digestion

Question 1

what happens in the buccal cavity

Answer 1

• food is broken up into tiny pieces by the chewing action of the teeth
• it is moistened by saliva

Question 2

what does saliva consist of

Answer 2

• mineral salts
• water
• mucus
• lysozyme
• salivary amylase

Question 4

explain the stomach

Answer 4

• muscular sac that can hold up to 5 liters
• ridges help with mechanical digestion
• cardiac sphincter relaxes at the upper end which allows the food to enter
• pyloric sphincter relaxes at the bottom end which allows the contents into the duodenum
• food stays for 2-4 hours
• mucus secreted form the goblet cells, protecting the lining from the acid
• 3 thick layers of muscle
• stomach absorbs simple chemicals such as alcohol, aspirin, water, salts

Question 5

what’s the functions of the stomach

Answer 5

• hydrochloric acid released which kills any bacteria
• secretes pepsin out of the gastric juices

Question 6

explain the liver

Answer 6

• produces bile
• bile is stored in the gall bladder
• bile emulsifies fats and makes them have a larger surface area so the lipase can break them down quicker
• aids in neutralising the stomach acid as it enters the duodenum

Question 7

explain the pancreas

Answer 7

• exocrine gland secrete the pancreatic juices
• juice enters the duodenum via the pancreatic duct

Question 8

what is the duodenum

Answer 8

• makes up the first 20cm of the ileum
• receives secretions from the liver and pancreas
• produces its own digestive juice

Question 9

what is the structure of the ileum

Answer 9

• very long
• has villi and microvilli which increase the surface area for absorption and enzyme activity
• has many mitochondria as absorption requires ATP

Question 10

how is glucose absorbed

Answer 10

• co-transport with sodium ions
• goes into the capillaries by facilitated diffusion
• sodium ions are actively pumped out of the cell which needs ATP

Question 11

how are amino acids absorbed

Answer 11

• active transport
• facilitated diffusion into the capillaries

Question 12

how is fatty acids and glycerol absorbed

Answer 12

• diffuse into the SER
• recombine into triglycerides and are packaged into vesicles
• transported in the lymphatic system to the subclavian vein
• renter the blood stream at the thoracic duct

Question 13

how are water soluble vitamins absorbed

Answer 13

• pass through the epithelial membrane
• facilitated diffusion
• go through transport proteins and dissolve in the plasma

Question 14

how are fat soluble molecules absorbed

Answer 14

• diffuse through the phospholipid bilayer