The Digestive System: Stomach Structure and Sphincters

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Questions and Answers

Which of the following is one of the main pairs of salivary glands?

Parotid gland (correct)

Pituitary gland

Thyroid gland

Sweat gland

How do the salivary glands empty their secretions into the mouth?

Through ducts (correct)

Through lymphatic vessels

Through blood vessels

Through alveoli

Which muscle is located near the parotid gland?

Biceps muscle

Sternocleidomastoid muscle

Temporalis muscle

Masseter muscle (correct)

Where is the submandibular gland located?

Below the jaw Signup and view all the answers

Which structure is associated with the submandibular gland?

Submandibular duct Signup and view all the answers

What is the function of the gall bladder?

To store bile produced by the liver Signup and view all the answers

Which duct connects the gall bladder to the common bile duct?

Cystic duct Signup and view all the answers

Which part of the biliary tract empties bile into the duodenum?

Common bile duct Signup and view all the answers

Through which sphincter does bile enter the duodenum?

Hepatopancreatic sphincter Signup and view all the answers

What is the main structural layer of the gall bladder that facilitates expansion and contraction?

Mucous membrane with folds Signup and view all the answers

Which cell type is found in the gastric glands?

Chief cells Signup and view all the answers

Where does the small intestine begin?

Pyloric sphincter Signup and view all the answers

What is the diameter of the small intestine?

2.5 cm Signup and view all the answers

What type of tissue covers the outer surface of the stomach and intestines?

Serosa Signup and view all the answers

Which section of the small intestine is directly connected to the stomach?

Duodenum Signup and view all the answers

Which sphincter controls the opening from the pyloric portion of the stomach into the duodenum?

Pyloric sphincter Signup and view all the answers

What is the name of the folds in the stomach when it is empty?

Rugae Signup and view all the answers

What type of cells are NOT part of the gastric glands?

Goblet cells Signup and view all the answers

How many layers of smooth muscle does the muscularis in the stomach have?

Three Signup and view all the answers

What is the main characteristic of the gastric mucosa when the stomach is full?

It has a smooth velvety appearance. Signup and view all the answers

Which movement type is NOT provided by the stomach’s muscle layer?

Segmentation Signup and view all the answers

Where are gastric glands most abundantly situated?

In the fundus and body of the stomach Signup and view all the answers

How many types of secretory cells do the gastric glands have?

Three Signup and view all the answers

Which is the largest serous membrane of the body?

Peritoneum Signup and view all the answers

What type of epithelium does the parietal peritoneum consist of?

Simple squamous epithelium Signup and view all the answers

What is the function of the visceral peritoneum?

It covers some organs in the abdominopelvic cavity. Signup and view all the answers

What contains a small amount of serous fluid?

Peritoneal cavity Signup and view all the answers

How many layers does the peritoneum have?

Two Signup and view all the answers

What is the primary function of teeth?

Organs of mastication Signup and view all the answers

Which action is NOT performed by teeth?

Absorbing nutrients Signup and view all the answers

Where are teeth embedded?

In the alveoli of mandible and maxilla Signup and view all the answers

What does mastication refer to?

Chewing Signup and view all the answers

Food mixed with saliva and prepared for swallowing is the result of which process?

Mastication Signup and view all the answers

Where does the descending colon lie?

On the left side, below the spleen Signup and view all the answers

What is the shape of the sigmoid colon?

S-shaped Signup and view all the answers

How long is the rectum?

13 cm Signup and view all the answers

Where does the sigmoid colon terminate?

In the rectum Signup and view all the answers

Where is the rectum located?

In the pelvic cavity Signup and view all the answers

What is the approximate length of the large intestine?

1.5 to 1.8 meters Signup and view all the answers

Which part of the large intestine is continuous with the ascending colon superiorly?

Caecum Signup and view all the answers

Where does the ileocaecal valve open from?

Ileum Signup and view all the answers

Which part of the large intestine is described as a narrow blind tube?

Vermiform appendix Signup and view all the answers

What is the usual length of the vermiform appendix?

8-10 cm Signup and view all the answers

Which part of the large intestine lies in a vertical position on the right side of the abdomen?

Ascending colon Signup and view all the answers

Which part of the colon curves acutely to the left at the right colic flexure?

Ascending colon Signup and view all the answers

Which part of the large intestine is the longest?

Transverse colon Signup and view all the answers

What shape are the hepatic lobules?

Hexagonal Signup and view all the answers

Which cells in the liver ingest and destroy bacteria and worn RBCs?

Kupffer cells Signup and view all the answers

What is the main function of hepatic macrophages?

Ingesting and destroying bacteria Signup and view all the answers

What is found between two pairs of columns of hepatocyte cells?

Sinusoids Signup and view all the answers

Which vein is the central vein of a liver lobule connected to?

Hepatic vein Signup and view all the answers

Which structure carries blood containing a high concentration of nutrients to the liver cells?

Portal vein Signup and view all the answers

Where is the pancreas located?

Behind the stomach Signup and view all the answers

Which part of the pancreas fits into the C-shaped curve of the duodenum?

Head Signup and view all the answers

Which of the following organs is associated with the liver superiorly?

Diaphragm Signup and view all the answers

Which ligament separates the two lobes of the liver?

Falciform ligament Signup and view all the answers

Which structure opens into the duodenum?

Hepatopancreatic ampulla Signup and view all the answers

Which tissues support the lobules in the pancreas?

Loose connective tissue Signup and view all the answers

What controls the opening of the hepatopancreatic ampulla in the duodenum?

Hepatopancreatic sphincter (of Oddi) Signup and view all the answers

Which lobe of the liver is the smallest?

Left lobe Signup and view all the answers

How much does the pancreas generally weigh?

60g Signup and view all the answers

Study Notes

The Digestive System

Lower Esophageal Sphincter and Pyloric Sphincter

The lower esophageal sphincter controls the opening of the esophagus into the stomach
The pyloric sphincter controls the opening from the pyloric portion of the stomach into the duodenum (first part of the small intestine)

Structure of the Stomach

Gastric Mucosa

The epithelial lining of the stomach is thrown into longitudinal folds called rugae when empty
The rugae disappear when the stomach is full, giving it a smooth velvety appearance
Gastric glands are situated below the surface in the mucous membrane, especially in the fundus and body of the stomach
The glands consist of mucus-secreting goblet cells, chief cells, parietal cells, and endocrine cells

Gastric Muscle

The muscularis is a thick layer consisting of three distinct layers of smooth muscle fibers:
- Outer layer of longitudinal fibers
- Middle layer of circular fibers
- Inner layer of oblique fibers
This arrangement allows the stomach to provide two types of movements: churning and peristalsis

Peritoneum

The peritoneum is the largest serous membrane of the body
It consists of two layers:
- Parietal peritoneum, which lines the wall of the abdominopelvic cavity
- Visceral peritoneum, which covers some of the organs in the abdominopelvic cavity and is considered their serosa
The space between the two layers is called the peritoneal cavity, containing a small amount of serous fluid

Salivary Glands

There are three pairs of salivary glands: parotid, submandibular, and sublingual
They are tubuloalveolar glands that empty their secretions into the mouth through ducts

Large Intestine

The large intestine, or colon, is about 1.5 to 1.8 meters long
It consists of four parts: caecum, ascending colon, transverse colon, and sigmoid colon
The parts of the colon are continuous with each other

Caecum

The caecum is the first part of the large intestine, located in the right iliac fossa of the abdomen
It is about 5-8 cm long and has a blind end inferiorly
The vermiform appendix arises from the caecum just below the ileocaecal valve

Vermiform Appendix

The appendix is a narrow, blind tube projecting from the caecum
It is usually about 8-10 cm long and contains more lymphatic tissue than the large intestine

Ascending Colon

The ascending colon lies in a vertical position on the right side of the abdomen, extending from the caecum to the lower border of the liver
It curves acutely to the left at the right colic flexure to become the transverse colon

Transverse Colon

The transverse colon is the longest part of the colon, passing horizontally across the abdomen
It extends from the hepatic flexure to the splenic flexure, where it curves acutely downward to continue as the descending colon

Teeth

Teeth are the organs of mastication, designed to cut, tear, and grind ingested food
They are embedded in the alveoli or sockets of the alveolar ridges of the mandible and maxilla

Gastric Pits and Glands

The gastric glands consist of mucus neck cells, chief cells, parietal cells, and endocrine cells
The surface mucous cells, lamina propria, and gastric glands are found in the mucosa
The muscularis and serosa are also present in the wall of the stomach

Small Intestine

The small intestine is a continuation of the stomach at the pyloric sphincter and leads into the large intestine at the ileocaecal valve
It is a tube measuring about 6 meters long and 2.5 cm in diameter
It consists of three main divisions: duodenum, jejunum, and ileum

Pancreas

The pancreas is a gland with both exocrine and endocrine functions
It is a greyish-pink colored gland lying transversely across the posterior abdominal wall
The exocrine pancreas consists of a large number of lobules supported by fine loose connective tissue

Liver

The liver is the largest visceral organ in the body
It is a wedge-shaped, reddish-brown colored, solid organ weighing about 1.5 kg
It is located mainly in the upper right hypochondriac region, part of the epigastric region, and extends into the left hypochondriac region

Organs Associated with the Liver

Superiorly: diaphragm
Inferiorly: stomach, duodenum, hepatic flexure of the colon, right kidney, adrenal gland, and bile ducts
Anteriorly: anterior abdominal wall
Posteriorly: inferior vena cava, gallbladder, abdominal aorta, and esophagus

Structure of the Liver

The liver is enclosed by a fibrous capsule and incompletely covered by a layer of peritoneum
It consists of two lobes separated by the falciform ligaments
Each lobe is divided into numerous lobules by small blood vessels and fibrous strands

Descending Colon

The descending colon lies in a vertical position on the left side of the abdomen, extending from a point below the spleen to the level of the iliac crest

Sigmoid Colon

The sigmoid colon passes downwards below the iliac crest, describing an S-shaped curve in the pelvis, and continues downwards to become the rectum

Rectum

The rectum lies in the pelvic cavity, about 13 cm long, and leads from the sigmoid colon to the anal canal

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Description

Learn about the lower esophageal sphincter, pyloric sphincter, and the structure of the stomach wall, including the gastric mucosa and other layers.