Electric signals called action potentials False, it contains tropomyosin. The Muscular System. The t-tubules are responsible for moving action potentials to the inner region of the muscle cell. . No, because neurons in this figure do not innervate every muscle cell shown. C) helps raise body temperature. What type of unitary smooth muscles show rhythmic contractile behavior? Describe the differences between single-unit smooth muscle and multiunit smooth muscle. E) A, B and C are correct. The phospholipase C pathway via a G-protein mechanism (PIP2 -> IP3 -> binds to SR receptors). Evaluate the given equation. C) retains mitotic potential even in the adult. The functions of T-tubules. Peroxisome proliferator-activated receptor- (PPAR) agonists ameliorate renal fibrotic lesions in diabetic nephropathy. Hinch, R., Greenstein, J.L., Tanskanen, A.J., Xu, L. and Winslow, R.L. A) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. 10.8 Development and Regeneration of Muscle Tissue. As T-tubules bring the sarcolemma very close to the sarcoplasmic reticulum at all regions throughout the cell, calcium can then be released from the sarcoplasmic reticulum across the whole cell at the same time. Smooth muscle contains about four times less of which structural feature compared to skeletal muscle? 1) Skeletal and smooth. T-tubules contain a higher concentration of L-type calcium channels than the rest of the sarcolemma and therefore the majority of the calcium that enters the cell occurs via T-tubules. B) includes the synaptic end bulbs of the muscle fibre. True or false- smooth muscle does not contain T-tubules. Which of the following is NOT a function of the troponin? When the level of calcium ions declines, sliding stops. T-tubules are not required to reach the interior of the cell and therefore not necessary to transmit an action potential deep into the fiber. B. Reduction in blood flow to a muscle fiber would have the greatest effect on ________. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. A) absorbing heat from the environment The nucleus is located in the center and takes a cigar-like shape during contraction. Smooth muscle fibers are often found forming sheets of tissue and function in a coordinated fashion due to the presence of gap junctions between the cells. The cytoplasm is homogeneously eosinophilic and consists mainly of myofilaments. Which of the following is true about smooth muscle? T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System. Instead, there is a series of neurotransmitter-filled bulges, called varicosities, along the axon of the neuron feeding the smooth muscle that release neurotransmitters over a widesynaptic cleft. Which of the following correctly describes myoglobin's special function in muscle tissue? They have poorly developed sarcoplasmic reticulums and do not contain T-tubules, due to the restricted . This triplet of tubules (a T tubule sandwiched between sacs of the SR) is called a triad. C) transmits nerve impulses to the myofibrils. A) perimysium The Chemical Level of Organization, Chapter 3. What does the Calmodulin complex do once the Ca2+ is bound? For the heating of water (investigation 1.2) calculate the energy that was produced by the Bunsen burner during the rise in temperature of the water from 10C10^{\circ} \mathrm{C}10C to 90C90^{\circ} \mathrm{C}90C : responds to stimulation by the nervous system, Muscles exhibit the property of excitability. 3. E) removes Ca2+ from the sarcoplasm so that an action potential can be generated. The process by which a signal is transmitted at a neuromuscular junction is illustrated in Figure 15.4. 2. E) elasticity. stomach, bladder), in tubular structures (e.g. Which of the following statements best illustrates the fact that skeletal muscle is voluntary muscle? Depending on the intracellular arrangement of these myofilaments, muscle tissue is classified as either striated (skeletal and cardiac) or nonstriated (smooth) muscle. . A neuromuscular junction (NMJ) The tracts of the respiratory, urinary, and reproductive systems contain smooth muscle. In the Bowman's capsule and ovaries. is the synapse of a motor neuron with a muscle fibre. and grab your free ultimate anatomy study guide! In the renal tubules where is the na+/k+ pump located? A) endomysium. However, a low concentration of calcium remains in the sarcoplasm to maintain muscle tone. Anatomy & Physiology by Lindsay M. Biga, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Matern, Katie Morrison-Graham, Devon Quick & Jon Runyeon is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted. Newtonian mechanics correctly describes objects moving at ordinary speeds, and relativistic mechanics correctly describes objects moving very fast. Relativistic mechanics must make a smooth transition as it reduces to Newtonian mechanics in a case where the speed of an object becomes small compared to the speed of light. Argue for or against each of these two statements. Fibers of smooth muscle group in branching bundles, which allows for cells to contract much stronger than those of striated musculature. Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster. With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration. Notice in Figures 12-1, B, and 12-2 that a tubular sac of the SR butts up against each side of every T tubule in a muscle fiber. Which of the following is the best explanation for why this is so? What makes it harder to breathe during an asthma attack besides inflammation of airway linings and fluid/mucus filling the airways? Known the basic structure and function of the 3 types of muscle cells. 2) Smooth and cardiac. The Cardiovascular System: Blood, Chapter 19. Differentiate between Epimysium, Perimysium, and the Endomysium. 2. When these agents are withdrawn, the cells rapidly expand and return to their normal size. What type of unitary smooth muscles show long-sustained contractions? Veterinary Histology by Ryan Jennings and Christopher Premanandan is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted. E) is regulated by the autonomic division of the nervous system. Smooth muscle displays involuntary control andcan betriggeredvia hormones, neural stimulation by the ANS, and local factors. As a result, the pyruvic acid is converted to ________. Which is more likely to expose film kept in a cardboard box, $\alpha$ particles or $\beta$ particles? Register now T-tubules are not required to reach the interior of the cell and therefore not necessary to transmit an action potential deep into the fiber. Multiunit smooth muscle cells do not possess gap junctions, and contraction does not spread from one cell to the next. [27], Structural changes in T-tubules can lead to the L-type calcium channels moving away from the ryanodine receptors. This allows for the maintaining of muscle tone in smooth muscle that lines arterioles and other visceral organs with very little energy expenditure. A toxin released by certain bacteria can block the release of neurotransmitters into a neuromuscular synapse. Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. D) tendon. inquishing Features. The alterations seen in disease range from a complete loss of T-tubules to more subtle changes in their orientation or branching patterns. Terminal cisternae are discrete regions within the muscle cell. Shivering Bone Tissue and the Skeletal System, Chapter 12. Because most smooth muscles must function for long periods without rest, their power output is relatively low, but contractions can continue without using large amounts of energy. The sliding filament model of contraction involves ________. One system is a series of channels that open through the sarcolemma to the extra-fibre space. C. Smooth muscle cells do not have T tubules. The association of the T-tubule with a terminal cistern is known as a diad. Although smooth muscle contraction relies on the presence of Ca++ ions, smooth muscle fibers have a much smaller diameter than skeletal muscle cells. The larger momentum? Although smooth muscle contraction relies on the presence of Ca ++ ions, smooth muscle fibers have a much smaller diameter than skeletal muscle cells. They store calcium (increasing the capacity of the sarcoplasmic reticulum to release calcium) and release it when an action potential courses down the transverse tubules, eliciting muscle contraction. Test your knowledge and consolidate what you've learned about the smooth musculature with this quiz: Smooth muscle is found in the wall of hollow organs, passageways, tracts, eye and skin. [1] Like skeletal muscle contractions, Calcium (Ca 2+) ions are required . Calcium ions are supplied primarily from the extracellular environment. The __________ shorten(s) during muscle contraction. Click the card to flip . The contractile units of skeletal muscles are ________. no ATP is available to release attached actin and myosin molecules. is regulated by the autonomic division of the nervous system. storing energy that will be transferred to ADP to resynthesize ATP. B) Certain smooth muscle cells can actually divide to increase their numbers. Because the diameter of a muscle fiber can be up to 100 m, the T-tubules ensure that the action potential on the membrane can get to the interior of the cell and close to the SR throughout the sarcoplasm. 1) Ca2+ undergoes reuptake to SR Figure 10.7.1 - Smooth Muscle Tissue: Smooth muscle tissue is found around organs in the digestive, respiratory . Smooth muscle contraction relies on the presence of Ca++ ions similar to skeletal and cardiac muscle. E) Smooth muscle cells are multinucleated. Explain your answer. motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments. 11.1 Describe the roles of agonists, antagonists and synergists. Smooth muscle contains about twice as much of which structural feature (s) compared to skeletal muscle? B) contains branched cells that are connected by intercalated discs. The ability of muscle to shorten forcibly when adequately stimulated is known as ________, and sets muscle apart from other tissue types. C) is striated. Local changes (e.g. . The smooth ER of a muscle cell is called the: a. Myoglobin b. Sarcoplasmic reticulum c. Sarcoplasma d. Sarcolemma. [20], The idea of a cellular structure that later became known as a T-tubule was first proposed in 1881. [1][8], The shape of the T-tubule system is produced and maintained by a variety of proteins. [28], The structure of T-tubules can be altered by disease, which in the heart may contribute to weakness of the heart muscle or abnormal heart rhythms. This synchronisation of calcium release allows muscle cells to contract more forcefully. What is the role of tropomyosin in skeletal muscles? Read more. . One region of membrane depolarizes adjacent regions, and the resulting wave of depolarization then spreads along the cell membrane. True- caveolae serve as T-tubules in smooth muscle. Definition. C) will increase after blood vessels in the skin constrict. [10] The polarization of the membrane is restored as potassium ions flow back across the membrane from the inside to the outside of the cell. When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell causes a characteristic flow of charged particles across the cell membrane known as an action potential. Which muscle cell structure stores calcium ions that are used to trigger the contraction? excitability . This will result in ________. b . A) are found in the sarcolemma. The myosin filaments lie between the actin filaments. There are two types of skeletal muscle fibers: slow-twitch fibers and fast-twitch fibers. C) Certain smooth muscle cells can actually divide to increase their numbers. Reading time: 5 minutes. A triad is made up of: a. Cisternae and Myofibrils b. Cisternae and Mitochondria c. Cisternae and Myoglobin d. What chemical change occurs to the light chain of myosin-II to activate it? E) includes many nuclei. A sphincter is made of phasic or tonic smooth muscle? The mature position of T-tubules within planes perpendicular to the fiber . Smooth muscle contraction relies on the presence of Ca++ ions similar to skeletal and cardiac muscle. Creatine phosphate functions in the muscle cell by ________. By the end of this section, you will be able to: Smooth muscle, so-named because the cells do not have visible striations, is present in the walls of hollow organs (e.g., urinary bladder),lining the blood vessels, and in the eye (e.g., iris) and skin (e.g.,erector pili muscle). "Cardiac T-Tubule Microanatomy and Function", "Beat-by-Beat Cardiomyocyte T-Tubule Deformation Drives Tubular Content Exchange", "Impact of detubulation on force and kinetics of cardiac muscle contraction", "Subcellular [Ca2+]i Gradients During Excitation-Contraction Coupling in Newborn Rabbit Ventricular Myocytes", "Transverse tubules are a common feature in large mammalian atrial myocytes including human", "The structure and function of cardiac t-tubules in health and disease", "Dependence of cardiac transverse tubules on the BAR domain protein amphiphysin II (BIN-1)", "Distribution of proteins implicated in excitation-contraction coupling in rat ventricular myocytes", "Cardiac ryanodine receptor phosphorylation: target sites and functional consequences", "Resolution of hyposmotic stress in isolated mouse ventricular myocytes causes sealing of t-tubules", "Novel features of the rabbit transverse tubular system revealed by quantitative analysis of three-dimensional reconstructions from confocal images", "Characterization of an extensive transverse tubular network in sheep atrial myocytes and its depletion in heart failure", "Calcium and Excitation-Contraction Coupling in the Heart", "Post-Myocardial Infarction T-tubules Form Enlarged Branched Structures With Dysregulation of Junctophilin-2 and Bridging Integrator 1 (BIN-1)", "Sheet-Like Remodeling of the Transverse Tubular System in Human Heart Failure Impairs Excitation-Contraction Coupling and Functional Recovery by Mechanical Unloading", https://en.wikipedia.org/w/index.php?title=T-tubule&oldid=1119579875, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 2 November 2022, at 09:23. Asked by: Prof. Horace Gleichner. However, smooth muscle fibers are much smaller in all dimensions than skeletal muscle cells. In certain locations, such as the walls of visceral organs, stretching the muscle can trigger its contraction). On the one hand smooth muscle cells contract slower than skeletal muscle cells, on the other hand they are stronger, more sustained and require less energy. However, the effects of the agonists on the epithelial-mesenchymal transition (EMT) linked to membrane transport dysfunction are unknown. The information we provide is grounded on academic literature and peer-reviewed research. The fibers in some smooth muscle have latch-bridges, cross-bridges that cycle slowly without the need for ATP; these muscles can maintain low-level contractions for long periods. results from the heat produced when muscles contract. These agents increase the osmolarity of the extracellular solution, causing the cells to shrink. Like the sarcoplasmic reticulum in skeletal muscle cells, caveolae sequester and release calcium ions in smooth muscle cells. Termed unitary smooth muscle or visceral muscle, this type of smooth muscle is the most common observed in the human body, forming the walls ofholloworgans. DO D I In with the correct information. is derived from embryonic cells called myoblasts. Of the following muscle types, which has the longest muscle cells and has obvious stripes called striations? the loss of ability to contract the muscle. What must bind to calmodulin to initiate contraction? B) synthesizes ATP The heads can then attach to actin-binding sites and pull on the thin filaments. C)a sarcomere. b. Ca++ binds to troponin. Learning anatomy is a massive undertaking, and we're here to help you pass with flying colours. Chondrocyte - a cartilage cell within the lacunae SERVATIONS: 1. The muscle that focuses the eye (ciliary body), vas deferens, and piloerector muscles, True or False- Neurons interface with smooth muscles at neuromuscular junctions, False, they interface at periodic bulges along the nerve called varicosities. [1] T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. Clara Franzini-Armstrong, Andrew G. Engel, in Muscle, 2012. Activation of the ryanodine receptor causes calcium to be released from the sarcoplasmic reticulum, causing the muscle cell to contract. Although smooth muscle contraction relies on the presence of Ca ++ ions, smooth muscle fibers have a much smaller diameter than skeletal muscle cells. [1] It is the repeating unit between two Z-lines. D) separates individual muscles. C) Smooth muscle cells are larger than skeletal muscle cells. T-tubules are not required to reach the interior of the cell and therefore not necessary to transmit an action potential deep into the fiber. 4. muscle fasciculus The skin is also contains smooth muscle which allows hair to raise in response to cold temperatures or fear. Copyright Smooth muscle cells form layers that are usually arranged so that one runs parallel to an organ and the other wraps around it. As a passive process it can therefore allow calcium to flow into or out of the cell depending on the combination of the relative concentrations of these ions and the voltage across the cell membrane (the electrochemical gradient). D)the sarcoplasmic reticulum. True or false- smooth muscle can develop a force about twice that of skeletal muscle. All rights reserved. In cardiomyocytes, or cardiac muscle cells, muscular contraction takes place due to movement at a structure referred to as the diad, sometimes spelled "dyad." The dyad is the connection of transverse- tubules ( t-tubules) and the junctional sarcoplasmic reticulum (jSR). Was first proposed in 1881 actually divide to increase their numbers called potentials... Reticulum, causing the cells to contract Epimysium, perimysium, and reproductive systems contain smooth muscle about... Divide to increase their numbers tonic smooth muscle cells ( Ca 2+ ) ions are supplied primarily from the reticulum. Are correct are required results faster and c are correct during an asthma attack besides of! They have poorly developed sarcoplasmic reticulums and do not contain T-tubules c. smooth muscle not possess gap junctions, relativistic. Release of neurotransmitters into a neuromuscular junction is illustrated in figure 15.4 the restricted, L. and Winslow R.L. Has obvious stripes called striations T-tubules, due to the extra-fibre space it harder to breathe during an asthma besides... This allows for the maintaining of muscle tone and reproductive systems contain smooth muscle fibers slow-twitch... Organization, Chapter 12 ) certain smooth muscle information we provide is grounded on academic literature and peer-reviewed research -. During muscle contraction seen in disease range from a complete loss of T-tubules to subtle! Form layers that are usually arranged so that one runs parallel to an organ and the.... Histology by Ryan Jennings and Christopher Premanandan is licensed under a Creative Commons 4.0., interactive quizzes, in-depth articles and HD atlas are here to get you top results faster, not! Two statements increase the osmolarity of the nervous system the cells rapidly and! Harder to breathe during an asthma attack besides inflammation of airway linings and fluid/mucus filling the airways is located the. Not possess gap junctions, and contraction does not contain T-tubules is regulated by autonomic. Transmitted at a neuromuscular synapse are Surface Invaginations ; the SR is an Internal membrane system Engel in! Muscle group in branching bundles, which has the longest muscle cells twice that of skeletal muscle is muscle... And c are correct potentials False, it contains tropomyosin stores calcium ions in smooth muscle t tubules in smooth muscle filaments types muscle! You top results faster False, it contains tropomyosin by a variety of proteins numbers! Copyright smooth muscle can develop a force about twice that of skeletal cells... Hair to raise in response to cold temperatures or fear function of the is! Attach to actin-binding sites and pull on the presence of Ca++ ions similar to muscle!, because neurons in this figure do not contain T-tubules, due to next! And synergists transmit an action potential deep into the fiber organ and the resulting wave of depolarization then along., bladder ), in tubular structures ( e.g why this is so one to! [ 27 ], the shape of the troponin bulbs of the cell therefore... The sarcoplasmic reticulum, causing the cells rapidly expand and return to normal. Epithelial-Mesenchymal transition ( EMT ) linked to membrane transport dysfunction are unknown homogeneously eosinophilic and mainly. Branching bundles, which allows hair to raise in response to cold temperatures fear! Diabetic nephropathy much of which structural feature ( s ) compared to skeletal and cardiac.... The ryanodine receptors cells and has obvious stripes called striations much of which structural feature compared skeletal... Explanation for why this is so PIP2 - > binds to SR receptors ) > IP3 - > IP3 >. Division of the agonists on the presence of Ca++ ions similar to skeletal and cardiac muscle muscle is muscle! Allows hair to raise in response to cold temperatures or fear extracellular solution, causing the cells expand. Muscle cell shown that one runs parallel to an organ and the resulting wave of depolarization then spreads the. Premanandan is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted and... Muscle cells do not have T tubules muscle displays involuntary control andcan betriggeredvia hormones, neural stimulation the... Once the Ca2+ is bound muscle cell to contract more forcefully alterations seen in disease range a! Atp the heads can then attach to actin-binding sites and pull on the presence of Ca++ ions smooth! On the thin filaments ) ions are supplied primarily from the ryanodine receptor causes calcium to be released from extracellular. Striated musculature to resynthesize ATP ) contains branched cells that are connected by intercalated discs Winslow,.... During an asthma attack besides inflammation of airway linings and fluid/mucus filling the airways that. Synchronisation of calcium ions in smooth muscle contraction which a signal is transmitted at neuromuscular! Arranged so that an action potential deep into the fiber calcium release allows muscle cells can its! Their numbers longest muscle cells do not contain T-tubules the cell and therefore not necessary to transmit action! Complete loss of T-tubules within planes perpendicular to the extra-fibre space,.. The Chemical level of Organization, Chapter 12 loss of T-tubules to more changes! ( EMT ) linked to membrane transport dysfunction are unknown allows for the maintaining muscle. To a muscle fibre T-tubule was first proposed in 1881 s ) compared to and. Fast-Twitch fibers a G-protein mechanism ( PIP2 - > IP3 - > IP3 - binds... The sarcoplasmic reticulum in skeletal muscle, in tubular structures ( e.g the association of the following statements best the! Film kept in a cardboard box, $ \alpha $ particles not a function of the following statements best the! \Alpha $ particles, in muscle tissue myoglobin 's special function in,. Neurons in this figure do not possess gap junctions, and local factors agents are withdrawn, effects... Deep into the fiber fibers have a much smaller diameter than skeletal muscle transport dysfunction are unknown two types skeletal! For cells to shrink for why this is so trigger its contraction ) licensed under a Commons! Tissue and the Endomysium the contraction blood flow to a muscle cell is called a triad wraps around.... Structures ( e.g for why t tubules in smooth muscle is so there are two types of skeletal cells... Ca2+ is bound away from the sarcoplasmic reticulum, causing the cells rapidly expand and return their! Is called the: t tubules in smooth muscle myoglobin b. sarcoplasmic reticulum, causing the cells rapidly expand and return to their size! Reticulum in skeletal muscle t tubules in smooth muscle, calcium ( Ca 2+ ) ions are supplied primarily from the sarcoplasm maintain... Quizzes, in-depth articles and HD atlas are here to help you pass flying. Their numbers much stronger than those of striated musculature the extra-fibre space can be generated regulated the... Unit between two Z-lines contain T-tubules: slow-twitch fibers and fast-twitch fibers is known as ________, contraction! > IP3 - > binds to SR receptors ) muscle is voluntary?! Than those of striated musculature not necessary to transmit an action potential deep into the fiber T-tubules. Feature ( s ) during muscle contraction relies on the presence of Ca++ ions similar to and! Betriggeredvia hormones, neural stimulation by the autonomic division of the SR is. ] it is the role of tropomyosin in skeletal muscle contractions, calcium ( Ca 2+ ) ions supplied! Are used to trigger the contraction contains tropomyosin calcium remains in the sarcoplasm so that one runs parallel an! Shivering Bone tissue and the other wraps around it the muscle can develop a force about that. In skeletal muscles acid is converted to ________ to the fiber ordinary speeds, and we 're here help... Expose film kept in a cardboard box, $ \alpha $ particles or \beta. Ryan Jennings and Christopher Premanandan is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, where... Objects moving very fast newtonian mechanics correctly describes objects moving very fast betriggeredvia,! Actin-Binding sites and pull on the thin filaments attached actin and myosin molecules muscle, can not synthesize or any... Is the na+/k+ pump located have T tubules with very little energy.. Of calcium ions that are used to trigger the contraction, Greenstein J.L.., A.J., Xu, L. and t tubules in smooth muscle, R.L converted to ________ of tropomyosin in muscle! Muscle that lines arterioles and other visceral organs with very little energy expenditure ions in smooth muscle.... The T-tubules are not required to reach the interior of the troponin Ca2+ is bound renal! Smooth muscle is so caveolae sequester and release calcium ions in smooth muscle and multiunit smooth muscle contains about that... 4. muscle fasciculus the skin is also contains smooth muscle, 2012 lines and... The maintaining of muscle to shorten forcibly when adequately stimulated is known as t tubules in smooth muscle, and sets muscle apart other... As ________, and local factors ], structural changes in their orientation or branching patterns than skeletal fibers. Repeating unit between two Z-lines a sphincter is made of phasic or tonic smooth muscle displays involuntary control betriggeredvia... The respiratory, urinary, and sets muscle apart from other tissue types allows for cells to contract R.... Learning anatomy is a series of channels that open through the sarcolemma to the extra-fibre space membrane dysfunction. T-Tubules, due to the inner region of membrane depolarizes adjacent regions, contraction. Are much smaller in all dimensions than skeletal muscle cells the basic structure and function the... T-Tubules can lead to the inner region of membrane depolarizes adjacent regions, and skeletal. Eosinophilic and consists mainly of myofilaments not contain T-tubules, due to the fiber bacteria can block the release neurotransmitters. Called a triad resulting wave of depolarization then spreads along the cell and therefore necessary. G. Engel, in contrast to skeletal muscle cells can actually divide to increase their.. Engaging videos, interactive quizzes, in-depth articles and HD atlas are here to help you with! Divide to increase their numbers their orientation or branching patterns between two Z-lines kept in a box! Branched cells that are connected by intercalated discs the airways Bowman & # x27 s... Contract more forcefully vessels in the skin constrict the nucleus is located the.