Slide 1 :
Slide 2 : ANIMAL NUTRITION
Slide 3 :
Session Objectives : Session Objectives What is Nutrition?
Modes of nutrition
Holozoic nutrition
Digestion in amoeba
Digestive system in animals
Digestive system of cockroach
Digestive system of humans
Alimentary canal
Histology of alimentary canal
Accessory glands
Summary of digestion
Nutrition : Nutrition “Nutrine”–To nourish Nutrition is the process involving intake and utilization offood by which growth, repair and maintenance of activities in the body are accomplished .
Slide 6 : Modes of nutrition
Slide 7 : Modes of nutrition
Holozoic nutrition : Holozoic nutrition Egestion
Digestion in amoeba : Digestion in amoeba a. Vacuole
b. Food vacuole
c. Nucleus
Slide 10 : Illustrative Problem
Digestive system in animals : Digestive system in animals
Digestive system in animals : Digestive system in animals
Digestive system in Cockroach : Digestive system in Cockroach Anus
The Digestive System of man : The Digestive System of man Alimentary canal andaccessory glands
Histology of alimentary canal : Histology of alimentary canal
Mouth : Mouth Teeth
– Incisors
– Canines
– Molars
– Premolars Tongue
– Vallate papillae
– Filiform papillae
– Fungiform papillae
Teeth : Teeth Crown is capped with enamel made up of calcium phosphate
Teeth are dissimilar or Heterodont
Neck and root are held in socket, hence, human teeth are regarded as Thecodont
Milk teeth are replaced by permanent teeth ---- Diphyodont
What is the dental formula of man ? : What is the dental formula of man ? Can you tell me dental formula of human child ?
Tongue : Tongue
Slide 20 : Mouth
Saliva : Saliva Saliva contains – Mucous to lubricate food– Bicarbonate ions to neutralise the acids in foods
– Thiocynate ions to act as antimicrobial agent
– Ptyalin or Salivary amylase for breaking down starch into disaccharide (maltose). 30% of starch is hydrolysed in mouth
Swallowing : Swallowing Coordinated activity of tongue, pharynx, soft palate and oesophagus
Tongue blocks mouth
Soft palate closes off the nose
Larynx rises so that epiglottis close off trachea
Food moves into pharynx and passes downwards to oesophagus
Peristalsis : Peristalsis Peristalsis refers to
Involuntary alternate contractions in the
circular and longitudinal
muscle layers which help in movement of bolus through the alimentary
canal.
Esophagus : Esophagus – Least complex part of alimentary canal
– Fibromuscular tube about 25 cm long
– Connects pharynx to stomach
– Salivary amylase remains active as food moves through esophagus
– Peristalsis moves food through esophagus. At the end of oesophagus, the sphincter opens allowing the passage of bolus into stomach
Stomach : Stomach C-shaped sac located at left side in upper portion of abdominal cavity. It has three regions
Glands in Stomach : Glands in Stomach
Specialized cells in stomach : Specialized cells in stomach
Functions of stomach : Functions of stomach Mixes food with gastric juice( Mucous, HCl, Pepsinogen, gastrin)
Acts as a churn for foodand liquefies it into chyme
Retains food giving enzymes time to act
Digests proteins through action of enzymes
Performs some absorption of salts and alcohol
Produces gastric intrinsic factor (GIF) – Helps in absorption of vitamin B12
Gastric Digestion : Gastric Digestion Cephalic (reflex) phase
(Gastrin prepares stomach for
digestion)
Gastric phase
(When food enters stomach
gastric juice is released)
Intestinal phase
(When food enters the intestine
chyme triggers intestinal juice)
Gastric Digestion : Protein containing food stimulate secretion of gastrin from pyloric gland
Gastrin stimulate gastric gland for the secretion of HCl, pepsinogen and mucus
Pepsinogen in acidic medicum forms pepsin which digest proteins
Small quantities of other gastric juice is also secreted – gastric lipase, gastric amylase, gelatinase Gastric Digestion
Gastric juice : Gastric juice
Illustrative problem : Illustrative problem What are stomach ulcers? An ulcer is an irritation in the gastric mucosa through which gastric juices digest the stomach wall. Solution : What is achlorhydria ? It leads to pernicious anemia. How ?
Structure of intestine : Structure of intestine Duodenum
Jejunum
Ileum
Intestinal villi : Intestinal villi Adaptations of villi for absorption
Large surface area for absorption
Thin walled for easy passage of nutrients
Rich supply of blood capillariesand lacteals
Illustrative problem : Illustrative problem How much time does it take to digest food? The complete passage of food from mouth
to anus is called the “intestinal transit time”
and is about 24hrs to 3 weeks depending
mainly on the fiber content of the diet. Solution :
The small intestine - Duodenum : The small intestine - Duodenum C-shaped structure (about 25cm long)
Most fixed part of the intestine
Begins at pyloric sphincter and ends into jejunum
Bile and pancreatic ducts open into it
Possesses Brunner’s glands (help neutralize stomach
acidity) Pancreas lies within its loop
Illustrative Problem : Illustrative Problem Jejunum of man is
(a) connected with ileum (b) connected with colon
(c) connected with pyloric stomach(d) the largest of all
The small intestine – Jejunum and ileum : The small intestine – Jejunum and ileum Jejunum(2.5m long), ileum(4m long)
They occupy central position in the abdominal cavity
They are extremely mobile and attached by a mesentery
They do not possess Brunner’s glands
Specialized cells in the intestine : Specialized cells in the intestine Crypt’s of Leiberkuhn (intestinal glands)-tubular glands possessing various specialized cells.
Enterocytes (absorptive cells)-Present on villi tips, have microvilli and perform many important functions- digestion and absorption of nutrients, processing of fats, transport of small nutrients.
Goblet cells-secrete mucous for lubrication and protection of alimentary canal.
Paneth’s cells -secrete lysozyme.
Peyer’s patches - extensions of lymphatic system.
M cell’s -overlie lymph nodules and Peyer’s patches initiating immune responses.
Functions of small intestine : Functions of small intestine Small intestine Duodenum – site for maximum chemical digestion by enzymes (receives bile and pancreatic juice)
Jejunum – Cellulose digestion (larger in ruminants, smaller in man) maximum absorption of nutrients
Ileum – Absorption of food material
Animation of digestion in small intestine : Animation of digestion in small intestine
Illustrative Problem : Illustrative Problem Caecum is a part of the
(a) large intestine (b) rectum (c) pyloric stomach(d) small intestine
The large intestine : The large intestine
The large intestine : The large intestine Extends from ileocaecal junction to anus (about 1.5m long)
The surface bears longitudinal bands of muscles called taenia coli
It bears sacculations (called haustra) which are a characteristic feature of large intestine
It is divided into the caecum, colon, rectum and anus.
The Large intestine : The Large intestine Caecum Blind ending sac between the ileum and colon
The opening of ileum into the caecum is guarded by the iliocolic valve
It is functional in herbivores, but has lost its importance in man
The vermiform appendix is attached to the caecum
It is an elongated (10 cm) projection made up of lymphoid tissue
The Large intestine : The Large intestine Colon - (upto 5ft long) distinguished into
Ascending colon- reabsorbs useful materials
Distal colon (transverse, descending and sigmoid) excretes wastes Absorbs large amounts of water
Reabsorbes bile salts and electrolytes
Powerful storage and waste disposal site in the body
Stores wastes till excretion
Through involuntary contractions pushes wastes to anus. Functions
Functions of the Large Intestine : Functions of the Large Intestine Water absorption
Reabsorption of salts and electrolytes
Fermentation – to breakdown the dietary fibres with the help of intestinal bacteria- Lactobacillus acidophilus, E.coli, Klebsiella Bacterial fermentation produces-
Short chain fatty acids
Protein metabolites
Gases (methane, ammonia and hydrogen sulphide)
Illustrative problem : Illustrative problem What do the intestinal bacteria do ? Solution: They mainly have a protective role.
By inhabiting the large intestine they keep out bacteria that may cause disease.
They take up all the available nutrients and space and crowd out dangerous competitors.
Some also synthesize vitamins K and B12.
They do not contribute much to digestion but form bulk of the faeces (constitute 20 – 50%) of the dry weight of feces).
Accessory glands : Accessory glands Liver
Gall bladder
Pancreas
Accessory glands– The Liver : Accessory glands– The Liver For digestion produces bile
Stores glucose as glycogen
Processes fats and amino acids
Stores some vitamins
Detoxifies poisons and drugs(clearing house)
Makes blood proteins
Illustrative Problem : Which of the following is the largest gland of adult man? Thymus
Liver
Thyroid
Pancreas Illustrative Problem
Accessory Gland - The Gall Bladder : Accessory Gland - The Gall Bladder Small pear shaped organ (3-4 inches long)
It is connected to liver by the cystic duct
It stores and concentrates bile
Opens into the duodenum through the bile duct Bile
Is produced from cholesterol in the liver
It emulsifies fats and neutralizes acids in partly digested food.
Bile salts – Glycocholic acid, taurocholic acid.
Pancreas : Pancreas Acinar cells produce –
Pancreatic juice
– Sodium bicarbonate
– Pancreatic amylase Carboxypeptidase
Endopeptidase
Lipase
Trypsin
chymotrypsin
Illustrative Problem : carbohydrates
fats
proteins
All of these If the pancreas is removed, the compound
which remains undigested is Illustrative Problem
Summary of digestion : Summary of digestion