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Chapter 7 and 8
Nervous and Muscular Tissue
| Question | Answer |
|---|---|
| Which are the components of the Nervous System? | brain, spinal cord, cranial nerve branches, spinal nerve branches, ganglia, enteric plexuses, and sensory receptors |
| What is the Central Nervous System? | Brain and Spinal Cord |
| What is the Peripheral Nervous System? | Cranial Nerves, Spinal Nerves, Sensory & Afferent neurons which transmit nerve impulses from sensory receptors to the CNS, and Motor & Efferent neurons which transmit nerve impulses from the CNS to muscle and glands |
| Nerve | a bundle of axons (plus associated connective tissue and blood vessels) located outside the brain and spinal cord. |
| Ganglia | Small masses of nervous tissue, consisting primarily of neuron cell bodies that are located outside the brain and spinal cord |
| Enteric Plexuses | Networks of neurons located in the walls of GI tract organs; help regulate digestive system activities |
| Sensory Receptors | structures that monitor changes in the internal and external environment |
| Sensory Afferent Neurons | Transmit sensory information |
| Interneurons | receive and analyze data to provide perception, storing some of it and making decisions regarding appropriate behaviors |
| Motor Efferent Neurons | respond to integration decisions by initiating actions in efferents including muscle fibers and glandular cells |
| What type of neuron is most abundant? | Interneurons |
| Afferent impulses travel from ______ to _____? | Receptors to CNS |
| Efferent impulses travel from ______ to ______? | CNS to effectors |
| What are the 2 divisions of the efferent portion of the autonomic nervous system? | Sympathetic and Parasympathetic Division |
| Sympathetic Division | Fight or flight |
| Parasympathetic Division | Rest and Digest |
| Neurons | Bigger but fewer highly specialized cells, lost the ability to undergo mitotic division connect all region of the body to the nervous system |
| Neuroglia | Smaller but more numerous support, nourish, protect neurons, continue to divide throughout an individuals lifetime |
| Dendrites | short, tapering, unmyelinated, and highly branched processes that emerge from the cell body receiving or input portion of a neuron |
| Soma (cell body) | contains the nucleus surrounded by cytoplasm that includes typical organelles |
| Nissl bodies | rough er, high levels of protein synthesis |
| Axon Hillock | beginning of the the axon |
| Axon | long, thin cylindrical process that may be myelinated and transmits nerve impulses away from cell body |
| Axon Terminal | nonmyelinated, fine line |
| Synaptic end bulbs | tip of some axon terminals are bulbous |
| Most axons are what? | Myelinated; surrounded by myelin sheath |
| Synapse | Site of communication |
| Presynaptic Neuron | Transmits nerve impulses toward the synapse |
| Postsynaptic cell | is as postsynaptic neuron or a muscle cell or a gland cell that receives the signal |
| Multipolar Neuron | Several dendrites and one axon, most neurons in the brain and spinal cord are of this type |
| Bipolar Neurons | Have one main dendrite and one axon, these are located in the retina, inner ear, and olfactory are of the brain "special senses" |
| Unipolar Neurons | Sensory neurons have just one process extending from he cell body; process is essentially an axon with dendrites at its peripheral end, 'most sensory' |
| What cells produce myelin sheath around several adjacent axons of CNS neurons? | Oligodendrocytes |
| Oligodendrocytes | have few processes and produce a myelin sheath, each Oligodendrocyte can myelinate parts of several axons |
| What cells myelin sheath in the PNS | Schwann Cells |
| What are star- shaped, and one of their functions is providing nutrients to neurons? | Astrocytes |
| What cells protect CNS from disease by engulfing invading microbes? | Microglia cells |
| What cells line ventricles of the brain and central canal of the spinal cord? | Ependymal cells |
| Which type of axon is more numerous? | Unmyelinated |
| What are the functions of myelin sheath? | Protect axon, electrically insulate fibers from one another, increase the speed of nerve impulse transmission |
| What is Neurolemma? | Outer, nucleated cytoplasmic layer of Schwann Cell |
| Where is neurolemma located? | PNS ONLY |
| What structures are included in gray matter? | neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia (all unmyelinated= gray color) |
| What structures are included in white matter? | unmyelinated axons and myelinated axons (all myelinated= white color) |
| Skeletal Muscle Tissue | Mutlinuclei, moves bones, striated, voluntary |
| Cardiac Muscle Tissue | One nucleus, one muscle fiber, forms most of the wall of the heart, striated, some cells have autorhythmicity, involuntary |
| Smooth Muscle Tissue | One nucleus, located in walls of hollow internal structures (arrector pili muscle) non striated, involuntary, some cells have autorhythmicity |
| What type of muscle shows the striation and autorhythmicity? | Cardiac Muscle |
| Functions of muscular tissue | producing body movement, stabilizing body position, storing and moving substances within body, producing heat |
| Endomysium | Surrounds individual muscle fibers |
| Perimysium | Surrounds fascicles (bundles of muscle fibers) |
| Epimysium | outer, encircles the entire muscle belly (around each muscle) |
| Tendon | bone to bone |
| Sarcolemma | Plasma Membrane of muscle fiber |
| T tubules | conduct signals, continuous with the sarcolemma, impulses signal for the release of Ca2+ from adjacent terminal cisternae |
| Sarcoplasmic Reticulum | SR is an elaborate, smooth endoplasmic reticulum that surrounds each myofibril |
| Terminal Cisterns | Form perpendicular cross channels, stores Ca2+ in a relaxed muscle fiber, release Ca2+ triggers muscle contraction |
| Triad | T Tubule and the 2 terminal cisterns of the SR on either side of it form a triad |
| Myofibrils | Are NOT fascicles, contractile elements, make up most of the muscle volume |
| What proteins make up thick filaments? | Myosin |
| What proteins make up thin filaments? | Actin, Troponin, Tropomyosin |
| A Band | dark band, entire length of thick filaments, part of thin filament |
| I Band | Light band, contains THIN filaments ONLY |
| H Zone | In the center of each A Band, contains thick but NOT thin filaments |
| M Line | Center of h zone |
| Z- Disc | Coin- shaped sheet proteins (connections) that anchors the thin filaments and connects myofibrils to one another |
| Which segment contains thick filaments only? | H Zone |
| Which segment contains thin filaments only? | I Bnad |
| What is the contractile unit of muscle? | Sarcomere |
| During contraction, which segments are unchanged in length? | isometric contraction |
| During contraction, which segments are shortened? | concentric isotonic contraction |
| Isotonic Contraction | Tension remains almost constant while the muscle changes in length |
| Concentric Isotonic Contraction | Tension overcomes the resistance and the muscle shortens |
| Eccentric Isotonic Contraction | Tension slows the lengthening of the muscle so that the muscle lengthens as it contracts |
| Isometric Contraction | Muscle develops tension but does not shorten b/c the tension is not great enough to exceed the resistance |
| Muscle organization | Filaments, myofibrils, muscle fibers, fascicles, muscle |
| Motor unit | Motor neuron & all the muscle fibers it supplies |
| Neurotransmitter receptors are found where on the sarcolemma? | Motor end part of a muscle |
| Step 1 of Muscle Excitation | Action potential (nerve impulse) reaches the synaptic end bulbs of a motor neuron |
| Step 2 of Muscle Excitation | Triggers exocytosis of the synaptic vesicles |
| Step 3 of Muscle Excitation | Released ACh diffuses across the synaptic cleft |
| Step 4 of Muscle Excitation | ACh binds to ACH receptors, allow inflow of Na+, initiating a muscle action potential |
| Step 5 of Muscle Excitation | Muscle action potential propagates along the sarcolemma through the T Tubule system to the SR |
| Step 6 of Muscle Excitation | Triggers Ca2+ release from terminal cisternae |
| Step 7 of Muscle Contraction | Ca2+ binds to troponin & causes: blocking action of tropomyosin to cease actin active binding sites to be exposed |
| Step 8 of Muscle Contraction | Myosin heads attach to thin filaments at both ends of a sarcomere, and pulling thin filaments toward the M Line |
| Step 9 of Muscle Contraction | As thin filaments slide inward & meet at the center of a sarcomere, the Z discs come close together, sarcomere closes |
| Step 10 of Muscle Contraction | Hydrolysis of ATP powers this cycling process |
| Step 11 of Muscle Contraction | Ca2+ is removed into the SR, tropomyosin blockage is restored and the muscle fiber relaxes |
| Origin | Attachment of a muscle tendon to the stationary bone (not movable) |
| Insertion | Attachment of a muscles tendon to the movable bone and skin |
| Lever | Rigid bar that moves on a fulcrum or fixed point |
| Effort | Force applied to a lever |
| Load | Resistance moved by the effort |
| Third class | (FEL) Effort applied between fulcrum and the load Most common levers in the body |
| Prime Movers (Agonists) | Provide the major force for producing a specific movement |
| Antagonists | Oppose or reverse a particular movement (one contracts and one releases) |
| Synergists | work together, add force to a movement, reduce undesirable or unnecessary movement |
| Bicep brachia and triceps brachia are what? | antagonist |
| Sensation | conscious or subconscious of changes in the external or internal conditions of the body |
| Somatic Senses | touch, pressure, vibration, warm, cold, pain, and proprioceptive sensations |
| Special Senses | smell, taste, vision, hearing, equilibrium |
| Exteroceptors | located at or near body surface, provide information about external environment, convey visual, smell, taste, touch, pressure, vibration, thermal, and pain sensations |
| Interoceptors | in blood vessels, visceral organs, & nervous system, provide information about internal environment, impulses produced usually are not consciously perceived but occasionally may be felt as pain or pressure |
| proprioceptors | located in muscles, tendons, joints, and inner ear. provide information about body position, muscle length and tension, position and motion of joints and equilibrium |
| first-order neuron | carry signals from somatic receptors into the brain stem or spinal cord via cranial nerves or spinal nerves |
| second-order neuron | carry signals from the spinal cord and brain stem to the thalamus, axons of second-order neurons decussate to the opposite side BEFORE ascending to the thalamus |
| Third-order neuron | project from the thalamus to the primary somatosensory areas where conscious perception of sensations results |
| Where do decussation of sensory pathways occur? | second-order neuron |
| Does the decussation occur before or after the pathways reaches the thalamus? | before |
| Upper motor neurons | axons descend into the medulla where most of the axons decussate and terminate in nuclei of cranial nerves or in the anterior gray horns of the spinal cord |
| Lower motor neurons | axons innervate skeletal muscles, since each LMN receives and integrates excitatory and inhibitory inut from many presynaptic neurons |
| tract | bundle of axons in white matter cns |
| nuclei | clusters of neuronal cell bodies in white matter |
| what 3 tracts belong to the director motor pathways? | lateral corticospinal tracts anterior corticospinal tracts corticobulbar tracts |
| Corticobulbar tracts | some axons of UMNs extend to the midbrain where they form the corticobulbar tracts in right & left cerebral peduncles |
| Function of corticobulbar tracts | control precise, voluntary movement of eyes, tongue, neck, chewing, facial expression, and speech |
| Lateral corticospinal tracts | most axons of the UMNs decussate in the medulla in the right and left lateral white columns of the spinal cord |
| Function of lateral corticospinal tracts | limbs, hand, and feet |
| Anterior corticospinal tracts | the axons in the UMNs that didn't cross over in the medulla but descend on the same side in the right and left anterior white columns |
| Indirect motor pathways | Involved in the coordination of movement Help control gross movements of proximal limbs and trunk |
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_melgozacaroo15
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