Digestion. Digestive System (Blank) Digestive System (Labeled)
Digestive system. Learning objectives zTo outline the digestive system and metabolism. zTo identify...
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Transcript of Digestive system. Learning objectives zTo outline the digestive system and metabolism. zTo identify...
Learning objectives
To outline the digestive system and metabolism.
To identify the source of energy.To describe the process of digestion and
absorption of food.To describe energy conversion.
Learning objectives
To describe the storage of energy.To define metabolic rate.To describe energy balance of human body.To stat the metabolic rate of the liver.
Ingestion
The process of food intake
Chewing : Teeth ~ Incisor, canine, premolar & molar
Tongue
Mouth
Swallowing
Digestion
Mechanical( mastication & peristalsis) + Chemical process
solid food smaller pieces
large molecule smaller molecules
soluble forms
simple ones
Processes of digestion
Food
Mouth: teeth, saliva
Oesophagus: peristalsis
Stomach: gastric juice
Intestine: intestinal juice
Digested food
Digestion in Mouth cavity
Mechanical digestion ~ chewingChemical digestion
~ salivary amylase ( Starch maltose)
~ lysozyme ( Pathogenic microbes)
~ Salts ( provide alkaline condition)
~ Mucus ( lubrication)Swallowing
Digestion in stomach
Mechanical ( peristalsis)Chemical ( gastric juice)
~ Pepsin (protein polypeptides)
~ Renin ( coagulate casinogen)
~ HCl activator
kills or inhibit bacterial growth
stimulates gastric secretion
~ Mucus ( lubrication)
Digestion in small intestine I
Duodenum (25cm) + Jejunum(2.5m) + ileum (3.6m)
Bile
~ produced by liver
~ contain no enzyme
~ Sodium bicarbonate, bile salts, bile pigments
Digestion in small intestine II
Pancreatic juice
~ produced by pancreas
~ sodium bicarbonate
~ enzymes
amylase
lipase
trysinogen
nuclease
Digestion in small intestine III
Intestinal juice
~ produced in the intestinal wall
~ alkaline mucus
~ enzymes
maltase amylase
sucrase peptidase
lactase
Digestion in small intestine IV
Mechanical
~ the chyme is mixed with intestinal juices by intestinal movement.
Peristalsis- rhythmic contraction & relaxation of gut wall
Dividing movement
Absorption
No absorption in mouth & oesophagus
Absorption of alcohol & water in stomach
Absorption in small & large intestine
Adaptation for absorption in small intestine
Thin surface ~ easier to pass throughTransport vessels ~ current of bloodGreat surface area ~ numerous finger-like cilli
& microvilli
Absorption via blood vessels
Amino acids. Monosaccharides, water soluble vitamins, salts & water
Carbohydrates
~ galactose >glucose >fructose
~ by active transport
Amino acids ~ by active transport
vitamins & mineral
water ~ by osmosis
Absorption via lacteal
Glycerines, fatty acids &fat soluble vitaminsAbsorbed through epithelial cell into the lymphatic du
cts
superior vena cava
Heart
Different parts of body
Absorption in large intestine
Water & mineral salts
excess water, nutrients & undigested materials faeces
Others
bacteria ~ produces Vitamin B & K as by-products
Diarrhoea & Constipation
Assimilation of food
Carbohydrate
~ mainly glucose
~ as chief energy source
~ excess glucose converted into glycogen & subcutaneous fat
Amino acids
~ synthesis protein
~ excess not stored but deaminated
~ Amino acid urea+CO2
Fats
~ as energy source
~ as structural substances
~ secreted as oil
~ excess stored as adipose tissues
Function of liver
Regulation
~ glucose glycogen
~ amino acid urea+CO2
~ Fat & oil glycogenProduction
~ Heat
~Bile
~Cholesterol
~ Red blood cells
Storage
~ blood & vitaminsElimination of
hemoglobinDetoxificationHomeostasis
~ blood clottingDefense
~ phagocyte cells
Pancreas
It is a mixed gland consisting of exocrine and endocrine tissues;
It is an elongated gland lying in the loop formed by duodenum and the under surface of stomach.
Function of pancreas
Exocrine secretion:
~ pancreatic juice ( amylase, maltose, trypsin)Endocrine secretion
~ insulin: glucose in blood glycogen in liver;
blood glucose level
lacking of insulin: Diabetes mellitus
~ glucagons: glycogen in liver glucose in blood
blood glucose level
Balanced diet
It is a diet contains all the essential nutrients in the correct proportion so as to provide enough energy, mineral salts and vitamins for regulation and protection.