Digestive System

Question 1

6 basic functions of the digestive system

Answer 1

1. Ingestion (food+water)
2. Mechanical digestion of food
3. Chemical digestion of food
4. Movement of food along the alimentary canal
5. Absorption of digested food+water into blood+ lymph
6. Eliminate material that is not absorbed

Question 2

Types of Teeth (and function)

Answer 2

Teeth alignment: 2123

Incisors: 2, chisel shaped, used for biting and cutting
Canines: 1, conical shaped, used for tearing
Pre-molars: 2
Molars: 3
- both molars have broad crowns and rounded cusps for crushing and grinding

Question 3

Pepsin

Answer 3

• Digestive enzyme
• Begins the digestion of proteins into polypeptides
• Acidic conditions in stomach = necessary for pepsin to work
• Kills any bacteria that have entered the stomach

Question 4

Stomach

Answer 4

• Performs mechanical digestion that begins the chemical digestion of proteins
  3 layers of muscle:
• oblique
• circular
• longitudinal
  Layers work together to churn and mix food, turning to chyme.

Question 5

Gastric juice

Answer 5

Contains:
- HCl
- Mucus 
- Pepsin (digestive enzyme)
Gastric glands secrete gastric juice. Located in gastric pit

Question 6

Saliva

Answer 6

• Made up of mucus and amylase (digestive enzyme)
• Made by 3 pairs of salivary glands
• Lubricates, dissolves and creates bolus.
• Amylase chemical digestion of starch, also known as carbohydrates

Question 7

Oesophagus

Answer 7

• After food passes through the pharynx it enters the oesophagus
• Has a 2 layers of muscle called longitudinal and circular muscle
• Layers push bolus through the stomach by muscular contractions called peristalsis
• The inner lining secretes mucus to lubricate walls

Question 8

Alimentary Canal

Answer 8

• Continuous tube the runs from mouth to anus

- As food passes through, it is slowly digested and absorbed

Question 9

Mechanical Digestion

Answer 9

Physical break up of food by actions of structures

-Catabolic chemical reaction

Question 10

Chemical digestion

Answer 10

Break-up of larger food molecules using enzymes

-catabolic chemical reaction

Question 11

The Small Intestine

Answer 11

• First section called duodenum
• Inner lining (folded area): mucosa
• Finger like projections: villi, help increase surface area
  Structure:
• Villi
• Mucosa
• Submucosa
• Serosa

Question 12

Villi

Answer 12

• Villi have a network of blood vessels inside the lymph vessel called a lacteal.
• Cells lining the villi have microvilli

Question 13

Absorption in small intestine

Answer 13

• Products of digestion either enter blood capillaries or lacteals inside the villi through simple diffusion or active transport

Question 14

Simple diffusion

Answer 14

Absorption into intestinal cells using concentration gradient
- High to low

Question 15

Active transport

Answer 15

The use of energy to take nutrients into the blood against the concentration gradient
- Low to high

Question 16

Accessory Organs (liver, gall bladder and pancreas)

Answer 16

Food doesn’t pass through these structures, but still have an important role in the digestion of food.

• Liver makes bile, stored in gall bladder
• Bile enters duodenum through small duct, acts as detergent, emulsifies fat
• Pancreatic juice enters duodenum through the same duct

Question 17

Method of absorption, products of digestion and the structure they enter

Answer 17

- Simple diffusion: 
Fatty acids and glycerol (lacteal), 
Fat (lacteal)
Water soluble vitamins (blood)
- Active transport: 
Amino acids, monosaccharides (blood)

Question 18

Osmosis

Answer 18

• Predominately associated with water movement
• Same principal as diffusion (high-low)
• Occurs across a differentially permeable membrane, some things pass through, others don’t

Question 19

The large intestine

Answer 19

• No villi, no enzymes secreted
• Large amount of mucus secreted
• 18-24 hours to pass through
• Bacteria break down remaining organic matter
• Absorbs water, vitamins and minerals
• Peristalsis moves food through
• Semi solid material left after water absorption and faeces

Question 20

Faeces

Answer 20

Contains:
- Bile pigments 
- Undigested food (cellulose) 
- Bacteria 
- Intestinal wall cells 
Elimination or dedication are the correct terms for the removal of faeces