Digestion

Question 1

Alimentary canal

Answer 1

consists of organs through which food actually passes (stomach, small and large intestine…)

Question 2

Accessory organs

Answer 2

aid in digestion but do not actually transfer food (salivary gland, liver)

Question 3

Oesophagus (alimentintary canal)

Answer 3

• hollow tube connecting oral cavity to stomach
• food is mixed with saliva and moved down

Question 4

Stomach (alimentary)

Answer 4

• temporary storage tank where food is mixed by churning and protein digestion begins
• lined by gastric pits that release digestive juices

Question 5

small intestine (alimentary)

Answer 5

• long highly folded tube where usable food substances are absorbed
• three sections: the duodenum, jejunum and ileum

Question 6

Large intestine (alimentary)

Answer 6

• final section of alimentary canal, where water and dissolved minerals are absorbed
• consists also of the rectum

Question 7

Salivary Glands (Accessory organs)

Answer 7

• release saliva to moisten food and contains enzymes to initiate starch breakdown
• include many glands

Question 8

Pancreas (Accessory)

Answer 8

• Produce a broad spectrum of enzymes that are released into the small intestine via the duodenum
• also secretes certain hormones (insulin, glucagon) which regulate the blood sugar

Question 9

Liver (Accessory)

Answer 9

• Takes raw materials absorbed by the small intestine and uses them to make key chemicals
• role includes detoxification, storage metablolism, bile production and haemoglobin

Question 10

Gall Bladder

Answer 10

• stores the bile produced by the liver
• releases this into the small intestine via the common bile duct

Question 11

Mechanical digestion

Answer 11

Food is physically broken down into smaller fragments via the acts of chewing (mouth), churning (stomach) and segmentation (small intestine)

Question 12

Movement of food

Answer 12

Peristalsis (principal mechanism of movement in the oesophagus)

Question 13

chemical digestions

Answer 13

food is broken down by the action of chemical agents (such as enzymes, acids and bile)

Question 14

Stomach acids

Answer 14

the stomach contains gastric glands which release digestive acids to create a low PH environment

Question 15

Bile

Answer 15

the liver produces a fluid called bile which is stored and concentrated within the gall bladder prior to release into the intestine

Question 16

Enzymes

Answer 16

Enzymes are biological catalysts which speed up the rate of a chemical reaction

Question 17

Pancreatic juice

Answer 17

1) Proteases (digest proteins)
2) Amylase (digest sugars)
3) Nuclease (digest DNA)
4) Lipase (digest fats)

Question 18

Bile (from liver)

Answer 18

1) Lipase (digest fats)
2) Bile salts (emulsify salts)

Question 19

Carbohydrate digestion

Answer 19

begins in the mouth with the release of amylase
from the salivary glands

Question 20

Proteins

Answer 20

digestion begins in the stomach with the release of protease that functions optimally in an acidic PH

Question 21

Lipids

Answer 21

breakdown occurs in the intestines, beginning with emulsification of fat globules by bile released from the gall bladder

Question 22

Nucleic acids

Answer 22

Pancreas also releases nucleases which digest nucleic acids into smaller nucleosides

Question 23

Structure of the small intestine

Answer 23

1) Serosa - a protective outer covering
2) Muscle layer - outer layer of longitudinal muscle and inner layer of circular muscle
3) Submucusoa - composed of connective tissue separating the muscle layer from inner mucosa
4) Mucosa - highly folded in layer which absorbs materials through its surface epithelium

Question 24

Epithelial lining of the intestine

Answer 24

folded into finger like projections called villi

Question 25

Features of Villi

Answer 25

1) Microvilli (increase surface area)
2) Rich blood supply (rapid transport)
3) Single layer epithelium (minimises diffusion)
4) Lacteals (absorbs lipids from the intestine)
5) Intestinal glands (Exocrine pits)
6) Membrane proteins (facilitates transport)

Question 26

structure of Villus Epithelium

Answer 26

1) Tight junctions
2) Microvilli
3) Mitochondria
4) Pinocytotic vesicles