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level: Smooth Muscle + Digestive Tract

Questions and Answers List

level questions: Smooth Muscle + Digestive Tract

QuestionAnswer
What muscle is used for the digestion process?Smooth muscle
Where can smooth muscle tissue be found (in terms of the digestive system)Smooth muscle is primarily found in the walls of Viscera
What are characteristics of smooth muscle tissue?Fibers are elongated One centrally located nucleus Grouped into sheets - creates a longitudinal and circular layer
Name structures (both blue and green region)blue region: Longitudinal layer of smooth muscle green region: Circular layer of smooth muscle
What is the function of the Longitudinal layer?The longitudinal layer causes organ dilation and shortening
what is the function of the circular layer?the circular layer causes organ constriction and elongation
What innervates the smooth muscle?Autonomic nervous system fibers - sympathetic motor fibers -parasympathetic motor fibers - Visceral sensory fibers
Name structure coveredAutonomic nerve fibers in smooth muscle
Name structure coveredVaricosities
Define Varicositiesrelease their neurotransmitters into a wide synaptic cleft.
What stimulates contraction?Entry of Calcium into the Sarcoplasm stimulates contraction
What is the process of contraction?1. Calcium enters the sarcoplasm from the sarcoplasm reticulum or extracellular fluid and makes it way to the cytosol. 2. Calcium binds and activates calmodulin 3. The activated calmodulin activates the kinase enzymes 4. Kinase enzymes catalyze transfer of phosphate to myosin 5. Activated myosin forms cross bridges with actin of the thin filaments and shortening begin.
Is smooth muscle contraction fast or slow?contraction is slow and sustained - takes 30x longer to contract and relax - resistant to fatigue -energy requirements are low (so mitochondria is not abundant)
Where are contractions over long periods needed?smooth muscle of arteries and visceral organs must sustain contraction over long periods.
Smooth muscle fibers contract or relax in response to....- action potentials from ANS - stretching -hormones -changes in pH, oxygen/carbon dioxide levels, tempature
Name the structure coveredIntermediate filament bundles - thick filaments (myosin) - thin filaments (actin)
Name structure coveredDense Bodies
Define Dense bodiesDense bodies function the same way as Z discs.  During contraction, sliding myofilaments shorten the muscle cell by pulling on the dense bodies and overall the cytoskeleton. Causes a squeezing movement
Name structure coveredCaveolae
Define Myenteric Nerve Plexusa nerve plexus situated in the muscular layers of the intestines
Where is the myenteric nerve plexus?Myenteric nerve plexus lies between the circular and longitudinal muscularis.
What is the function of the Myenteric Nerve PlexusControls peristalsis and segmentation - mainly controls GI motility (increases number and speed of contractions)
Name the structureMyenteric nerve plexus
Where is the Submucosal nerve plexus found?lies in the submucosa of the intestinal wall and is derived from the myenteric plexus.
What is the function of the submucosal nerve plexus?signals glands to secrete. - helps control intestinal secretion, absorption, blood flow, and local contraction.
Name structuresubmucosal nerve plexus