Anatomy Of Human Brain


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A Tour of Human Brain & Alzheimer

Anatomy Of Human Brain

  1. 1. A Tour of Human Brain & Alzheimer
  2. 2. Anatomy Of The Brain <ul><li>The image on the left is a side view of the outside of the brain, showing the major lobes (frontal, parietal, temporal and occipital) and the brain stem structures (pons, medulla oblongata and cerebellum). </li></ul><ul><li>The image on the right is a side view showing the location of the limbic system inside the brain. The limbic system consists of a number of structures, including the fornix, hippocampus, cingulate gyrus, amygdala, the parahippocampal gyrus and parts of the thalamus. The hippocampus is one of the first areas affected by Alzheimer's disease. As the disease progresses, damage extends throughout the lobes. </li></ul>
  3. 3. Glossary Terms of The Brain <ul><li>Amygdala – limbic structure involved in many brain functions, including emotion, learning and memory. It is part of a system that processes &quot;reflexive&quot; emotions like fear and anxiety. </li></ul><ul><li>Cerebellum – governs movement. </li></ul><ul><li>Cingulate gyrus – plays a role in processing conscious emotional experience. </li></ul><ul><li>Fornix – an arch-like structure that connects the hippocampus to other parts of the limbic system. </li></ul><ul><li>Frontal lobe – helps control skilled muscle movements, mood, planning for the future, setting goals and judging priorities. </li></ul><ul><li>Hippocampus – plays a significant role in the formation of long-term memories. </li></ul><ul><li>Medulla oblongata – contains centers for the control of vital processes such as heart rate, respiration, blood pressure, and swallowing. </li></ul><ul><li>Limbic system – a group of interconnected structures that mediate emotions, learning and memory. </li></ul><ul><li>Occipital lobe – helps process visual information. </li></ul><ul><li>Parahippocampal gyrus – an important connecting pathway of the limbic system. </li></ul><ul><li>Parietal lobe – receives and processes information about temperature, taste, touch, and movement coming from the rest of the body. Reading and arithmetic are also processed in this region. </li></ul><ul><li>Pons – contains centers for the control of vital processes, including respiration and cardiovascular functions. It also is involved in the coordination of eye movements and balance. </li></ul><ul><li>Temporal lobe – processes hearing, memory and language functions. </li></ul><ul><li>Thalamus – a major relay station between the senses and the cortex (the outer layer of the brain consisting of the parietal, occipital, frontal and temporal lobes). </li></ul>
  4. 4. Comparative Anatomy of Brains
  5. 5. Three Pounds, Three Parts <ul><li>Your brain is your most powerful organ, </li></ul><ul><li>yet weighs only about three pounds. It has a texture similar to firm jelly. </li></ul><ul><li>The Three Main Parts: </li></ul><ul><li>1. The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. It also controls movement. </li></ul><ul><li>2. The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance. </li></ul><ul><li>3. The brain stem sits beneath your cerebrum in front of your cerebellum. It connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate and blood pressure. </li></ul>1 2 3
  6. 6. Supply Lines <ul><li>Your brain is nourished by one of your body's richest networks of blood vessels. </li></ul><ul><li>With each heartbeat, arteries carry about 20 to 25 percent of your blood to your brain, where billions of cells use about 20 percent of the oxygen and fuel your blood carries. </li></ul><ul><li>When you are thinking hard, your brain may use up to 50 percent of the fuel and oxygen. </li></ul><ul><li>The whole vessel network includes veins and capillaries in addition to arteries. </li></ul>
  7. 7. The Cortex: &quot;Thinking Wrinkles&quot; <ul><li>Your brain’s wrinkled surface is a specialized outer layer of the cerebrum called the cortex. Scientists have “mapped” the cortex by identifying areas strongly linked to certain functions. </li></ul><ul><li>Specific regions of the cortex: </li></ul><ul><li>1. Interpret Sensations from your body, </li></ul><ul><li>2. Sights </li></ul><ul><li>3. Sounds </li></ul><ul><li>4. Smells from the outside world </li></ul><ul><li>5. Generates thoughts, solve </li></ul><ul><li>problems and make plans </li></ul><ul><li>6. Form and store memories </li></ul><ul><li>7. Control voluntary movement </li></ul>1 2 3 4 5 6 7
  8. 8. Left Brain/Right Brain <ul><li>Your brain is divided into right and left halves. Experts are not certain how the &quot;left brain&quot; and &quot;right brain&quot; may differ in function, except: </li></ul><ul><li>1.The left half controls </li></ul><ul><li>movement on body’s right side </li></ul><ul><li>2. The right half controls the </li></ul><ul><li>body's left side. </li></ul><ul><li>3. In most people, the language </li></ul><ul><li>area is chiefly on the left. </li></ul>1 2 1 2 Softer, Trumpets 3
  9. 9. The Neuron Forest <ul><li>The real work of your brain goes on in individual cells. An adult brain contains about 100 billion a. nerve cells , or neurons, with b. branches that connect at more than 100 trillion points. Scientists call this dense, branching network a &quot;neuron forest.“ c . Signals travel through the neuron forest form the basis of memories, thoughts, and feelings. </li></ul><ul><li>Neurons are the chief type of cell destroyed by Alzheimer's disease. </li></ul>a a a b b b c
  10. 10. Cell Signaling <ul><li>Signals that form memories and thoughts move through an individual nerve cell as a . tiny electrical change </li></ul><ul><li>Nerve cells connect to one another at b . synapses . When a charge reaches a synapse, it may trigger release of tiny bursts of chemicals called c . neurotransmitters . The neurotransmitters travel across the synapse, carrying signals to other cells. Scientists have identified dozens of neurotransmitters. </li></ul><ul><li>Alzheimer's disease disrupts both the way electrical charges travel within cells and the activity of neurotransmitters. </li></ul>a b c
  11. 11. Signal Coding <ul><li>100 billion nerve cells… 100 trillion synapses… dozens of neurotransmitters… This “strength in numbers” provides your brain’s raw material. Over time, our experiences create patterns in signal type and strength. These patterns of activity explain how, at the cellular level, our brains code our thoughts, memories, skills and sense of who we are. </li></ul><ul><li>The positron emission tomography (PET) scan on the left shows typical patterns of brain activity associated with: </li></ul><ul><ul><li>a. Reading words </li></ul></ul><ul><ul><li>b. Hearing words </li></ul></ul><ul><ul><li>c. Thinking about words </li></ul></ul><ul><ul><li>d. Saying words </li></ul></ul><ul><li>Activity is highest in red areas and then decreases through the other colors of the rainbow from yellow to blue - violet . </li></ul><ul><li>Specific activity patterns change throughout life as we meet new people, have new experiences and acquire new skills. The patterns also change when Alzheimer’s disease or a related disorder disrupts nerve cells and their connections to one another. </li></ul>b a d c
  12. 12. Alzheimer’s Changes The Whole Brain <ul><li>Alzheimer’s disease leads to </li></ul><ul><li>nerve cell death and tissue loss </li></ul><ul><li>throughout the brain. Over time, </li></ul><ul><li>the brain shrinks dramatically, </li></ul><ul><li>affecting nearly all its functions. </li></ul><ul><li>These images show : </li></ul><ul><li>a. Brain without the disease </li></ul><ul><li>b. Brain with advanced Alzheimer's </li></ul><ul><li>c. How the two Brains compare </li></ul>c a b
  13. 13. More Brain Changes <ul><li>Here is another view of how massive cell loss changes the whole brain in advanced Alzheimer's disease. This slide shows a crosswise &quot;slice&quot; through the middle of the brain between the ears. </li></ul><ul><li>In the Alzheimer brain: </li></ul><ul><ul><li>a. The cortex shrivels up , damaging areas involved in thinking, planning and remembering. </li></ul></ul><ul><ul><li>b. Shrinkage is especially severe in the hippocampus , an area of the cortex that plays a key role in formation of new memories. </li></ul></ul><ul><ul><li>c. Ventricles (fluid-filled spaces within the brain) grow larger. </li></ul></ul>a a b b c c
  14. 14. Under The Microscope <ul><li>Scientists can also see the terrible effects of Alzheimer's disease when they look at brain tissue under the microscope: </li></ul><ul><li>Alzheimer tissue has many fewer nerve cells and synapses than a healthy brain. </li></ul><ul><ul><li>a. Plaques abnormal clusters of protein fragments, build up between nerve cells. </li></ul></ul><ul><ul><li>b. Dead and dying nerve cells contain tangles , which are made up of twisted strands of another protein. </li></ul></ul><ul><li>Scientists are not absolutely sure what causes cell death and tissue loss in the Alzheimer brain, but plaques and tangles are prime suspects. </li></ul>a a b
  15. 15. More About Plaques <ul><li>Plaques form when protein pieces called a. beta- amyloid (BAY-tuh AM-uh-loyd) clump together. Beta-amyloid comes from a larger protein found in the fatty membrane surrounding nerve cells. </li></ul><ul><li>Beta-amyloid is chemically &quot;sticky&quot; and gradually builds up into b. plaques. </li></ul><ul><li>The most damaging form of beta-amyloid may be c. groups of a few pieces rather than the plaques themselves. The small clumps may block cell-to-cell signaling at synapses. They may also activate immune system cells that trigger inflammation and devour disabled cells. </li></ul>a a c b
  16. 16. More About Tangles <ul><li>Tangles destroy a vital cell transport system made of proteins. This electron microscope picture shows a cell with some healthy areas and other areas where tangles are forming. </li></ul><ul><li>In healthy areas </li></ul><ul><li>a. The transport system is organized in orderly parallel strands somewhat like railroad tracks. Food molecules, cell parts and other key materials travel along the “tracks.” </li></ul><ul><li>b. A protein called tau (rhymes with wow) helps the tracks stay straight. </li></ul><ul><li>In areas where tangles are forming: </li></ul><ul><li>c. Tau collapses into twisted strands called tangles. </li></ul><ul><li>d. The tracks can no longer stay straight. They fall apart and disintegrate </li></ul><ul><li>Nutrients and other essential supplies can no longer move through the cells, which eventually die. </li></ul>a d d c b
  17. 17. Progression Through The Brain <ul><li>Plaques and tangles (shown in the blue-shaded areas) tend to spread through the cortex in a predictable pattern as Alzheimer’s disease progresses. </li></ul><ul><li>The rate of progression varies greatly. People </li></ul><ul><li>with Alzheimer’s live an average of eight years, </li></ul><ul><li>but some people may survive up to 20 years. </li></ul><ul><li>The course of the disease depends in part on </li></ul><ul><li>age at diagnosis and whether a person has </li></ul><ul><li>other health conditions. </li></ul><ul><li>a. Earliest Alzheimer's – changes may </li></ul><ul><li>begin 20 years or more before diagnosis. </li></ul><ul><li>b. Mild to moderate Alzheimer stages – </li></ul><ul><li>generally last from 2 - 10 years. </li></ul><ul><li>c. Severe Alzheimer’s – may last from 1 - 5 years. </li></ul>c b a
  18. 18. Earliest Alzheimer Stages <ul><li>In the earliest stages, before symptoms can be detected with current tests, plaques and tangles begin to form in brain areas involved in: </li></ul><ul><ul><li>a. Learning and memory </li></ul></ul><ul><ul><li>b. Thinking and planning </li></ul></ul>b a
  19. 19. Mild To Moderate Alzheimer's <ul><li>In mild to moderate stages, brain regions important in a. memory and b. thinking and planning develop more plaques and tangles than were present in early stages. As a result, individuals develop problems with memory or thinking serious enough to interfere with work or social life. They may also get confused and have trouble handling money, expressing themselves and organizing their thoughts. Many people with Alzheimer’s are first diagnosed in these stages. </li></ul><ul><li>Plaques and tangles also spread to area </li></ul><ul><li>involved in: </li></ul><ul><ul><li>c. Speaking and understanding speech </li></ul></ul><ul><ul><li>d. Your sense of where your body is in </li></ul></ul><ul><ul><li>relation to objects around you </li></ul></ul><ul><li>As Alzheimer’s progresses, individuals may experience changes in personality and behavior and have trouble recognizing friends and family members. </li></ul>a b c d
  20. 20. Severe Alzheimer's disease <ul><li>In advanced Alzheimer’s disease, most of the cortex is seriously damaged. The brain shrinks dramatically due to widespread cell death. Individuals lose their ability to communicate, to recognize family and loved ones and to care for themselves. </li></ul>
  21. 21. A History of Alzheimer's Disease (from AHAF) <ul><li>Progressive mental deterioration in old age has been recognized and described throughout history. However, it was not until 1906 that a German physician, Dr. Alois Alzheimer, specifically identified a collection of brain cell abnormalities as a disease. One of Dr. Alzheimer’s patients died after years of severe memory problems, confusion and difficulty understanding questions. Upon her death, while performing a brain autopsy, the doctor noted dense deposits surrounding the nerve cells (neuritic plaques). Inside the nerve cells he observed twisted bands of fibers (neurofibrillary tangles). Today, this degenerative brain disorder bears his name, and when found during an autopsy, these plaques and tangles mean a definite diagnosis of Alzheimer's disease (AD). </li></ul><ul><li>Since its discovery more than 100 years ago, there have been many scientific breakthroughs in AD research. In the 1960s, scientists discovered a link between cognitive decline and the number of plaques and tangles in the brain. The medical community then formally recognized Alzheimer’s as a disease and not a normal part of aging. In the 1970s, scientists made great strides in understanding the human body as a whole, and AD emerged as a significant area of research interest. This increased attention led in the 1990s to important discoveries and a better understanding of complex nerve cells in the brains of AD patients. More research was done on AD susceptibility genes, and several drugs were approved to treat the cognitive symptoms of the disease. </li></ul><ul><li>Over the last decade, scientists have substantially progressed in understanding potential environmental, genetic and other risk factors for AD, the processes leading to formation of plaques and tangles in the brain, and the brain regions that are affected. Specific genes related to both the early-onset and late-onset forms of AD have been identified, but genetic risk factors alone do not fully explain its causes, so researchers are actively exploring environment and lifestyle to learn what role they might play in the development of this disease. More effective treatment options have been approved by the Food and Drug Administration (FDA). However, AD is still incurable. The drugs currently in use treat only the symptoms, not the cause of the disorder, and they only slow the progression of cognitive decline. </li></ul>
  22. 22. Alzheimer's Disease & Dementia <ul><li>Dementia is a decline in cognitive function or mental ability – thinking, reasoning and remembering. People with dementia have difficulty independently carrying out daily tasks they have performed routinely throughout their lives. The most common forms of dementia in the elderly are Alzheimer’s disease and vascular dementia, a hardening of the arteries in the brain that causes blockage in blood flow. These two conditions account for the vast majority of cases, and although their symptoms can sometimes be managed, they are irreversible. The dementia associated with Alzheimer’s will progressively worsen. </li></ul><ul><li>Dementia can also be caused by infection; drug interactions; metabolic disorders of the thyroid, liver, pancreas or kidneys; nutritional deficiencies, especially the lack of vitamin B-12; head injury; brain tumors; depression; or other progressive diseases such as Parkinson's, Lewy-body, Huntington’s or Pick’s. </li></ul><ul><li>If a decline in mental function makes an impression on friends and family, and begins to interfere with daily activities, employment tasks, social interactions, and family chores, set up an appointment with a doctor to accurately determine the underlying cause of the symptoms. </li></ul>
  23. 23. Enjoy The Beauty