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Chapter 7 and 8

Nervous and Muscular Tissue

QuestionAnswer
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
Created by: _melgozacaroo15