PowerPoint Presentation

The Human Brain

Submitted to Dr. SikandarSubmitted by M. Mubashar BeigRoll No. 386-1503008Group CSection 1

Submitted to Dr. SikandarSubmitted by M. Mubashar BeigRoll No. 386-1503008Group CSection 1

If the human brain were so simple that we could understand it, we would be so simple that we couldnt

-Emerson Pugh, The Biological Origin of Human Values (1977)

If the human brain were so simple that we could understand it, we would be so simple that we couldnt

-Emerson Pugh, The Biological Origin of Human Values (1977)

Phineas GageSeptember 13th, 1848Phineas 25 years old Rutland & Burlington Railroad, Cavendish, VTPaving the way for new RR tracksTamping Iron1.25in x 3ft

Phineas GageAccidentQuick RecoveryMonths later: No longer GageBefore: capable, efficient, best foreman, well-balanced mindAfter: extravagant, anti-social, liar, grossly profaneStint with P.T BarnumDied 12 years later

Evolution of the Brain

Reptilian Paleomammalian Neomammalian

The Brain

weighs 1300 - 1400 g

made up of about 100 billion neurons

the most complex living structure on the universe Society for Neuroscience

makes us who we are

The BrainThe brain is responsible for many of the qualities that make each individual unique-thoughts, feelings, emotions, talents, memories, and the ability to process information.

Much of the brain is dedicated to running the body, the brain is responsible for maintaining Homeostasis by controlling and integrating the various systems that make up the body.

Protection of BrainThe Brain is Protected by a BONY Covering called the SKULL.

The Brain is also WRAPPED in THREE LAYERS of CONNECTIVE TISSUE known as the MENINGES.

Connective Tissue connects one tissue to another.

The INNER most layer, which covers and is bound to the surface of the brain, is called PIA MATER. It is a FIBEROUS LAYER made up of many Blood Vessels which carry FOOD and OXYGEN to the Brain.

The OUTER Layer, called the DURA MATER, is composed of Thick Connective Tissue.

The ARACHNOID is the THIN, elastic, weblike layer between the PIA MATER and the DURA MATER. Between the Pia Mater and the Arachnoid is a space filled with CEREBROSPINAL FLUID.

Cerebrospinal Fluid separates the middle and inner Meninges and fills four interconnected VENTRICLES, or Cavities in the Brain. Within the Ventricles, Cerebrospinal Fluid acts as a Transport Medium for substances that are important to Brain Function.

The Cerebrospinal Fluid is a clear liquid that PROTECTS the Brain from mechanical injury by acting as a Shock Absorber.

In order for the Brain to perform its functions, it must have a constant supply of Food and Oxygen.

If the Oxygen supply to the brain is cut off even for a few minutes, the brain will usually suffer enormous damage. Such damage may result in DEATH.

PARTS OF THE BRAIN

THE CEREBRUM

THE CEREBRUMTHE CEREBRUM IS THE CONTROL CENTER OF THE BRAIN.

The LARGEST and most PROMINENT part of the Human Brain is the CEREBRUM. 85% OF THE WEIGHT OF A HUMAN BRAIN.

The Cerebrum is responsible for all the VOLUNTARY (CONSCIOUS) ACTIVITIES OF THE BODY. It is the site of INTELLIGENCE, LEARNING AND JUDGMENT.

THE CEREBRUMIT FUNCTIONS IN LANGUAGE, CONSCIOUS THOUGHT, MEMORY, PERSONALITY DEVELOPMENT, VISION, AND OTHER SENSATIONS.

The Cerebrum takes up most of the space in the cavity that houses the Brain. (SKULL)

The CEREBRUM IS DIVIDED INTO TWO HEMISPHERES, THE LEFT AND RIGHT CEREBRAL HEMISPHERES.

THE CEREBRUM

THE CEREBRUMThere is a DEEP GROVE that separates the Two Hemispheres.

The Hemispheres are Connected in a region known as the CORPUS CALLOSUM.

THE CEREBRUMThe right and left cerebral hemispheres are linked by a bundle of neurons called A TRACT tells each half of the brain what the other half is doing. The MOST Obvious FEATURE on the surface of each hemisphere are NUMEROUS FOLDS.

These FOLDS and the GROOVES INCREASE the Surface Area of the Cerebrum. The Ridges are called GYRI, and the grooves are called SULCUS.

The Cerebrum, which looks like a wrinkled mushroom, is positioned over the rest of the brain.

THE CEREBRUMIt contains thick layers of Unmyelinated Neurons, which look GRAY. ("GRAY MATTER") The increased surface area permits the large number of neurons to fit easily within the confines of the Skull.

Lobes of the cerebrum

Lobes of the cerebrumEach Hemisphere of the Cerebrum is divided into Four regions called LOBES.

These LOBES are named for the SKULL BONES that cover them, FRONTAL, PARIETAL, TEMPORAL, AND OCCIPITAL LOBES.

Frontal LobeFound under your forehead.Center of reasoningPlanningsome parts of speechmovement (motor cortex)Emotionsproblem solving.

Parietal LobeFound on the top of your head.Receives sensory input from the skin. (touch, pressure, temperature, & pain)

Occipital lobeFound at the back of your head.Receives input from the eyesOften referred to as the visual cortex

Temporal LobeFound on the sides of your head above your ears.Functions include:speech perceptionhearing,some types of memory

THE CEREBELLUM The CEREBELLUM is the SECOND LARGEST part of the Brain, and is located at the back of the Skull. It coordinates muscle movements

THE CEREBELLUM The Cerebellum coordinates and balances the actions of Muscles so that the body can move gracefully and efficiently.

The Cerebellum CONTROLS BALANCE, POSTURE, and COORDINATION.

The Cerebellum receives sensory impulses from muscles, tendons, joints, eyes, and ears, as well as input from other brain centers.

THE CEREBELLUM It processes information about position and controls posture by keeping skeletal muscles in a constant state of partial contraction.

The Cerebellum Coordinates rapid and ongoing movements.

This is a small CAULIFLOWER SHAPED Structure.

THE CEREBELLUM A Major part of learning how to perform physical activities seems to be related to training the Cerebellum to coordinate the proper muscles. Because the function of the Cerebellum is INVOLUNTARY (not under conscious control), learning a completely new physical activity can be very difficult.

THE BRAIN STEM The BRAIN STEM CONNECTS the BRAIN to the SPINAL CORD.

THE BRAIN STEM The brain stem, which maintains life support systems, consist of the diencephalon, medulla oblongata, pons, and the midbrain.

The Brain Stem Controls Vital Body Processes.

The Brain stem not only coordinates and integrates all INCOMING INFORMATION; it also serves as the place of entry or exit for ten of the Twelve Cranial Nerves.

THE BRAIN STEM The Upper Brain Stem, the Diencephalon, contains important relay centers for information entering an exiting the brain.

The Lower Brain Stem consists of the MEDULLA OBLONGATA, PONS, AND MIDBRAIN.

The Lowest Part of the Brain Stem is the Medulla Oblongata (Sometimes just called the Medulla).

THE BRAIN STEM The Medulla contains WHITE MATER that conducts impulses between the Spinal Cord and Brain.

The MEDULLA controls involuntary functions that include, breathing, blood pressure, heart rate, digestion, swallowing, and coughing.

Another important part of the Medulla is a GROUP of CELLS known as THE RETICULAR ACTIVATING SYSTEM or RETICULAR FORMATION (RAS).

THE BRAIN STEM The Reticular Activation System (RAS) actually helps to alert, or awaken, the upper parts of the Brain, including the Cerebral Cortex. Such actions keep the Brain alert and conscious.

The RAS also helps to control respiration and circulation and serves as a filtering system for incoming sensory signals. For example, we awaken to the sound of an alarm clock, to a bright light flash, or to a painful pinch because activity in the RAS that arouses the Cerebral Cortex.

THE BRAIN STEM Just above the Medulla, the brainstem enlarges to form the PONS. PONS mean BRIDGE, and this area of the brain stem contains mostly white matter that provides a link between the cerebral cortex and the cerebellum. Above the PONS and continuous with it is the MIDBRAIN, the smallest division of the lower brain stem.

DIENCEPHALONTHE THALAMUS AND HYPOTHALAMUS The Thalamus and Hypothalamus are found in the part of the brain between the Brain Stem and Cerebrum.

The Thalamus, which is composed of Gray Matter, serves as a SWITCHING STATION FOR SENSORY INPUT. With the Exception of SMELL, each Sense Channels its Sensory Nerves through the Thalamus.

DIENCEPHALONThe Thalamus passes information to the proper region of the Cerebrum for further processing.

Immediately Below the Thalamus is the Hypothalamus, which is the CONTROL CENTER for hunger, thirst, fatigue, anger, and body temperature.

Parts of the Diencephalon and the Cerebrum are included in an important group of connected Brain Centers called the LIMBIC SYSTEM.

DIENCEPHALONThe Limbic System includes the Thalamus, the Hypothalamus, some deeper parts of the Cerebral Cortex, and centers in the Temporal Lobes.

The Limbic system plays an important role in emotions, memory, and motivation, among other things.

BRAIN GROWTH IN FETUS

Nervous SystemThe nervous system comprises the central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system, consisting of the cranial, spinal, and peripheral nerves, together with their motor and sensory endings.

Classification Of Nervous System

Central nervous system

The central nervous system is composed of millions of nerve and glial cells, together with blood vessels and a little connective tissue. The nerve cells, or neurons, are characterized by many processes and are specialized for reception and transmission of signals. The glial cells, termed neuroglia, are characterized by short processes that have special relationships to neurons, blood vessels, and connective tissue.

Peripheral Nervous SystemA nerve is a collection of nerve fibers that is visible to the naked eye. The constituent fibres are bound together by connective tissue. Each fiber is microscopic in size and is surrounded by a sheath formed by a neurilemmal cell (comparable to the glial cells of the central nervous system). Hundreds or thou sands of fibers are present in each nerve. Thus, according to the number of constituent fibers, a nerve may be barely visible, or it may be quite thick. A nerve as a whole is surrounded by a connective tissue sheath, the epineurium. Connective tissue fibers run inward from the sheath and enclose bundles of nerve fibers. Such bundles are termed fasciculi (funiculi); the connective tissue that encloses them is called perineurium. Very small nerves may consist of only one fasciculus derived from the parent nerve. Finally, each nerve fiber and its neurilemmal sheath are enclosed by a connective tissue sheath termed endoneurium.

Somatic Nervous SystemA collection of neurons that carries messages from the central nervous system to muscle cells.

Autonomic nervous systemA collection of neurons that carry messages from the central nervous system to the heart, smooth muscles, and glands generally not as a result of conscious action on the part of the brain.

Autonomic nervous system is further divided into two typesSympathetic nervous systemParasympathetic nervous system

Comparison Between Sympathetic and Parasympathetic nervous systemParasympathetic nervous systemSympathetic nervous systemIntroductionThe parasympathetic nervous system is one of the two main divisions of the autonomic nervous system (ANS). Its general function is to control homeostasis and the body's rest-and-digest response.The sympathetic nervous system (SNS) is one of two main divisions of the autonomic nervous system (ANS). Its general action is to mobilize the body's fight-or-flight response.FunctionControl the body's response while at rest.Control the body's response during perceived threat.

Originates inSpinal cord, medullaSpinal cord, thoracic and lumbar spinal cordActivates Response ofRest and digestFight or FlightNeuron PathwaysLonger pathways, slower systemVery short neurons, faster systemGeneral Body ResponseCounterbalance; restores body to state of calm.Body speeds up, tenses up, becomes more alert. Functions not critical to survival shut down.Cardiovascular System (heart rate)Decreasesheart rateIncreases contraction, heart ratePulmonary System (lungs)Bronchial tubes constrictBronchial tubes dilateMusculoskeletal SystemMuscles relaxMuscles contract

PupilsConstrictDilateGastrointestinal SystemIncreases stomach movement and secretionsDecreases stomach movement and secretionsSalivary GlandsSaliva production increasesSaliva production decreasesAdrenal GlandNo involvementReleases adrenalineGlycogen to Glucose ConversionNo involvementIncreases; converts glycogen to glucose for muscle energyUrinary ResponseIncrease in urinary outputDecrease in urinary output