Digestion

Digestion

Carbohydrate Digestion:

SALIVARY AMYLASE- Produced by the salivary glands and secreted into the mouth.
--Acts on starch to break it into many molecules of maltose.
--Maltose is later broken down in the system to glucose.

PANCREATIC AMYLASE
 - Also acts on starch to convert it to maltose.
--Occurs in the duodenum, but is produced by the pancreas.

MALTASE
 - Produced in the small intestine.
-- Converts maltose to glucose.
maltase
Maltose + Water -----------> 2 Glucose


Protein Digestion

PROTEASES - Break down proteins to peptides.
- There are two types of proteases:
a) Pepsin - Produced by the gastric glands of the stomach.
b) Trypsin - Produced by the pancreas.

Pepsin/Trypsin
Protein + Water ------------------> Peptides

PEPTIDASES - Break down peptides into A.A.
-- Produced by the small intestine.

Peptidases
Peptides + Water ---------------> Amino Acids 







Fat Digestion

BILE - Produced by the liver
- Stored in the gall bladder
- Breaks down fat in the duodenum into fat droplets
**not an enzyme, but rather an emulsifier**
EMULSIFICATION: The breaking down of fats to fat droplets by bile.

NOTE: A person who has had his/her gall bladder removed will have trouble digesting fatty foods. The gall bladder stores bile for use at the proper time during the digestive process
 Bile
Fat -----> Fat Droplets

LIPASE - Produced by the pancreas
-- Breaks down fat droplets into glycerol and 3 fatty acids.
---Lipase
Fat droplets + Water --------> Glycerol + 3 Fatty Acids
NUCLEASE - produced by the Small intestine and Pancreas
- works in the small intestine
- breaks down RNA and DNA into nucleotides
NUCLEOSIDASES - produced by the Small intestine
- works in the small intestine
- breaks down nucleotides into base, sugar and phosphate components

VIDEO: Lipid Digestion

Digestive Enzymes Summary Table


Enzyme

Glandular Source

Site of Action and pH

Substrate or food acted upon

Product

Salivary Amylase

Salivary Glands (Mouth)

Mouth neutral (7)

Starch

Maltose

Pepsin

Gastric Glands (Stomach)

Stomach acidic (3.5)

Proteins

Peptides

Pancreatic Amylase

Pancreas

Small Intestine basic (7.5)

Starch

Maltose

Trypsin

Pancreas

Small Intestine basic (7.5)

Protein

Peptides

Lipase

Pancreas

Small Intestine basic (7.5)

Fat Droplets

Glycerol and fatty acids

Nuclease

Pancreas and small intestine

Small Intestine basic (7.5)

Nucleic Acids (DNA & RNA)

Nucleotides

Peptidases

Small Intestine

Small Intestine basic (7.5)

Peptides

Amino Acids

Maltase

Small Intestine

Small Intestine basic (7.5)

Maltose

Glucose

Nucleosidases

Small Intestine

Small Intestine basic (7.5)

Nucleotides

Base, Sugar, Phosphate

Insulin and Glucagon

SOURCE GLAND AND FUNCTION OF INSULINinsulin

Insulin - Hormone
- Production by pancreas
- Secreted when blood sugar concentration is high.
- Causes liver and muscles to take up and store excess glucose as Glycogen.
- Also promotes synthesis of protein and fats.
**LOWERS BLOOD SUGAR LEVEL**


Glucagon - Another pancreatic hormone.
- Secreted when blood sugar concentration is low.
- Causes liver and muscles to break down glycogen to glucose.
- Stops protein and fat synthesis.

***RAISES BLOOD SUGAR LEVEL***
Pancreas is called both an Exocrine and an Endocrine organ

Exocrine - Produces some enzymatic substances.
Endocrine - Produces hormones.

Liver


Six Major Functions of the Liver

  1. Destroys old red blood cells and converts hemoglobin to a product in bile.
  2. Produces Bile that is stored in the gall bladder before entering the Duodenum where it emulsifies fat.
  3. Store Glucose as Glycogen after eating, and breaks down glycogen to glucose between eating to maintain the glucose concentration of the blood.
  4. Produces Urea from the breakdown of amino acids (deamination)
  5. Makes Blood Proteins from amino acids.
  6. Detoxifies the blood by removing poisonous substances and metabolizing them (converting them to harmless substances).
**The liver is an essential organ**
liver
**Be sure you know the structures and functions of each part of the digestive system, all the enzymes including where they are produced, the substrate they work on, and the product produced, how insulin and glucagon regulate blood sugar levels and finally, know all 6 functions of the liver**