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239 Cards in this Set
- Front
- Back
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What types of muscle are striated?
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Skeletal and Cardiac
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What types of muscle are smooth?
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Vascular and Visceral
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Where do voluntary muscles receive signals from?
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Central Nervous System
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Where do involuntary muscles mostly receive their signals from?
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Autonomic Nervous System
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What attaches muscle to bone?
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Tendon
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What is the connective tissue surrounding individual muscle fibers?
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Endomysium
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What is the connective tissue surrounding bundles of muscle fibers?
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Perimysium
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What is the connective tissue surrounding the entire muscle?
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Epimysium
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On which band can the thick filaments of the myofibril be found?
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A band
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On which band can the thin filaments of the myofibril be found?
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I band
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What runs across the center of the A band on the myofibril?
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M line
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What runs across the center of the I band on the myofibril?
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Z line
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What is the fundamental repeating unit of bands from the Z disk to successive Z disk?
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Sarcomere
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What are the three main types of proteins found in the thin filaments of skeletal muscle?
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Actin, tropomyosin, and troponin
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What is the most abundant protein of the thin filament?
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Actin
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Where is the main site for calcium regulation in the skeletal muscle?
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The thin filament
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Which type of troponin is the calcium sensor in skeletal and cardiac muscle?
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Troponin C
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Which type of troponin is the structural glue that holds the troponin-tropomyosin-actin complex together?
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Troponin I
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What is the primary protein of the thick filaments in skeletal muscle?
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Myosin
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What part of the myosin interacts with actin to generate force and filament sliding?
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The head structure (SI region)
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How does the plasma membrane of skeletal muscle fiber differ from cardiac and other cell types?
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It does not contain gap junctions or tight junctions
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What are the tubular extensions of the sarcolemma?
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T-tubules
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What is the specialized endoplasmic reticulum adapted for the uptake, storage and release of calcium ions?
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Sarcoplasmic Reticulum (SR)
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How does the sarcoplasmic reticulum tubular network run in relation to the myofilaments?
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Parallel
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What are the enlarged portions of the sarcoplasmic reticulum contacting T-tubules?
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Terminal cisternae
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What is the term for a group of one T-tubule and two terminal cisternae?
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A triad
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Where is calcium required for contraction stored in skeletal muscle?
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Terminal cisternae
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What is the process by which depolarization of the sarcolemma causes calcium release into the cytoplasm, and subsequent binding of calcium to regulatory sites to initiate crossbridge cycling?
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Excitation-Contraction Coupling
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What does calcium ions bind to after being released from the sarcoplasmic reticulum to initiate contraction?
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Troponin C
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What are two ways that Calcium is sequestered after contraction?
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Calcium pumps in the SR pumps calcium back
Calsequestrin helps concentrate calcium ions in the sarcoplasmic reticulum. |
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What molecule is responsible for interfering with the interaction between actin and myosin?
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Tropomyosin
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How many actin monomers can one tropomyosin molecule control due to its geometry?
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7
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What type of muscle regulation works via the action on the thin filaments?
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Actin-linked regulation
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What does the permanent binding of myosin to actin filaments cause?
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Rigor mortis
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What are two components required for crossbridge cycling?
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Calcium and ATP
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What causes the myosin cross bridge to detatch?
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ATP binding
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What energizes the cross bridge?
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Hydrolysis of ATP
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What are two important distinctions between cardiac muscle and skeletal muscle?
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Cardiac action potential is not initiated by neural activity (Initiation by specialized muscle tissue in heart)
Cardiac muscle cells (cardiac myocytes) are smaller than skeletal muscle |
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What does the gap junction in cardiac muscle cells provide?
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Electrical connection between cells
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What is the functional contractile unit-one motor neuron plus all of the muscle fibers it innervates?
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Motor Unit
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Where does the transfer of signal from nerve to muscle take place?
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Neuromuscular Junction
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What is the transmitter substance secreted at the neuromuscular junction of skeletal muscles?
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Acetylcholine
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What does the postsynaptic membrane of skeletal muscle allow to flow through its ion channels after binding acetylcholine to its receptors?
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Sodium and Potassium Ions
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What hydrolyzes acetylcholine?
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Cholinesterase enzyme
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Where does the choline go after being hydrolized by cholinesterase enzyme?
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The presynaptic terminal
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What do gap junctions in cardiac muscle help with?
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They enhance the spread of action potentials through out the heart
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What is the force of contraction dependent on in cardiac muscle?
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Extracellular calcium concentration
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How does calcium mainly enter the cell of cardiac muscle?
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Voltage-dependent slow calcium channels (L-type calcium channels)
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Where does the calcium required for contraction come from in the cardiac muscle?
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Extracellular calcium pool
Calcium pool in the sarcoplasmic reticulum lumen |
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What nerves can be stimulated to increase the force of heart contraction?
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Sympathetic nerves (norepinephrine release)
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What nerves can be stimulated to decrease the force of heart contraction?
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Parasympathetic nerves (acetylcholine release)
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What unit of the muscle has ATPase activity?
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Myosin
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What prompts the resynthesis of ATP during muscle contraction?
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Phosphate group transfer from creatine phosphate to ADP
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What is the most important storage form of high energy phosphate in the muscle?
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Creatine phosphate
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What are two major metabolic pathways to supply ATP and replenish the creatine phosphate pool
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Glycolysis
Citric acid cycle |
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What is the largest contributor to oxygen debt?
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Lactic acid accumulation
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What is a contraction that generates only force with no muscle shortening?
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Isometric contraction
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What is a contraction that results in shortening against a constant force?
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Isotonic contraction
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What is the contraction and relaxation of a skeletal muscle to a single stimulus (single action potential)?
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Twitch
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What are two factors that total tension of a muscle depends on?
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Number of fibers contracting
Tension developed by each fiber |
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What is the process by which the force of a second stimulus can add to the force left from the first
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Summation
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What occurs when a muscle fiber is stimulated so rapidly that it does not have an opportunity to relax between stimuli?
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Tetanus
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How much stronger is a tetanic contraction over a single twitch?
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Three to four times stronger
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What causes the color difference of white and red skeletal muscle?
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The difference in the amount of myoglobin
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What type of muscle fibers are found in muscles that depend heavily on aerobic metabolism for their ATP supply?
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Red muscle fibers
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What type of red muscle fibers have higher ATPase activity?
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Fast twitch fibers
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What type of muscle fibers rely primarily on glycolytic metabolism and fatigue quickly?
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White muscle fibers
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Between white and red muscle fibers, which have more mitochondria?
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Red muscle fibers
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What is the term for contraction followed by relaxation?
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Phasic
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What is the term for sustained contraction?
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Tonic
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In most organs, with the exception of the gut, what is the orientation of smooth muscle?
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Circular or circumferential
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What type of muscle has single uninuclear cells, no transverse striations, no T-tubules, abundant caveolae, and numerous cell-cell junctions?
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Smooth Muscle
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What are two fundamental functions of cell-cell junctions of smooth muscle?
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Mechanical coupling (Force, intermediate junctions)
Ionic coupling (excitation, gap junctions) |
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In comparison to skeletal muscle, what regulatory protein is absent in the thin filaments of smooth muscle?
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Troponin
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What are two unique proteins of thin filaments found in smooth muscle?
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Calponin and Caldesmon
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What is the main component of intermediate filaments in visceral muscles?
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Desmin
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What is the main component of intermediate filaments in vascular muscles?
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Vimentin
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What are two categories of smooth muscle based on how the muscle cells are stimulated to contract?
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Multiunit smooth muscle
Single-unit smooth muscle |
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Where can multiunit smooth muscle be found?
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Walls of large blood vessels, large airways of the respiratory tract, and in the eye muscles
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What type of smooth muscle requires nerve stimulus to initiate contraction?
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Multiunit smooth muscle
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What type of smooth muscle is myogenic (self-excitable) and does not require nervous stimulation for contraction?
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Single-unit smooth muscle
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What is required in smooth muscle for myosin-ATPase activity to be actin-activated?
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Phosphorylation of myosin light chains
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What initiates smooth muscle contraction?
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Calcium-dependent phosphorylation of myosin light chain
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What do calcium-calmodulin complexes bind to activate?
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MLC kinase
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What regulates smooth muscle contraction?
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MLC kinase
MLC phosphatase |
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What is the term for the depolarization of the membrane electrical potential leading to the opening of voltage-gated calcium channels followed by elevation in cytosolic calcium?
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Electro-mechanical coupling
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What type of receptors in smooth muscle are involved in calcium-induced calcium release?
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Ryanodine receptors
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What is the term for the binding of a contractile agonist to its receptor on the muscle membrane leading to elevation in cytosolic calcium without any change in membrane electrical potential?
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Pharmaco-mechanical coupling
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Which type of coupling involves a second messanger?
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Pharmaco-mechanical coupling
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What is the main calcium mobilizing messenger in smooth muscle?
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IP3
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What are the second messengers involved in smooth muscle relaxation?
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Cyclic nucleotides, (cAMP, cGMP)
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What drugs trigger cAMP in smooth muscle relaxation?
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Beta-Adrenergic drugs
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What drugs trigger cGMP in smooth muscle contraction?
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Nitric Oxide
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What are two subdivisions of the autonomic nervous system?
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Sympathetic
Parasympathetic |
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Why is the sympathetic division also called the thoracolumbar division and the parasympathetic the craniosacral division?
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Sympathetic fibers leave the CNS from the thoracic and lumbar regions
Parasympathetic leave the CNS from the brain and sacral portion of the spinal cord |
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Which fibers (pre or post ganglionic) of the sympathetic division are often shorter?
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Preganglionic
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Which fibers (pre or post ganglionic) of the parasympathetic division are often short?
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Postganglionic
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What is one example where the sympathetic and parasympathetic nerves work in a synergistic fashion?
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When innervating the exocrine glands
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Which nerve plexus functions to coordinate peristalsis along the gut?
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Myenteric Plexus
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Which nerve plexus functions to regulate ion and water transport across the gut epithelium?
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Submucosal plexus
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Where does the transmission of signals between pre and postganglionic autonomic neurons take place?
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True synapses
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What is the term for the transmission of signals between postganglionic autonomic neurons and effector cells?
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Neuroeffector junction
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What are the irregular expansions within the terminal part of the axon of post ganglionic neurons called?
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Varicosities
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What are the classic autonomic neurotransmitters?
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Acetylcholine
Norepinephrine |
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What are the fibers that secrete acetylcholine?
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Cholinergic
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What are the fibers that secrete norepinephrine?
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Adrenergic
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(T/F) All preganglionic neurons are cholinergic in both the sympathetic and parasympathetic nervous systems.
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True
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(T/F) Few postganglionic neurons of the parasympathetic system are cholinergic.
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False, Either all or almost all are cholinergic
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(T/F) Most of the postganglionic sympathetic neurons are adrenergic.
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True
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How fast is acetylcholine destroyed after release?
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Milliseconds (by acetylcholinetransferase)
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How is norepinephrine in sympathetic postganglionic nerve terminals inactivated?
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By reuptake
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Where is epinephrine or norepinephrine stored in large vesicles that are released directly into the blood?
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Adrenal medulla |
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What are two categories of receptors that transduce chemical signals in the autonomic nervous system?
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Directly-gated receptors
Second messenger-linked receptors |
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Where do directly-gated receptors predominate?
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In the ganglia
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Where do second messenger-linked receptors predominate?
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In the autonomic neuroeffector junctions
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What type of autonomic receptor is a nicotinic acetylcholine receptor?
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Directly-gated receptor
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What type of autonomic receptor is a muscarinic acetylcholine receptor?
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Second messenger-linked receptor
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What is the predominate receptor type in autonomic ganglia on postganglionic cells?
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Nicotinic acetylcholine receptor
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What specific G protein alpha subunit hydrolyzes PIP2 to generate IP3 and DAG?
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G-Alpha Q
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What does DAG activate?
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Protein Kinase C
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What is the effector of the G-protein alpha subunit Q?
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PLC-Beta
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What are adenylyl cyclase isoforms activated by?
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G-Alpha s (Hydrolyzes ATP to generate cAMP)
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What are adenylyl cyclase isoforms inhibited by?
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G-Alpha i/o
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Where can alpha1 adrenergic receptors be found?
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Smooth muscle and gland
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What are Alpha-1 adrenergic receptors coupled to?
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Gq protein (Activation releases IP3 and Ca for smooth muscle contraction and glandular secretion)
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Where can Alpha-2 adrenergic receptors be found?
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Presynaptic nerve terminals
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Which type of adrenergic receptors provides feedback inhibition?
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Alpha-2
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Where can Beta-1 Adrenergic receptors be found?
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Heart (They are excitatory)
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Where can Beta-2 Adrenergic receptors be found?
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Tracheal and Bronchial smooth muscle (They are inhibitory)
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Which of the four adrenergic receptors does not respond to norepinephrine (requires epinephrine)?
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Beta-2
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What are Beta-2 Adrenergic receptors coupled to?
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G-Alpha S (stimulates the production of cAMP)
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Which of the five muscarinic receptors are coupled to G-Alpha Q?
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M1, M3, M5
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Which of the five muscarinic receptors are coupled to G-Alpha I?
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M2, M4
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Which type of neurotransmitter binds to muscarinic receptors?
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Acetylcholine
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Which nerves increase the rate of generation of action potentials in pacemaker cells of the cardiac muscle?
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Sympathetic nerves via release of norepinephrine and activation of Beta-1 Adrenergic receptors
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Which nerves decrease the rate of generation of action potentials in cardiac muscle?
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Parasympathetic nerves via release of acetylcholine and activation of m2 muscarinic receptors
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What elicits secretion of secretory cells?
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Release of acetylcholine from secretomotor postganglionic parasympathetic nerves
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Which neurotransmitter released from sympathetic nerves mediates vascular smooth muscle contraction by binding to Alpha-1 Adrenergic receptors?
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Norepinephrine
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Which neurotransmitter mediates airway smooth muscle relaxation by activation of Beta-2 Adrenergic receptors?
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Epinephrine
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Where does the sympathetic cascade begin, and what does it activate?
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Signals are sent via the <i>hypothalamus</i> and activates:
<i> Chromaffin cell in the adrenal medulla Sympathetic post ganglionic neurons</i> |
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What are four processes carried out by the gastrointestinal tract?
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Motility
Secretion Absorption Excretion |
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What is located between each major region of the gastrointentinal tract and is a thickening of the muscle layer?
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A sphincter
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What is food reduced to in the stomache?
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chyme
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What is the main function of the small intestine?
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Digestion and Absorption
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What is the main function of the large intestine?
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Drying of Chyme into feces
Storage of feces |
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What is the role of the pancreas in gastrointestinal function?
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Exocrine (secretion of digestive enzymes and bicarbonate ions)
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What is the function of liver in gastrointestinal functions?
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Exocrine (bile secretion)
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Where is the storage and concentration of bile acids?
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Gall bladder
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What is the major smooth muscle coat of the GI tract surrounding the submucosa?
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Muscularis externa
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What is the outer connective tissue covering the GI tract?
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Serosa
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What are the slow waves of the autonomous smooth muscle generated by?
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Pacemaker Cells - Interstitial cells of Cajal (ICC)
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What type of stimulus does parasympathetic stimulation lead to in the gut?
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Excitation (increased motility, increased secretion)
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What is the primary neurotransmitter of the postganglionic fibers of the sympathetic nervous system affecting the GI tract?
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Norepinephrine
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How can the activation of the sympathetic chain produce an inhibition of gut function?
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Termination of neurons on blood vessels cause vasoconstriction
Termination on glands can cause secretion Termination on smooth muscle cells of sphincters can cause constriction |
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What is the intrinsic innervation of the GI tract provided by?
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Enteric Nervous System
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What is the largest endocrine organ in the body?
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GI Tract
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What are four GI hormones?
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Secretin
Cholecystokinin (CCK) Gastrin Gastric Inhibitory Peptide (GIP) |
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What inhibits Gastrin release?
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Low gastric luminal pH
Somatostatin Certain Prostaglandins |
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What is the most appropriate action of gastrin in vivo?
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Stimulation of acid secretion
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What cell releases Gastrin?
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G cells (Antral Gastrin Cells)
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What cell releases CCK?
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I cells of the duodenal and jejunal mucosa
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What is the function of CCK in the GI tract?
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Stimulates gallbladder contraction
Pancreatic Enzyme Secretion Satiety Inhibits gastric emptying and acid secretion |
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What cells release secretin?
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S cells of the duodenal mucosa
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What is the primary effect of secretin?
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Stimulation of pancreatic bicarbonate and water secretion
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What does secretin inhibit?
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Gastric Acid Secretion
Gastric Emptying |
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What is an important action aside from inhibiting acid secretion of the Gastric Inhibitory Peptide?
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Stimulation of insulin release in the presence of hyperglycemia
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What two hormones are located in the duodenum?
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CCK
Secretin |
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What are three candidate hormones in the GI tract?
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Motilin
Pancreatic Polypeptide (PP) Somatostatin |
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What candidate hormone is released during fasting and has significant effects on GI smooth muscle?
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Motilin
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When is PP released?
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During meals
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What is the most obvious biological function of PP?
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Inhibition of pancreatic exocrine secretion
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What are the three phases according to stimulus location of neural and hormonal control of the GI system?
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Cephalic, Gastric, and Intestinal
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What stimulates the cephalic phase of GI system?
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Sight, smell, taste, and chewing stimulates receptors in the head
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What neurotransmitter has an inhibitory effect on smooth muscle?
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Epinephrine
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What neurotransmitter has a stimulatory effect on smooth muscle?
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Acetylcholine
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Where can phasic muscle contractions be found in the GI tract?
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Esophagus, Distal 1/3 of stomach (antrum), and small intestine
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What are the parts of the GI system that are made up of skeletal muscle?
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Upper 1/3 of esophagus
External Anal Spincter |
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(T/F) The longitudinal and circular layers of the smooth muscle of the GI tract can contract at the same time.
|
False, the circular and longitudinal muscle contractions are out of phase.
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What are three motility patterns of the GI tract?
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Peristalsis
Segmentation (mixing movements) Tonic contractions |
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What is the law of intestine?
|
The propulsive segment (contraction behind the bolus,) and the receiving segment (relaxation ahead of it) is the response known as the law of intestine
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What is contraction above the site of distension mediated by?
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Cholinergic (Acetylcholine) neurons and tachykinin (Substance P) contatining neurons
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What is relaxation below the site of distension mediated by?
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Vasoactive intestinal peptide (VIP) and Nitric Oxide containing neurons
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What type of movement is used to mix intestinal chyme through squeezing action?
|
Segmentation
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Where can tonic contractions be found?
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Areas where sphincters divide the gut into functional segments
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During which phase of swallowing does the epiglottis close over the larynx to close the opening to the trachea?
|
Pharyngeal phase
|
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What is the difference between primary and secondary peristalsis?
|
In secondary peristalsis, the contraction is not preceded by the oral and pharyngeal phases
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What keeps the acidic stomach contents out of the esophagus?
|
Lower esophageal sphincter (LES)
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What part of the stomach has no slow waves or myoelectrical rhythms, and serves as the major storage site for a meal?
|
Upper portion (Fundus and orad corpus)
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What is the term of the mixed stomach secretions and food?
|
Chyme
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What separates the stomach from the duodenal bulb?
|
Pyloric Sphinctor
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What is the reflex that is initiated by distension of the stomach and conducted through the myenteric plexus from the stomach to the small intestine?
|
Gastro-enteric Reflex
|
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What is the main function of the ileocecal valve?
|
Prevent backflow of fecal contents from the colon into the small intestine
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What is the term for the muscles organized into three flat bands in the colon?
|
Tenia Coli
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What enzyme is involved in the formation of gastric, pancreatic, and intestinal secretions?
|
Carbonic Anhydrase
|
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What are five major secretory tissues in the digestive system?
|
Salivary Glands
Stomach Pancreas Hepatic-Biliary System Intestine |
|
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What are two types of secretions in the GI system?
|
serous and protein
|
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What is the serous component of secretions composed of?
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Water and Electrolytes
|
|
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What is the protein component of secretions composed of?
|
Enzymes
Mucus (mucopolysaccharides and glycoproteins) |
|
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What type of glands are gastric pits and intestinal crypts?
|
Tubular glands
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What type of glands are the salivary gland and exocrine pancreas?
|
Compound glands
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What is a substance that stimulates a particular cell to secrete?
|
Secretagogue
|
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What is the mechanism by which Beta-Adrenergic agents, VIP, and Histamine lead to secretion?
|
They activate a G-Protein, which activates adenylate cyclase to increase intracellular cAMP
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What is the mechanism by which acetylcholine, gastrin, cholecystokinin, and tachykinins cause secretion?
|
Hydrolyze PIP2, to release IP3 which enters the cytoplasm and causes a rise in intracellular calcium when calcium is released from intracellular stores
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|
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About how much saliva is produced each day?
|
1L
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What cells secrete the digestive enzymes of saliva?
|
Cells of the acinus
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What enzyme is secreted by salivary glands of the tongue and begins digestion of triglycerides?
|
Lingual lipase
|
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What ion is found in higher concentration in saliva than plasma?
|
Potassium
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What do the excretory and striated ducts do with saliva?
|
They modify the primary secretion by extracting Na+ and Cl- and adding K+ and HCO3-
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What are the major secretions of the stomach?
|
HCl
Pepsin Intrinsic Factor Mucus Bicarbonate |
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What is secreted from the chief cell and begins the digestion of lipids and fast-soluble materials?
|
Lipase
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What is needed for vitamin B12 absorption in the ileum and is secreted by parietal cells?
|
Intrinsic factor
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What protects stomach from auto-digestion?
|
Mucus
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What part of the stomach synthesizes and releases gastrin?
|
Pyloric Gland Mucosa
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What is the ionic composition of gastric juice related to?
|
Rate of secretion
|
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What are three major stimulants of acid secretion?
|
Gastrin
Histamine Acetylcholine |
|
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What is a major inhibitor of gastric acid secretion?
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Somatostatin
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What does the acid-secreting parietal cell have receptors for?
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Acetylcholine, gastrin, histamine, and somatostatin
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What does Gastrin and Ach increase in the parietal cell to induce acid secretion?
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Cytosolic Calcium
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What does histamine increase in the parietal cell to induce acid secretion?
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cAMP
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What factors stimulate the release of Gastrin?
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Gastric distension
Presence of protein digestion products Vagal stimulation |
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What stimulates somatostatin release?
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Acid in the antrum
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What are three phases of acid secretion?
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Cephalic Phase (Meal Preparation)
Gastric Phase (Maximal Acid Secretion) Intestinal Phase (Acid Inhibition) |
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What molecule stimulates the secretion of the aqueous component of the pancreas?
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Secretin
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What molecule stimulates the secretion of pancreatic enzymes?
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Cholecystokinin (CCK)
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What is the major functional unit of the exocrine pancreas?
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Acinus
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What structure regulates the flow of bile and pancreatic juice into the duodenum and prevents the reflex of intestinal contents into the bile ducts?
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Sphincter of Oddi
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What is the osmolarity of pancreatic fluid to that of plasma?
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Equal to that of plasma at all rates of secretion
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Where are all enzymes stored?
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Membrane-Bound Vesicles - Zymogen Granules
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What do pancreatic enzymes need to be exposed to before being activated?
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Enterokinase
Trypsin |
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What type of enzyme digests carbohydrates?
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Amylases
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What does pancreatic amaylase generate when it cleaves starch?
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Maltose, maltotriose
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Which pancreatic proteolytic enzyme is active at aromatic amino acids?
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Chymotrypsin(ogen)
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Which pancreatic proteolytic enzyme is active at basic amino acids?
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Trypsin(ogen)
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Which pancreatic proteolytic enzyme is active at C-terminal end of peptide?
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(Pro)carboxypeptidase A & B
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What other factors are required for Lipase to split triglycerides into glycerol and free fatty acids?
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Oil/water interface
Bile salts Colipase |
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What happens when secretion surpasses absorption in the intestine and colon?
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Watery diarrhea
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What are the pits located over the entire surface of the small intestine?
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Crypts of Lieberkuhn
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What are two types of cells found in the crypts of lieberkuhn?
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Goblet cells
Enterocytes |
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What is the Cl- ion channel in the crypt of Lieberkunh?
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Cystic Fibrosis Transmembrane Regulator (CFTR)
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