Nervous System PPT PDF

2  Master control and communication system of the body Every thought, action, and emotion is a result of its activity Uses electrical impulses to interpret and respond to what’s happening inside and outside the body 3  Brain Spinal Cord Sensory...

2  Master control and communication system of the body Every thought, action, and emotion is a result of its activity Uses electrical impulses to interpret and respond to what’s happening inside and outside the body 3  Brain Spinal Cord Sensory Organs Nerves - connect these components throughout the body 4  Sensory Input: You’re driving and see a red light ahead Integration: Your nervous system integrates this information as “red light means stop” Motor Output: The muscles of your right leg and foot move to press the brake 6  Central Nervous System (CNS) Brain Spinal Cord Peripheral Nervous System (PNS) Nerves outside the CNS 7  Acts as the integration and command center Takes in all conscious and subconscious sensory information Makes decisions and initiates responses to maintain homeostasis 8  Includes all parts of the nervous system outside the CNS Links all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to glands or muscles 9 Two Subdivisions of the PNS: Sensory or Afferent Division Nerves that carry information TO the CNS Motor or Efferent Division Nerves that carry information FROM the CNS 10 11  Allows conscious or Regulates events voluntary control of that are automatic skeletal muscles or involuntary Includes reflexes Ex: smooth and cardiac muscles and glands 12 13  Supporting Cells or neuroglia – insulate, support, and protect delicate neurons Neurons – nerve cells 14 15  Dendrites: fibers that receive & convey messages to cell body Cell body: metabolic center of the cell; contains the nucleus Axon: fibers that conduct impulses away from the cell body Axon terminal: branching fibers at the end of the axon; contain vesicles filled with chemicals called neurotransmitters 16  NEURON DETAILS Dendrite Axon Terminal Node of Ranvier Cell Body direction of impulse Axon Schwann Cell Myelin Sheath Nucleus 17  Some neurons have a covering composed of a whitish, fatty material called myelin Insulates fibers and increases the rate of transmission of the nerve impulse 18  Nerve cells outside the CNS are myelinated by Schwann cells Wrap themselves around the axon Gaps between Schwann cells, Nodes of Ranvier, allow impulse to jump from node to node, increasing transmission speed 19  At their terminal end, axons branch into hundreds or thousands of axon terminals Each contains vesicles or sacs of neurotransmitters When a nerve impulse reaches an axon terminal, it stimulates the release of neurotransmitters 20  Neurons do not actually touch each other The junction between them is called a synapse Neurotransmitters diffuse across the synapse to continue cell to cell communication 21  In CNS, bundles of nerve fibers are called tracts White matter – myelinated axons in tracts Gray matter – unmyelinated cell bodies In PNS, they are called nerves 22  Sensory Neurons (green) carry impulses from receptors such as the skin to the CNS Interneurons connect sensory and motor neurons in the CNS (yellow) Motor Neurons (purple) carry impulses from the CNS to a muscle or gland 23  Sensory receptors in the muscles and tendons Detect stretch or tension in skeletal muscles, tendons and joints Maintain balance and posture 24 Four types based on the number of processes extending from the cell body. 1. Unipolar 2. Bipolar 3. Multipolar (most common) 4. Pseudounipolar 25 2 Major Functional Properties of Neurons Irritability – ability to respond to a stimulus and convert it into a nerve impulse Conductivity – ability to transmit the impulse to other neurons, muscles, or glands 26  The plasma membrane at rest is polarized There are fewer positive ions along the inside of the membrane than there are along the outside the cell membrane 27  Light Sound Waves Pressure Chemicals Neurotransmitters 28  A stimulus temporarily changes the permeability of the neuron membrane A depolarized membrane allows sodium (Na+) to flow in The exchange of ions completely reverses membrane polarity 29 If the stimulus is strong enough and the influx of sodium ions is great enough the depolarization activates a nerve impulse or action potential 30  If stimulus is strong enough an action potential is generated The impulse is either conducted over the entire axon or it doesn’t happen at all There is no partial impulse 31  Almost immediately after an action potential, the neuron membrane becomes impermeable to Na+ ions again K+ ions diffuse out to restore the negative charge on the inside of the membrane, an event known as repolarization 32 33  Tiny vesicles containing neurotransmitters fuse with axon membrane This chemical is released into the synapse and binds with receptor molecules on receiving neuron’s membrane 34  Chemicals released at the end of an axon terminal that diffuse across the synapse and transfer the nerve impulse to another nerve, muscle, or gland Ex: serotonin (top), norepinephrine (bottom), and acetylcholine 35  Action potential along the axon is electrical Transmission of the impulse across the synapse is chemical 36  Reflexes are rapid, predictable, involuntary responses to stimuli Protect the body Signal goes to spinal cord and immediate response is sent Occur over pathways called reflex arcs 37  Skeletal Muscles Smooth muscles Ex: pulling your Heart hand away from a Glands hot object Ex: secretion of saliva, dilation of pupils 38 1. Receptor – responds to stimulus 2. Sensory (afferent) Neuron 3. Integration center – spinal cord 4. Motor (efferent) Neuron 5. Effector – muscle or gland stimulated 39 40 1. Cerebrum 2. Diencephalon 3. Brain stem 4. Cerebellum 41  The largest and most superior part of the brain is the cerebrum The cerebrum is composed of two cerebral hemispheres divided by the longitudinal fissure Surface shows elevated ridges of tissue called gyri and shallow grooves called sulci 42  Outermost layer of the cerebrum Composed of gray matter Responsible for thinking and processing information from the five senses 43  Grooves or fissures divide the cerebral cortex into sections or lobes Lobes are named for the cranial bones that cover them Frontal (orange) Parietal (pink) Temporal (green) Occipital (purple) 44  Motor function Processes sensory Problem solving information such as Memory touch, temperature, and taste Language Judgment Socially acceptable behavior 45  Auditory perception Visual processing center Olfactory area is deep inside 46  Large fiber tract that connects the two cerebral hemispheres Allows communication between the two sides of the cerebral cortex 47  Superior to the brainstem 3 major structures: Thalamus Hypothalamus Epithalamus Thalamus: relay station for sensory impulses traveling to the sensory cortex Epithalamus: contains the pineal gland and choroid plexus which forms the cerebrospinal fluid 48  Important in maintaining homeostasis; maintains body temperature, water balance, and metabolism Part of the limbic system which controls emotions and drives such as hunger & thirst Controls the pituitary gland 49  Midbrain – reflex center for vision and hearing, eye movements Pons – coordinates information between brain areas, involved in breathing Medulla Oblongata – blood pressure, breathing, heart rate 50  Precise timing for skeletal muscle activity Balance and equilibrium Makes body movements smooth & coordinated 51  Bones: skull and vertebrae Meninges: connective tissue membranes Cerebrospinal Fluid (CSF) 52  Dura mater: tough, outer, double-layered membrane Arachnoid mater: web-like layer spans the subarachnoid space (purple) Pia mater: innermost membrane that clings tightly to the surface of the brain and spinal cord (pink) 53  Continually formed from plasma by clusters of capillaries in cavities called ventricles Provides a watery cushion for the brain & spinal cord Significant changes in CSF composition may indicate problems 54  The brain depends on a very stable internal environment Neurons are protected from blood-borne substances by the least permeable capillaries in the body 55  Continuous with the brain stem; connects the brain to nerves Enclosed within vertebrae; extends from the foramen magnum to L1 or L2 Provides a 2-way path to and from the brain Major reflex center 56  Gray matter forms the letter H in cross section Sensory neurons enter by the dorsal roots Motor neurons exit by the ventral roots Dorsal and ventral roots fuse to form spinal nerves 57 58  Endoneurium: surrounds each neuron Perineurium: surrounds a group of neurons or fascicle Epineurium: surrounds a nerve 59  31 pairs of spinal nerves exit from the vertebral column Intercostal nerves exit from T1-T12 All other spinal nerves form complex networks, each called a plexus, which serve the motor and sensory needs of the limbs 60  12 pairs of cranial nerves serve primarily the head and neck Optic, olfactory & vestibulocochlear are purely sensory All others serve both sensory and motor functions 61 62  Motor subdivision of the PNS that automatically controls body activities Maintains homeostasis Includes neurons that control: cardiac muscle smooth muscle glands 63 Both serve the same organs but counterbalance each other to keep body systems running properly. 64  Mobilizes the body Allows us to unwind during extreme and conserve energy situations Most active when the Ex: fear, exercise, or body is at rest and not rage threatened in any way 65  The sympathetic nervous system prepares the body to either fight or run from a threat Enables the body to cope rapidly and vigorously with situations that may disrupt homeostasis 66 67 68  Occurs when an external force injures the brain Common causes are falls, auto accidents, and violence Can result in physical, cognitive, social, or emotional symptoms 69  A mild form of traumatic brain injury Caused by a jolt, bump, or blow to the head that causes the brain to move rapidly inside the skull Symptoms include confusion, dizziness, headache, & nausea 70  Acute inflammation of the meninges Most often caused by viral or bacterial infection May lead to deafness, epilepsy, brain damage, or death Most common symptoms are severe headache and neck stiffness 71  Occurs when the myelin sheath around neurons is gradually destroyed and hardens into “scleroses” Nerve impulses are distorted or interrupted Autoimmune disease with no cure 72  A type of mental illness caused by progressive brain cell death Leads to problems with memory, thinking, and behavior Symptoms worsen over time No cure 73  A motor system disorder that leads to trembling of the hands, arms, legs, jaw or face and impaired balance and coordination Results from a loss of brain cells in an area of the midbrain called the substantia nigra 74  A loss of ability to move or feel anything in all or part of the body Results from illness, poison, or injury Most often results from stroke or spinal cord injury 75  A stroke is the death of brain cells that occurs when an area of the brain is deprived of oxygen due to poor blood flow Ischemic: blood flow is blocked by a clot Hemorrhagic: blood vessel leaks or ruptures 76 77  EXTRA SLIDE Insert text or an Change the layout image here of the slide under Hit RETURN or Insert Home > Layout > New Slide to insert Use View > Slide a new slide in a Sorter to drag the matching theme slide into the sequence you prefer 78