DIGESTION IN HUMANS II

 

Below is a table of all the juices, where they are secreted and their site of work

Digestive Juice	Site of secretion	Site of Action	Enzymes contained
Saliva	Salivary glands (mouth)	Mouth	Salivary amylase
Gastric Juice	Gastric glands (stomach)	Stomach	Rennin and Pepsin (it also contains HCl)
Bile	Liver	Duodenum	No enzyme
Pancreatic juice	Pancreas	Duodenum	Trypsin, amylase, and lipase
Intestinal Juice	Illeum	Illeum	Maltase, lactase, sucrase and erepsin.

ENZYMES ANDTHEIRFUNCTIONS

Enzyme	Function
Ptyalin ( salivary amylase)	It converts starch to maltose
Pancreatic amylase	Converts starch to maltose
Maltase	Converts maltose into glucose
Lactase	Converts lactose into glucose and galactose
Sucrase	Converts sucrose into glucose and fructose
Lipase	Converts fats and oils into fatty acids and glycerol
Rennin	It curdles liquid milk protein into solid
Pepsin	Converts proteins into polypeptides
Trypsin	Converts polypeptides into peptides
Erepsin	Converts peptides into amino acids.

NB: Proteases are enzymes that work on proteins.

A digestive enzyme is a chemical that speeds up digestion.

An enzyme is a biological catalyst that speeds up chemical reactions.

END PRODUCTS OF DIGESTION

Food	End Product
Starch	Glucose
Fats and oils	Fatty acids and glycerol
Proteins	Amino Acids

SUMMARY OF DIGESTION

What happens to a meal of rice and beans stew in the digestive system.

The mixture (food) is masticated (chewed) by the teeth in the mouth, saliva softens it and the rice (starch) is then converted into maltose by ptyalin (salivary amylase). The tongue rolls it into bolus and it is then sent into the stomach through the oesophagus (gullet)

In the stomach, the beans (protein) are converted into peptides by pepsin. The chime is then sent into the duodenum for further digestion.

The pancreas secretes pancreatic juice which contains the enzymes amylase to digest the remaining rice into maltose, it also secretes trypsin to convert polypeptides into peptides and the liver produces bile to emulsify the oil (fats) in the food before lipase converts it into fatty acids and glycerol.

In the ileum, erepsin converts peptides into amino acids, maltase converts maltose into glucose and lipase converts the lipids into fatty acids and glycerol before it is absorbed into the blood stream.

The undigested food is passed into the large intestine and water is absorbed from it leaving a semi solid substance (faeces) which is stored in the rectum and latter excreted through the anus.

DISEASES THAT AFFECTS THE DIGESTIVE SYSTEM.

1.    Indigestion: It is the stomachs in ability to digest food because of too much acid and spices. This causes a burning sensation in the body.

2.    Haemorrhoids (piles/Kooko): This occurs when undigested food stays far longer in the large intestines than its supposed to. Causing it to be hardened. During egestion, the is an inflammation of the walls of the rectum which raptures producing blood and mucus in the faeces.

3.    Constipation: It is the inability to empty your bowels.

4.      Peptic ulcer: It is caused by too much acid concentration in the stomach and duodenum which results in the inflammation of the gastric walls

5.    Diarrhoea: It is the frequent release of watery stools.

NB: Other functions of the liver includes

1.      Production of insulin to covert excess glucose into and glycogen and vise versa

2.      Converts excess amino acids into urea

3.      Helps store food substances when they are in excess.

Define the following terms

a.       Digestion:

b.      Ingestion:

c.       Absorption:

d.      Assimilation:

a.       State three (3) things that happen in the mouth during digestion?

a.       State two functions of Saliva in the mouth

1.      State three (3) functions of hydrochloric acid in the stomach

1.      Mention two (2) enzymes found in the stomach

1.      State the function of the following parts

Oesophagus

Teeth

Tongue