Download Brain Structures Defined Part 1

BRAIN STRUCTURES DEFINED
BASIC BRAIN STRUCTURES
Medulla
The medulla is involved in the vital functions of the human body such as heart rate, blood pressure, and breathing.
Pons
The pons is located in front of the medulla and is involved in regulating body movement, attention, sleep, and
alertness.
Cerebellum
The cerebellum looks like a ball of yarn a little larger than a golf ball, and it hooks onto the base of the brain below
the visual or occipital lobe. Its job is complex. Whenever you move, it makes sure you stay in balance, remain
coordinated, and get where you want to go. The cerebellum also calculates speed and direction.
Reticular Activating System
This is sometimes called the reticular formation. The RAS sits right at the base of the brain inside the spinal cord.
The word reticular means “net,” and is named this because it acts as a net that catches nerve impulses. The
reason for its design is to monitor the nerve impulses to and from the brain and the body to take a reading of the
level of activity throughout the whole system. This helps regulate how alert we are. If a lot of impulses arrive from
the body, alertness increases. However, if there are few impulses, then the body tends to head toward sleep.
Hypothalamus
The word hypo means “below.” The hypothalamus gets its name because it sits below the thalamus. While only the
size of a large pea, it helps control rage, pleasure, hunger, thirst, and sexual desire. Thus, if its rage center is
electrically stimulated, it can cause a person to go wild and start smashing things.
Cerebrum
This is the top portion of the brain. Only in humans does the cerebrum make up such a large part of the brain. It
accounts for 70% of the weight of the brain. This area is responsible for memory, language, perception, emotions,
and complex motor functions. The surface of the cerebrum is covered by wrinkles that look like ridges and valleys.
This is called the Cerebral Cortex. (See Below)
Cerebral Cortex
The cerebral cortex is the outermost layer of the brain and the surface of the cerebrum. This unit controls very
high-level thought processes. In the human the cerebral cortex takes up over 2/3 of the brain’s nerve cells. These
nerve cells can connect with one another in infinite ways. No matter how fantastic it is, though, the cortex will not
keep the body running. For that we need the “Lower” Brain
Corpus Callosum
Since the cerebral cortex is composed of two sides, a left and a right side, these two halves must be connected.
The structure that connects the two hemispheres is called the corpus callosum.
The body is “cross-wired,” or in other words, information received by one side of the body is transmitted by the
opposite hemisphere of the brain. For example, motions of the right hand will be controlled by the left hemisphere
of the cerebral cortex.
Frontal Lobe
This is the division of the brain that contains the motor strip (stimulation in the motor cortex area will cause
movement of certain parts of the body) and the association area. The frontal association area is very heavily
packed with nerve cells because its task is very complex: to interpret what is going on and tell us what to do and
what to feel. In many ways, the frontal association area seems to form the core of a person’s personality, since so
many decisions are made there.
Temporal Lobe
The part of the brain that looks like the thumb of a boxing glove is the temporal lobe. This area contains the major
centers for hearing. This is also where some of the centers related to speech are located, although there is overlap
into other lobes to handle different aspects of language. (If you are actually speaking, for instance, a place in the
frontal lobe’s motor strip will be involved, etc.) If someone is unfortunate enough to damage this portion of the
brain, one could still speak, but that person would only be able to manage saying jumbled words that make no
sense.
Occipital Lobe
The entire back of the brain is devoted to making sense out of what we see. This area is called the occipital
(visual) lobe. Words that you read will travel through the lens of the eyes and land on the back of the eyeball. The
image is then coded and then sent through the nerves to the occipital lobe. The event of see of “seeing stars” after
being hit is caused by the crashing of the occipital lobe into the back of the skull. The collision causes a stirred up
electrical system in the visual area, making strange images.
Parietal Lobe
This area of the brain contains the sensory strip. It is located in the middle of the brain, between the frontal lobe
and the occipital lobe. If an exposed brain was to be stimulate in the sensory strip then a person would feel
sensations in different areas of the body - in the leg, the ear, mouth, etc. - depending on what area of the sensory
strip is touched.
Thalamus
The term thalamus comes from the Greek word for “couch.” Note that it is shaped like one, an oval mass of nerve
cells. It acts as a relay station to send incoming and outgoing messages to and from various parts of the brain. So,
if you want to move your big toe, the brain sends a message to the thalamus, which then sends it to the correct
place on the motor strip. Otherwise, you might wind up blinking your eye instead.
ADVANCED STRUCTURES
Limbic System
Amygdala - Emotional memory center & creates fear responses. Sense of smell linked directly to amygdala.
Means "almond" in greek.
Pineal Gland - only structure in the brain that is not bifricated - there is only one of them not two like all the other
structures that are present in both hemispheres.
Hypothalamus - see other notes
Thalamus - same as above
Putamen - unconscious learned motor actions - i.e. you tend to drive your car now after having a license for many
years, so you don't have to think about your actions... they are automatic
Language Structures
1. Eyes - Retinas are actually part of the brain and the beginning of the optic nerve... long axons
2. Occipital lobe - allows you to read.
3. Angular Gyrus - you brain can't understand written symbols. It only understands auditory code... verbal
instructions. Therefore it needs a translator. The AG translates written to auditory. If this were damaged you would
not be able to read or write.
4. Wernicke's Area - This Comprehends auditory speech. If you heard someone speak... the sound would come up
the auditory nerve to this area for processing. If this were damaged, you would know someone was speaking, but
you would not understand what they were saying to you.
5. Broca's Area - This area is the liasion betweent he motor cortex (makes your lips move) and you brain. This
allows you to respond... to speak back.
If this were damaged you could listen and understand, but you could not respond or talk.
Three Types of Neural tissues
Cerebrospinal Fluid
White Matter - from Myelin
Gray Matter - densely packed cell bodies
Misc. Wrinkles
Gyrus
Fissues
Sulcus
brain = 3 lbs
30 watts
100 billion neurons
one amazing organ!