Bile is produced by the liver and pancreatic juice is secreted by pancreas.Liver and pancreas are the two glands of alimentary canal these produce substances (enzymes and bile free) involved in the digestion of fat.

Lysozyme and salivary amylase.Lysozyme kills bacteria and amylase digest carbohydrate,specially starch

The alkaline pH is provided by the following type of secretions
(i) Secretion of Brunner's glands,
(ii) The bicarbonates from the pancreas
(iii) Bile
Actions of trypsin are  follows as
(i) Activates other proteases and
(ii) Acts on the proteins proteases and peptones.

Ileocaecal valve is present where an ileum of small intestine enters the cecum of the large intestine. It helps in preventing the backflow of fecal matter from caecum into ileum.

The salivary glands present in our  mouth produce saliva, which makes our mouth watery. The brain registers, that food is coming and instructs the salivary gland present underneath the tongue to produce saliva, which helps in breakdown of food as we chew it. Thus, making it softer as it enters the gut.

The local digestive hormones are produced by gastric and intestinal mucosa e.g., secretin, cholesyctokinine, etc. The hormones stimulate the activity of enzymes. If these are not produced, the process of digestion will be hindered and digestive system will not work properly.

A - Starch, B - Pepsin, C - Duodenum, D - Fatty acids + Glycerol, E - Nucleases and F - Lactose.

If the liver would stop secreting the bile,following may happen
(i) The fats in our diet would not digested, it is because bile helps in emulsiying fats and breaks it down for the body to absorb
(ii) The liver makes bile from chlesterol.Thus,higher levels of cholesterol in the body may occur.
(iii) Bilirubin is made from our dead red blood cells and is a type of a pigment , that also acts as a part of the bile.Hence, if the liver does not secrete bile, the bilirubin would stay in blood instead of being converted by the liver into soluble form and flows with the bile.
(iv) This may our skin,white of the wyes more yellow in color(jaundice),darken our urine and the stools would be whiter in color.

Constipation In this condition,the faces are retained within the rectum as the bowl movement occur irregularly.The causes of constipation are water defiency,lack of roughage in diet,etc.
Indigestion In this condition,the food is not properly digested leading to a feeling of fullness.The causes of indegestion are inadequate enzyme secretion,anxiety,food poisoning,over eating and spicy food

Absorption of fat takes place in the following ways
(i) Digested fat is absorbed in the small intestine
(ii) Bile salts break up bigger molecules of fat into small droplets called micelles that move into intestinal mucosa
(iii) They are reformed into small protein coated fat globules called chylomicrons
(iv) These are transported to lymph vessels(lacteals) in this villi
(v) These lymph vessels ultimately release the absorbed substances into bloodstream.

Functions of Liver:
Synthesis
1. A large part of amino acid synthesis.
2. The liver performs several roles in carbohydrate metabolism:
3. The liver is responsible for the mainstay of protein metabolism, synthesis as well as degradation.
4. The liver also performs several roles in lipid metabolism:
5. The liver produces coagulation factors I (fibrinogen), II (prothrombin), V, VII, IX, X and XI, as well as protein C, protein S and antithrombin.
6. In the first trimester of fetus the liver is the main site of red blood cell production. By the 32nd week of gestation, the bone marrow has almost completely taken over that task.
7. The liver produces and excretes bile (a greenish liquid) required for emulsifying fats. Some of the bile drains directly into the duodenum, and some is stored in the gallbladder.
Breakdown
1.The breakdown of insulin and other hormones.
2. The liver breaks down hemoglobin, creating metabolites that are added to bile as pigment (bilirubin and biliverdin).
3. The liver breaks down toxic substances and most medicinal products in a process called drug metabolism.
4. The liver converts ammonia to urea.

Digestion of proteins in stomach
The proenzyme pepsinogen on exposure to HCl, gets converted into active enzyme pepsin.
Protein  \(\rightarrow\)Proteoses + Peptones
Pepsin always acts in acidic medium (pH 1.8). In infants, milk proteins are digested by rennin.
Digestion of protein in small intestine  Pancreatic juice contains proenzyme, i.e., trypsinogen that gets activated by an enterokinase, which is secreted by intestinal mucosa, into active trypsin. Trypsin acts in alkaline medium.
 \(Protein\underrightarrow { Trypsin\quad /\quad Chymotrypsin } Dipeptides\)
The dipeptides are changed into amino acids by the enzyme succus entericus (intestinal juice).
 \(Dipeptides\underrightarrow { Dipeptidases } Amino\quad acids\) 

(i) Digestion of butter Butter is a fatty substance and by esterases most importat of which is lipase.Digestion of butter starts in stomach and gets completed in small intestine
(a)In stomach Gastric juices contain a weak lipolytic gastric lipase,which hydrolyses only small amount of fats
(b) In intenstine Bilw salts of the bile juice emulsify the fats and increase the surface area for the action of lipases,while its sodium bicarbonate provides alkaline medium in small intestine.
Pancreatic lipase is strongest lipolytic enzyme that hydrolyses about two-third of triglycerides.Intestinal liapse hydrolyses remaining triglycerids.But,fat digestion is never complete.Digestion products include glycerol,fatty acids,monoglycerides and small amount of aiglycerides