Q: Which of the following terms describe human dentition?

\$\textbf{Correct answer: D}\$ \$\textbf{Option (A):}\$ \$\bullet\$ Pleurodont teeth have long roots with weak attachments to the mandible. There is no socket for the teeth to be placed on the jaw. \$\bullet\$ Monophyodont teeth mean the presence of only one set of teeth for the entire lifetime.\$\bullet\$ Homodont means the presence of a single type of teeth. \$\bullet\$ None of these characters are observed in human dentition. \$\textbf{Option (B):}\$ \$\bullet\$ The thecodont teeth are the type of teeth containing the base of the tooth which is completely immersed inside the socket present on the jawbone. \$\bullet\$ Diphyodont teeth are the presence of two sets of teeth throughout the entire lifecycle. \$\bullet\$ Human dentition shows the thecodont and diphyodont character. But the homodont character is not observed.\$\textbf{Option (C):}\$ \$\bullet\$ Heterodont teeth mean the presence of different types of teeth with different functions. \$\bullet\$ Human dentition does not have the pleurodont character, but it is both diphyodont and heterodont. \$\textbf{Option (D):}\$ \$\bullet\$ Human dentition is thecodont because of the presence of sockets in the jawbone where the teeth are embedded. \$\bullet\$ Human dentition shows a diphyodont character because of the presence of two sets of teeth throughout the life cycle. The first set is called the deciduous teeth and the second set is the permanent teeth. \$\bullet\$ Human dentition shows heterodont character because of the presence of four types of teeth which are incisors, canine, premolars and molars. Hence, the correct answer is option (D).

Question 1

What are the basic layers of the wall of alimentary canal?

Accepted Answer

The wall of alimentary canal possesses four layers- serosa, muscularis, sub mucosa, and mucosa. Serosa is the outermost layer and is made up of a thin mesothelium and connective tissue. Muscularis is formed by smooth muscles usually arranged into an inner circular and an outer longitudinal layer. Sub-mucosa layer is formed of loose connective tissues containing nerves, blood and lymph vessels. Glands are also present in sub-mucosa of duodenum. Mucosa is the innermost layer lining the lumen of the alimentary canal. Mucosa forms irregular folds (rugae) in stomach and villi in small intestine.

Question 2

How is small intestine designed to absorb digested food?

Accepted Answer

correct answer is option D.The small intestine is the most important part of the alimentary canal for digestion and absorption of food. It has three regions a U-shaped duodenum, a long coiled middle portion jejunum and highly coiled ileum.The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine. These modifications increase the surface area for more absorption. Villi are supplied with a network of capillaries and a large lymph vessel called the lacteal.It transports lipid molecules. The wall of the intestine is surrounded by the blood vessels which assimilates the food molecules to the different parts of the body.

Question 3

Which of the following is not present in pancreatic juice?

Accepted Answer

Pancreatic juice is secreted by the pancreas, which contains a variety of enzymes, including trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase and amylase. Pepsin in not present in pancreatic juice. It is secreted by the peptic cells of the stomach.

Question 4

The most important function of villi in the small intestine is

Accepted Answer

Villi are tiny, finger-like projections from the wall of the small intestine. They line the inner surface of the small intestine. Their role is to increase the surface area within the small intestine. This will lead to the increase of the surface area of absorption as it is the main function of the small intestine.

Question 5

Which of the following is the correct sequence of parts in human alimentary canal?

Accepted Answer

Hint - The digestion of food starts from the mouth and ends at the anus.Part 1 - Alimentary canalThe alimentary canal is a hollow muscular tube organ that starts at the mouth and terminates at the anus.The function of the alimentary canal is digestion and absorption of the food.The important parts of the alimentary canal are &#8211; Mouth, Oesophagus, Stomach, Small intestine and Large intestine.Part 2 - Parts of the Alimentary canalThe different organs of the alimentary canal can be explained as &#8211;Mouth is the first part of the alimentary canal where partial digestion of food takes place with the help of saliva secreted by the salivary gland. From the mouth, food enters the Oesophagus.Oesophagus is a long and thin muscular tube that passes through the neck, thorax and diaphragm and opens into a muscular bag-like structure called the stomach.Stomach is a muscular organ consist of three regions &#8211; cardiac region, fundic region and pyloric region. The pyloric region of the stomach opens into the &#8216;C&#8217; shaped duodenum of the small intestine.Small Intestine - The longest part of the alimentary canal is divided into three parts- Duodenum, Jejunum, and Ileum. The ileum opens into the large intestine.Large Intestine - It is a wide tube consists of three parts- Caecum, Colon, and Rectum. The colon is divided into four regions- ascending colon, the transverse colon, descending colon and the sigmoid colon. Through the sigmoid colon the descending part of the colon opens into Rectum. The rectum is the distal part of the alimentary canal that opens into the anus.Part 3 - ConclusionFood enters the body through the mouth. Then enters the stomach through the oesophagus. From the stomach, the semi-digested food enters into the small intestine where digestion and absorption take place. At last, the food travels through the large intestine and excess water get absorbed.Final stage - The correct sequence of the human alimentary canal is Mouth $\rightarrow$ Oesophagus $\rightarrow$ Stomach $\rightarrow$ Small intestine $\rightarrow$ Large intestine.

Question 6

Which of the following terms describe human dentition?

Accepted Answer

$\textbf{Correct answer: D}$ $\textbf{Option (A):}$ $\bullet$ Pleurodont teeth have long roots with weak attachments to the mandible. There is no socket for the teeth to be placed on the jaw. $\bullet$ Monophyodont teeth mean the presence of only one set of teeth for the entire lifetime.$\bullet$ Homodont means the presence of a single type of teeth. $\bullet$ None of these characters are observed in human dentition. $\textbf{Option (B):}$ $\bullet$ The thecodont teeth are the type of teeth containing the base of the tooth which is completely immersed inside the socket present on the jawbone. $\bullet$ Diphyodont teeth are the presence of two sets of teeth throughout the entire lifecycle. $\bullet$ Human dentition shows the thecodont and diphyodont character. But the homodont character is not observed.$\textbf{Option (C):}$ $\bullet$ Heterodont teeth mean the presence of different types of teeth with different functions. $\bullet$ Human dentition does not have the pleurodont character, but it is both diphyodont and heterodont. $\textbf{Option (D):}$ $\bullet$ Human dentition is thecodont because of the presence of sockets in the jawbone where the teeth are embedded. $\bullet$ Human dentition shows a diphyodont character because of the presence of two sets of teeth throughout the life cycle. The first set is called the deciduous teeth and the second set is the permanent teeth. $\bullet$ Human dentition shows heterodont character because of the presence of four types of teeth which are incisors, canine, premolars and molars. Hence, the correct answer is option (D).

Question 7

In human alimentary canal, name the site of complete digestion of various components of food. Explain the process of digestion.

Accepted Answer

Answer:i) Small intestine is the site of complete digestion of various components of a food.ii)  Process of digestionFood is chewed with digestion of starch by the action of salivary amylase present in the mouth. The formed bolus passes down the esophagus into the stomach by the action of peristalsis. Gastric juices further acts on food for the digestion of proteins and forms chyme.This chyme enters the duodenum where digestive enzymes from pancreas and bile juice from liver mixes with it and then passes through the small intestine. Absorption of nutrients occurs in the small intestine. The reabsorption of water and minerals happens majorly in the large intestine.

Question 8

What is the role of HCl in our stomach?

Accepted Answer

HCl is one of the gastric juices secreted by stomach.HCl converts the inactive enzyme pepsinogen into its active form pepsin. Pepsin digests proteins and breaks them into amino acids. HCl also kills harmful pathogens or particles in our food when it reaches the stomach through the gastrointestinal duct.

Question 9

In the wall of the alimentary canal, what is the correct sequence of layers, starting from the outside to the inside?

Accepted Answer

The alimentary canal walls have four basic tunics or layers. The outermost one is the serosa which is a thin membranous covering. Inner to serosa is the muscle layer of outer longitudinal muscles and the inner layer of circular&#10;muscles.Then&#10;there is&#10;submucosa which is then followed by the innermost layer of mucosa. The mucosa is the epithelial membrane lining the lumen of the alimentary canal.So, the correct answer is (C).

Question 10

What are Villi ? Mention their functions.

Accepted Answer

The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, are present numerous blood vessels that absorb the digested food and carry it to the bloodstream. It is hence from the bloodstream, the absorbed food is delivered to each and every cell of the body.

Histology of Alimentary Canal

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