Digestive System

Question 1

5 processes of the digestive system

Answer 1

Ingestion
Propulsion
Digestion
Absorption
Elimination

Question 2

Components of digestive system

Answer 2

Mouth
Oesophagus
Stomach
Small intestine
Large intestine
Rectum

Question 3

Accessory organs of digestive system

Answer 3

Salivary glands
Liver
Pancreas
Gall bladder

Question 4

Alimentary tract

Answer 4

Tube that extends from mouth to rectum.

As food moves through it is mixed with various digestive juices.

Also known as alimentary canal, gastrointestinal tract or digestive tract.

Question 5

Alimentary tract function

Answer 5

Converts food into small nutritional molecules for absorption and distribution by circulation.

Also part of immune system
- Low pH (stomach)
- Enzymes (saliva, bile)
- Mucous (IgA), lysozyme

Question 6

Four layers of digestive tract

Answer 6

Adventitia/serosa
Muscularis
Submucous
Mucosa

Question 7

Adventitia/serosa

Answer 7

Areolar connective tissue outer covering of digestive tract.

Question 8

Muscularis

Answer 8

Smooth muscle that contracts to move food.

Lies under adventitia/serosa.

2 layers; longitudinal outer layer and inner circular layer.

Question 9

Submucous

Answer 9

Loose connective tissue containing blood vessels, lymphatic vessels, nerves and glands.

Lies under muscularis.

Question 10

Mucosa

Answer 10

Inner epithelial layer covered in mucous.

Lies under submucous.

Question 11

Ingestion

Answer 11

Process of taking in food or drink through the mouth.

Question 12

Digestion

Answer 12

Process of breaking down food into smaller molecules.

Mechanical or chemical.

Question 13

Propulsion

Answer 13

Movement of food through digestive tract through mixing and propelling.

Question 14

Absorption

Answer 14

Process by which digestive food molecules pass through wall of small intestine and into blood stream to be used by body cells.

Majority occurs in the Jejunum.

Question 15

Elimination

Answer 15

Process of removing food and waste products.

Question 16

Mouth - mechanical

Answer 16

Teeth - Tear, rip and chew food to produce a bolus.

Uvula - Stops food and liquid entering nasal cavity.

Tongue - Voluntary muscular structure important for mastication and deglutition.

Question 17

Mouth - chemical

Answer 17

Salivary amylase breaks down polysaccharides (starch) into a bolus of maltose (less complex sugar).

Question 18

Bolus

Answer 18

Round or oval shaped mass of food formed in the mouth after chewing in preparation for swallowing.

Question 19

Oesophagus

Answer 19

Muscular tube from mouth to stomach.

About 25cm long.

Lined with mucous membrane.

Secretes fluid to lubricate downward movement of movement.

Smooth muscle walls contracts to squeeze bolus towards stomach. I

Question 20

Peristalsis

Answer 20

Wave-like contraction of smooth muscles that propels contents through digestive tract.

Involuntary and rhythmic.

Question 21

Oesophageal sphincter

Answer 21

Separates stomach from oesophagus.

Question 22

Segmentation

Answer 22

Muscular movement in the small intestine without movement backwards or forwards.

Mixing rather than propulsive.

Question 23

Vomiting

Answer 23

Propulsion comes from contraction of abdominal muscles.

Question 24

Swallowing

Answer 24

1st phase voluntary:
- Tongue forces food into pharynx.

2nd phase involuntary:
- Tongue blocks mouth
- Soft palate closes nose
- Larynx rises so the epiglottis closes trachea.

Food moves into pharynx and onwards by peristalsis.

Question 25

Stomach

Answer 25

Hollow J-shaped muscular organ. Highly acidic environment. Temporary storage area for food (3-4 hours) which is churned by muscular layers to form chyme. Numerous folds: rugae. Mechanical and chemical breakdown.

Question 26

Pyloric sphincter

Answer 26

Separates stomach from small intestine.

Question 27

Stomach - chemical

Answer 27

Numerous gastric glands secrete gastric juices into stomach. (Enzymes, hormones and mucous)

Question 28

Parietal cells

Answer 28

Produce hydrochloric acid that denatures proteins.

Question 29

Chief cells

Answer 29

Produce pepsin that begins protein digestion.

Question 30

Mucous cells

Answer 30

Produce mucous that protects from hydrochloric acid.

Question 31

Stomach - mechanical

Answer 31

Muscles relax and contract to aid mechanical breakdown.

Question 32

What’s the food called within the stomach?

Answer 32

Chyme

Question 33

Stomach pH

Answer 33

Highly acidic, between 1.5-3.5

Question 34

Small intestine

Answer 34

Site of majority of digestion. Absorb water and nutrients from digested food. Longest part of system. Comprises of: - Duodenum - Jejunum - Ileum

Question 35

Duodenum

Answer 35

First part of small intestine. Chemical degradation of small amounts of food begins.

Question 36

2 ducts that enter small intestine (duodenum)

Answer 36

Bile duct - draining gall bladder from liver. Pancreatic duct - draining pancreas. Both deliver enzymes to aid in digestion of fats.

Question 37

Jejunum and Ileum

Answer 37

Continue absorption process of carbohydrates, proteins and fats. Large surface area for nutrient absorption.

Question 38

Villi

Answer 38

Increases surface area of Jejunum and Ileum. Micro-projections called microvilli. Lacteal - absorb fat into lymphatic system. Capillaries - absorb everything else.

Question 39

Liver

Answer 39

Largest solid organ and largest glands in body. Multifunctional. Secretes bile which accumulates in gall bladder between meals. Small intestine capillaries drain fat and other nutrient rich lymph into liver via hepatic duct.

Question 40

Gall bladder

Answer 40

Small pear-shaped organ underside of liver. Stores and concentrates bile during fasting stage.

Question 41

What happens in the gall bladder when fat enters duodenum?

Answer 41

Mucosal cells release peptide hormone (cholecystokinin) to stimulate gall bladder to contract and discharge bile.

Question 42

Bile

Answer 42

Watery greenish fluid produced by liver and secreted via hepatic and cystic duct to gall bladder for storage. Released via common bile duct to duodenum. Bile salts and phospholipids emulsify fats, the rest are for excretion.

Question 43

What happens to majority of bile?

Answer 43

95% reabsorbed into the ileum, returned to liver and reused.

Question 44

Pancreas - exocrine

Answer 44

Secretes digestive enzymes in response to cholecystokinin to help with digestion of fats, starches and proteins. Secretes aqueous bicarbonate solution (pancreatic fluid) to help neutralise stomach acid entering small intestine.

Question 45

Large intestine (colon)

Answer 45

Food not broken down anymore. Absorption of remaining water and electrolytes from indigestible food. Absorbs vitamins produced by gut bacteria (Vit K and certain Vit B). Stores and eliminates waste products.

Question 46

Chyme mixed with mucous and bacteria

Answer 46

Faeces

Question 47

Rectum

Answer 47

Last 13cm of large intestine. Stores solid waste until it leaves body.

Question 48

Reason for gas production in large intestine

Answer 48

Bacterial fermentation of undigested material.

Question 49

Digestive juices

Answer 49

Stomach and small intestine each produce a digestive juice. Contain digestive enzymes which speed up reactions involved in breakdown of food.

Question 50

Digestive enzymes

Answer 50

Amylase Protease Lipase

Question 51

Amylase

Answer 51

Starch — maltose — glucose (Salivary glands, pancreas, small intestine)

Question 52

Protease

Answer 52

Protein — amino acids (Stomach, pancreas, small intestine)

Question 53

Lipase

Answer 53

Lipids — fatty acids and glycerol (Pancreas, small intestine)