The gastric glands are the tube-like, branched structures that are present at the inner lining of the stomach. These glands are the basic secretory unit of the digestive system and are composed of various cell components which perform certain specific functions. These glands originate at the opening of the stomach’s lumen, the gastric pits, which itself is present at the gastric mucosa of the stomach. The gastric pit has pale-staining mucous droplets due to the presence of mucous-secreting cells. The base consists of the isthmus and neck of the gland. The gastric glands are mostly known to be exocrine in nature and help in the synthesis and secretion of the gastric juices along with protective mucous.
There are various types of gastric glands present in the digestive system and depending on the region in the stomach, these gastric glands are divided into 3 major parts:-
1. Cardiac Glands – These glands are located close to the cardiac orifice. They usually contain cardiac glands. Also, they are comparatively very few in number and are positioned in the mucosa shallowly. These are generally of two kinds, which are the simple tubular (like those of pyloric ends) and short ducted, and the compound racemose resembling the duodenal glands. Their main function in the digestive system is to secrete mucus.
2. Fundic Glands – These glands are located in the fundus or body of the stomach. They are straight, parallel, tube-like structures. It has been observed that two or more of such tubes open into a common duct. Also, these tubes are at most one-sixth the length of the entire gland. These glands are much shorter than the pyloric glands. These glands are lined by columnar epithelium. Their main function in the digestive system is to produce digestive enzymes.
3. Pyloric Glands – These glands are the endocrine glands located in the antrum, known as the pyloric portion of the stomach. They consist of two or three short, wavy closed tubes which open into a common duct. These tubes are generally half the length of the entire duct. The duct is usually lined by columnar cells and the tubes by short, granular cubical cells. The main function of these glands is to secrete gastrin (produced by G cells) and mucus.
The mucus which is produced by the Cardiac glands and the Pyloric glands coats the stomach, dilutes the acids and enzymes, and hence protects the oesophagus and the duodenum from self-digestion.
1. What are the types of cells which are present in these gastric glands?
Every tube of the gastric glands consists of multiple types of gastric cells which help these glands achieve their desired functions in the digestive system. These cells are of various types and each type has very defined characteristics. The 5 major cell types are:-
2. What is the role of Parietal Cells or Oxyntic Cells in gastric glands?
The Parietal cells are found to be round, large, or pyramidal in shape which have rounded nuclei at the center. These parietal cells secrete Hydrochloric Acid(HCl) which is one of the most important components of gastric acid, that activates the other enzymes. These cells are highly acidophilic, which means they stain pink color. These cells are found in the Fundic glands and the walls of the tubes.
3. What is the nature of the pH environment present inside the human digestive system and what is its relevance?
The pH level inside the human digestive system is extremely acidic which means that the pH level is below 7. This is important because the food that we intake need to be broken down into its more simple form so that the nutrients can be absorbed inside the small intestines. The acid present inside the stomach is secreted by gastric glands and one of the most commonly found acids in the human digestive system is the Hydrochloric Acid of HCl.
4. What are the different phases that simulate gastric secretion?
The production of gastric juices in the human digestive system is constant but their secretion is also simulated. The Neutral and hormonal mechanisms generally regulate the secretion of gastric juices from the gastric glands. The three phases in the simulation of gastric secretion are the Cephalic phase, the Gastric phase and the Intestinal phase. Psychological factors like sadness or fear can also affect the secretion of gastric enzymes.
5. I am having trouble in the digestive system while going through my biology syllabus, what shall I do?
The digestive system is one of the most important topics for the NEET Examinations, there are a large number of questions that are asked from this topic, so it is necessary that students have a good command of the topic. Try asking your teachers whatever doubts you may be having during the class and approach your friends who have solved those questions in which you are having trouble. Vedantu provides quality online resources including explanations and solved exercises which are easily accessible to the students to get a good command over the subject.
6. What is Fundic Gland Polyposis?
When numerous polyps are formed in the fundus of the stomach, this medical syndrome is called the Fundic gland Polyposis. Patients do not have any symptoms for FGPs but a higher percentage of such victims suffer from nausea, weight loss, vomiting, and epigastric pain. Depending upon the base cause of polyposis, fundic gland polyposis may lead to the risk of cancer development. In acquired cases, the risk remains low while with congenital polyposis syndrome, the risk is quite high. During diagnosis, consideration in patients with both sporadic form and syndromic form are to be evaluated differently. This makes sure the risk of gastric cancer development and concomitant colon cancer development.
7. What is Pernicious Anemia?
When the Parietal cells get damaged, it fails to produce the intrinsic factor which in turn leads to an issue in absorbing Vitamin B12 in the small intestine. This leads to Vitamin B12 deficiency in the body. The progression of this disease is slow in the body and so, the victim gets used to the following symptoms – headache, weight loss, weakness, pale skin, and fatigue.
In severe cases, the victim might suffer from memory loss, unsteady gait, depression, and peripheral neuropathy. Pernicious anemia is a genetic disorder that prevents the child from synthesizing intrinsic factors. Depending on the level of intrinsic factor deficiency, the victim is firstly injected with doses of Vitamin B12 for a period. Then, the regular oral dosage is prescribed based on the condition.