Absorption, Assimilation And Egestion Of Food Flashcards
Where does the digested food enter
The digested food enters into the bloodstream through the stomach wall and the intestinal wall
Absorption in stomach
Small molecules (glucose, alcohol, drugs) may be absorbed into the capillaries of the stomach wall
Adaptation of small intestine for food absorption (1)
It is the longest part of the digestive tract
The time for absorption is increased
This increases the surface area for water and food absorption
Adaptation of small intestine for food absorption (2)
It has numerous villus
This increases surface area for water and food absorption
Structural adaptation of the villus for food structure (1)
Numerous finger-like projection
Increased surface area for absorption of digested food
Structural adaptation of the villus for food absorption (2)
One-cell thick epithelium
Reduce distance of diffusion for the absorption of digested food
The rates of absorption will be faster
Structural adaptation of the villus for food absorption (3)
Dense capillary network
Absorb the water soluble food (glucose, amino acid) and mineral and water-soluble vitamins (B/C) by diffusion and/or active transport
Absorb water by osmosis
And transport away the absorbed food quickly
Structural adaptation of the villus for food absorption (4)
Presence of lacteal
Absorb fat and fat soluble vitamins (A/D) by diffusion
And transport them away by lymph quickly
Types of peristaltic muscle
Longitudinal muscle (outer) Circular muscle (inner)
Fate of Glucose
Villus > capillaries > hepatic portal vein > liver > hepatic vein > vena cava > heart > lungs > heart > aorta > all parts of the body (except the lungs)
Used in respiration to produce energy
Excess glucose is converted into glycogen and stored in liver (muscle)
Excess glucose in converted to fat in liver
Fate of amino acids
Villus > capillaries > hepatic portal vein > liver > hepatic vein > vena cava > heart > lungs > heart > aorta > all parts of the body except the lungs
Used to form proteins for growth and repair
Used to form enzyme, haemoglobin, antibodies and some hormones (insulin / glucagon)
Excess amino acids are deaminated into urea and carbohydrates in liver
Fate of fat
Villus > lacteal > lymph vessel > vein near the heart > vena cava > heart > lungs > heart > aorta > all parts of the body except the lungs
Used in respiration to produce energy when necessary
Used to form cell membrane (phospholipid) and some hormones (sex hormone)
Excess fat are stored in
Liver
Under the skin (subcutaneous fat)
Around the heart and kidneys ( act as shock absorber)
Role of liver for food assimilation (1)
Storage 
Glycogen
Iron
Vitamin A&D
Role of liver for food assimilation (2)
Regulation of blood glucose level
Maintain a constant blood glucose level With insulin Glucose > glycogen (stored in liver) With glucagon Glycogen > glucose (enter bloodstream)
Role of liver for food assimilation (3)
Deamination
Breakdown of excess amino acid
Amino group are converted to urea for excretion
The remaining carbon parts are converted to carbohydrate or fat
