Presentation on theme: "Nervous System. Nerves Hold out your hand in front of you Now wave at yourself Now, tap your head Put your arms down Say out loud to “Move Arm”…Just tell."— Presentation transcript:
Nerves Hold out your hand in front of you Now wave at yourself Now, tap your head Put your arms down Say out loud to “Move Arm”…Just tell it to move ▫Did it move? ▫Why not?
Nerves How does our arm know when you want it to move? Our experiment shows that your arm does not understand spoken commands. So what does it understand? What tells it to move. If you think it is your brain, you are correct.
Nerves But wait a moment. Your brain is clear up in your head, while your arm is clear down on your body. How does your brain talk to your arm? Somehow they must be connected. The connection between your brain and your arm, as well as every other part of your body is known as your nervous system.
Nervous System How are messages transmitted along your nervous system? Interestingly enough, messages travel from your brain to your various body parts via electricity, in much the same way cable television signals travel from the cable company to your house, or in the same way that this web page traveled from our web servers to your computer.
Are your Synapses Firing? Remember that the cells making up your nervous system are called neurons. Neurons are connected to other neurons, as well as to other tissues within the body via synapses. The location where a neuron connects to another cell is called a synapse.
Brain neurons firing When a message is transferred through a neuron it passes to the next neuron via an amazing fast chemical and electrical reaction. Because of its lightning speed, it is often said that a person’s synapses are firing when they are in deep thought. Regardless of whether you are solving a problem, or taking a nap, your synapses are always busy transporting messages.
The Central Nervous System (CNS) The Central Nervous System is made up of your brain, and your spinal cord. It is the main control center of your body, and the center of thought. Your Central Nervous System controls most of the actions within your body.
Peripheral Nervous System 3 kinds of neurons connect CNS to the body ▫sensory ▫motor ▫interneurons Motor - CNS to muscles and organs Sensory - sensory receptors to CNS Interneurons: Connections Within CNS Spinal Cord Brain Nerves
Peripheral Nervous System Skeletal (Somatic) SympatheticParasympathetic Autonomic Peripheral Nervous System
Neurons Generate Nerve Impulses A nerve impulse travels along the axon and dendrites as electrical current caused by ions moving in and out of the neuron through voltage-gated channels ▫these membrane channels open and close in response to electrical voltage changes The impulse starts when pressure or other sensory inputs disturb a neuron’s plasma membrane, causing Na + channels to open
Neurons Generate Nerve Impulses When Na + channels open, Na + floods into the neuron from the outside ▫for a brief moment, the inside of the neuron is “depolarized,” becoming more positive ▫the open Na + channels in the small patch of depolarized membrane remain open for only a half a millisecond ▫if the voltage change of the depolarization is great enough, it causes nearby voltage-gated Na + and K + channels to open
Neurons Generate Nerve Impulses The Na + channels open first, which starts a wave of depolarization moving down the neuron ▫this moving local reversal of voltage is called an action potential an action potential follows an all-or-none law: a large enough depolarization produces either a full action potential or none at all
Neurons Generate Nerve Impulses The K + voltage-gated channels open after a slight delay, causing K + to flow out of the cell ▫this makes the interior of the neuron more negative, causing the voltage-gated Na + channels to close The period of time after an action potential has passed but before the resting potential is restored is called the refractory period
Somatic System Nerves to/from spinal cord ▫control muscle movements ▫somatosensory inputs Both Voluntary and reflex movements Skeletal Reflexes ▫simplest is spinal reflex arc Muscle Motor Neuron Interneuron Skin receptors Sensory Neuron Brain
Autonomic System Two divisions: ▫sympathetic ▫Parasympatheitic Control involuntary functions ▫heartbeat ▫blood pressure ▫respiration ▫perspiration ▫digestion Can be influenced by thought and emotion
Sympathetic “Fight or flight” response Release adrenaline and noradrenaline Increases heart rate and blood pressure Increases blood flow to skeletal muscles Inhibits digestive functions CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney
Parasympathetic “Rest and digest” system Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil
Sensory Information sent to opposite hemisphere Principle is Contralateral Organization Sensory data crosses over in pathways leading to the cortex Visual Crossover ▫left visual field to right hemisphere ▫right field to left Other senses similar Left visual field Right visual field Optic nerves Corpus Callosum Left Visual Cortex Right Visual Cortex
Brain Your mind is a powerful and amazing organ. Its ability to calculate, control and think exceeds that of every computer on Earth put together. Your brain has three main parts. ▫Cerebrum ▫Cerebellum ▫Brain Stem.
Cerebrum Largest portion of the brain Your cerebrum is responsible for all the voluntary processes that you do each day, including thought. Voluntary means that you want to do something, or that you decide to do something, like hold your hand in the air, wave to yourself, and tap yourself on the head.
Cerebrum As you do these actions, your cerebrum sends electrical messages out to your body using the neurons of your nervous system. When the message reaches your arm, your muscles obey, and do as they are instructed.
Cerebellum Your cerebellum aids your cerebrum in the task of moving your muscles. It helps to maintain balance, moving the muscles you don’t think to move, as you make your arm wiggle around. This allows you to move about smoothly, with little effort.
Brain Stem Your brain stem sites at the base of the brain, and connects it to the spinal cord. The brain stem controls the flow of information between the brain and the rest of the body, and also controls many of the involuntary movements that your body does, every single day.
Localization of function Frontal Parietal Occipital Temporal
Occipital Lobe Input from Optic nerve Contains primary visual cortex most is on surface inside central fissure Outputs to parietal and temporal lobes Occipital Lobe Visual Lobe
Temporal Lobe Inputs are auditory, visual patterns speech recognition face recognition word recognition memory formation Outputs to limbic System, basal Ganglia, and brainstem z Contains primary auditory cortex Temporal Lobe Temporal Lobe Auditory Cortex
Parietal Lobe Parietal Lobe Inputs from multiple senses z contains primary somatosensory cortex z borders visual & auditory cortex z Outputs to Frontal lobe z hand-eye coordination z eye movements z attention Somatosensory Cortex
Frontal Lobe Frontal Lobe Motor action/behavior Contains primary motor cortex Motor Cortex Motor Cortex Broca’s Area Motor Cortex Working Memory No direct sensory input Important planning and sequencing areas Broca’s area for organization/speech Prefrontal area for working memory
Frontal Lobe Disorders Broca’s area productive aphasia-- an acquired language disorder affecting all modalities such as writing, reading, speaking, and listening and results from brain damage Prefrontal area lose track of ongoing context fail to inhibit inappropriate responses
The Nervous System: Summary Major structures of the nervous CNS, Somatic, Autonomic Two hemispheres & 4 lobes Organization contralateral input & output primary sensory areas motor areas Commissure Localization of functions Central Nervous System Peripheral Nervous System
Corpus Callosum What happens when the corpus callosum is cut? Sensory inputs are still crossed Motor outputs are still crossed Hemispheres can’t exchange data Epileptic
The ‘Split Brain’ studies Surgery for epilepsy : cut the corpus callosum Roger Sperry, 1960’s Special apparatus ▫picture input to just one side of brain ▫screen blocks objects on table from view Nonverbal right hemisphere Verbal left hemisphere
Nonverbal right hemisphere Verbal left hemisphere ?? “What did you see?” Picture to left brain ▫can name the object ▫left hand cannot identify by touch Picture to right brain can’t name the object left hand can identify by touch “Using your left hand, Pick up what you saw.” The ‘Split Brain’ studies I saw an apple. “What did you see?” Nonverbal right hemisphere Verbal left hemisphere
Super Highway Like a powerful broadband Internet connection, your spinal cord can move a lot of data very quickly. Its job is to carry messages to and from the body to the brain. There are 32 different nerves that connect directly into the spinal cord, and that branch outward towards the rest of the body. Reflexes are processed directly in the spinal cord, allowing you to respond very quickly to danger, without wasting time thinking about what you should do.
Addictive Drugs Act on Chemical Synapses Emotional states (mood, pleasure, pain, etc.) are determined by particular groups of neurons that use special sets of neurotransmitters and neuromodulators ▫many researchers think that depression results from a shortage of serotonin ▫Prozac, an anti-depressant, inhibits the reabsorption of serotonin
Drugs alter transmission of impulses across the synapse
Addictive Drugs Act on Chemical Synapses Nerve cells are particularly prone to the loss of sensitivity when exposed to a chemical signal for a long time ▫if receptor proteins within synapses are exposed to high levels of neurotransmitters for prolonged periods, the nerve cell often responds by inserting fewer receptor proteins into the membrane
Addictive Drugs Act on Chemical Synapses Cocaine acts a neuromodulator, causing abnormal amounts of neurotransmitters to remain in the synapse for long periods ▫it affect neurons in the brain’s pleasure pathways these cells transmit pleasure messages using the neurotransmitter dopamine ▫cocaine works by blocking transporter proteins on the presynaptic membrane that normally reabsorb dopamine because dopamine cannot bind to a transporter, it remains in the synapse and continues to stimulate
Addictive Drugs Act on Chemical Synapses When receptor proteins in the pleasure pathways of the brain are exposed to high levels of dopamine due to cocaine, the nerve cells respond by lowering the number of receptor proteins ▫with so few receptors, the drug user needs the drug to maintain even normal nerve activity levels ▫this is addiction, the physiological adaptation of the nervous system due to drug abuse
How drug addiction works
Addictive Drugs Act on Chemical Synapses Nicotine, also an addictive drug, binds to postsynaptic receptors in the brain that normally bind to Ach The brain responds by ▫making fewer receptors to which nicotine can bind ▫altering the pattern of activation of the nicotine receptors (i.e., their sensitivity to neurotransmitters) This leads to profound changes in the patterns of release of many neurotransmitters, and addiction results
How the Brain Works The cerebrum is the center for thought and association and makes up about 85% of the weight of the brain ▫the cerebrum is divided into right and left halves, called cerebral hemispheres Much of the neural activity of the cerebrum occurs within a thin, gray outer layer called the cerebral cortex
Senses We use our senses to get information about the world around us into our brains. There are five main senses that most of us use each day. ▫Sight ▫Hearing ▫Touch ▫Taste ▫smell Without senses, your brain would have no way of knowing what was going on around you. Life would be a very lonely, dark, and quiet place.
Eyes The human eye is an amazing and powerful organ. As you read the words on this screen, your eyes see the shapes of the letters, and transmit the information back to your brain. Light travels from the computer screen to your eyes, entering them through a transparent layer of tissue called the cornea.
Eyes The light of your computer screen then travels onward through the lens. The lens of your eye focuses the light onto a special tissue called the retina. The retina is lined with special photoreceptors called rods and cones. Rods are more sensitive to light, but cannot distinguish between colors. While cones are less sensitive, but can differentiate the different colors, giving us color vision. Not all animals have cones. What does this mean? It means that many animals see in black and white.
Eyes As light lands on the rods and cones it is converted into electrical impulses and is transmitted to the brain, where it is interpreted as the beautiful images all around us.
Sensing Light: Vision Color blindness occurs when individuals are not able to perceive all three colors ▫it typically occurs due to an inherited lack of one or more types of cones ▫it is a sex-linked trait, so men are more likely to be colorblind than women
Test for color blindness
Sometimes your eyes can play tricks on you…
Optical Illusion The brain also uses information learned in the past to help it perceive the images that the eyes send the brain can have a tendency to “force” an image into something that the image is not, just so the image looks more familiar. These are called cognitive illusions optical illusion isn’t “real,” although the brain interprets the illusion as being true
Hearing How do we hear? As objects move, or interact with other objects, they cause the air to vibrate. Think of a swimming pool. What happens if you jump in? First you make a big splash, followed by a series of ripples. The harder you jump, the bigger your ripples will be.
Hearing The air of our atmosphere works in much the same way as a swimming pool. Even though we cannot see the ripples, every time, we move they go traveling through the air. Some of these ripples, or vibrations reach our ears. Inside of your ear is a thin tissue known as the tympanum, or eardrum.
Hearing The vibrations in the air cause your eardrum to begin vibrating. Behind your eardrum are three tiny bones called Hammer Anvil Stirrup
Hearing As your eardrum begins to vibrate, so do these tiny bones. The last of these bones, the stirrup transmits these vibrations into the fluid filled cochlea. This causes tiny hairs within the cochlea to vibrate. The vibration of these hairs is converted into electrical impulses, which are then transmitted to the brain for interpretation.
Taste and Smell The senses of taste and smell are interpreted from tiny objects on your tongue, and in your nose. Receptors within your nose detect and transmit smells to your brain, while your taste buds detect and transmit flavors to your brain
Taste and Smell Much of what we think we are tasting is actually smell. Try an experiment. Next time you are eating something, plug your nose. What happens? Much of the flavor disappears.
Touch The senses we have discussed so far have been located in one specific location, such as the eye, or nose. However, your sense of touch is not restricted to one small area, but covers your entire body. Your skin is sensitive to heat, to pressure, and to pain. Within your body, there are also many nerve endings that are sensitive to touch.
Things to keep your mind moving… Leave your comfort zone. Getting good at sudoku? Time to move on. Brain teasers don't form new neural connections once you've mastered them. So try something that's opposite your natural skills: If you like numbers, learn to draw. If you love language, try logic puzzles.
Curry up. The active ingredient in Indian curry, turmeric, contains resveratrol, the same powerful antioxidant that makes red wine good for brain health. Eat curry once a week, or sprinkle it on salads, to protect brain cells from harmful free radicals.
Redecorate and redesign your environment. Plant new flowers in front of your house. Redecorate the kitchen. Rearrange your closets and drawers. Replace the candles in your living room with some that have a different scent. Making such changes can alter motor pathways in the brain and encourage new cell growth.
Sleep. Shut-eye isn't a luxury. It's when your brain consolidates memories. Poor sleep, caused by medical conditions, worry, depression, or insomnia, can interfere with your rest. So treat yourself to relaxing scents like vanilla before bed. They raise the chemical dopamine and reduce cortisol, a stress hormone.
Play Games Whether you choose Risk, Pictionary, Scrabble, Sudouku, Wii, XBOX or Boggle, games are associated with a lower risk of developing dementia. They activate strategic, spatial, and memory parts of the brain, and require you to socialize, which can help form new neural pathways.
Switch hands. It may be uncomfortable, but writing with your nondominant hand or operating a computer mouse with that hand can activate parts of the brain that aren't easily triggered otherwise. Anything that requires the brain to pay close attention to a formerly automatic behavior will stimulate brain-cell growth.