Diagram of Digestive System

A well labelled diagram of the Digestive System showing its different parts is shown below:

Mouth

The mouth is present in the anterior part, which opens into the oral cavity. The mouth consists of lips, cheeks, palate (roof of the mouth), tongue, and teeth. The lips and cheeks help contain food in the mouth, while the mouth is separated from the nasal cavity through palate. The tongue is a muscular organ that help in food mixes with saliva and speech, and teeth are responsible for grinding and chewing of food.

Teeth

Teeth consists enamel that forms the outer layer of the tooth followed by dentin and pulp.There are 32 permanent teeth are divided into four types depending on its functions (Heterodont dentition), namely, incisors (I), canine (C), premolars (PM) and molars (M). The upper and lower jaw each contain a set of teeth arranged in the order I, C, PM, M. The dental formula in the human is 2123/2123 .

Salivary Gland

Salivary glands are present in the oral cavity and it produces saliva. Saliva contains enzymes like amylase that starts the process of digestion of carbohydrates. Saliva also lubricates food, making it easier to swallow. There are three types of salivary gland submandibular, sublingual and the parotid gland.

Pharynx

The pharynx is a thin muscular tube measuring 5 inches (12.7 centimeters) in length in the throat. The esophagus and larynx is connected to the oral and nasal cavity through pharynx. Pharynx is divided into three parts: the nasopharynx, oropharynx, and laryngopharynx. The wind pipe or trachea and oesophagus open into the pharynx. It act as a common passageway for both air and food.

Esophagus

The esophagus is a thin muscular tube that measures approximately 10 to 13 inches in length. It starts in the posterior part and pass through the neck, thorax and diaphragm. It opens into a ‘J’ shaped bag like structure known as stomach. Its primary function is to allow the movement of liquid and food to the stomach from the mouth for digestion. During swallowing, a thin flap-like structure known as the epiglottis in the throat, ensures that liquid and food enter the esophagus and not the windpipe.

Stomach

The stomach is present in the upper left part of the abdominal cavity between the esophagus and the small intestine. It consists of three main parts, that are, a cardiac portion where the oesophagus opens, a fundic portion and a pyloric part both of which leads to the first part of small intestine. Gastric glands found in the stomach secretes gastric juice, along with hydrochloric acid and digestive enzymes aids in digestion of protein and killing microorganisms.

Small Intestine

Small intestine measures about 20 feet in length and is a slender tube-like structure. It is divided into three parts, a ‘C’ shaped duodenum, in the middle part jejunum which is coiled in shape and ileum that is highly coiled. Its primary functions include nutrient absorption, particularly of carbohydrates, proteins, and fats, facilitated by the extensive surface area provided by villi and microvilli.

Large Intestine

The large intestine, is approximately 5 to 6 feet in length and is also known as the colon. In the large intestine the final stages of digestion, water absorption, and the elimination of waste products takes place. It follows the small intestine in the digestive tract and is formed of various parts including the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum.

Liver

The liver is the largest reddish-brown, and triangular-shaped organ in the human body. It is present in the upper right part of the abdomen. It takes part in digestion, metabolism, and detoxification. Functions of the liver include producing bile to aid in fat digestion, processing nutrients, storing glycogen and filtering toxins from the blood.