Term
| Is Smooth Muscle striated or unstriated muscle? |
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Definition
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Term
| Is Smooth Muscle voluntary or involuntary muscle? |
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Definition
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Term
| Is Smooth Muscle innervated by the SNS or ANS? |
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Definition
| The Autonomic Nervous System |
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Term
| Where is smooth muscle GENERALLY found? |
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Definition
| In the walls of hollow organs and tubes |
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Term
| Give 3 examples of where smooth muscle is found in the body |
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Definition
| Arteries and Veins; Trachea and Bronchioles; GI Tract; Uterus; Bladder; Ureters; Iris of the Eye |
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Term
| True or False: Smooth Muscle helps organs maintain their shape |
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Definition
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Term
| True or False: Smooth Muscle does NOT function in muscle contraction |
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Definition
| FALSE; The main function of smooth muscle is contraction |
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Term
| List 3 functions, other than contraction, of smooth muscle |
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Definition
| Produces motility through a hollow organ or tube; Maintains pressure against contents within the hollow organ; Regulates internal flow of contents by changing tube diameter |
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Term
| True or False: Smooth Muscle filaments form myofibrils |
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Definition
| FALSE; They do NOT form myofibrils |
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Term
| True or False: Smooth Muscle is NOT arranged in a sarcomere pattern |
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Definition
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Term
| What is the shape of Smooth Muscle and how many nuclei does it have? |
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Definition
| Smooth Muscle is a spindle- shaped cell with one nucleus |
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Term
| What are the two directions in which smooth muscle sheets can be arranged? |
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Definition
| Circumferential OR Longitudinal |
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Term
| True or False: Smooth Muscle contains gap junctions to couple cells |
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Definition
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Term
| What are the 2 BROAD groups of smooth muscle? |
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Definition
| Single- Unit and Multi- Unit |
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Term
| True or False: Smooth Muscle has t- tubules |
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Definition
| FALSE; The thin cells of smooth muscle do NOT contain t- tubules |
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Term
| Describe the structure of smooth muscle cells |
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Definition
| There is a less developed sarcomere; But contact with the plasma membrane; And Caveolae are invaginations in the membrane which provide a means for extracellular communication |
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Term
| What do Gap Junctions allow and in which group are they found? |
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Definition
| Gap Junctions allow for "full recruitment" and are found in SINGLE- UNIT smooth muscle |
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Term
| What are the two ions conducted by gap junctions? |
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Definition
| Na+ (Sodium) and Ca2+ (Calcium) |
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Term
| Fill in the blank: Cells function as a _____________ and are connected anatomically and electrically via ______ _________. |
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Definition
| Cells function as a SYNCTIUM and are connected anatomically and electrically via GAP JUNCTIONS. |
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Term
| What are the 3 types of filaments found in smooth muscle? |
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Definition
| Myosin, Actin, and Intermediate Filaments |
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Term
| Are myosin filaments longer in smooth muscle or skeletal muscle? |
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Definition
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Term
| True or False: Actin filaments in smooth muscle contain troponin and tropomyosin |
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Definition
| FALSE; Actin filaments contain tropomyosin, but do NOT contain troponin |
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Term
| What do intermediate filaments do in smooth muscle? |
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Definition
| They form part of he cytoskeletal framework which supports the shape of the cell AND they hold dense bodies in place |
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Term
| What are varicosities and how do they function? |
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Definition
| Swellings in the muscle that contain neurotransmitter and mitochondria; They engage in smooth muscle innervation |
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Term
| How many nerves innervate single- unit smooth muscle? |
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Definition
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Term
| How many nerves innervate multi- unit smooth muscle? |
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Definition
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Term
| Which type of smooth muscle contains MORE gap junctions? |
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Definition
| Single- Unit Smooth Muscle |
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Term
Single- Unit Smooth Muscle is _____________?
Myogenic or Neurogenic |
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Definition
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Term
| What does it mean for a single- unit cell to be myogenic? |
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Definition
| The single- unit smooth muscle cells are self- excitable, thus they do not require nervous stimulation for contraction |
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Term
| True or False: Single- unit contraction is rapid and energy- efficient |
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Definition
| FALSE; While single- unit smooth muscle contraction is energy efficient, it is SLOW |
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Term
| Where is single- unit smooth muscle found in the body? |
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Definition
| GI, Bladder, Small Blood Vessels, Uterus, and Ureter |
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Term
Multi- Unit Smooth Muscle is ___________?
Myogenic or Neurogenic |
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Definition
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Term
| What does it mean for a multi- unit cell to be neurogenic? |
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Definition
| In order for multi- unit smooth muscle to contract, it must be stimulated by nerves |
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Term
| Can neurogenic smooth muscle contract as a single unit? |
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Definition
| NO; Each unit must be separately stimulated by nerves before contraction can occur |
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Term
| Where is multi- unit smooth muscle found in the body? |
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Definition
| Walls of Large Blood Vessels, Small Airways to Lungs, Eye Muscles, Base of Hair Follicles |
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Term
| Which type of smooth muscle has stretch- initiated contractions and relaxations? |
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Definition
| Single- Unit Smooth Muscle |
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Term
| What is the numerical range of the resting membrane potential in smooth muscle cells? |
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Definition
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Term
| Which type of smooth muscle fires action potentials? |
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Definition
| Single- Unit Smooth Muscle; Most Multi- Unit Smooth Muscle cells do NOT fire action potentials |
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Term
| True or False: Smooth Muscle action potentials are dependent on Calcium instead of Sodium |
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Definition
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Term
| Which type of smooth muscle exhibits spontaneous depolarization of its resting membrane potential? |
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Definition
| Single- Unit Smooth Muscle |
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Term
| Define Pacemaker potential |
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Definition
| Membrane potential gradually depolarizes until it reaches threshold for firing a single action potential |
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Term
| Define Slow Wave potential |
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Definition
| Membrane potential alternately depolarizes and hyperpolarizes, until threshold is reached and an action potential is fired |
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Term
| Where does regulation of cross- bridge cycling occur in smooth muscle? |
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Definition
| On the thick myosin filament |
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Term
| What prevents actin and myosin from binding at the cross- bridges in the resting state? |
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Definition
| Light- weight proteins attached to the myosin molecules, known as Myosin Light- Chains |
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Term
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Definition
| A low level of force in the absence of extrinsic factors; Cytosolic calcium concentration is sufficient to maintain a low level of cross- bridge recyclingWhere |
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Term
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Definition
| Rapid production of force and subsequent rapid relaxation of smooth muscle as calcium concentration returns to basal level |
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Term
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Definition
| Continuous production of force in the presence of falling calcium concentrations that remain above basal levels; Cross- bridge cycling continues at a low level |
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Term
| Where are phasic contractions common in the body? |
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Definition
| GI tract and urogenital organs |
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Term
| Where are tonic contractions common in the body? |
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Definition
| Airways, Blood Vessels, GI |
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