea: MACULA, critical for reading and driving
42
receptive field
the region of visual space providing input to a visual neuron is called its receptive field.
43
3 retina layers
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.
44
optic nerve
The axons of the ganglion cells form the optic nerve.
45
primary visual cortex
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.
46
primary visual cortex layers
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.
47
oval window
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.
48
cochlea
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.
49
hair cells
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.
50
auditory nerve
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.
51
taste buds
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.
52
odorant
``` 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. ```
53
odor pcoess
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
54
skeletal muscles
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.
55
motor unit
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.
56
reflexes
Perhaps the simplest and most fundamental movements are reflexes. These are relatively fixed, automatic muscle responses to particular stimul.
57
inhibitory interneurons
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.
58
gamma motor neurons
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.
59
Golgi tendon organs
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.
60
flexion
source of potential injury
61
flexion withdrawal
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.
62
motor cortex
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.
63
During the early stages of embryonic | development, three layers emerge
the endoderm, the ectoderm, and the mesoderm. These layers undergo many interactions to grow into organ, bone, muscle, skin, or nerve tissue.
64
growth cone signaling molecules
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.
65
cochlear implants
cochlear implants introduced in infancy are most effective in restoring hearing to the congenitally deaf.