Chapter 9 - The Digestive Sytem Flashcards Preview

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Flashcards in Chapter 9 - The Digestive Sytem Deck (21)
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1

Digestion

The breakdown of food into components that can be used within the body is called digestion.

2

Types of Digestion

Digestion occurs in two ways: Mechanical and Chemical

3

Mechanical Digestion

Mechanical Digestion is the physical breakdown of food into smaller pieces

4

Chemical Digestion

Chemical Digestion is the chemical breakdown of food by substances known as enzymes.

5

Food is Intaken

Food is intaken into the body through the mouth, where both mechanical and chemical digestion first occur.

6

The digestive process

1. Ingestion is the intake of food into the mouth, where it is chewed and swallowed

2. Digestion is the breakdown of food by mechanical and chemical means

3. Absorption takes place when food that has been digested enters the bloodstream.

4. Assimilation is the use and conversion of absorbed nutrients within the body.

5. Egestion is the removal from the body of undigested matierial remaining from the digestive process.

7

Teeth

Teeth are used in the first stages of digestion to break up food into smaller pieces by tearing, crushing and grinding it.

8

Types of Tooth

There are four types of tooth: incisor, canine, premolar and molar. Each has a different shape and function.

9

Number and Type of teeth

The number and type of teeth present in an animal's mouth is related to the diet of the animal.

10

Incisor

Chisel-like tooth used for cutting and biting

11

Canine

Pointed, sharp tooth used for tearing food

12

Premolar

Relatively flat tooth used for grinding

13

Molar

Flat tooth used for crushing food.

14

Herbivores

Herbivores only eat plant material. The use their premolars and molars for crushing and grinding material such as grass. Sheep, cattle and horses are all herbivores.

15

Carnivores

Carnivores only eat meat. They use their canine teeth for tearing flesh.

16

Omnivores

Omnivores, such as pigs, eat both plant material and meat. They do not have a specialised dentition but use all the types of teeth listed to aid the digestion of a variety of foods.

17

Dental Formulas

Dental Formulas are written to represent the dentition in the upper and lower jaw of the mouth of the animal. The formulas show the number of incisors, canines, premolars and molars present on one side of the mouth, as the other side of the mouth is identical.

18

Dental Formula of a pig

I:3/3 C:1/1 P:4/4 M:3/3

19

Dental formula of a herbivore (cow, sheep, goat)

I:0/3 C:0/1 P:3/3 M:3/3

20

Chemical Digestion in the mouth

-The mouth has three pairs of salivary glands
-The glands secrete an enzyme called amylase
-The amylase breaks down starch to maltose
-Saliva also acts as a lubricant that wets the food and makes it easier to chew and swallow.
-When food is swallowed, it is passed to the oesophagus. It is moved along the oesaphagus to the stomach by peristalsis.

21

Peristalsis

Food entering the oesophagus is moved along to the stomach by muscular contractions, which have a rhythmic, wave-like motion.