ANIMAL NUTRITION

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ANIMAL NUTRITION:

ANIMAL NUTRITION

DEFINITION OF DIGESTION:

THE PROCESS OF BREAKING DOWN LARGE FOOD MOLECULES INTO SMALL ONES SO THAT THEY CAN BE ABSORBED BY THE BODY. Two major processes in breaking down food are: Physical breakdown - in the mouth Chemical breakdown – begins in mouth and continues along alimentary canal. DEFINITION OF DIGESTION

MECHANICAL AND PHYSICAL DIGESTION:

Involves breaking down of food into small lumps by: TEETH PERISTALTIC MOVEMENT OF GUT MECHANICAL AND PHYSICAL DIGESTION

Herbivores :

Herbivores They have teeth and jaws adapted for eating grass and vegetation. Incisors in the lower jaw are used to cut through grass by biting against a hard pad on the upper jaw. Canines are similar in shape and function to the incisors. Flat surface of premolars and molars is used to grind the vegetation. Jaws move from side to side to help grind vegetation better.

Carnivores :

Carnivores Their teeth and jaws are adapted to catching and killing prey, cutting flesh, and cracking bones. Carnassial teeth, premolars and molars help to shear meat and grind bones Sharp pointed incisors and canines tear meat Jaws have strong scissor action because they only move up and down.

Omnivores (humans):

Omnivores (humans) Their teeth and jaws are adapted for eating both vegetables ( though cellulose cannot be digested) and meat. Incisors – biting into soft food Canine – tearing into tough food Premolars & molars – crushing and grinding food

Slide 7:

As food enters the mouth digestion begins Food is ground by the teeth into smaller pieces Taste, smell and appearance of food stimulate saliva secretion Saliva moistens food and the amylase present in it starts the chemical breakdown of starch Chewed food is called the bolus which is pushed to the back of the mouth by the tongue; this triggers swallowing

Structure of tooth:

Structure of tooth

Slide 10:

Parts of tooth include: Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral . Dentin : A layer underlying the enamel. Dentin is made of living cells, which secrete a hard mineral substance . Pulp : The softer, living inner structure of teeth. Blood vessels and nerves run through the pulp of the teeth. Cementum : A layer of connective tissue that binds the roots of the teeth firmly to the gums and jawbone. Periodontal ligament: Tissue that helps hold the teeth tightly against the jaw.

Tooth decay:

Tooth decay As food gets stuck in crevices between teeth and the bacteria grow on them, they make acids and also from a plaque. Acids corrode the tooth enamel, resulting in tooth decay (cavities). Cavities can affect every layer of tooth. If not treated, can cause pain, infection and tooth loss.

Dental care:

Dental care Brushing twice daily Flossing teeth regularly Avoiding excessive consumption of too sweet and too acidic foods Using mouthwash after eating something too acidic or too sweet Using alkaline toothpaste like fluoride toothpaste Visiting a dentist every 6 months.

Use of fluorides:

Use of fluorides Strengthens tooth enamel Added to toothpaste and drinking water (concentration of 1 parts per million) Excessive intake of fluorides leads to: Dental fluorosis Mild – tiny white streaks or specks on teeth Severe – appearance of black or brown stains on tooth enamel as well as cracking & pitting of teeth Kidney stones Bone fragility & cancer Very high doses are toxic so some people are opposed to its addition to drinking water

Dental fluorosis:

Dental fluorosis

Peristalsis :

Oesophagus has 2 layers of muscles in its walls. Outer layer – longitudinal muscle Inner layer – circular muscle Food is pushed down the digestive tract by peristalsis. peristalsis- - wave of muscular contraction which pushed the food down the alimentary canal Peristalsis