Why is it necessary for the stomach contents to be so acidic? How does the stomach protect itself from digestion?
What will be an ideal response
HCl is necessary for the activation and optimal activity of pepsin, and it kills many of the bacteria ingested with food. Mucous cells in the lining of the stomach secrete an alkaline mucus that clings to the stomach wall and helps to shield it from the acid. The epithelial cells of the mucosa are joined together by tight junctions that prevent gastric juice from leaking into underlying tissue layers. Damaged epithelial cells are shed and quickly replaced by cell division.
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A myosin molecule in the thick filaments can be considered a protein having a quaternary structural level. Which of the following best describes this structural level?
A) Myosin molecules consist of two heavy and to light polypeptide chains. B) Myosin has an ATP binding site, actin binding site and flexible hinge region. C) Myosin is a primary component within a myofibril. D) Myosin is involved in the power stroke of muscle contraction.
Membranes are organs formed by the combination of which tissues?
A) connective and muscle B) muscle and neural C) epithelial and connective D) epithelial and muscle E) connective and neural
The primary function of the proximal convoluted tubule is ________.
Fill in the blank(s) with the appropriate word(s).
Gonadotropins include FSH and LH
Indicate whether the statement is true or false