Railway Science (Biology – Digestive System)

Salivary amylase (ptyalin) is an enzyme that is found in human saliva. Amylase is a protein enzyme that breaks the starch and glycogen into glucose and maltose. It is present in both pancreatic juice and saliva.
Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes.
Proteins are made up of another chain of amino acids and Hair and nails are made of keratin protein.
Lipids are naturally occurring molecules, which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, phospholipids, and others.

Salivary amylase (Ptyalin) present in the human saliva. It helps in the process of digestion as it breaks down complex carbohydrates (a polymer of glucose) such as starch into simpler sugars like glucose and maltose.
Saliva is mainly produced by three pairs of salivary glands, the parotids (cheek), the sub-maxillary / sub-mandibular (lower jaw) and the sublinguals (below the tongue).

The bile juice secreted by the liver contains bile salts that break down large fat globules into smaller globules, increasing the surface area for the action of lipase. Lipase acts and breaks down the globules into molecules.
This process is the emulsification of fats. The fats cannot be digested easily because they are insoluble in water.

Caecum is part of the digestive tract. It is the first part of the large intestine in which digested food enters after leaving the small intestine, and is shaped like a sac. Digestion Process - Ingestion, Mixing and Movement, Secretion, Digestion, Absorption, assimilation and Excretion.
Oesophagus: A muscular tube that connects the pharynx (part of an upper section of the gastrointestinal tract) to the stomach.
Small intestine: The largest part of the digestive system (around 6 meters) and divided into three parts (duodenum, jejunum and ileum).

Intestinal Juice is secreted by intestinal glands which include maltase, lactase, lipase etc. Erepsin is found in the intestinal juices that digest peptones into amino acids.

Other functions of Body Parts: Mouth or oral cavity, is the first part of the digestive tract. It is adapted to receive food by ingestion, break it into small particles by mastication, and mix it with saliva.
Teeth - Help in bitting, tearing and grinding food, Tongue - Helps in movement of food during mastication, speech and taste sensation. Saliva - Maintenance of oral hygiene, lubrication and swallowing.

Milk of magnesia {Mg(OH)₂} is a suspension of magnesium hydroxide in water. pH - 10.5. Uses - used as a laxative to relieve occasional constipation, Antacid to relieve indigestion , sour stomach.
Milk of Magnesia is a basic compound and the stomach contains hydrochloric acid (HCl) when both solution mixes get neutralised.

Rumens are found in animals such as cows, goats, shee, deer, etc. Cows rely on rumen microbes to convert feed components into useable sources of energy and protein Three steps are involved in cows obtaining nutrients from their diet: ingestion: taking food into the body , digestion: food is mechanically and chemically broken down, absorption: nutrients pass from the digestive system into the cow's blood stream.

Bile: neutralizes the acidity of the chyme that comes from the stomach. Gastric juice: helps in the digestion of food, contains enzymes like pepsin, lipase, and rennin and, It has low pH to destroy various pathogens.
Pancreatic juice: contains digestive enzymes like trypsinogen, chymotrypsinogen, procarboxypeptidase, amylases, lipases, and nucleases.

Adults have 32 teeth in total, called permanent or secondary teeth, and it includes: Eight incisors - Four incisors in the upper jaw and four incisors in the lower jaw. Four canines - Two canines in the upper jaw and two canines in the lower jaw.
Eight premolars - Four premolars in the upper jaw and four premolars in the lower jaw. Twelve molars - Six molars in the upper jaw and six in the lower jaw. It also includes four wisdom teeth.