Transcript
Human Brain
Introduction to Psychology by Dr. Shoaib Ahmed
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Human Brain
Brain,
portion of the central nervous
system contained within the skull.
The
brain is the control center for every other vital activity
movement, sleep, hunger, thirst, and virtually necessary to survival.
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All human emotions—including love, hate, fear, anger, elation (a feeling of extraordinary happiness and excitement ), and sadness—are controlled by the brain. It also receives and interprets the countless signals that are sent to it from other parts of the body and from the external environment. The brain makes us conscious, emotional, and intelligent.
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Skeleton
Cerebrum (Front of Brian)
Cerebellum (Rear of Brian)
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Parts of Brain
The human brain has three major
structural components:
The large dome-shaped cerebrum (top), The smaller somewhat right), spherical and the
cerebellum
(lower
brainstem (center).
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Prominent in the brainstem are the medulla
oblongata (the egg-shaped enlargement at center) and the thalamus (between the medulla and the
cerebrum).
The cerebrum is responsible for intelligence and reasoning. The cerebellum helps to maintain balance and posture. The medulla is involved in maintaining involuntary functions such as respiration, and the thalamus acts as a relay center for electrical impulses traveling to and from the cerebral cortex.
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Metabolism
The brain consumes up to twenty percent of the energy used by the human body, more than any other organ.
Brain metabolism normally is completely dependent upon blood glucose as an energy source, since fatty acids do not cross the blood-brain barrier.
During times of low glucose (such as fasting), the brain will primarily
use ketone bodies for fuel with a smaller requirement for glucose.
The brain can also utilize lactate during exercise. The brain does not store any glucose in the form of glycogen, in contrast, for example, to skeletal muscle.
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Although the human brain represents only 2% of the body weight,
It receives 15% of the cardiac output, 20% of total body oxygen consumption, and 25% of total body glucose utilization. The need to limit body weight in order, for example, to fly, has led to selection for a reduction of brain size in some species, such as bats.
The brain mostly uses glucose for energy, and deprivation of glucose, as can happen in hypoglycemia, can result in loss of consciousness.
The energy consumption of the brain does not vary greatly over time, but active regions of the cortex consume somewhat more energy than inactive
regions:
this fact forms the basis for the functional brain imaging methods PET and fMRI. These are nuclear medicine imaging techniques which produce a three-dimensional image of metabolic activity.
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Simplified Model of Memory
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In this information-processing model of memory
Information
that enters the brain is
briefly recorded in sensory memory. If we focus our attention on it, the information may become part of working memory (also called shortterm memory)
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Where
it can be manipulated and
used. Through encoding techniques such as repetition and rehearsal, information may be transferred to long-term memory. Retrieving long-term memories makes them active again in working memory.
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LEFT AND RIGHT PART FUNCTIONS
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Left and Right Brain Functions
Although
the
cerebrum
is
symmetrical
in
structure, with two lobes emerging from the brain stem and matching motor and sensory areas in each, certain intellectual functions are restricted to one hemisphere.
A person’s dominant hemisphere is usually
occupied with language and logical operations, while the other hemisphere controls emotion and artistic and spatial skills.
In nearly all right-handed and many left-handed people, the left hemisphere is dominant.
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