Smooth Muscle Contraction Research Paper

732 Words2 Pages

Larry Oliver
EXSC 223
08 November 2016
Assignment 3
1. Explain how smooth graded contractions of a skeletal muscle are produced.
When a single stimulus is delivered the muscle will contract and relax. But if another stimulus is applied before the muscle completely relaxes then the result is more tension. At higher stimulus frequencies there is no relaxation between stimuli which is called fused tetanus. At each point of the stimulus, more and more calcium is released increasing the amount of cross bridges being formed between myosin and actin. These types of contractions cannot continue indefinitely, as prolonged tetanus leads to muscle fatigue causing the muscle to no longer contract and tension dropping to zero.
Marieb, Elaine Nicpon, and …show more content…

Special Features of Smooth Muscle Contraction
(1) Smooth muscle initially contracts when stretched, but contraction is brief, and then the cells relax to accommodate the stretch
(2) Smooth muscle stretches more and generates more tension when stretched than skeletal muscle
(3) Hyperplasia, an increase in cell number through division, is possible in addition to hypertrophy, an increase in individual cell size
"Muscles and Muscle Tissue." Chapter 9: Muscles and Muscles Tissue. Midlands Tech, n.d. Web. 03 Nov. 2016.
Marieb, Elaine Nicpon, and Katja Hoehn. Human Anatomy & Physiology. 10th ed. N.p.: Pearson Education, 2016. Pg. 279-314. Print.

3. Describe the stimuli and controls of digestive activity.
Digestive activities within the GI tract are triggered by mechanical and chemical stimuli (mechanoreceptors and chemoreceptors that respond to stretch, changes in osmolarity and pH, as well as the presence of substrate and end products of digestion). External stimuli (sight, smell, taste, thought of food). Controls of the digestive activity are both extrinsic (CNS centers and autonomic nerves) and intrinsic (nerve plexuses and local hormone producing …show more content…

Although the parietal cells appear spherical when viewed with a light microscope, they actually have three prongs that bear dense microvilli (they look like fuzzy pitchforks!). This structure provides a huge surface area for secreting H and Cl into the stomach lumen. HCl makes the stomach contents extremely acidic (pH 1.5–3.5), a condition necessary for activation and optimal activity of pepsin. The acidity also helps in food digestion by denaturing proteins and breaking down cell walls of plant foods, and is harsh enough to kill many of the bacteria ingested with foods. Intrinsic factor is a glycoprotein required for vitamin B12 absorption in the small

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