Tag: bio-chemistry

Single layered of flattened cells with irregular boundaries constitute the squamous epithelium which is found in walls of blood vessels and air sacs of lungs. The epithelium that lines the oesophagus is stratified epithelium.

• The oesophagus is a hollow, muscular tube that connects the mouth to the stomach and also carries food and liquids to the stomach from the mouth.
• It is usually around 9 to 10 inches in adults which begins at the pharynx and passes behind the trachea or windpipe.
• The upper part of the oesophagus is made up of striated or voluntary muscles.
• The middle part is composed of both striated and smooth or involuntary muscles.
• The lower part is made up of smooth muscles only.
• The oesophagus consists of two sphincters.
• The upper oesophagal sphincter is single ringlike cartilage which is both voluntary and involuntary in nature and it prevents food and liquids from entering the windpipe (trachea,)
• The lower oesophagal sphincter is involuntary and prevents gastric acids from travelling into the oesophagus and it opens into the diaphragm.
  
• So, the correct answer is 'Both voluntary and involuntary'.

• The oesophagus is a hollow distensible muscular part of the alimentary canal.
• The ability to stretch and expand is called distensibility.
• The distensibility of the oesophagus allows any kind of food to pass through it with ease.
• The oesophagus dilates and propels the food from the region of the pharynx to the stomach.
• The stomach is a J shaped distensible bag like structure and is a highly distensible part of the alimentary canal.
• It may take varying shapes and can hold about 1 litre of food.
• The gastric folds in the inner walls of the stomach allow it to get expanded.
• So, the correct answer is 'Stomach'.

Peristalsis is the rhythmic contraction and relaxation of muscles that moves food through the digestive tract, most notably in the oesophagus.

The typhlosole is a median internal fold of the intestine in earthworms (Pheretima) that significantly increases the surface area for the absorption of digested nutrients.

The wall of the alimentary canal from the oesophagus to the rectum consists of four primary tissue layers from outside to inside: serosa, muscularis, submucosa, and mucosa.

The fundus is the upper, rounded part of the stomach, located above the level of the cardiac orifice. The cardiac part is where the esophagus enters, and the pyloric part is the lower section leading to the duodenum.

Lacteals are lymphatic capillaries located in the villi of the small intestine of vertebrates, specialized for the absorption of dietary fats and fat-soluble vitamins.

The gastric juice is made up of hydrochloric acid, pepsinogen and other digestive enzymes, gastrin, mucus, and bicarbonates. It has a pH ranging from 1 to 2. Its low pH is essential in activating digestive enzyme such as pepsinogen and convert it into the active pepsin, a Proteolytic activity of pepsin and in destroying various pathogens. 

The stomach wall consists gastric gland which secretes gastric juice for digestion of food. The gastric juice is made up of hydrochloric acid, pepsinogen and other digestive enzymes, gastrin, mucus, and bicarbonates. It has a pH ranging from 1 to 2. Its low pH is essential in activating many digestive enzymes and in destroying various pathogens. Thus, the correct answer is option C.