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Ch. 22 The Digestive System
Amerman - Human Anatomy & Physiology 2nd Edition
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksAmerman 2nd EditionCh. 22 The Digestive SystemProblem 3b
Chapter 22, Problem 3b

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The muscularis externa of most of the alimentary canal consists of inner circular and outer longitudinal layers of smooth muscle.

Verified step by step guidance
1
Understand the structure of the muscularis externa: The muscularis externa is a layer of the alimentary canal wall that is primarily responsible for peristalsis and segmentation. It typically consists of two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.
Evaluate the statement: The statement claims that the muscularis externa of most of the alimentary canal consists of inner circular and outer longitudinal layers of smooth muscle. This is generally true for most parts of the alimentary canal, such as the esophagus, stomach, small intestine, and large intestine.
Identify exceptions: Note that there are exceptions to this general structure. For example, in the stomach, there is an additional oblique layer of smooth muscle, making it unique compared to other parts of the alimentary canal.
Determine the truth of the statement: Since the statement specifies 'most of the alimentary canal,' and the described structure applies to the majority of the alimentary canal, the statement is true.
Conclude and correct if necessary: If the statement were false, you would need to correct it by specifying the exceptions (e.g., the stomach's additional oblique layer). However, in this case, no correction is needed as the statement is accurate.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Muscularis Externa

The muscularis externa is a layer of the alimentary canal that primarily consists of two layers of smooth muscle: an inner circular layer and an outer longitudinal layer. This structure is crucial for the peristaltic movements that propel food through the digestive tract. Understanding its anatomy and function is essential for analyzing statements related to the digestive system.
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Alimentary Canal

The alimentary canal, also known as the gastrointestinal tract, is a continuous tube that extends from the mouth to the anus. It includes various organs such as the esophagus, stomach, and intestines, each playing a specific role in digestion and absorption. Knowledge of its structure and function is vital for evaluating statements about its components.
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Smooth Muscle

Smooth muscle is a type of involuntary muscle found in various systems of the body, including the digestive tract. Unlike skeletal muscle, smooth muscle is not striated and is controlled by the autonomic nervous system. Its role in the muscularis externa is to facilitate the rhythmic contractions necessary for moving food along the alimentary canal.
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Related Practice
Textbook Question

The common hepatic duct and main pancreatic duct enter into the:

a. Pyloric sphincter

b. Duodenum

c. Ileum

d. Cecum

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Textbook Question

Match the following terms with the correct definition. 

__Chief cells          

__Parietal cells           

__Gastrin           

__Pyloric sphincter         

__Diffuse neuroendocrine (DNES) cells         

__Gastroesophageal sphincter         

__Pepsin         

__Chyme

a. Hormone that stimulates multiple digestive processes

b. Enzyme that begins protein digestion

c. Produce acid and intrinsic factor

d. Liquid produced as a result of stomach churning

e. Produce pepsinogen

f. Cells in gastric glands that produce hormones

g. Controls passage of bolus from esophagus to stomach

h. Controls passage of stomach contents to duodenum

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Textbook Question

Individuals experiencing prolonged vomiting lose a great deal of hydrochloric acid with the vomitus. Predict the effect this loss of acid will have on the pH of the blood. How will the respiratory system respond to the change in pH?

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Textbook Question

Mr. Williams presents to your clinic with a complaint of abdominal pain in the right upper quadrant. He says that the pain worsens when he eats, particularly when he eats fatty meals. He has noticed that his stool has been an unusual clay color recently. You perform an ultrasound of his abdomen and find that gallstones are blocking his common bile duct, preventing bile from entering the duodenum.

Explain why his feces have become a clay color instead of a normal brown color.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The mucosa of the esophagus, pharynx, and oral cavity contains simple squamous epithelium to protect it from abrasion.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The mucosa from the stomach to the anus consists of an inner layer of stratified columnar epithelium.

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