The Nervous System - Brain and Anatomy Presentation PDF

The Nervous System The Nervous System  What is the nervous system? The nervous system consists of two divisions: the central nervous system containing the brain and spinal cord, and the peripheral nervous system which is a network of nerves and neural tissues branching out througho...

The Nervous System The Nervous System  What is the nervous system? The nervous system consists of two divisions: the central nervous system containing the brain and spinal cord, and the peripheral nervous system which is a network of nerves and neural tissues branching out throughout the body.  Functions of the Nervous System 1. Sensory input – gathering information  To monitor changes occurring inside and outside the body (changes = stimuli) 2. Integration –  to process and interpret sensory input and decide if action is needed. 3. Motor output  A response to integrated stimuli  The response activates muscles or glands Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.1a  Structural Classification of the Nervous System  Central nervous system (CNS)  Brain  Spinal cord  Peripheral nervous system (PNS)  Nerve outside the brain and spinal cord Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.2  Functional Classification of the Peripheral Nervous System  Sensory (afferent) division  Nerve fibers that carry information to the central nervous system Figure 7.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.3a  Functional Classification of the Peripheral Nervous System  Motor (efferent) division  Nerve fibers that carry impulses away from the central nervous system Figure 7.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.3b  Functional Classification of the Peripheral Nervous System  Motor (efferent) division  Two subdivisions  Somatic nervous system = voluntary  Autonomic nervous system = involuntary Figure 7.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.3c Organization of the Nervous System  Neuron Anatomy  Cell body  Nucleus  Large nucleolus Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.9b  Neuron Anatomy  Extensions outside the cell body  Dendrites – conduct impulses toward the cell body  Axons – conduct impulses away from the cell body (only 1!) Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.10  Nerve Fiber Coverings  Schwann cells – produce myelin sheaths in jelly-roll like fashion  Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.12  Functional Classification of Neurons 1. Sensory (afferent) neurons Carry impulses from the sensory receptors 2. Motor (efferent) neurons Carry impulses from the central nervous system 3. Interneurons (association neurons) Connect sensory and motor neurons  Neuron Classification Figure 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.15  Structural Classification of Neurons  Multipolar neurons – many extensions from the cell body  Bipolar neurons – one axon and one dendrite  Unipolar neurons – have a short single process leaving the cell body What do you know about the brain? The brain has 2 sides: hemispheres  The brain is made up of different areas Cortex There are billions of neurons in the brain!!! Corpus callosum Cerebellum Neuron Neurons make networks  Regions of the Brain  Cerebral hemispheres  Diencephalon  Brain stem  Cerebellum  Lobes of the Cerebrum  Fissures (deep grooves) divide the cerebrum into lobes  Surface lobes of the cerebrum  Frontal lobe  Parietal lobe  Occipital lobe  Temporal lobe Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Layers of the Cerebrum  Gray matter  Outer layer  Composed mostly of neuron cell bodies Figure 7.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Diencephalon  Sits on top of the brain stem  Enclosed by the cerebral heispheres  Made of three parts  Thalamus  Hypothalamus  Epithalamus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Thalamus  Surrounds the third ventricle  The relay station for sensory impulses  Transfers impulses to the correct part of the cortex for localization and interpretation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.35  Hypothalamus  Under the thalamus  Important autonomic nervous system center  Helps regulate body temperature  Controls water balance  Regulates metabolism Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Epithalamus  Forms the roof of the third ventricle  Houses the pineal body (an endocrine gland)  Includes the choroid plexus – forms cerebrospinal fluid Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.37  Brain Stem  Attaches to the spinal cord  Parts of the brain stem  Midbrain  Pons  Medulla oblongata Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Brain Stem Figure 7.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Midbrain  Mostly composed of tracts of nerve fibers  Reflex centers for vision and hearing  Cerebral aquaduct – 3rd-4th ventricles Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.39  Pons  The bulging center part of the brain stem  Mostly composed of fiber tracts  Includes nuclei involved in the control of breathing Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.40  Medulla Oblongata  The lowest part of the brain stem  Merges into the spinal cord  Includes important fiber tracts  Contains important control centers  Heart rate control  Blood pressure regulation  Breathing  Swallowing  Vomiting Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.41  Cerebellum  Two hemispheres with convoluted surfaces  Provides involuntary coordination of body movements Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Protection of the Central Nervous System  Scalp and skin  Skull and vertebral column  Meninges Figure 7.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Meninges  Dura mater  Double-layered external covering  Periosteum – attached to surface of the skull  Meningeal layer – outer covering of the brain Folds inward in several areas Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Meninges  Arachnoid layer  Middle layer  Web-like  Pia mater  Internal layer  Clings to the surface of the brain Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Spinal Cord  Extends from the medulla oblongata to the region of T12  Below T12 is the cauda equina (a collection of spinal nerves)  Enlargements occur in the cervical and lumbar regions Figure 7.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.52  Spinal Cord Anatomy  Exterior white mater – conduction tracts Figure 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Spinal Cord Anatomy  Internal gray matter - mostly cell bodies  Dorsal (posterior) horns  Anterior (ventral) horns Figure 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Spinal Cord Anatomy  Central canal filled with cerebrospinal fluid Figure 7.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Spinal Cord Anatomy  Meninges cover the spinal cord  Nerves leave at the level of each vertebrae  Dorsal root  Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system Ventral root Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.54  Peripheral Nervous System  Nerves and ganglia outside the central nervous system  Nerve = bundle of neuron fibers  Neuron fibers are bundled by connective tissue Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.55  Spinal Nerves  There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.63  Spinal Nerves Figure 7.22a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.64  Autonomic Nervous System  The involuntary branch of the nervous system  Consists of only motor nerves  Divided into two divisions  Sympathetic division  Parasympathetic division Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.67 Autonomic nervous system… The sympathetic nervous system is responsible for the ‘flight or fight’ responses… increased alertness, metabolic rate, respiration, blood pressure, heart rate, and sweating AND a decrease in digestive and urinary function. The parasympathetic nervous system counteracts the responses of the sympathetic system… restoring homeostasis.  Anatomy of the Autonomic Nervous System Figure 7.25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.73 Central Nervous System (CNS): Brain + spinal cord Peripheral Nervous System (PNS) The motor division of the PNS is subdivided in: Voluntary actions Involuntary actions  The involuntary system is divided into: Sympathetic ‘fight or flight’ Parasympathetic ‘rest and digest’ Faster messages: Reflexes Spinal cord Sensory nerve Motor nerve Muscl e The knee reflex experiment  How fast are you? Distance Time 5 seconds window 2 in (~5 cm) 0.10 sec (100 ms) 4 in (~10 cm) 0.14 sec (140 ms) 6 in (~15 cm) 0.17 sec (170 ms) 8 in (~20 cm) 0.20 sec (200 ms) 10 in (~25.5 cm) 0.23 sec (230 ms) 12 in (~30.5 cm) 0.25 sec (250 ms) 17 in (~43 cm) 0.30 sec (300 ms) 24 in (~61 cm) 0.35 sec (350 ms) 31 in (~79 cm) 0.40 sec (400 ms) 39 in (~99 cm) 0.45 sec (450 ms) The Human Immune System  What is the immune system? The body’s defense against disease causing organisms, malfunctioning cells, and foreign particles  The First Line of Defense ~Skin~ - The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders - You shed between 40 – 50 thousand skin cells every day!  The First Line of Defense ~Mucus and Cilia~ - As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck - Hair-like structures called cilia sweep this mucus into the throat for coughing or Don’t swallowed bacteria have a swallowing good chance of infecting you?  The First Line of Defense ~Saliva~ What’s the first thing you do when you cut your finger? - Saliva contains many chemicals that break down bacteria - Thousands of different types of bacteria can survive these chemicals, however  The First Line of Defense ~Stomach Acid~ - Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food - The stomach must produce a coating of special mucus or this acid would eat through the stomach!  Think of the human body as a hollow plastic tube… The food is digested within the hole in the tube, but it never actually enters into the solid plastic material. Tube inner surface Tube outer surface Plastic interior ~Digestive System~ ~Skin~ ~Body~  Escherichia coli is common and plentiful in all of our digestive tracts. Why are we all not sick? - These bacteria are technically outside the body and aid in digesting material we cannot - Only if E.Coli are introduced in an unnatural manner can they break through the first line of defense and harm us  The Second Line of Defense ~White Blood Cells~ - If invaders actually get within the body, then your white blood cells (WBCs) begin their attack - WBCs normally circulate throughout the blood, but will enter the body’s tissues if invaders are detected Video  White Blood Cells ~Phagocytes~ These white blood cells are responsible for eating foreign particles by engulfing them Once engulfed, the phagocyte breaks the foreign particles apart in organelles called ________ Lysosomes Where could invaders hide from phagocytes?  Viruses Viruses enter body cells, hijack their organelles, and turn the cell into a virus making-factory. The cell will eventually burst, releasing thousands of viruses to infect new cells. Cell before infection… …and after.  The Second Line of Defense ~Interferon~ - Virus-infected body cells release interferon when an invasion occurs - Interferon – chemical that interferes with the ability to viruses to attack other body cells What happens to already infected cells?  White Blood Cells ~T-Cells~ T-Cells, often called “natural killer” cells, recognize infected human cells and cancer cells T-cells will attack these infected cells, quickly kill them, and then continue to search for more cells to kill  The Second Line of Defense ~The Inflammatory Response~ - Injured body cells release chemicals called histamines, which begin inflammatory response - Capillaries dilate - Pyrogens released, reach hypothalamus, and temperature rises - Pain receptors activate - WBCs flock to infected area like sharks to blood  Two Divisions of the Immune System - The efforts of the WBCs known as phagocytes and T-cells is called the cell- mediated immune system. - Protective factor = living cells - Phagocytes – eat invaders - T-cells – kill invaders  Two Divisions of the Immune System The other half of the immune system is called antibody-mediated immunity, meaning that is controlled by antibodies This represents the third line of defense in the immune system  The Third Line of Defense ~Antibodies~ - Most infections never make it past the first and second levels of defense - Those that do trigger the production and release of antibodies - Proteins that latch onto, damage, clump, and slow foreign particles - Each antibody binds only to one specific binding site, known as an antigen  Antibody Production - WBCs gobble up invading particles and break them up - They show the particle pieces to T-cells, who identify the pieces and find specific B-cells to help - B-cells produce antibodies that are equipped to find that specific piece on a new Video - 1:58 particle and attach  Immunity - New particles take longer to identify, and a person remains ill until a new antibody can be crafted - Old particles are quickly recognized, and a person may never become ill from that invader again. This person is now immune.  What is immunity? - Resistance to a disease causing organism or harmful substance - Two types - Active Immunity - Passive Immunity  Active Immunity - You produce the antibodies - Your body has been exposed to the antigen in the past either through: - Exposure to the actual disease causing antigen – You fought it, you won, you remember it - Planned exposure to a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it What is this second type of exposure called?  Vaccine Antigens are deliberately introduced into the immune system to produce immunity Because the bacteria has been killed or weakened, minimal symptoms occur Have eradicated or severely limited several diseases from the face of the Earth, such as polio and smallpox  How long does active immunity last? It depends on the antigen Some disease-causing bacteria multiply into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot Booster shot - reminds the immune system of the antigen Others last for a lifetime, such as chicken pox  Think the flu is no big deal? - Think again… - In 1918, a particularly deadly strain of flu, called the Spanish Influenza, spread across the globe - It infected 20% of the human population and killed 5%, which came out to be about 100 million people  Do we get all the possible vaccines we can? Although the Center for Disease Control (CDC) recommends certain vaccines, many individuals go without them Those especially susceptible include travelers and students Consider the vaccine for meningitis, which is recommended for all college students and infects 3,000 people in the U.S., killing 300 annually Link  Passive Immunity You don’t produce the antibodies – A mother will pass immunities on to her baby during pregnancy - through what organ? Placenta – These antibodies will protect the baby for a short period of time following birth while its immune system develops. What endocrine gland is Why doesn’t the mother just responsible for this? Thymus pass on the WBCs that “remember” the antigens? – Lasts until antibodies die Immune Disorders ~Allergies~ - Immune system mistakenly recognizes harmless foreign particles as serious threats - Launches immune response, which causes sneezing, runny nose, and watery eyes - Anti-histamines block effect of histamines and bring relief to allergy sufferers  Aquired Immune Deficiency Syndrome Caused by the Human Immunodeficiency Virus Discovered in 1983 Specifically targets and kills T-cells Because normal body cells are unaffected, immune response is not launched  AIDS ~The Modern Plague~ - The HIV virus doesn’t kill you – it cripples your immune system - With your immune system shut down, common diseases that your immune system normally could defeat become life-threatening - Can show no effects for several months all the way up to 10 years  AIDS ~The Silent Spread~ Transmitted by sexual contact, blood transfusions, contaminated needles As of 2007, it affects an estimated 33.2 million people