More Related Content
What's hot
What's hot (20)
Similar to Human brain
Similar to Human brain (20)
Recently uploaded
Recently uploaded (20)
Human brain
- 1. HUMAN BRAIN
- 2. ACKNOWLEDGEMENT!! I would like to express my special thanks of gratitude to my teacher Mrs. Pr eeti as well as our principal Veena Sharma who gave me the golden opport unity to do this wonderful project on the topic human brain, which also help ed me in doing a lot of Research and i came to know about so many ne w things I am really thankful to them. Secondly, i would also like to thank my parents and friends who helped me a lot in finalizing this project within the limited time frame. “ “
- 3. INDEX 01 INTRODUCTION 02 STRUCTURE 03 COMPOSITION 05 BRAIN SIZE 06 DEVELOPMENT 04 07 08 LEFT V/S RIGHT BRAIN 09 11 12 10 4 LOBES FUNCTIONS FACTS THE MIND THE SKULL CONCLUSION
- 4. INTRODUCTION The brain is the most complex org an in the human body. It produces our every thought, action, memory, feeling and experience of the worl d. This jelly-like mass of tissue, weighing in at around 1.4 kilogra ms, contains a staggering one hu ndred billion nerve cells, or neuro ns. The complexity of the connectivit y between these cells is mind-boggl ing. Each neuron can make conta ct with thousands or even tens of thousands of others, via tiny structures called synapses. Our brains form a million new connections for every second of o ur lives. The pattern and strength of t he connections is constantly chan ging and no two brains are alike. It is in these changing connection s that memories are stored, habits learned and personalities shaped,
- 5. , STRUCTURE GROSS ANATOMY MICRO ANATOMY CEREBROSPINAL FLUID BLOOD SUPPLY The adult human brain weig hs on average about 1.2–1. 4 kg (2.6–3.1 lb.) which is a bout 2% of the total body we ight, with a volume of aroun d 1260 cm3 in men and 113 0 cm3 in women. There is su bstantial individual variation , with the standard reference range for men being 1,180– 1,620 g (2.60–3.57 lb.) and f or women 1,030–1,400 g (2. 27–3.09 lb.) The human brain is primarily comp osed of neurons, glial cells, neural stem cells, and blood vessels. Typ es of neuron include interneurons, pyramidal cells including Betz cells , motor neurons (upper and lower motor neurons), and cerebellar Purkinje cells. Betz cells are the largest cells (by size of cell body) i n the nervous system. The adult h uman brain is estimated to contain 86±8 billion neurons, with a roughly equal num ber (85±10 billion) of non-neuronal cell s. Out of these neurons, 16 billion (19 %) are located in the cerebral cortex, Cerebrospinal fluid is a clear , colourless trans cellular flui d that circulates around the brain in the subarachnoid sp ace, in the ventricular syste m, and in the central canal o f the spinal cord. It also fills some gaps in the subarachn oid space, known as subara chnoid cisterns. The four ve ntricles, two lateral, a third, and a fourth ventricle, all co ntain choroid plexus that pro duces cerebrospinal fluid. The internal carotid arterie s supply oxygenated bloo d to the front of the brain an d the vertebral arteries sup ply blood to the back of the brain. These two circulation s join together in the circle of Willis, a ring of connecte d arteries that lies in the int erpeduncular cistern betwe en the midbrain and pons.
- 6. • Cerebellum is located under the cer ebrum. Its function is to coordinate muscle movements, maintain postu re, and balance. COMPOSITIO N OF HUMAN BRAIN • Brainstem acts as a relay center connecting t he cerebrum and cerebellum to the spinal cor d. It performs many automatic functions such as breathing, heart rate, body temperature, w ake and sleep cycles, digestion, sneezing, co ughing, vomiting, and swallowing. • Cerebrum is the largest part of the brain and is composed of right and left hemispheres. It performs highe r functions like interpreting touch, vision and hearing, as well as spee ch, reasoning, emotions, learning, and fine control of movement.
- 7. 4 LOBES OF THE BRAIN FRONTAL LOBE OCCIPITAL LOBE TEMPORAL LOBE PARIETAL LOBE • Personality, behavior, emotions • Judgment, planning, problem solvin g • Speech: speaking and writing (Broc a’s area) • Body movement (motor strip) • Intelligence, concentration, self awa reness • Interprets language, words • Sense of touch, pain, temperature (sensory strip) • Interprets signals from vision, hea ring, motor, sensory and memory • Spatial and visual perception • Interprets vision (colour, light, movement • Understanding language (Wernicke’s area) • Memory • Hearing • Sequencing and organization
- 8. BRAIN SIZE The size of the brain and a person's intelligenc e are not strongly related. Studies tend to indicat e small to moderate correlations (averaging arou nd 0.3 to 0.4) between brain volume and IQ. The most consistent associations are observed within the frontal, tem poral, and parietal lobes, the hippocampi, and the cerebellum, but these only account for a relativel y small amount of variance in IQ, which itself has o nly a partial relationship to general intelligence a nd real-world performance. Other animals, including whales and elephants h ave larger brains than humans. However, when the br ain-to-body mass ratio is taken into account, the human brain is almost twice as large as that of a bottlenose dolphin, and three times as large as that of a chimpanzee. However, a high ratio does not of its elf demonstrate intelligence: very small animals h ave high ratios and the treeshrew has the largest quo tient of any mammal.
- 9. DEVELOPMENT At the beginning of the third week of development, the em bryonic ectoderm forms a thickened strip called the neural plate. By the fourth week of development the neural plate has widened to give a broad cephalic end, a less broad mi ddle part and a narrow caudal end. These swellings are kn own as the primary brain vesicles and represent the begin nings of the forebrain, midbrain and hindbrain. Neural crest cells (derived from the ectoderm) populate th e lateral edges of the plate at the neural folds. In the fourth week—during the neurulation stage—the neural folds clos e to form the neural tube, bringing together the neural cres t cells at the neural crest.The neural crest runs the length of the tube with cranial neural crest cells at the cephalic en d and caudal neural crest cells at the tail. Cells detach fro m the crest and migrate in a craniocaudal (head to tail) wa ve inside the tube. Cells at the cephalic end give rise to th e brain, and cells at the caudal end give rise to the spinal cord. A characteristic of the brain is the cortical foldi ng known as gyrification. During fetal develop ment, the cortex starts off smooth. By the ges tational age of 24 weeks, the wrinkled morphol ogy showing the fissures that begin to mark ou t the lobes of the brain is evident.
- 10. FUNCTIONS MOTOR CONTROL SENSORY REGULATION LANGUAGE LATERALISATION EMOTIONS COGNITION The frontal lobe is involved in reasoning, motor contr ol, emotion, and language. It contains the motor cort ex, which is involved in planning and coordinating m ovement; the prefrontal cortex , which is responsible for higher-level cognitive functioning; and Broca’s are a, which is essential for language production. The sensory nervous system is involved with the reception and processing of sensory infor mation. This information is received through t he cranial nerves, through tracts in the spinal cord, and directly at centres of the brain expo sed to the blood. Autonomic functions of the brain include the reg ulation, or rhythmic control of the heart rate an d rate of breathing, and maintaining homeostasi s. language functions were traditionally thought to be localized to Wernicke's area and Broca's area, it is now mostly accept ed that a wider network of cortical regions contributes to lan guage functions. The cerebrum has a contralateral organisation with each hemisphere of the brain interacting primarily with one half of the body: the left side of the brain interacts with the righ t side of the body, and vice versa. The developmental cau se for this is uncertain. Motor connections from the brain t o the spinal cord, and sensory connections from the spina l cord to the brain, both cross sides in the brainstem. Emotions are generally defined as two-step multic omponent processes involving elicitation, followed by psychological feelings, appraisal, expression, a utonomic responses, and action tendencies. The brain is responsible for cognition, which fun ctions through numerous processes and executi ve functions. Executive functions include the abi lity to filter information and tune out irrelevant sti muli with attention control and cognitive inhibitio n, the ability to process and manipulate informat ion held in working memory, the ability to think a bout multiple concepts simultaneously and switc h tasks with cognitive flexibility, the ability to inhi bit impulses and proponent responses with inhib itory control, and the ability to determine the rele vance of information or appropriateness of an a ction.
- 11. LEFT BRAIN V/S RIGHT BRAIN The human brain is divided into two hemispheres, th e left and right, connected by a bundle of nerve fiber s called the corpus callosum. The hemispheres are s trongly, though not entirely, symmetrical. The left br ain controls all the muscles on the right-hand side of the body and the right brain controls the left side. One hemisphere may be slightly dominant, as with le ft- or right-handedness. The popular notions about "left brain" and "right brai n" qualities are generalizations that are not well supp orted by evidence. Still, there are some important differences between these areas. The left brain cont ains regions involved in speech and language (call ed the Broca's area and Wernicke's area, respectivel y) and is also associated with mathematical calculati on and fact retrieval, Holland said. The right brain pl ays a role in visual and auditory processing, spatial skills and artistic ability — more instinctive or creativ e things, Holland said — though these functions invo lve both hemispheres. "Everyone uses both halves all the time," he said.
- 12. FACTS ABOUT HUMAN BRAIN • The human brain is the largest brain of all vertebr ates relative to body size. • It weighs about 3.3 lbs. (1.5 kilograms). • The average male has a brain volume of 1,274 cu bic centimetres. • The average female brain has a volume of 1,131 c m3. • The brain makes up about 2% of a human's body weight. • The cerebrum makes up 85% of the brain's weight . • It contains about 86 billion nerve cells (neurons) — the "gray matter." • It contains billions of nerve fibres • (axons and dendrites) — the "white matter." • These neurons are connected by trillions of connections, or synapses.
- 13. THE MIND A B C D The philosophy of the mind studi es such issues as the problem of understanding consciousness an d the mind–body problem. The r elationship between the brain a nd the mind is a significant chall enge both philosophically and sc ientifically. This is because of the difficulty in explaining how menta l activities, 5such as thoughts an d emotions, can be implemented by physical structures such as n eurons and synapses, or by any other type of physical mechani sm. This difficulty was express ed by Gottfried Leibnez in the an alogy known as Leibniz's Mi ll. Doubt about the possibility of a mechani stic explanation of thought drove Ren é Descartes, and most other philosoph ers along with him, to dualism: the b elief that the mind is to some degree ind ependent of the brain. There has always , however, been a strong argument in th e opposite direction. There is clear em pirical evidence that physical manipulat ions of, or injuries to, the brain can affect the mind in potent and intimate ways. In the 19th century, the case of Phineas G age, a railway worker who was injured by a stout iron rod passing through his brain, convinced both researchers and t he public that cognitive functions were lo calised in the brain. Following this line of thinking, a large body of empirical evi dence for a close relationship between b rain activity and mental activity has led most neuroscientists and contemporary philosophers to be materialists, believin g that mental phenomena are ultimately the result of, or reducible oto, physical p henomena.
- 14. The purpose of the bony skull is to protect the brain from injur y. The skull is formed from 8 bones that fuse together along suture lines. These bones include the frontal, parietal, tempo ral, sphenoid,occipital and ethmoid. The face is formed from 1 4 paired bones including the maxilla, zygoma, nasal, palatine, l acrimal, inferior nasal conchae, mandible, and vomer. Inside the skull are three distinct areas: anterior fossa, middle fossa and posterior fossa. Doctors sometimes refer to a tumor’ s location by these terms, e.g., middle fossa meningioma. Similar to cables coming out the back of a computer, all the arteries, veins and nerves exit the base of the skull through hol es, called foramina. The big hole in the middle (foramen magn um) is where the spinal cord exits. THE SKULL
- 15. CONCLUSION The brain is arguably the most impo rtant organ in the human body. It co ntrols and coordinates actions and r eactions, allows us to think and feel, and enables us to have memories a nd feelings—all the things that make us human. While the brain only weighs about th ree pounds, it is a highly complex or gan made up of many parts. Years o f scientific study have made it possi ble for scientists to identify the vario us areas of the brain and determine their specific functions. The followin g information provides a brief descri ption of some of the major parts of t he human brain.
- 17. THANK YOU EFFORTS BY:- VIHAAN BHAMBHANI CLASS:- X-D ROLL NO:- 38