Alimentary Canal Functions NEET

Definition of Alimentary canal

    The organs that food and liquids travel through after they are enveloped, digested, absorbed, and leave the body as feces. These organs embody the mouth, pharynx (throat), esophagus, stomach, intestine, rectum, and anus. The digestive tube is a component of the digestive system, also referred to as the channel and digestive tube.

Mouth

↓

Oesophagus

 ↓

Stomach

 ↓

Small intestine

 ↓

Large intestine

 ↓

Anus

Human Digestive System

  Mouth: (Buccal cavity)

    Digestion first takes place in the mouth. Food enters through it. Here all the food enters which is going to chew or mix with the saliva and after the mixing of food particles with saliva, it goes to the oesophagus.

Causal factors

Teeth

These are rigid structures in both the upper and lower jaw. They help in crushing food
(mastication) through grinding. There are two types of arrangements:

The codent

In mammals, teeth fit in the jaw.

Diphodent

This is of two types:

1. Milky teeth = Number of teeth= 20 (6-14 years)

2. Permanent teeth = Number of teeth= 32 (after 14 years)

Tounge

The very muscular sensory organ is present on the floor of the human buccal cavity. It has taste buds. 

It also helps in mining food with saliva and cleaning teeth.

Pharynx

A small funnel-shaped chamber is located just behind the oral cavity. It links esophagus (food pipe) and trachea (windpipe).

Oesophagus(food pipe)

It is a thin but long muscular tube-like structure that leads the food from the pharynx to the stomach. 

Bolos Food that is present in the esophagus.

Stomach

It is a muscular, J-shaped bag-like part of the body of the alimentary canal that stores food and does partial digestion.

Its muscular walls help in the mixing of food with the stomach's digestive juices.

It also has a sphincter (round) muscle at its end which helps in the release of food to the next level of digestion(small intestine).

It is divided into 3(three) parts:

Cardiac-Upper portion

Fundus-Middle portion

Pyloric-Lower portion

It contains three digestion enzymes.

HCL-Provide acidic medium

Pepsin-Act on protein

The mucus-Protects the inner lining of the stomach from HCL.

What is chyme?

Ans. Partially digested food that passes the stomach to the small intestine is known as chyme.

The Digestive System

Small Intestine:

The longest part of the alimentary canal.

It is very coiled in a small space.

Herbivores have a long small intestine to facilitate cellulose digestion. This is the main site of digestion.

While carnivores have short small intestines as meat gets digested easily.

 This is the main site of digestion.

The small intestine have also a tiny finger-like projection called villi that increases its surface area and helps in the absorption of food as well.

It is divided into three parts:

Duodenum

Jejunum

Ileum

In small intestine receives digestive enzymes from the liver and pancreas.

Large Intestine:

It is wider than the small intestine.

It is a place where the maximum amount of water is absorbed.

It is divided into three parts:

Caecium

Colon 

Rectum: It is the last chamber that stores fecal matter (undigested food) temporarily.

OR

The undigested food is stored in the form of water.

Anus:

The endpoint of the alimentary canal.

Helps in the exit of undigested food or feces from our bodies.

They are aided by the anal sphincter (external and internal).

1. Alimentary canal:

- mouth (buccal cavity)

 -esophagus (food pipe)

 -stomach

 -small intestine

 -large intestine

 -rectum

 -anus

2. Digestive glands:

 -Salivary glands

 -Liver

 -Pancreas

➵ Alimentary canal

1.) Mouth (Buccal cavity): In the mouth, food is crushed with the help of teeth. Here the process of ingestion of food takes place and then food is chewed and mixed in the mouth. The saliva present under the mouth helps to moisten food to get easily dissolved and allows you to taste it. Begins the chemical breakdown of carbohydrates.                                                                                                {pH 5-6}

Mouth

⭭

Salivary glands

⭭

Saliva

⭭

Secrete enzymes called salivary analyze

⭭

Sugar sucrose is a simpler form

2.) Esophagus (food pipe): Via the pharynx, food gets under the food pipe so-called esophagus. Here, the waves of muscle contraction push the food particles downwards. Propels food particles to the stomach.

3.) Stomach: It is a J-shaped structure. It mixed food particles with gastric juice to form chyme. Begins the chemical breakdown of proteins and stimulates all protein-digesting enzymes. Absorb fat and other essential substances. It pushes the food particles into the Duodenum of the small intestine.

It is divided into given parts:-

1). Cardiac 🠪 Upper portion (connected to the esophagus, which helps to prevent food to enter back the esophagus.)

2). Fundus 🠪 Middle portion (It is a dome-shaped structure that helps to breathe).

3). Pylorus 🠪 Bottom, the end portion (It has a pyloric sphincter, a ring of tissue that controls the food that goes to the small intestine).

Functions of the Digestive System

4.) Small intestine: The stomach opens by pylorus into the intestine. It mixes the chyme with digestive juices. Propels food at a slow rate enough to digest and absorb. Perform physical digestion via segmentation.

Absorbs breakdown products of all carbohydrates, proteins, lipids, and nucleic acids, along with vitamins, minerals, and water.

After this, the accessory organs like the liver, gallbladder, and pancreas are included in the digestion process.

5.) Large intestine: Itis the end segment of the alimentary canal and has more diameter. It is basically for the absorption of water and discharging the undigested wastes from the body. It further breakdown food residue. Propels and eliminates the feces towards the rectum. 

It has given parts:

1.) Cecum: It is found at the junction of the ileum and large intestine, which is a blind sac. It is the widest portion of the large intestine. It is the part where the food arrives large intestine from the small intestine. When it gets full, it triggers muscle movements. 

2.) Colon: It is present in the form of an inverted U in the abdominal cavity between the ileum & colon. The colon has mainly three parts: ascending colon, transverse colon, and descending colon. Any remaining water and electrolytes are absorbed from the ascending colon to the transverse colon so that the food waste that arrives in descending colon is mostly in solid form.

3.) Rectum and Anus: The rectum is a small muscular region at the end of the large intestine. It can store the undigested food for a very short time before passing it out.