 |
Iowa Teaching Standards
Science Standards & Benchmarks
Class Management Plan
Unit Plan
Lesson Plans
Video of Teaching
Sample of Power Point
Samples of Student Work
Student Appreciation
Link to experimental site
THE BRAIN & THE 5 SENSES
Link to main course page
| THE BRAIN & FIVE
SENSES UNIT OBJECTIVES: Describe all the major parts of the brain and their functions. Summarize the functions of the cerebrum, brain stem, and cerebellum. Describe how the brain is protected from injury. List and describe the five types of sensory receptors. Describe the structure of the eye and the roles of rods and cones. Identify the parts of the ear responsible for hearing and for maintaining balance. Compare the senses of smell and taste. Explain how taste and smell are detected. Identify the various sense receptors in the skin. Name the parts of the ear and explain the function of each part. Name the parts of the eye and explain the function of each part. THE BRAIN The human brain is responsible for overseeing the daily operations of the human body and for interpreting the vast amount of information it receives. The adult human brain weighs an average of 1.4 kg, or about 2 percent of the total body weight. Despite this relatively small mass, the brain contains approximately 100 billion neurons. Functioning as a unit, these neurons make up the most complex and highly organized structure on Earth. The 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. OBJECTIVES: Describe all the major parts of the brain and their functions. Summarize the functions of the cerebrum, brain stem, and cerebellum. Describe how the brain is protected from injury. 1. THE BRAIN IS THE MAIN SWITCHING UNIT OF THE CENTRAL NERVOUS SYSTEM; IT IS THE PLACE TO WHICH IMPULSES FLOW AND FROM WHICH IMPULSES ORIGINATE. 2. THE SPINAL CORD PROVIDES THE LINK BETWEEN THE BRAIN AND THE REST OF THE BODY. 3. THE BRAIN HAS THREE MAIN PARTS: A. THE CEREBRUM B. THE CEREBELLUM C. THE BRAIN STEM 4. The Brain is a highly organized ORGAN that contains approximately 100 billion neurons and has a MASS of 1.4 Kilograms. 5. The Brain is Protected by a BONY Covering called the SKULL. 6. The Brain is also WRAPPED in THREE LAYERS of CONNECTIVE TISSUE known as the MENINGES. 7. Connective Tissue connects one tissue to another. 8. The INNER most layer, which covers and is bound to the surface of the brain, is called PIA MATER. 9. It is a FIBEROUS LAYER made up of many Blood Vessels which carry FOOD and OXYGEN to the Brain. 10. The OUTER Layer, called the DURA MATER, is composed of Thick Connective Tissue. 11. The ARACHNOID is the THIN, elastic, weblike layer between the PIA MATER and the DURA MATER. 12. Between the Pia Mater and the Arachnoid is a space filled with CEREBROSPINAL FLUID. 13. 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. 14. The Cerebrospinal Fluid is a clear liquid that PROTECTS the Brain from mechanical injury by acting as a Shock Absorber. 15. In order for the Brain to perform its functions, it must have a constant supply of Food and Oxygen. 16. 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 1. THE CEREBRUM IS THE CONTROL CENTER OF THE BRAIN. 2. The LARGEST and most PROMINENT part of the Human Brain is the CEREBRUM. 85% OF THE WEIGHT OF A HUMAN BRAIN. 3. The Cerebrum is responsible for all the VOLUNTARY (CONSCIOUS) ACTIVITIES OF THE BODY. 4. It is the site of INTELLIGENCE, LEARNING AND JUDGMENT. 5. IT FUNCTIONS IN LANGUAGE, CONSCIOUS THOUGHT, MEMORY, PERSONALITY DEVELOPMENT, VISION, AND OTHER SENSATIONS. 6. The Cerebrum takes up most of the space in the cavity that houses the Brain. (SKULL) 7. The CEREBRUM IS DIVIDED INTO TWO HEMISPHERES, THE LEFT AND RIGHT CEREBRAL HEMISPHERES. 8. There is a DEEP GROVE that separates the Two Hemispheres. 9. The Hemispheres are Connected in a region known as the CORPUS CALLOSUM. 10. The right and left cerebral hemispheres are linked by a bundle of neurons called A TRACT. 11. THE TRACT TELLS EACH HALF OF THE BRAIN WHAT THE OTHER HALF IS DOING. 12. The MOST Obvious FEATURE on the surface of each hemisphere are NUMEROUS FOLDS. 13. These FOLDS and the GROVES INCREASE the Surface Area of the Cerebrum. The Ridges are called GYRI, and the grooves are called SULCUS. 14. The Cerebrum, which looks like a wrinkled mushroom, is positioned over the rest of the brain. 15. It contains thick layers of Unmyelinated Neurons, which look GRAY. (OUR "GRAY MATTER") 16. The increased surface area permits the large number of neurons to fit easily within the confines of the Skull. 17. Each Hemisphere of the Cerebrum is divided into Four regions called LOBES. 18. These LOBES are named for the SKULL BONES that cover them, FRONTAL, PARIETAL, TEMPORAL, AND OCCIPITAL LOBES. 19. Scientist have Discovered that the LEFT Side of the Body SENDS its Sensations to the RIGHT Hemisphere of Cerebrum, and the RIGHT Side of the body send its sensations to the LEFT Hemisphere. 20. Commands to move muscles are generated in the same way the Left Hemisphere controls the Right side of the body and the Right Hemisphere controls the Left side of the body. 21. The RIGHT Hemisphere is associated with CREATIVITY AND ARTISTIC ABILITY. 22. The LEFT Hemisphere is associated with ANALYTICAL AND MATHEMATICAL ABILITY. 23. Sometimes blood vessels in the brain are blocked by blood clots, causing a disorder called A STROKE. 24. During a Stroke, circulation to an area in the brain is blocked and the brain tissue dies. A severe Stroke in one side of the brain may cause PARALYSIS of the other side of the body. 25. The Cerebrum consists of TWO SURFACES. A. The FOLDED OUTER SURFACE is called the CEREBRAL CORTEX and consists of GRAY MATTER (UNMYELINATED NEURONS). B. The INNER SURFACE is called the CEREBRAL MEDULLA, which is made up of bundles of MYELINATED AXONS. THE WHITE MATTER. 26. The Myelin gives the White Mater its White Color. THE CEREBELLUM 1. The CEREBELLUM is the SECOND LARGEST part of the Brain, and is located at the back of the Skull. 2. THE CEREBELLUM COORDINATES MUSCLE MOVEMENTS. 3. The Cerebellum coordinates and balances the actions of Muscles so that the body can move gracefully and efficiently. 4. The Cerebellum CONTROLS BALANCE, POSTURE, and COORDINATION. 5. The Cerebellum receives sensory impulses from muscles, tendons, joints, eyes, and ears, as well as input from other brain centers. 6. It processes information about position and controls posture by keeping skeletal muscles in a constant state of partial contraction. 7. The Cerebellum Coordinates rapid and ongoing movements. 8. This is a small CAULIFLOWER SHAPED Structure, while well developed in mammals, is even more developed in BIRDS. 9. Bird performs more complicated feats of balance than most mammals, because they move through the air, as well as, along the ground. 10. Imagine the kind of balance and coordination needed for a bird to land on a branch at precisely the right moment. 11. A Major part of learning how to perform physical activities seems to be related to training the Cerebellum to coordinate the proper muscles. 12. 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 1. The BRAIN STEM CONNECTS the BRAIN to the SPINAL CORD. 2. THE BRAIN STEM, WHICH MAINTAINS LIFE SUPPORT SYSTEMS, CONSIST OF THE DIENCEPHALON, MEDULLA OBLONGATA, PONS, AND THE MIDBRAIN. 3. THE BRAIN STEM CONTROLS VITAL BODY PROCESSES. 4. 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. 5. The Upper Brain Stem, the Diencephalon, contains important relay centers for information entering an exiting the brain. 6. The Lower Brain Stem consists of the MEDULLA OBLONGATA, PONS, AND MIDBRAIN. 7. The Lowest Part of the Brain Stem is the Medulla Oblongata (Sometimes just called the Medulla). 8. The Medulla contains WHITE MATER that conducts impulses between the Spinal Cord and Brain. 9. THE MEDULLA CONTROLS INVOLUNTARY FUNCTIONS THAT INCLUDE, BREATHING, BLOOD PRESSURE, HEART RATE, DIGESTION, SWALLOWING, AND COUGHING. 10. Another important part of the Medulla is a GROUP of CELLS known as THE RETICULAR ACTIVATING SYSTEM or RETICULAR FORMATION (RAS). 11. The Reticular Activation System (RAS) actually helps to alert, or awaken, the upper parts of the Brain, including the Cerebral Cortex. 12. Such actions keep the Brain alert and conscious. 13. The RAS also helps to control respiration and circulation and serves as a filtering system for incoming sensory signals. 14. 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. 15. Just above the Medulla, the brainstem enlarges to form the PONS. 16. 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. 17. Above the PONS and continuous with it is the MIDBRAIN, THE SMALLEST DIVISION OF THE LOWER BRAIN STEM. 18. AREAS OF THE MIDBRAIN ARE INVOLVED IN HEARING AND VISION. THE UPPER BRAIN STEM - DIENCEPHALON THE THALAMUS AND HYPOTHALAMUS 1. The Thalamus and Hypothalamus are found in the part of the brain between the Brain Stem and Cerebrum. 2. 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. 3. The Thalamus passes information to the proper region of the Cerebrum for further processing. 4. Immediately Below the Thalamus is the Hypothalamus, which is the CONTROL CENTER for HUNGER, THIRST, FATIGUE, ANGER, AND BODY TEMPERATURE. 5. Parts of the Diencephalon and the Cerebrum are included in an important group of connected Brain Centers called the LIMBIC SYSTEM. 6. The Limbic System includes the Thalamus, the Hypothalamus, some deeper parts of the Cerebral Cortex, and centers in the Temporal Lobes. 7. The Limbic system plays an important role in emotions, memory, and motivation, among other things. SENSORY SYSTEMS Human experience is effected by both internal and external stimuli. Humans are able to distinguish among many different types of stimuli by means of a highly developed system of SENSE ORGANS. Sensory Systems represent an integration of the functions of the Peripheral Nervous System and the Central Nervous System. The Sensory Division of the Peripheral Nervous System gathers information about the Body's Internal Conditions and External Environment. Sensory Systems translate light, sound, temperature, and other aspects of the Environment to Electrical Signals and transmit these signals, in the form of Action Potentials, to the Central Nervous System, where they are Interpreted. OBJECTIVES: List and describe the five types of sensory receptors. Describe the structure of the eye and the roles of rods and cones. Identify the parts of the ear responsible for hearing and for maintaining balance. Compare the senses of smell and taste. Explain how taste and smell are detected. Identify the various sense receptors in the skin. Name the parts of the ear and explain the function of each part. Name the parts of the eye and explain the function of each part. 1. There are million of neurons in the body that do not receive impulses from other neurons. Instead these neurons which are called SENSORY RECEPTORS, REACT DIRECTLY TO STIMULATION FROM THE ENVIRONMENT. 2. Many Receptors that enable the Body to RECEIVE INFORMATION from the ENVIRONMENT are located in highly specialized Organs called SENSE ORGANS. 3. Examples of stimulation include: LIGHT, SOUND, MOTION, CHEMICAL, PRESSURE, PAIN OR CHANGES IN THE TEMPERATURE. 4. Once these Sensory Receptors are Stimulated, they TRANSFORM one form of ENERGY from the Environment (LIGHT, SOUND) into another form of ENERGY (ACTION POTENTIAL) that can be transmitted to other neurons. These Action Potentials (IMPULSES) reach the Central Nervous System (CNS). 5. A Sensory Receptor is a Neuron that is Specialized to detect a Stimulus. There are many kinds of Sensory Receptors, and they can be categorized on the Basis of the Type of Stimuli they Respond To: A. MECHANORECEPTORS - Respond to Movement, Pressure, and Tension. B. PHOTORECEPTORS (RODS AND CONES) - Respond to Variations in Light. C. CHEMORECEPTORS - Respond to Chemicals. D. THERMORECEPTORS - Respond to Changes in Temperature. E. PAIN RECEPTORS - Respond to Tissue Damage - PAIN! 6. THE SENSORY RECEPTORS ARE CONTAINED IN THE SENSE ORGANS. 7. EACH OF THE FIVE SENSES (SIGHT, HEARING, SMELL, TASTE, AND TOUCH) HAS A SPECIFIC SENSE ORGAN ASSOCIATED WITH IT. 8. The MOST familiar Sense Organs are the EYES, EARS, NOSE, SKIN AND TASTE BUDS. These Organs have RECEPTORS that can respond to Stimuli by producing NERVE IMPULSES in a Sensory Neuron. 9. The Receptors CONVERT the ENERGY of a Stimulus into ELECTRICAL ENERGY that can travel in the NERVOUS SYSTEM. 10. Receptors INSIDE the body inform the CNS about the CONDITIONS OF THE BODY. 11. EXAMPLE: TEMPERATURE Receptors throughout the body detect Changes in Temperature. This information travels to the HYPOTHALAMUS, which helps control body temperature. 12. SPECIALIZED CELLS (Receptors) WITHIN EACH SENSE ORGAN ENABLE IT TO RESPOND TO PARTICULAR STIMULI. 13. Messages from Sense Organs to the CNS are all in the form of Nerve Impulses. How does are brain know whether incoming impulse is sound or light? 14. This Information is built into the "WIRING" in the Pathways of Neurons that Synapse with each other, and into the location in the Brain where the information arrives. 15. The Brain knows if the information received is from a Sensory Neuron that comes from LIGHT RECEPTORS CELLS when it gets the message. HEARING AND BALANCE 1. The EAR is really TWO Sense Organs in ONE. It not only detects Sound Waves, it also senses the Position of the HEAD, whether it is STILL, MOVING IN A STRAIGHT LINE, OR ROTATING. 2. Sound is nothing more than Vibrations in the Air around us. 3. Deep LOW-PITCHED Sounds result from slow vibrations. HIGH-PITCHED Sounds are caused from faster Vibrations. 4. In addition to Pitch, sounds differ by their Loudness or Volume. 5. The Sense Organ that can distinguish BOTH PITCH AND LOUDNESS of SOUNDS are the EARS. 6. The External Ear consists of the visible fleshy part helps to COLLECT Sounds and FUNNEL them into the AUDITORY CANAL. The Auditory Canal connects the External Ear with the TYMPANIC MEMBRANE, also called the Eardrum. 7. The Auditory Canal contains small Hairs and WAX Producing GLANDS that PREVENT Foreign objects from entering the ear. 8. The Auditory Canal extends into the bone of the head, but stops at the EARDRUM OR TYMPANIC MEMBRANE. 9. The Eardrum is the beginning of the MIDDLE EAR. 10. Sound Vibrations STRIKE the EARDRUM and are Transmitted through THREE TINY BONES: THE MALLEUS (HAMMER), INCUS (ANVIL), AND STAPES (STIRRUP). 11. The Stirrup transfers the Vibrations to a thin membrane covering an opening called the OVAL WINDOW. 12. This Membrane transmits the vibrations to the COCHLEA, which begins the INNER EAR. 13. The COCHLEA is SNAIL SHAPED, consisting of Three FLUID FILLED Chambers that are separated by membranes. 14. The Middle Chamber contains the ORGAN OF CORTI, which is the organ of Hearing. 15. When the Fluid Vibrates, tiny Hair Cells lining the Cochlea are PUSHED back and forth, providing Stimulation that is turned into NERVE IMPULSES. 16. These Nerve Impulses are carried to the Brain by the AUDITORY OR ACOUSTIC NERVE. 17. The EARS also contain structures for DETECTING STIMULI that make us aware of our MOVEMENTS and allow us to maintain our BALANCE. 18. Located within the INNER EAR just above the Cochlea are three tiny canals that lie at right angles to each other. 19. They are called the SEMICIRCULAR CANALS BECAUSE THEY EACH MAKE HALF A CIRCLE. 20. The Semicircular Canals and the TWO Tiny Sacs located behind them help us to SENSE BALANCE OR EQUILIBRIUM. 21. Both the Canals and the Sacs are filled with Fluid and Lined with Hair Cells (Mechanoreceptors). 22. There are also Tiny Grains of Calcium Carbonate and Protein called OTOLITHS, Otoliths roll back and forth in response to gravity, acceleration, and deceleration. 23. The Movement of Fluid and Otoliths bend the hair on the Hair Cells, and in turn sends the impulses to the Brain that enable it to determine BODY MOTION AND POSITION. VISION – THE EYE 1. The Sense Organ we use to sense Light is the EYES. 2. The EYE is composed of THREE LAYERS: A. The OUTER Layer consists of the SCLERA AND CORNEA. B. The MIDDLE Layer contains the CHOROID, CILIARY BODY, AND IRIS. C. The INNER Layer consists of the RETINA. 3. The SCLERA (WHITE OF THE EYE) consist of tough white connective tissue. The Sclera helps MAINTAIN the SHAPE OF EYE, and also provides a means of ATTACHMENT for the MUSCLES THAT MOVE THE EYE. 4. IN THE FRONT OF THE EYE, THE SCLERA FORMS A TRANSPARENT LAYER CALLED THE CORNEA. 5. The CORNEA is the part of the eye through which LIGHT ENTERS. 6. Just inside the Cornea is a small chamber filled with FLUID known as the AQUEOUS HUMOR. 7. At the BACK of this chamber, the PIGMENTED CHOROID, WHICH CONTAINS THE BLOOD VESSELS OF THE EYE, BECOMES a disk-like structure called the IRIS. 8. The IRIS (A DIAPHRAGM) is the portion of the eye that gives your eye its COLOR. The Iris controls the amount of Light entering the eye by altering the Diameter of the Pupil. 9. In the MIDDLE of the Iris is a small opening called the PUPIL, through which LIGHT ENTERS THE EYE. 10. The Pupil appears as a small black disk in the CENTER of the Eye. Tiny muscles in the Iris REGULATE the SIZE of the Pupil, controlling the amount of Light to enter the Eye. 11. In DIM LIGHT the Pupil OPENS to INCREASE the amount of Light, In BRIGHT LIGHT the Pupil CLOSES to DECREASE the amount of Light entering the Eye. 12. Behind the Iris is the LENS. Light is Focused by the Lens, which changes shape when pulled by muscles around its edges. 13. The CELLS that form the Lens contain a special PROTEIN called CRYSTALIN. CRYSTALIN is almost transparent and allows light to pass through. 14. Small Muscles attached to the Lens cause it to bend, this enables the eye to FOCUS on close and distant objects. 15. Behind the Lens is a Large Chamber called the VITREAL CHAMBER filled with a transparent Jelly-like Fluid called VITREOUS HUMOR. 16. Special Light Sensitive RECEPTOR CELLS, or PHOTORECEPTORS, are arranged in a layer in the RETINA, at the BACK of the EYE. 17. The PHOTORECEPTORS CONVERT LIGHT ENERGY INTO IMPULSES THAT ARE CARRIED TO THE CNS. 18. THERE ARE TWO TYPES OF PHOTORECEPTORS: RODS AND CONES. We have about 125 million RODS and 7 million CONES on a single Retina. 19. Photoreceptors contain a PIGMENT called RHODOPSIN, that can respond to most wavelengths of light. 20. RODS are extremely sensitive to ALL COLORS of LIGHT, but DO NOT DISTINGUISH DIFFERENT COLORS. 21. CONES are less sensitive than RODS, but they DO RESPOND DIFFERENTLY TO LIGHT OF DIFFERENT COLORS, PRODUCING COLOR VISION. 22. Humans have three kinds of cones. Each type of cone contains a pigment that absorbs different wavelengths of light. When the signals from these three kinds of cone are integrated, a person is able to see all the colors in the visible spectrum. 23. In DIM Light, when only RODS are activated, you may see objects clearly, but not their colors. 24. As the amount of Light INCREASE, the CONES are stimulated and the colors become clear. 25. The Impulses leave the Eye by way of the OPTIC NERVE, and CARRIED to the part of BRAIN Known as the OPTIC LOBE OR OCCIPITAL LOBE. Here the Brain Interprets the visual images and provides information about the external world. SMELL 1. The Sense of Smell is a CHEMICAL SENSE, the Cells responsible for smell are Specialized Chemoreceptors called OLFACTORY RECEPTORS. 2. These Cells are located in the Upper Part of the Nasal Cavity. 3. Chemoreceptors contain Cilia that extend into the air passageways of the nose and react to Chemicals in the Air. Chemicals that come into contact with the Chemoreceptors Stimulate them, causing Impulses to be sent to the Brain by the OLFACTORY NERVE. TASTE 1. The Sense of Taste is a Chemical Sense. 2. The Cells that are Stimulated by the Chemicals are called CHEMORECEPTORS. 3. The Sense Organ that detects Taste are the TASTE BUDS. NOT THE TONGUE! 4. Most of the 10,000 Taste Buds are embedded between bumps called PAPILLAE on the tongue, but can also be found on the roof of the mouth, on the lips, and in the throat. 5. Humans can detect FOUR main kinds of TASTE: SWEET, SALTY, SOUR, AND BITTER. 6. Each Taste Bud shows a particular Sensitivity to one of these taste. The Sense of Taste is converted to Nerve Impulses in the Taste Buds and transmitted to the Brain by TWO Nerves - The FACIAL NERVE AND GLOSSOPHARYNGEAL NERVES. 7. Many of the Sensation associated with taste are actually SMELL Sensations, You depend on both Senses to detect Flavors in Food. 8. That is why when you have a Cold and Your Smell Receptors are blocked, food seems to have little or no taste. TOUCH AND RELATED SENSES 1. All Regions of our bodies are sensitive to TOUCH. 2. YOUR LARGEST SENSE ORGAN IS YOUR SKIN. 3. MECHANORECEPTORS located throughout the Skin make it possible to sense touch, pressure, and tension. 4. In humans, the receptors for touch are concentrated in the face, tongue, and fingertips. 5. Body hair also plays an important role in the ability to sense touch. Large numbers of Mechanoreceptors are found in the skin at the base of hair follicles. 6. Our Skin has several different types of Sensory Receptors that are just below the surface of the Skin. 7. Two Types respond to Heat or Cold - THERMORECEPTORS; Two others respond to TOUCH - MECHANORECEPTORS; one Type responds to TISSUE DAMAGE WHICH CAUSES PAIN - PAIN RECEPTORS. 8. Sensory receptors for Hot or Cold are scattered directly below the surface of the skin. There are THREE to FOUR WARM Receptors for every COLD Receptor. 9. Sensory Receptor can be more concentrated in different places of our bodies. 10. The MOST TOUCH-Sensitive areas are the FINGERS, TOES, AND LIPS. 11. Pain Receptors are located throughout the skin. The Sensation of Pain can be experienced as either Prickling Pain (FAST PAIN) or Burning and Aching Pain (SLOW PAIN). Pain receptors are Stimulated by mechanical, thermal, electrical, or chemical Energy. |