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ch15 nervous tissue
all ch 15 terms on structures and functions of the nervous system
| Question | Answer |
|---|---|
| one of the two subdivisions of the nervous system consistion of the brain and spinal cord | The central nervous system(CNS) |
| one of the two main subdivisions of the nervous system which include all nervous tissue outside the brain and spinal cord | The Peripheral nervous system (PNS) |
| A bundle of hundreds to thousands of axons plus associated connective tissue and blood vessles that lie outside the brain and spinal cord. | Nerves |
| One of 12 pairs of nerves that leave the brain: Pass through foramina in the skull; and supply sensory and motor neurons to the head, neck, and part of the trunk, and viscera of the thorax and abdomen. Each is designated by a Roman numeral and a name. | Cranial Nerve |
| This Connects to the brain, contains about 100 million neurons and is encircled by the bones of the vertebral column. | Spinal cord |
| One of 31 pairs of nerves that originate on the spinal cord frpm posterior and anterior roots. | Spinal Nerve |
| Swelling or knot, containing cell bodies of neurons, are located outside the brain and spinal cord, and are closely associated with cranial and spinal nerves. | Ganglia |
| Found in the walls of organs of the gastrointestinal tract containing extensive networks of neurons that help regulate the digestive sytem. | Enteric Plexuses |
| Seperate, specialized cells that monitor changes in the internal or external environment also known as the dendrites of sensory neurons | Sensory Receptors |
| Carries sensory information into the brain and spinal cord through cranial and spinal nerves. | Sensory or Afferent Neurons |
| The nervous system integrates sensory info by analyzing and storing some of it by making decisions for appropriate responses. | Integrative Funcion |
| The conscious awareness of sensory stimuli accuring in the brain. | Perception |
| Neurons that conduct impulses from the brain toward the spinal cord or out of the brain and spinal cord into cranial or spinal nerves to effectors that may be either muscles or glands. | Motor Neurons or Efferent Neurons |
| Pns is subdivided into three systems | 1)Somatic Nervous System (SNS) 2)Autonomic nervous system (ANS) 3)Entric Nervous System (ENS) |
| This pns system consists of sensiory neurons that convey information from somatic receptors in the head, body wall, viscera and limbs and from special sensess whick is voluntary-Skeletal muscle | Somatic Nerous System |
| This PNS system conducts nerve impulses from the cns to smooth muscle, cardiac muscle and glands. This is innoluntary. THIs also consists of 2 divisions Sypatetic and Parasympathetic.(Fight or Flight Response)Smooth muscle,cardia muscle and glands | The Autonomic nervous system- ANS |
| This PNS system is the "Brain of the gut" and its operation is involuntary. It extends most of the GI tract their endocrine cells, Smooth muscle, and glands | Enteric Nervous System |
| The basic information-processing units of the nervous system and are specialized for nerve impulse (action potentiol) condution. | Neurons |
| Support nourish and protect the nerons and maintain homeostasis in the interstitial fluid that bathes neurons. | Neuroglia |
| Three main parts 1)A cell body, 2)Dendrites and 3) an axon make up this | A neuron |
| Contains a nucleus surrounded by cytoplasm that includes typical organelles such as Rough ER, and Ribosomes, Lysosomes, Mitochondria, and golgi complex make up this | Cell Body |
| The receiving or input parts of a neuron, usually short, tapering and highly branched forming a tree-shapped array of processess that emerge from the cell body | Dendrites |
| Conducts nerve impulses toward another neuron, a muscle fiber or a gland cell. Long thin Cylindrical projection that often joins the cell body at a cone-shaped elevation. | Axon |
| The cone-Shaped elevation on a cell body | Axon Hillock |
| The part of the axon closest to the axon hillock | Initial segment |
| In most neurons nerve impulses arise at the juncion of the axon hillock and initial segment of an area from whcih they travel along the axon to thier destination. | Trigger zone. |
| The cytoplasm of an axon | axoplasm |
| a plasma membrane that surrounds the axoplasm | axolemma |
| The side branches of a axon that end by dividing into axon terminals | axon collaterals |
| axons and dendrites are collectively referred to as | Nerve fibers |
| The site where a neuron and an effector cell can communicate | Synapse. |
| A bulb-shapped structrue, containing synaptic vesicles that release chemicals in the neuro transmitters. | synaptic end bulb |
| 2types of transport systems that carries materials from the cell body to the axon and back are | 1)the slow axonal transport 1-5mm per day 2)Fast axonal transprot 200-400mm prt day. |
| These usually have several dendrites and one axon. Most neurons in the brain and spinal cord are of this type. | Multipolar neurons |
| These have one main dendrite and one axon. They are found only in the retina of the eye, in the inner ear, and in the olfactory area of the brain. | Bipolar neurons |
| These are sensory neurons that begin in the embryo as bipolar neurons. During development, the the axon and dendrite fuse into a single process that divides into 2branches a short distance from the cell body. | Unipolar neurons |
| A many-layered covering composed of lipid and protein that surrounds most neurons. | Myelin sheath |
| The two types of neuroglia produce myelin sheaths: | Schwann cells (PNS) and oligodendrocytes in the (CNS) |
| The outer nucleated cytoplasmic layer of a schwann cell, which encloses the myelin sheath,Which is only found around axons in the PNS. | Neurolemma (sheath of Schwann) |
| Gaps in the myelin sheath and appear at intervals along the axon.more frequently in schwann cells | nodes of Ranvier. |
| AxonsThat have a myelin sheath | Myelinated |
| Axons without a myelin sheath | Unmyelinated |
| Aggregations or bundles of myelinated an unmyelinated axons located in the brain and spinal cord. | White Matter |
| areas in the central nervous system and ganglia containing neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia; Nissl bodies impart a gray color and there is little or no myelin. | Grey Matter |
| Cells of the nervous system that perform various supportive functions. The 4 of the CNS are Astrocytes, oligodendrocytes, microglia, and ependymal cells; The 2 of the PNS include Schwann Cells and Satellite cells also called glial cells. | Neuralgia |
| Brain tumors derived from glia, often highly malignangt and grow rapidly. | Gliomas |
| Neurons Communicate with one another using 2 types of electrical signals | 1) Graded potentials-for short distance 2) Action potentials-for long and short distance communication. |
| The outer part of the brain where perception occurs. | Cerebral Cortex |
| A type of motor neuron that synapses with a lower motor neuron farther down in the CNS to contract a skeletal muscle. | Upper motor neuron |
| A type of motor neuron that directly supplies skeletal muscle fibers. | Lower motor neuron |
| A difference in the amt of electrical charge on the inside of the plasma membrane as compared to the outside | Membrane potential |
| A cell membrane that has the potential is | Polarized |
| When muscle fibers and neurons are "at rest" (not conduction action potentials) the voltage across the plasma membrane is termed | Resting membrane potential |
| A type of ion channel that allow a small but steady stream of ions to leak across the membrane following the electrochemical gradient, they are perminantly K+ | Leakage Channels |
| These ion channels open and close on command in response to chemical or mechanical stimuli | Gated channels |
| channels that open in response to a change in membrane potential, are used to generate and conduct action potentials | Voltage-gated channels |
| A sequence of rapidly occurring events that decrease and reverse the membrane potential and eventually restore it to the resting state. | Action potential |
| The ability of muscle fibers and neurons to convert stimuli into aceion potentials is called | elecrical exciltability |
| Anything in the cell's environment that can change the resting membrane potential | Stimulus |
| When a stimulus causes the membrane to depoloarize to a critical level, an action potential arises Typically abou-55mV | Threshold |
| An action potential has 2 main phases | 1) depolarizing phase-negative membrane potential becomes less negative, reaches zero and then becomes positive 2)Repolarization- the membrane potential is restored to its resting state of -70mV. |
| During hyperpolarization the membrane potential becomes even more negative than the resting level.As K+ channels close, the membrane potential returns to the resting level of -70 mV | After-hyperpolarixing phase |
| Action potentials arise according to this principle. | All-or-none principle |
| For a brief time after an action potential begins, a muscle fiber or neuron cannot conduct another action potential | refractory period |
| A time period during which a second action potential can be initiated, but only by a larger-than-norman stimulus. | relative refractory period |
| To communicate information from one part of the body to another, nerve umpulses must travel from where they arise, usually at the trigger zone of the axon to the axon terminals. This type of impulse movement, which operates by positive feedback is called | Conduction or propagation. |
| Propagation of an action potential (nerve impulse) in a step-by-step depolarization of each adjacent area of an axon membrane. | Continuous conduction |
| current flows across the membrane only at nodes, the impulse appears to leap from node to node as each nodal area depolarizes to thresh-old. This thpe of impulse conduction is called | Saltatory conduction |
| The largest-diameter axon. They are myelinated. The axons of sensory neurons that propagate impulses associated with touch, pressure, position of joints | A Fibers |
| These are axons with intermediate diameters. They are myelinated and exhibit saltatory conduction. 15 m/sec. they have longer absolute refractory period. These conduct sensory nerve impulses from the brain and spinal cord. | B fibers |
| The smalles diameter axons and all are unmyelinated. These are the longest absoluste refractory periods. ranges from .5- to 2m/sec | C fibers |
| At synapses, neurons communicate with other neurons or with effectors by a series of events known as | Synaptic transmission |
| In the synapses between neurons, the neuron sending the signal is called | Presynaptic neuron |
| In the synapses between neurons, the neuron recieving the message is called | Postsynaptic neuron |
| Although the presynaptic and postsynaptic neurons are in close proximity at a synapse, thier plasma membranes do not touch. They are separated by a tiny space filled with interstitual fluid called | Synaptic Cleft |
| The first 2steps of the events at a synapse | 1)nerve impulses arrives at a synaptic end bulb of a presynaptic axon. 2)The depolarizing phase of the nerve impulse opens Voltage-gated Ca2+ channels in the membrane. |
| The 3rd and 4th step in the events at a synapse | An increase in the concentration of Ca2+ inside the synaptic end bulb triggers exocytosis of some of the synaptic vesicles whice release neurotransmitters 4)The neuro transmitter molecules flood the synaptic cleft and bind to neurotransmitter receptors |
| The 5th and 6th step in the events at a synapse | 5) Binding of neurotransmitter molecules opens ion channels-certain ions flow across 6)As ions pass the voltage across membrane changes, depending on the ions there may be a depolarization or hyperpolarization |
| The 7th step in the events at a synapse | 7) If a depolarization occurs in the postsynaptic ceuron and reaches threshold, then it triggers one of more nerve impulses. |
| One of the best-studied neurotransmitters, which is released my many PNS neurons and my some CNS neurons. It is an excitatory neurotransmitter at some synapse. | Acetylcholine (ACh) |
| Inportant inhibitory neurotransmitter amino acids include | Glutamate,aspartate, gamma-aminobutyric acid, and glycine |
| Some neuro transmitters are modified amino acids. These include | Norepinephrine, dopamine, and serotonin |
| This modified amino acid plays roles in awakening from deep sleep and regulating moods | Norepinephrine (NE) |
| This modified amino acid are active during an emotional responses, addictive behaviors and pleasurable experiences.this also hels regulate skeletal muscle tone | Dopamine (DA) |
| This modified amino acid is thought to be involved in sensory perception, temperature regulation and control of mood, appetite and onset of sleep | Serotonin |
| neurotransmitters consisting of amino acids linked by peptide bonds are called | neuropeptides |
| The neuropeptides that are the body's natural painkillers. | endorphins |
| A new recognized neurotransmitters is a simple gas. | Nitric oxide (NO) |
| The capability to change based on experience. | Plasticity |
| The capability to replicate or repair themselves. | Regeneration |
| The birth of new neurons from undifferentiated stem cells | Neurogenesis |
| After 24 to 48 hours after injusry to a process of a normal peripheral neuron, the nissl bodies break up into granular masses. this is called | Chromatolysis |
| Degeneration of the distal portion of the axon and myelin sheath | Wallerian degeneration |
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amygarcia
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