digestion in monogastric animal and hormonal control
TRANSCRIPT
What is Digestion
Digestion is the breakdown of food into smaller components that can be more easily absorbed and assimilated by the body
These smaller substances are absorbed through the small intestine into the blood stream
Digestion is a form of catabolism that is often divided into two processes based on how food is broken down:
1. Mechanical digestion2. Chemical digestion
Mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes.
chemical digestion, enzymes break down food into the small molecules the body can use
Monogastric animal different from Ruminant animal
I. A monogastric organism has a simple single-chambered stomach
II. In ruminantorganism, like a cow, goat, or sheep, which has a four-chambered complex stomach
III. Monogastrics cannot digest the fiber molecule cellulose as efficiently as ruminants
IV. No rumination like ruminant animal
V. A monogastric digestive system works as soon as the food enters the mouth
VI. Saliva moistens the food and begins the digestive process.
VII. After being swallowed, the food passes from the esophagus into the stomach, where stomach acid and enzymes help to break down the food
VIII. While in ruminant,it undergo degradation by means of microbe like protozoa,bacteria,fungus
IX. Bile salts stored in the gall bladder empty the contents of the stomach into the small intestines where most fats are broken down. The pancreas secretes enzymes and alkali to neutralize the stomach acid.
Consist of 6-main parts: 1. Mouth2. Esophagus3. Stomach4. Small Intestine (SI)5. Large Intestine (LI)6. Supportive organsa. Liverb. Pancreasc. gall bladder
Digestion in Mouth
1-Receive feed with the help of Lips, teeth and tongue help in prehension
2-Saliva secretion 3-paired saliva glands in the mouth
i. Parotids glandii. Submandibular (submaxillary) glandiii. Sublingual gland
4-Digestion- Mechanical (chewing)- Enzymatic (α-amylase → starch digestion)
Food taste5- tasted buds
Composition and Function of saliva(mouth)
Composition- 99% water
Mucus → lubrication aid for swallowingBicarbonate salts (Na) → buffer to regulate pH of stomachAmylase enzyme in some species Human-strong activityPigs- limitedHorses- not exist
Function of Saliva
1.Lubricant2. Protection of membranes in mouth3. Digestion (amylase)4. Thermoregulations (dogs-panting; cats-grooming
Factors affecting saliva production
1. Feed intakeas intake increase → saliva flow ↑
2. Feed moisture contentwet feed → ↓saliva
3. Diet composition (fiber) fiber increase chewing → saliva flow ↑
4. Health 5.Healing power
Esophagus
Hollow muscular tube lined with mucosal cells that transport ingesta from the mouth to stomachPeristaltic muscular contractionsCardiac valve (sphincter) at the end of esophagus prevent ingesta from moving back
Size and various enzyme in stomach
Size vary between species Human: 1.5 L (20% of human GI relative capacity) Pigs: 7.9 L (30% of pigs GI relative capacity) Horses: 18.2 L (9% of horses GI relative capacity)
Secretions in the stomach (gastric Juices)1.Hydrochloric acid (HCL)2. Pepsinogen3. Mucus
1.Hydrochloric acid (HCL)Lowers stomach pH = 1-3
Low pH cause: a. Initiate protein digestion (denaturation) b. Activate a protein digestive enzyme (pepsin) c. Kill pathogenic bacteria in ingested feeds
Contd….
2.Pepsinogen-inactive proteolytic enzyme- conversion to pepsin (active proteolytic enzyme) requires HCL (low pH condition)
3.Mucus- Protecting stomach wall from acid and pepsin- Malfunction → Ulcer - No absorption of nutrients in the stomach - Materials leaving the stomach called Chyme
Functions of Stomach
1. Storage of ingested feed (control flow)2. Reduce feed particle size through its muscular movements3. Initiate protein digestion4. Secretions of gastirc juices
Liver
1.Bile synthesis
2. Site for urea formation
3. Detoxification of harmful compounds
4. Storage of CHO (glycogen) and vitamins
5. Synthesis of glucose
6. Synthesis of cholesterol and triglycerides
7. Synthesis and degradation of amino acids
Bile
Bile Synthesis(Liver Function)
-Made in the liver- Stored in gallbladder -Secreted bile enters duodenum (small intestine) via duct (bile duct)
Bile Function(Liver Function)
a.Emulsification of fats to facilitate lipids b.digestion and absorption in small intestine Activate pancreatic lipase enzyme
Contd….Assist in CHO, proteins and lipids digestion in small intestinePancreatic secretions enter duodenum (small intestine) via duct
Pancreatic secretions: 1.Digestive enzymes: 2. Bicarbonate (buffer)3. Hormones
Digestive enzymes
a. Amylase → digest starchb. Trypsin c. Chymotrypsin d. Carboxypeptidasee. Neucleaseb - e → involve in proteins digestionf. Lipase → digest lipidsg. cholesterol esterase → digest cholesterol
Contd…
Bicarbonate (buffer)- Neutralize small intestine pH- Enzymes require pH > 6.5 to function in small intestine (duodenum)
- Pancreatic enzymes and bicarbonate are made in pancreas → released into duodenum (small intestine) via duct.
Hormonesa. Insulinb. Glucagon
- Released into blood- Regulate (maintain) blood glucose level
High blood glucose → insulin release →↑ glucose uptake by cells and also increase glycogen synthesis
Low blood glucose → ↑ glucagon release →a. breakdown glycogen to glucoseb. increase synthesis of glucose from AA
Contd…Different part of Small Intestine (SI) 1. Duodenum 2. Jejunum 3. ileumDuodenum- First section of SI ,Shortest section- Main site for CHO, protein and lipid digestion - pH = 6.0-6.5
- Digestion accomplished by secretions from: a. Pancreas (enzymes and buffer) b. Duodenal wall (enzymes) c. Liver (bile)Duodenal wall secretions-Enzymes1. Maltase 2. Sucrase 3. Lactase 4. Aminopeptidase 5. Dipeptidase help in protein digestin
Contd….
Jejunum and ileumJejunum = Middle sectionIleum = Last section
Jejunum & ileum are the main site for nutrients absorption (AA, glucose, FA, vit & minerals)
Walls of lower intestine are folded and lined with villi (fingerlike projections) → help in ↑ing surface area
Each villi has minute projections called microvilli → more ↑ in surface area
Absorption in SI1. Passive diffusion2. Facilitated diffusion 3. Active absorption
Passive diffusionfrom high to low concentration eg. minerals, water
Facilitated diffusion-from high to low concentration but use carrier proteins in intestinal surface- eg. Vitamins
Active absorption:-from low to high concentration- requires energy and specific carrier proteinseg. Glucose and amino acids
Contd….
Sections of LI1.Cecum2. Colon: 3. Rectum
Cecum-first section of LI- Contain active bacteria similar to rumen bacteria - Fermentation siteMonogastric animals however, don't benefit from these vitamins and bacterial protein
Colon:Storage sitewater absorption (also some minerals absorption)No absorption of amino acids and sugars
Contd…..
Rectum last section of LI functions 1. Fiber digestion- Digestion by bacteria inhabiting the cecum (very limited in monogastric animals except in horses) - End-products of fermentation (VFA, B-vits, bactereial protein) have little use.
2. Absorption- water (mainly)- very limited absorption of nutrients (feedstuff or microbial origin)- No AA or glucose absorption