Human brain

this is a presentation on the mysterious body parts of the humans:
HUMAN BRAIN!!!!!

1. HUMAN BRAIN

2. ACKNOWLEDGEMENT!! I would like to express my special thanks of gratitude to my teacher Mrs. Preeti as well as our principal V eena S harma who gave me the golden opportunity to do this wonderful project on the topic human brain, which also helped me in doing a lot of Research and i came to know about so many new 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 1 1 12 10 4 LOBES FUNCTIONS FACTS THE MIND THE SKULL CONCLUSION

4. INTRODUCTION The brain is the most complex organ in the human body. It produces our every thought, action, memory,  feeling  and experience of the world. This jelly-like mass of tissue, weighing in at around 1.4 kilograms, contains a staggering one hundred billion nerve cells, or neurons. The complexity of the connectivity   between these cells is mind-boggling. Each neuron can make contact 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 our lives . The pattern and strength of the connections is constantly changing and no two brains are alike. It is in these changing connections  that  memories are stored, habits learned  and personalities shaped, by reinforcing certain patterns of brain activity , and losing others.

5. , STRUCTURE GROSS ANATOMY MICRO ANATOMY CEREBROSPINAL FLUID BLOOD SUPPLY The adult human brain weighs on average about 1.2–1.4 kg (2.6–3.1  lb.) which is about 2% of the total body weight ,  with a volume of around 1260 cm 3  in men and 1130 cm 3  in women .  There is substantial individual variation , with the standard reference range for men being 1,180–1,620 g (2.60–3.57  lb.)  and for women 1,030–1,400 g (2.27–3.09  lb.) The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. Types 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) in the nervous system. The adult human brain is estimated to contain 86±8 billion neurons , with a roughly equal number ( 85±10 billion) of non-neuronal cells. Out of these neurons, 16 billion (19 %) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum. Cerebrospinal fluid is a clear, colourless  trans cellular fluid that circulates around the brain in the subarachnoid space, in the ventricular system, and in the central canal of the spinal cord. It also fills some gaps in the subarachnoid space, known as subarachnoid cisterns. The four ventricles, two lateral, a third, and a fourth ventricle, all contain choroid plexus that produces cerebrospinal fluid. The internal carotid arteries supply oxygenated blood to the front of the brain and the vertebral arteries supply blood to the back of the brain. These two circulations join together in the circle of Willis, a ring of connected arteries that lies in the interpeduncular cistern between the midbrain and pons.

6. Cerebellum  is located under the cerebrum. Its function is to coordinate muscle movements, maintain posture, and balance. COMPOSITION OF HUMAN BRAIN Brainstem acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Cerebrum   is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, 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 solving Speech: speaking and writing (Broca’s area) Body movement (motor strip) Intelligence, concentration, self awareness Interprets language, words Sense of touch, pain, temperature (sensory strip) Interprets signals from vision, hearing, 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 intelligence are not strongly related .  Studies tend to indicate small to moderate correlations (averaging around 0.3 to 0.4) between brain volume and  IQ. The most consistent associations are observed within the frontal, temporal, and parietal lobes, the hippocampi, and the cerebellum , but these only account for a relatively small amount of variance in IQ, which itself has only a partial relationship to general intelligence and real-world performance. Other animals, including whales and elephants have larger brains than humans. However, when the brain-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 itself demonstrate intelligence: very small animals have high ratios and the treeshrew has the largest quotient of any mammal .

9. DEVELOPMENT At the beginning of the third week of development, the  embryonic 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 middle part and a narrow caudal end. These swellings are known as the primary brain vesicles and represent the beginnings of the forebrain, midbrain and hindbrain . Neural crest cells (derived from the ectoderm) populate the lateral edges of the plate at the neural folds. In the fourth week—during the neurulation stage—the neural folds close to form the neural tube, bringing together the neural crest cells at the neural crest. The neural crest runs the length of the tube with cranial neural crest cells at the cephalic end and caudal neural crest cells at the tail. Cells detach from the crest and migrate in a craniocaudal (head to tail) wave inside the tube .  Cells at the cephalic end give rise to the brain, and cells at the caudal end give rise to the spinal cord. A characteristic of the brain is the cortical folding known as gyrification. During fetal development, the cortex starts off smooth. By the gestational age of 24 weeks, the wrinkled morphology showing the fissures that begin to mark out 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 control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex , which is responsible for higher-level cognitive functioning; and Broca’s area, which is essential for language production. The sensory nervous system is involved with the reception and processing of sensory information. This information is received through the cranial nerves, through tracts in the spinal cord, and directly at centres of the brain exposed to the blood. Autonomic functions of the brain include the regulation, or rhythmic control of the heart rate and rate of breathing, and maintaining  homeostasis. language functions were traditionally thought to be localized to Wernicke's area and Broca's area ,  it is now mostly accepted that a wider network of cortical regions contributes to language 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 right side of the body, and vice versa. The developmental cause for this is uncertain .  Motor connections from the brain to the spinal cord, and sensory connections from the spinal cord to the brain, both cross sides in the brainstem. Emotions are generally defined as two-step multicomponent processes involving elicitation, followed by psychological feelings, appraisal, expression, autonomic responses, and action tendencies. The brain is responsible for cognition ,  which functions through numerous processes and executive functions .  Executive functions include the ability to filter information and tune out irrelevant stimuli with  attention control and cognitive inhibition, the ability to process and manipulate information held in working memory, the ability to think about multiple concepts simultaneously and switch tasks with cognitive flexibility, the ability to inhibit impulses and  proponent responses with inhibitory control, and the ability to determine the relevance of information or appropriateness of an action .

11. LEFT BRAIN V/S RIGHT BRAIN The human brain is divided into two hemispheres, the left and right, connected by a bundle of nerve fibers called the corpus callosum. The hemispheres are strongly, though not entirely, symmetrical. The left brain 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 left- or right-handedness . The popular notions about "left brain" and "right brain" qualities are generalizations that are not well supported by evidence . Still, there are some important differences between these areas. The left brain contains regions involved in speech and language (called the Broca's area and Wernicke's area, respectively) and is also associated with mathematical calculation and fact retrieval, Holland said. The right brain plays a role in visual and auditory processing, spatial skills and artistic ability — more instinctive or creative things, Holland said — though these functions involve 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 vertebrates relative to body size. It weighs about 3.3 lbs. (1.5 kilograms). The average male has a brain volume of 1,274 cubic centimetres. The average female brain has a volume of 1,131 cm3. 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 studies such issues as the problem of understanding consciousness  and the   mind–body problem. The relationship between the brain and the mind is a significant challenge both philosophically and scientifically. This is because of the difficulty in explaining how mental activities, 5such as thoughts and emotions, can be implemented by physical structures such as neurons and synapses, or by any other type of physical mechanism . This difficulty was expressed by Gottfried Leibnez  in the analogy known as   Leibniz's Mill. Doubt about the possibility of a mechanistic explanation of thought drove René Descartes, and most other philosophers along with him, to   dualism : the belief that the mind is to some degree independent of the brain. There has always, however, been a strong argument in the opposite direction. There is clear empirical evidence that physical manipulations of, or injuries to, the brain can affect the mind in potent and intimate ways .  In the 19th century, the case of Phineas Gage, a railway worker who was injured by a stout iron rod passing through his brain , convinced both researchers and the public that cognitive functions were localised in the brain .  Following this line of thinking, a large body of empirical evidence for a close relationship between brain activity and mental activity has led most neuroscientists and contemporary philosophers to be materialists, believing that mental phenomena are ultimately the result of, or reducible o to , physical phenomena.

14. The purpose of the bony skull is to protect the brain from injury. The skull is formed from 8 bones that fuse together along suture lines . These bones include the frontal, parietal, temporal, sphenoid,occipital and ethmoid . The face is formed from 14 paired bones including the maxilla, zygoma , nasal, palatine, lacrimal, 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 holes, called foramina. The big hole in the middle (foramen magnum) is where the spinal cord exits . THE SKULL

15. CONCLUSION The brain is arguably the most important organ in the human body. It controls and coordinates actions and reactions, allows us to think and feel, and enables us to have memories and feelings—all the things that make us human . While the brain only weighs about three pounds, it is a highly complex organ made up of many parts. Years of scientific study have made it possible for scientists to identify the various areas of the brain and determine their specific functions. The following information provides a brief description of some of the major parts of the human brain.

16. BIBLOGRAPHY 01 02 03 04 www.livescience.com en.wikipedia.org http://www.mayfieldclinic.com www.newscientist.com 05 www.princetonbrainandspine.com

17. THANK YOU EFFORTS BY:- VIHAAN BHAMBHANI CLASS:- X-D ROLL NO:- 38